--- /dev/null
+/*
+ *
+ * Copyright 2018 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+/// Implementation of the gRPC LB policy.
+///
+/// This policy takes as input a list of resolved addresses, which must
+/// include at least one balancer address.
+///
+/// An internal channel (\a lb_channel_) is created for the addresses
+/// from that are balancers. This channel behaves just like a regular
+/// channel that uses pick_first to select from the list of balancer
+/// addresses.
+///
+/// When we get our initial update, we instantiate the internal *streaming*
+/// call to the LB server (whichever address pick_first chose). The call
+/// will be complete when either the balancer sends status or when we cancel
+/// the call (e.g., because we are shutting down). In needed, we retry the
+/// call. If we received at least one valid message from the server, a new
+/// call attempt will be made immediately; otherwise, we apply back-off
+/// delays between attempts.
+///
+/// We maintain an internal child policy (round_robin) instance for distributing
+/// requests across backends. Whenever we receive a new serverlist from
+/// the balancer, we update the child policy with the new list of
+/// addresses.
+///
+/// Once a child policy instance is in place (and getting updated as
+/// described), calls for a pick, or a cancellation will be serviced right away
+/// by forwarding them to the child policy instance. Any time there's no child
+/// policy available (i.e., right after the creation of the xDS policy), pick
+/// requests are added to a list of pending picks to be flushed and serviced
+/// when the child policy instance becomes available.
+///
+/// \see https://github.com/grpc/grpc/blob/master/doc/load-balancing.md for the
+/// high level design and details.
+
+// With the addition of a libuv endpoint, sockaddr.h now includes uv.h when
+// using that endpoint. Because of various transitive includes in uv.h,
+// including windows.h on Windows, uv.h must be included before other system
+// headers. Therefore, sockaddr.h must always be included first.
+#include <grpc/support/port_platform.h>
+
+#include "src/core/lib/iomgr/sockaddr.h"
+#include "src/core/lib/iomgr/socket_utils.h"
+
+#include <inttypes.h>
+#include <limits.h>
+#include <string.h>
+
+#include <grpc/byte_buffer_reader.h>
+#include <grpc/grpc.h>
+#include <grpc/support/alloc.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/time.h>
+
+#include "include/grpc/support/alloc.h"
+#include "src/core/ext/filters/client_channel/client_channel.h"
+#include "src/core/ext/filters/client_channel/lb_policy.h"
+#include "src/core/ext/filters/client_channel/lb_policy/xds/xds.h"
+#include "src/core/ext/filters/client_channel/lb_policy/xds/xds_channel.h"
+#include "src/core/ext/filters/client_channel/lb_policy/xds/xds_client_stats.h"
+#include "src/core/ext/filters/client_channel/lb_policy/xds/xds_load_balancer_api.h"
+#include "src/core/ext/filters/client_channel/lb_policy_factory.h"
+#include "src/core/ext/filters/client_channel/lb_policy_registry.h"
+#include "src/core/ext/filters/client_channel/parse_address.h"
+#include "src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h"
+#include "src/core/ext/filters/client_channel/server_address.h"
+#include "src/core/ext/filters/client_channel/service_config.h"
+#include "src/core/lib/backoff/backoff.h"
+#include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/channel/channel_stack.h"
+#include "src/core/lib/gpr/string.h"
+#include "src/core/lib/gprpp/manual_constructor.h"
+#include "src/core/lib/gprpp/map.h"
+#include "src/core/lib/gprpp/memory.h"
+#include "src/core/lib/gprpp/orphanable.h"
+#include "src/core/lib/gprpp/ref_counted_ptr.h"
+#include "src/core/lib/gprpp/sync.h"
+#include "src/core/lib/iomgr/combiner.h"
+#include "src/core/lib/iomgr/sockaddr.h"
+#include "src/core/lib/iomgr/sockaddr_utils.h"
+#include "src/core/lib/iomgr/timer.h"
+#include "src/core/lib/slice/slice_hash_table.h"
+#include "src/core/lib/slice/slice_internal.h"
+#include "src/core/lib/slice/slice_string_helpers.h"
+#include "src/core/lib/surface/call.h"
+#include "src/core/lib/surface/channel.h"
+#include "src/core/lib/surface/channel_init.h"
+#include "src/core/lib/transport/static_metadata.h"
+
+#define GRPC_XDS_INITIAL_CONNECT_BACKOFF_SECONDS 1
+#define GRPC_XDS_RECONNECT_BACKOFF_MULTIPLIER 1.6
+#define GRPC_XDS_RECONNECT_MAX_BACKOFF_SECONDS 120
+#define GRPC_XDS_RECONNECT_JITTER 0.2
+#define GRPC_XDS_DEFAULT_FALLBACK_TIMEOUT_MS 10000
+#define GRPC_XDS_MIN_CLIENT_LOAD_REPORTING_INTERVAL_MS 1000
+#define GRPC_XDS_DEFAULT_LOCALITY_RETENTION_INTERVAL_MS (15 * 60 * 1000)
+
+namespace grpc_core {
+
+TraceFlag grpc_lb_xds_trace(false, "xds");
+
+namespace {
+
+constexpr char kXds[] = "xds_experimental";
+
+class ParsedXdsConfig : public LoadBalancingPolicy::Config {
+ public:
+ ParsedXdsConfig(const char* balancer_name,
+ RefCountedPtr<LoadBalancingPolicy::Config> child_policy,
+ RefCountedPtr<LoadBalancingPolicy::Config> fallback_policy)
+ : balancer_name_(balancer_name),
+ child_policy_(std::move(child_policy)),
+ fallback_policy_(std::move(fallback_policy)) {}
+
+ const char* name() const override { return kXds; }
+
+ const char* balancer_name() const { return balancer_name_; };
+
+ RefCountedPtr<LoadBalancingPolicy::Config> child_policy() const {
+ return child_policy_;
+ }
+
+ RefCountedPtr<LoadBalancingPolicy::Config> fallback_policy() const {
+ return fallback_policy_;
+ }
+
+ private:
+ const char* balancer_name_ = nullptr;
+ RefCountedPtr<LoadBalancingPolicy::Config> child_policy_;
+ RefCountedPtr<LoadBalancingPolicy::Config> fallback_policy_;
+};
+
+class XdsLb : public LoadBalancingPolicy {
+ public:
+ explicit XdsLb(Args args);
+
+ const char* name() const override { return kXds; }
+
+ void UpdateLocked(UpdateArgs args) override;
+ void ResetBackoffLocked() override;
+
+ private:
+ // Contains a channel to the LB server and all the data related to the
+ // channel. Holds a ref to the xds policy.
+ class LbChannelState : public InternallyRefCounted<LbChannelState> {
+ public:
+ // An LB call wrapper that can restart a call upon failure. Holds a ref to
+ // the LB channel. The template parameter is the kind of wrapped LB call.
+ template <typename T>
+ class RetryableLbCall : public InternallyRefCounted<RetryableLbCall<T>> {
+ public:
+ explicit RetryableLbCall(RefCountedPtr<LbChannelState> lb_chand);
+
+ void Orphan() override;
+
+ void OnCallFinishedLocked();
+
+ T* lb_calld() const { return lb_calld_.get(); }
+ LbChannelState* lb_chand() const { return lb_chand_.get(); }
+
+ private:
+ void StartNewCallLocked();
+ void StartRetryTimerLocked();
+ static void OnRetryTimerLocked(void* arg, grpc_error* error);
+
+ // The wrapped LB call that talks to the LB server. It's instantiated
+ // every time we start a new call. It's null during call retry backoff.
+ OrphanablePtr<T> lb_calld_;
+ // The owing LB channel.
+ RefCountedPtr<LbChannelState> lb_chand_;
+
+ // Retry state.
+ BackOff backoff_;
+ grpc_timer retry_timer_;
+ grpc_closure on_retry_timer_;
+ bool retry_timer_callback_pending_ = false;
+
+ bool shutting_down_ = false;
+ };
+
+ // Contains an EDS call to the LB server.
+ class EdsCallState : public InternallyRefCounted<EdsCallState> {
+ public:
+ // The ctor and dtor should not be used directly.
+ explicit EdsCallState(
+ RefCountedPtr<RetryableLbCall<EdsCallState>> parent);
+ ~EdsCallState() override;
+
+ void Orphan() override;
+
+ RetryableLbCall<EdsCallState>* parent() const { return parent_.get(); }
+ LbChannelState* lb_chand() const { return parent_->lb_chand(); }
+ XdsLb* xdslb_policy() const { return lb_chand()->xdslb_policy(); }
+ bool seen_response() const { return seen_response_; }
+
+ private:
+ static void OnResponseReceivedLocked(void* arg, grpc_error* error);
+ static void OnStatusReceivedLocked(void* arg, grpc_error* error);
+
+ bool IsCurrentCallOnChannel() const;
+
+ // The owning RetryableLbCall<>.
+ RefCountedPtr<RetryableLbCall<EdsCallState>> parent_;
+ bool seen_response_ = false;
+
+ // Always non-NULL.
+ grpc_call* lb_call_;
+
+ // recv_initial_metadata
+ grpc_metadata_array initial_metadata_recv_;
+
+ // send_message
+ grpc_byte_buffer* send_message_payload_ = nullptr;
+
+ // recv_message
+ grpc_byte_buffer* recv_message_payload_ = nullptr;
+ grpc_closure on_response_received_;
+
+ // recv_trailing_metadata
+ grpc_metadata_array trailing_metadata_recv_;
+ grpc_status_code status_code_;
+ grpc_slice status_details_;
+ grpc_closure on_status_received_;
+ };
+
+ // Contains an LRS call to the LB server.
+ class LrsCallState : public InternallyRefCounted<LrsCallState> {
+ public:
+ // The ctor and dtor should not be used directly.
+ explicit LrsCallState(
+ RefCountedPtr<RetryableLbCall<LrsCallState>> parent);
+ ~LrsCallState() override;
+
+ void Orphan() override;
+
+ void MaybeStartReportingLocked();
+
+ RetryableLbCall<LrsCallState>* parent() { return parent_.get(); }
+ LbChannelState* lb_chand() const { return parent_->lb_chand(); }
+ XdsLb* xdslb_policy() const { return lb_chand()->xdslb_policy(); }
+ bool seen_response() const { return seen_response_; }
+
+ private:
+ // Reports client-side load stats according to a fixed interval.
+ class Reporter : public InternallyRefCounted<Reporter> {
+ public:
+ Reporter(RefCountedPtr<LrsCallState> parent,
+ grpc_millis report_interval)
+ : parent_(std::move(parent)), report_interval_(report_interval) {
+ GRPC_CLOSURE_INIT(
+ &on_next_report_timer_, OnNextReportTimerLocked, this,
+ grpc_combiner_scheduler(xdslb_policy()->combiner()));
+ GRPC_CLOSURE_INIT(
+ &on_report_done_, OnReportDoneLocked, this,
+ grpc_combiner_scheduler(xdslb_policy()->combiner()));
+ ScheduleNextReportLocked();
+ }
+
+ void Orphan() override;
+
+ private:
+ void ScheduleNextReportLocked();
+ static void OnNextReportTimerLocked(void* arg, grpc_error* error);
+ void SendReportLocked();
+ static void OnReportDoneLocked(void* arg, grpc_error* error);
+
+ bool IsCurrentReporterOnCall() const {
+ return this == parent_->reporter_.get();
+ }
+ XdsLb* xdslb_policy() const { return parent_->xdslb_policy(); }
+
+ // The owning LRS call.
+ RefCountedPtr<LrsCallState> parent_;
+
+ // The load reporting state.
+ const grpc_millis report_interval_;
+ bool last_report_counters_were_zero_ = false;
+ bool next_report_timer_callback_pending_ = false;
+ grpc_timer next_report_timer_;
+ grpc_closure on_next_report_timer_;
+ grpc_closure on_report_done_;
+ };
+
+ static void OnInitialRequestSentLocked(void* arg, grpc_error* error);
+ static void OnResponseReceivedLocked(void* arg, grpc_error* error);
+ static void OnStatusReceivedLocked(void* arg, grpc_error* error);
+
+ bool IsCurrentCallOnChannel() const;
+
+ // The owning RetryableLbCall<>.
+ RefCountedPtr<RetryableLbCall<LrsCallState>> parent_;
+ bool seen_response_ = false;
+
+ // Always non-NULL.
+ grpc_call* lb_call_;
+
+ // recv_initial_metadata
+ grpc_metadata_array initial_metadata_recv_;
+
+ // send_message
+ grpc_byte_buffer* send_message_payload_ = nullptr;
+ grpc_closure on_initial_request_sent_;
+
+ // recv_message
+ grpc_byte_buffer* recv_message_payload_ = nullptr;
+ grpc_closure on_response_received_;
+
+ // recv_trailing_metadata
+ grpc_metadata_array trailing_metadata_recv_;
+ grpc_status_code status_code_;
+ grpc_slice status_details_;
+ grpc_closure on_status_received_;
+
+ // Load reporting state.
+ grpc_millis load_reporting_interval_ = 0;
+ OrphanablePtr<Reporter> reporter_;
+ };
+
+ LbChannelState(RefCountedPtr<XdsLb> xdslb_policy, const char* balancer_name,
+ const grpc_channel_args& args);
+ ~LbChannelState();
+
+ void Orphan() override;
+
+ grpc_channel* channel() const { return channel_; }
+ XdsLb* xdslb_policy() const { return xdslb_policy_.get(); }
+ EdsCallState* eds_calld() const { return eds_calld_->lb_calld(); }
+ LrsCallState* lrs_calld() const { return lrs_calld_->lb_calld(); }
+
+ bool IsCurrentChannel() const {
+ return this == xdslb_policy_->lb_chand_.get();
+ }
+ bool IsPendingChannel() const {
+ return this == xdslb_policy_->pending_lb_chand_.get();
+ }
+ bool HasActiveEdsCall() const { return eds_calld_->lb_calld() != nullptr; }
+
+ void StartConnectivityWatchLocked();
+ void CancelConnectivityWatchLocked();
+ static void OnConnectivityChangedLocked(void* arg, grpc_error* error);
+
+ private:
+ // The owning LB policy.
+ RefCountedPtr<XdsLb> xdslb_policy_;
+
+ // The channel and its status.
+ grpc_channel* channel_;
+ bool shutting_down_ = false;
+ grpc_connectivity_state connectivity_ = GRPC_CHANNEL_IDLE;
+ grpc_closure on_connectivity_changed_;
+
+ // The retryable XDS calls to the LB server.
+ OrphanablePtr<RetryableLbCall<EdsCallState>> eds_calld_;
+ OrphanablePtr<RetryableLbCall<LrsCallState>> lrs_calld_;
+ };
+
+ // We need this wrapper for the following reasons:
+ // 1. To process per-locality load reporting.
+ // 2. Since pickers are UniquePtrs we use this RefCounted wrapper to control
+ // references to it by the xds picker and the locality entry.
+ class PickerWrapper : public RefCounted<PickerWrapper> {
+ public:
+ PickerWrapper(UniquePtr<SubchannelPicker> picker,
+ RefCountedPtr<XdsClientStats::LocalityStats> locality_stats)
+ : picker_(std::move(picker)),
+ locality_stats_(std::move(locality_stats)) {
+ locality_stats_->RefByPicker();
+ }
+ ~PickerWrapper() { locality_stats_->UnrefByPicker(); }
+
+ PickResult Pick(PickArgs args);
+
+ private:
+ static void RecordCallCompletion(
+ void* arg, grpc_error* error,
+ LoadBalancingPolicy::MetadataInterface* recv_trailing_metadata,
+ LoadBalancingPolicy::CallState* call_state);
+
+ UniquePtr<SubchannelPicker> picker_;
+ RefCountedPtr<XdsClientStats::LocalityStats> locality_stats_;
+ };
+
+ // The picker will use a stateless weighting algorithm to pick the locality to
+ // use for each request.
+ class Picker : public SubchannelPicker {
+ public:
+ // Maintains a weighted list of pickers from each locality that is in ready
+ // state. The first element in the pair represents the end of a range
+ // proportional to the locality's weight. The start of the range is the
+ // previous value in the vector and is 0 for the first element.
+ using PickerList =
+ InlinedVector<Pair<uint32_t, RefCountedPtr<PickerWrapper>>, 1>;
+ Picker(RefCountedPtr<XdsLb> xds_policy, PickerList pickers)
+ : xds_policy_(std::move(xds_policy)),
+ pickers_(std::move(pickers)),
+ drop_config_(xds_policy_->drop_config_) {}
+
+ PickResult Pick(PickArgs args) override;
+
+ private:
+ // Calls the picker of the locality that the key falls within.
+ PickResult PickFromLocality(const uint32_t key, PickArgs args);
+
+ RefCountedPtr<XdsLb> xds_policy_;
+ PickerList pickers_;
+ RefCountedPtr<XdsDropConfig> drop_config_;
+ };
+
+ class FallbackHelper : public ChannelControlHelper {
+ public:
+ explicit FallbackHelper(RefCountedPtr<XdsLb> parent)
+ : parent_(std::move(parent)) {}
+
+ ~FallbackHelper() { parent_.reset(DEBUG_LOCATION, "FallbackHelper"); }
+
+ RefCountedPtr<SubchannelInterface> CreateSubchannel(
+ const grpc_channel_args& args) override;
+ void UpdateState(grpc_connectivity_state state,
+ UniquePtr<SubchannelPicker> picker) override;
+ void RequestReresolution() override;
+ void AddTraceEvent(TraceSeverity severity, StringView message) override;
+
+ void set_child(LoadBalancingPolicy* child) { child_ = child; }
+
+ private:
+ bool CalledByPendingFallback() const;
+ bool CalledByCurrentFallback() const;
+
+ RefCountedPtr<XdsLb> parent_;
+ LoadBalancingPolicy* child_ = nullptr;
+ };
+
+ class LocalityMap {
+ public:
+ class LocalityEntry : public InternallyRefCounted<LocalityEntry> {
+ public:
+ LocalityEntry(RefCountedPtr<XdsLb> parent,
+ RefCountedPtr<XdsLocalityName> name);
+ ~LocalityEntry();
+
+ void UpdateLocked(uint32_t locality_weight, ServerAddressList serverlist,
+ LoadBalancingPolicy::Config* child_policy_config,
+ const grpc_channel_args* args);
+ void ShutdownLocked();
+ void ResetBackoffLocked();
+ void DeactivateLocked();
+ void Orphan() override;
+
+ grpc_connectivity_state connectivity_state() const {
+ return connectivity_state_;
+ }
+ uint32_t locality_weight() const { return locality_weight_; }
+ RefCountedPtr<PickerWrapper> picker_wrapper() const {
+ return picker_wrapper_;
+ }
+
+ private:
+ class Helper : public ChannelControlHelper {
+ public:
+ explicit Helper(RefCountedPtr<LocalityEntry> entry)
+ : entry_(std::move(entry)) {}
+
+ ~Helper() { entry_.reset(DEBUG_LOCATION, "Helper"); }
+
+ RefCountedPtr<SubchannelInterface> CreateSubchannel(
+ const grpc_channel_args& args) override;
+ void UpdateState(grpc_connectivity_state state,
+ UniquePtr<SubchannelPicker> picker) override;
+ void RequestReresolution() override;
+ void AddTraceEvent(TraceSeverity severity, StringView message) override;
+ void set_child(LoadBalancingPolicy* child) { child_ = child; }
+
+ private:
+ bool CalledByPendingChild() const;
+ bool CalledByCurrentChild() const;
+
+ RefCountedPtr<LocalityEntry> entry_;
+ LoadBalancingPolicy* child_ = nullptr;
+ };
+
+ // Methods for dealing with the child policy.
+ OrphanablePtr<LoadBalancingPolicy> CreateChildPolicyLocked(
+ const char* name, const grpc_channel_args* args);
+ grpc_channel_args* CreateChildPolicyArgsLocked(
+ const grpc_channel_args* args);
+
+ static void OnDelayedRemovalTimerLocked(void* arg, grpc_error* error);
+
+ RefCountedPtr<XdsLb> parent_;
+ RefCountedPtr<XdsLocalityName> name_;
+ OrphanablePtr<LoadBalancingPolicy> child_policy_;
+ OrphanablePtr<LoadBalancingPolicy> pending_child_policy_;
+ RefCountedPtr<PickerWrapper> picker_wrapper_;
+ grpc_connectivity_state connectivity_state_ = GRPC_CHANNEL_IDLE;
+ uint32_t locality_weight_;
+ grpc_closure on_delayed_removal_timer_;
+ grpc_timer delayed_removal_timer_;
+ bool delayed_removal_timer_callback_pending_ = false;
+ };
+
+ explicit LocalityMap(XdsLb* xds_policy) : xds_policy_(xds_policy) {}
+
+ void UpdateLocked(const XdsLocalityList& locality_list,
+ LoadBalancingPolicy::Config* child_policy_config,
+ const grpc_channel_args* args, XdsLb* parent,
+ bool is_initial_update = false);
+ void UpdateXdsPickerLocked();
+ void ShutdownLocked();
+ void ResetBackoffLocked();
+
+ private:
+ XdsLb* xds_policy_;
+ Map<RefCountedPtr<XdsLocalityName>, OrphanablePtr<LocalityEntry>,
+ XdsLocalityName::Less>
+ map_;
+ };
+
+ ~XdsLb();
+
+ void ShutdownLocked() override;
+
+ // Helper function used in UpdateLocked().
+ void ProcessAddressesAndChannelArgsLocked(ServerAddressList addresses,
+ const grpc_channel_args& args);
+
+ // Parses the xds config given the JSON node of the first child of XdsConfig.
+ // If parsing succeeds, updates \a balancer_name, and updates \a
+ // child_policy_config_ and \a fallback_policy_config_ if they are also
+ // found. Does nothing upon failure.
+ void ParseLbConfig(const ParsedXdsConfig* xds_config);
+
+ LbChannelState* LatestLbChannel() const {
+ return pending_lb_chand_ != nullptr ? pending_lb_chand_.get()
+ : lb_chand_.get();
+ }
+
+ // Methods for dealing with fallback state.
+ void MaybeCancelFallbackAtStartupChecks();
+ static void OnFallbackTimerLocked(void* arg, grpc_error* error);
+ void UpdateFallbackPolicyLocked();
+ OrphanablePtr<LoadBalancingPolicy> CreateFallbackPolicyLocked(
+ const char* name, const grpc_channel_args* args);
+ void MaybeExitFallbackMode();
+
+ // Name of the backend server to connect to.
+ const char* server_name_ = nullptr;
+
+ // Name of the balancer to connect to.
+ UniquePtr<char> balancer_name_;
+
+ // Current channel args from the resolver.
+ grpc_channel_args* args_ = nullptr;
+
+ // Internal state.
+ bool shutting_down_ = false;
+
+ // The channel for communicating with the LB server.
+ OrphanablePtr<LbChannelState> lb_chand_;
+ OrphanablePtr<LbChannelState> pending_lb_chand_;
+
+ // Timeout in milliseconds for the LB call. 0 means no deadline.
+ const grpc_millis lb_call_timeout_ms_;
+
+ // Whether the checks for fallback at startup are ALL pending. There are
+ // several cases where this can be reset:
+ // 1. The fallback timer fires, we enter fallback mode.
+ // 2. Before the fallback timer fires, the LB channel becomes
+ // TRANSIENT_FAILURE or the LB call fails, we enter fallback mode.
+ // 3. Before the fallback timer fires, if any child policy in the locality map
+ // becomes READY, we cancel the fallback timer.
+ bool fallback_at_startup_checks_pending_ = false;
+ // Timeout in milliseconds for before using fallback backend addresses.
+ // 0 means not using fallback.
+ const grpc_millis lb_fallback_timeout_ms_;
+ // The backend addresses from the resolver.
+ ServerAddressList fallback_backend_addresses_;
+ // Fallback timer.
+ grpc_timer lb_fallback_timer_;
+ grpc_closure lb_on_fallback_;
+
+ // The policy to use for the fallback backends.
+ RefCountedPtr<LoadBalancingPolicy::Config> fallback_policy_config_;
+ // Non-null iff we are in fallback mode.
+ OrphanablePtr<LoadBalancingPolicy> fallback_policy_;
+ OrphanablePtr<LoadBalancingPolicy> pending_fallback_policy_;
+
+ // The policy to use for the backends.
+ RefCountedPtr<LoadBalancingPolicy::Config> child_policy_config_;
+ const grpc_millis locality_retention_interval_ms_;
+ // Map of policies to use in the backend
+ LocalityMap locality_map_;
+ // TODO(mhaidry) : Add support for multiple maps of localities
+ // with different priorities
+ XdsLocalityList locality_list_;
+ // TODO(mhaidry) : Add a pending locality map that may be swapped with the
+ // the current one when new localities in the pending map are ready
+ // to accept connections
+
+ // The config for dropping calls.
+ RefCountedPtr<XdsDropConfig> drop_config_;
+
+ // The stats for client-side load reporting.
+ XdsClientStats client_stats_;
+};
+
+//
+// XdsLb::PickerWrapper::Pick
+//
+
+LoadBalancingPolicy::PickResult XdsLb::PickerWrapper::Pick(
+ LoadBalancingPolicy::PickArgs args) {
+ // Forward the pick to the picker returned from the child policy.
+ PickResult result = picker_->Pick(args);
+ if (result.type != PickResult::PICK_COMPLETE ||
+ result.subchannel == nullptr || locality_stats_ == nullptr) {
+ return result;
+ }
+ // Record a call started.
+ locality_stats_->AddCallStarted();
+ // Intercept the recv_trailing_metadata op to record call completion.
+ result.recv_trailing_metadata_ready = RecordCallCompletion;
+ result.recv_trailing_metadata_ready_user_data =
+ locality_stats_->Ref(DEBUG_LOCATION, "LocalityStats+call").release();
+ return result;
+}
+
+// Note that the following callback does not run in either the control plane
+// combiner or the data plane combiner.
+void XdsLb::PickerWrapper::RecordCallCompletion(
+ void* arg, grpc_error* error,
+ LoadBalancingPolicy::MetadataInterface* recv_trailing_metadata,
+ LoadBalancingPolicy::CallState* call_state) {
+ XdsClientStats::LocalityStats* locality_stats =
+ static_cast<XdsClientStats::LocalityStats*>(arg);
+ const bool call_failed = error != GRPC_ERROR_NONE;
+ locality_stats->AddCallFinished(call_failed);
+ locality_stats->Unref(DEBUG_LOCATION, "LocalityStats+call");
+}
+
+//
+// XdsLb::Picker
+//
+
+XdsLb::PickResult XdsLb::Picker::Pick(PickArgs args) {
+ // Handle drop.
+ const UniquePtr<char>* drop_category;
+ if (drop_config_->ShouldDrop(&drop_category)) {
+ xds_policy_->client_stats_.AddCallDropped(*drop_category);
+ PickResult result;
+ result.type = PickResult::PICK_COMPLETE;
+ return result;
+ }
+ // Generate a random number in [0, total weight).
+ const uint32_t key = rand() % pickers_[pickers_.size() - 1].first;
+ // Forward pick to whichever locality maps to the range in which the
+ // random number falls in.
+ return PickFromLocality(key, args);
+}
+
+XdsLb::PickResult XdsLb::Picker::PickFromLocality(const uint32_t key,
+ PickArgs args) {
+ size_t mid = 0;
+ size_t start_index = 0;
+ size_t end_index = pickers_.size() - 1;
+ size_t index = 0;
+ while (end_index > start_index) {
+ mid = (start_index + end_index) / 2;
+ if (pickers_[mid].first > key) {
+ end_index = mid;
+ } else if (pickers_[mid].first < key) {
+ start_index = mid + 1;
+ } else {
+ index = mid + 1;
+ break;
+ }
+ }
+ if (index == 0) index = start_index;
+ GPR_ASSERT(pickers_[index].first > key);
+ return pickers_[index].second->Pick(args);
+}
+
+//
+// XdsLb::FallbackHelper
+//
+
+bool XdsLb::FallbackHelper::CalledByPendingFallback() const {
+ GPR_ASSERT(child_ != nullptr);
+ return child_ == parent_->pending_fallback_policy_.get();
+}
+
+bool XdsLb::FallbackHelper::CalledByCurrentFallback() const {
+ GPR_ASSERT(child_ != nullptr);
+ return child_ == parent_->fallback_policy_.get();
+}
+
+RefCountedPtr<SubchannelInterface> XdsLb::FallbackHelper::CreateSubchannel(
+ const grpc_channel_args& args) {
+ if (parent_->shutting_down_ ||
+ (!CalledByPendingFallback() && !CalledByCurrentFallback())) {
+ return nullptr;
+ }
+ return parent_->channel_control_helper()->CreateSubchannel(args);
+}
+
+void XdsLb::FallbackHelper::UpdateState(grpc_connectivity_state state,
+ UniquePtr<SubchannelPicker> picker) {
+ if (parent_->shutting_down_) return;
+ // If this request is from the pending fallback policy, ignore it until
+ // it reports READY, at which point we swap it into place.
+ if (CalledByPendingFallback()) {
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(
+ GPR_INFO,
+ "[xdslb %p helper %p] pending fallback policy %p reports state=%s",
+ parent_.get(), this, parent_->pending_fallback_policy_.get(),
+ grpc_connectivity_state_name(state));
+ }
+ if (state != GRPC_CHANNEL_READY) return;
+ grpc_pollset_set_del_pollset_set(
+ parent_->fallback_policy_->interested_parties(),
+ parent_->interested_parties());
+ parent_->fallback_policy_ = std::move(parent_->pending_fallback_policy_);
+ } else if (!CalledByCurrentFallback()) {
+ // This request is from an outdated fallback policy, so ignore it.
+ return;
+ }
+ parent_->channel_control_helper()->UpdateState(state, std::move(picker));
+}
+
+void XdsLb::FallbackHelper::RequestReresolution() {
+ if (parent_->shutting_down_) return;
+ const LoadBalancingPolicy* latest_fallback_policy =
+ parent_->pending_fallback_policy_ != nullptr
+ ? parent_->pending_fallback_policy_.get()
+ : parent_->fallback_policy_.get();
+ if (child_ != latest_fallback_policy) return;
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] Re-resolution requested from the fallback policy (%p).",
+ parent_.get(), child_);
+ }
+ GPR_ASSERT(parent_->lb_chand_ != nullptr);
+ parent_->channel_control_helper()->RequestReresolution();
+}
+
+void XdsLb::FallbackHelper::AddTraceEvent(TraceSeverity severity,
+ StringView message) {
+ if (parent_->shutting_down_ ||
+ (!CalledByPendingFallback() && !CalledByCurrentFallback())) {
+ return;
+ }
+ parent_->channel_control_helper()->AddTraceEvent(severity, message);
+}
+
+//
+// XdsLb::LbChannelState
+//
+
+XdsLb::LbChannelState::LbChannelState(RefCountedPtr<XdsLb> xdslb_policy,
+ const char* balancer_name,
+ const grpc_channel_args& args)
+ : InternallyRefCounted<LbChannelState>(&grpc_lb_xds_trace),
+ xdslb_policy_(std::move(xdslb_policy)) {
+ GRPC_CLOSURE_INIT(&on_connectivity_changed_, OnConnectivityChangedLocked,
+ this, grpc_combiner_scheduler(xdslb_policy_->combiner()));
+ channel_ = CreateXdsBalancerChannel(balancer_name, args);
+ GPR_ASSERT(channel_ != nullptr);
+ eds_calld_.reset(New<RetryableLbCall<EdsCallState>>(
+ Ref(DEBUG_LOCATION, "LbChannelState+eds")));
+ lrs_calld_.reset(New<RetryableLbCall<LrsCallState>>(
+ Ref(DEBUG_LOCATION, "LbChannelState+lrs")));
+}
+
+XdsLb::LbChannelState::~LbChannelState() {
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO, "[xdslb %p] Destroying LB channel %p", xdslb_policy(),
+ this);
+ }
+ grpc_channel_destroy(channel_);
+}
+
+void XdsLb::LbChannelState::Orphan() {
+ shutting_down_ = true;
+ eds_calld_.reset();
+ lrs_calld_.reset();
+ Unref(DEBUG_LOCATION, "LbChannelState+orphaned");
+}
+
+void XdsLb::LbChannelState::StartConnectivityWatchLocked() {
+ grpc_channel_element* client_channel_elem =
+ grpc_channel_stack_last_element(grpc_channel_get_channel_stack(channel_));
+ GPR_ASSERT(client_channel_elem->filter == &grpc_client_channel_filter);
+ // Ref held by callback.
+ Ref(DEBUG_LOCATION, "LbChannelState+start_watch").release();
+ grpc_client_channel_watch_connectivity_state(
+ client_channel_elem,
+ grpc_polling_entity_create_from_pollset_set(
+ xdslb_policy_->interested_parties()),
+ &connectivity_, &on_connectivity_changed_, nullptr);
+}
+
+void XdsLb::LbChannelState::CancelConnectivityWatchLocked() {
+ grpc_channel_element* client_channel_elem =
+ grpc_channel_stack_last_element(grpc_channel_get_channel_stack(channel_));
+ GPR_ASSERT(client_channel_elem->filter == &grpc_client_channel_filter);
+ grpc_client_channel_watch_connectivity_state(
+ client_channel_elem,
+ grpc_polling_entity_create_from_pollset_set(
+ xdslb_policy_->interested_parties()),
+ nullptr, &on_connectivity_changed_, nullptr);
+}
+
+void XdsLb::LbChannelState::OnConnectivityChangedLocked(void* arg,
+ grpc_error* error) {
+ LbChannelState* self = static_cast<LbChannelState*>(arg);
+ if (!self->shutting_down_ &&
+ self->xdslb_policy_->fallback_at_startup_checks_pending_) {
+ if (self->connectivity_ != GRPC_CHANNEL_TRANSIENT_FAILURE) {
+ // Not in TRANSIENT_FAILURE. Renew connectivity watch.
+ grpc_channel_element* client_channel_elem =
+ grpc_channel_stack_last_element(
+ grpc_channel_get_channel_stack(self->channel_));
+ GPR_ASSERT(client_channel_elem->filter == &grpc_client_channel_filter);
+ grpc_client_channel_watch_connectivity_state(
+ client_channel_elem,
+ grpc_polling_entity_create_from_pollset_set(
+ self->xdslb_policy_->interested_parties()),
+ &self->connectivity_, &self->on_connectivity_changed_, nullptr);
+ return; // Early out so we don't drop the ref below.
+ }
+ // In TRANSIENT_FAILURE. Cancel the fallback timer and go into
+ // fallback mode immediately.
+ gpr_log(GPR_INFO,
+ "[xdslb %p] Balancer channel in state TRANSIENT_FAILURE; "
+ "entering fallback mode",
+ self);
+ self->xdslb_policy_->fallback_at_startup_checks_pending_ = false;
+ grpc_timer_cancel(&self->xdslb_policy_->lb_fallback_timer_);
+ self->xdslb_policy_->UpdateFallbackPolicyLocked();
+ }
+ // Done watching connectivity state, so drop ref.
+ self->Unref(DEBUG_LOCATION, "LbChannelState+watch_done");
+}
+
+//
+// XdsLb::LbChannelState::RetryableLbCall<>
+//
+
+template <typename T>
+XdsLb::LbChannelState::RetryableLbCall<T>::RetryableLbCall(
+ RefCountedPtr<LbChannelState> lb_chand)
+ : lb_chand_(std::move(lb_chand)),
+ backoff_(
+ BackOff::Options()
+ .set_initial_backoff(GRPC_XDS_INITIAL_CONNECT_BACKOFF_SECONDS *
+ 1000)
+ .set_multiplier(GRPC_XDS_RECONNECT_BACKOFF_MULTIPLIER)
+ .set_jitter(GRPC_XDS_RECONNECT_JITTER)
+ .set_max_backoff(GRPC_XDS_RECONNECT_MAX_BACKOFF_SECONDS * 1000)) {
+ GRPC_CLOSURE_INIT(
+ &on_retry_timer_, OnRetryTimerLocked, this,
+ grpc_combiner_scheduler(lb_chand_->xdslb_policy()->combiner()));
+ StartNewCallLocked();
+}
+
+template <typename T>
+void XdsLb::LbChannelState::RetryableLbCall<T>::Orphan() {
+ shutting_down_ = true;
+ lb_calld_.reset();
+ if (retry_timer_callback_pending_) grpc_timer_cancel(&retry_timer_);
+ this->Unref(DEBUG_LOCATION, "RetryableLbCall+orphaned");
+}
+
+template <typename T>
+void XdsLb::LbChannelState::RetryableLbCall<T>::OnCallFinishedLocked() {
+ const bool seen_response = lb_calld_->seen_response();
+ lb_calld_.reset();
+ if (seen_response) {
+ // If we lost connection to the LB server, reset backoff and restart the LB
+ // call immediately.
+ backoff_.Reset();
+ StartNewCallLocked();
+ } else {
+ // If we failed to connect to the LB server, retry later.
+ StartRetryTimerLocked();
+ }
+}
+
+template <typename T>
+void XdsLb::LbChannelState::RetryableLbCall<T>::StartNewCallLocked() {
+ if (shutting_down_) return;
+ GPR_ASSERT(lb_chand_->channel_ != nullptr);
+ GPR_ASSERT(lb_calld_ == nullptr);
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] Start new call from retryable call (lb_chand: %p, "
+ "retryable call: %p)",
+ lb_chand()->xdslb_policy(), lb_chand(), this);
+ }
+ lb_calld_ = MakeOrphanable<T>(
+ this->Ref(DEBUG_LOCATION, "RetryableLbCall+start_new_call"));
+}
+
+template <typename T>
+void XdsLb::LbChannelState::RetryableLbCall<T>::StartRetryTimerLocked() {
+ if (shutting_down_) return;
+ const grpc_millis next_attempt_time = backoff_.NextAttemptTime();
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ grpc_millis timeout = GPR_MAX(next_attempt_time - ExecCtx::Get()->Now(), 0);
+ gpr_log(GPR_INFO,
+ "[xdslb %p] Failed to connect to LB server (lb_chand: %p) "
+ "retry timer will fire in %" PRId64 "ms.",
+ lb_chand()->xdslb_policy(), lb_chand(), timeout);
+ }
+ this->Ref(DEBUG_LOCATION, "RetryableLbCall+retry_timer_start").release();
+ grpc_timer_init(&retry_timer_, next_attempt_time, &on_retry_timer_);
+ retry_timer_callback_pending_ = true;
+}
+
+template <typename T>
+void XdsLb::LbChannelState::RetryableLbCall<T>::OnRetryTimerLocked(
+ void* arg, grpc_error* error) {
+ RetryableLbCall* lb_calld = static_cast<RetryableLbCall*>(arg);
+ lb_calld->retry_timer_callback_pending_ = false;
+ if (!lb_calld->shutting_down_ && error == GRPC_ERROR_NONE) {
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] Retry timer fires (lb_chand: %p, retryable call: %p)",
+ lb_calld->lb_chand()->xdslb_policy(), lb_calld->lb_chand(),
+ lb_calld);
+ }
+ lb_calld->StartNewCallLocked();
+ }
+ lb_calld->Unref(DEBUG_LOCATION, "RetryableLbCall+retry_timer_done");
+}
+
+//
+// XdsLb::LbChannelState::EdsCallState
+//
+
+XdsLb::LbChannelState::EdsCallState::EdsCallState(
+ RefCountedPtr<RetryableLbCall<EdsCallState>> parent)
+ : InternallyRefCounted<EdsCallState>(&grpc_lb_xds_trace),
+ parent_(std::move(parent)) {
+ // Init the LB call. Note that the LB call will progress every time there's
+ // activity in xdslb_policy()->interested_parties(), which is comprised of
+ // the polling entities from client_channel.
+ GPR_ASSERT(xdslb_policy() != nullptr);
+ GPR_ASSERT(xdslb_policy()->server_name_ != nullptr);
+ GPR_ASSERT(xdslb_policy()->server_name_[0] != '\0');
+ const grpc_millis deadline =
+ xdslb_policy()->lb_call_timeout_ms_ == 0
+ ? GRPC_MILLIS_INF_FUTURE
+ : ExecCtx::Get()->Now() + xdslb_policy()->lb_call_timeout_ms_;
+ // Create an LB call with the specified method name.
+ lb_call_ = grpc_channel_create_pollset_set_call(
+ lb_chand()->channel_, nullptr, GRPC_PROPAGATE_DEFAULTS,
+ xdslb_policy()->interested_parties(),
+ GRPC_MDSTR_SLASH_ENVOY_DOT_API_DOT_V2_DOT_ENDPOINTDISCOVERYSERVICE_SLASH_STREAMENDPOINTS,
+ nullptr, deadline, nullptr);
+ GPR_ASSERT(lb_call_ != nullptr);
+ // Init the LB call request payload.
+ grpc_slice request_payload_slice =
+ XdsEdsRequestCreateAndEncode(xdslb_policy()->server_name_);
+ send_message_payload_ =
+ grpc_raw_byte_buffer_create(&request_payload_slice, 1);
+ grpc_slice_unref_internal(request_payload_slice);
+ // Init other data associated with the LB call.
+ grpc_metadata_array_init(&initial_metadata_recv_);
+ grpc_metadata_array_init(&trailing_metadata_recv_);
+ GRPC_CLOSURE_INIT(&on_response_received_, OnResponseReceivedLocked, this,
+ grpc_combiner_scheduler(xdslb_policy()->combiner()));
+ GRPC_CLOSURE_INIT(&on_status_received_, OnStatusReceivedLocked, this,
+ grpc_combiner_scheduler(xdslb_policy()->combiner()));
+ // Start the call.
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] Starting EDS call (lb_chand: %p, lb_calld: %p, "
+ "lb_call: %p)",
+ xdslb_policy(), lb_chand(), this, lb_call_);
+ }
+ // Create the ops.
+ grpc_call_error call_error;
+ grpc_op ops[3];
+ memset(ops, 0, sizeof(ops));
+ // Op: send initial metadata.
+ grpc_op* op = ops;
+ op->op = GRPC_OP_SEND_INITIAL_METADATA;
+ op->data.send_initial_metadata.count = 0;
+ op->flags = 0;
+ op->reserved = nullptr;
+ op++;
+ // Op: send request message.
+ GPR_ASSERT(send_message_payload_ != nullptr);
+ op->op = GRPC_OP_SEND_MESSAGE;
+ op->data.send_message.send_message = send_message_payload_;
+ op->flags = 0;
+ op->reserved = nullptr;
+ op++;
+ call_error = grpc_call_start_batch_and_execute(lb_call_, ops,
+ (size_t)(op - ops), nullptr);
+ GPR_ASSERT(GRPC_CALL_OK == call_error);
+ // Op: recv initial metadata.
+ op = ops;
+ op->op = GRPC_OP_RECV_INITIAL_METADATA;
+ op->data.recv_initial_metadata.recv_initial_metadata =
+ &initial_metadata_recv_;
+ op->flags = 0;
+ op->reserved = nullptr;
+ op++;
+ // Op: recv response.
+ op->op = GRPC_OP_RECV_MESSAGE;
+ op->data.recv_message.recv_message = &recv_message_payload_;
+ op->flags = 0;
+ op->reserved = nullptr;
+ op++;
+ Ref(DEBUG_LOCATION, "EDS+OnResponseReceivedLocked").release();
+ call_error = grpc_call_start_batch_and_execute(
+ lb_call_, ops, (size_t)(op - ops), &on_response_received_);
+ GPR_ASSERT(GRPC_CALL_OK == call_error);
+ // Op: recv server status.
+ op = ops;
+ op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
+ op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv_;
+ op->data.recv_status_on_client.status = &status_code_;
+ op->data.recv_status_on_client.status_details = &status_details_;
+ op->flags = 0;
+ op->reserved = nullptr;
+ op++;
+ // This callback signals the end of the LB call, so it relies on the initial
+ // ref instead of a new ref. When it's invoked, it's the initial ref that is
+ // unreffed.
+ call_error = grpc_call_start_batch_and_execute(
+ lb_call_, ops, (size_t)(op - ops), &on_status_received_);
+ GPR_ASSERT(GRPC_CALL_OK == call_error);
+}
+
+XdsLb::LbChannelState::EdsCallState::~EdsCallState() {
+ grpc_metadata_array_destroy(&initial_metadata_recv_);
+ grpc_metadata_array_destroy(&trailing_metadata_recv_);
+ grpc_byte_buffer_destroy(send_message_payload_);
+ grpc_byte_buffer_destroy(recv_message_payload_);
+ grpc_slice_unref_internal(status_details_);
+ GPR_ASSERT(lb_call_ != nullptr);
+ grpc_call_unref(lb_call_);
+}
+
+void XdsLb::LbChannelState::EdsCallState::Orphan() {
+ GPR_ASSERT(lb_call_ != nullptr);
+ // If we are here because xdslb_policy wants to cancel the call,
+ // on_status_received_ will complete the cancellation and clean up. Otherwise,
+ // we are here because xdslb_policy has to orphan a failed call, then the
+ // following cancellation will be a no-op.
+ grpc_call_cancel(lb_call_, nullptr);
+ // Note that the initial ref is hold by on_status_received_. So the
+ // corresponding unref happens in on_status_received_ instead of here.
+}
+
+void XdsLb::LbChannelState::EdsCallState::OnResponseReceivedLocked(
+ void* arg, grpc_error* error) {
+ EdsCallState* eds_calld = static_cast<EdsCallState*>(arg);
+ LbChannelState* lb_chand = eds_calld->lb_chand();
+ XdsLb* xdslb_policy = eds_calld->xdslb_policy();
+ // Empty payload means the LB call was cancelled.
+ if (!eds_calld->IsCurrentCallOnChannel() ||
+ eds_calld->recv_message_payload_ == nullptr) {
+ eds_calld->Unref(DEBUG_LOCATION, "EDS+OnResponseReceivedLocked");
+ return;
+ }
+ // Read the response.
+ grpc_byte_buffer_reader bbr;
+ grpc_byte_buffer_reader_init(&bbr, eds_calld->recv_message_payload_);
+ grpc_slice response_slice = grpc_byte_buffer_reader_readall(&bbr);
+ grpc_byte_buffer_reader_destroy(&bbr);
+ grpc_byte_buffer_destroy(eds_calld->recv_message_payload_);
+ eds_calld->recv_message_payload_ = nullptr;
+ // TODO(juanlishen): When we convert this to use the xds protocol, the
+ // balancer will send us a fallback timeout such that we should go into
+ // fallback mode if we have lost contact with the balancer after a certain
+ // period of time. We will need to save the timeout value here, and then
+ // when the balancer call ends, we will need to start a timer for the
+ // specified period of time, and if the timer fires, we go into fallback
+ // mode. We will also need to cancel the timer when we receive a serverlist
+ // from the balancer.
+ // This anonymous lambda is a hack to avoid the usage of goto.
+ [&]() {
+ // Parse the response.
+ XdsUpdate update;
+ grpc_error* parse_error =
+ XdsEdsResponseDecodeAndParse(response_slice, &update);
+ if (parse_error != GRPC_ERROR_NONE) {
+ gpr_log(GPR_ERROR, "[xdslb %p] EDS response parsing failed. error=%s",
+ xdslb_policy, grpc_error_string(parse_error));
+ GRPC_ERROR_UNREF(parse_error);
+ return;
+ }
+ if (update.locality_list.empty() && !update.drop_all) {
+ char* response_slice_str =
+ grpc_dump_slice(response_slice, GPR_DUMP_ASCII | GPR_DUMP_HEX);
+ gpr_log(GPR_ERROR,
+ "[xdslb %p] EDS response '%s' doesn't contain any valid locality "
+ "but doesn't require to drop all calls. Ignoring.",
+ xdslb_policy, response_slice_str);
+ gpr_free(response_slice_str);
+ return;
+ }
+ eds_calld->seen_response_ = true;
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] EDS response with %" PRIuPTR
+ " localities and %" PRIuPTR
+ " drop categories received (drop_all=%d)",
+ xdslb_policy, update.locality_list.size(),
+ update.drop_config->drop_category_list().size(), update.drop_all);
+ for (size_t i = 0; i < update.locality_list.size(); ++i) {
+ const XdsLocalityInfo& locality = update.locality_list[i];
+ gpr_log(GPR_INFO,
+ "[xdslb %p] Locality %" PRIuPTR " %s contains %" PRIuPTR
+ " server addresses",
+ xdslb_policy, i,
+ locality.locality_name->AsHumanReadableString(),
+ locality.serverlist.size());
+ for (size_t j = 0; j < locality.serverlist.size(); ++j) {
+ char* ipport;
+ grpc_sockaddr_to_string(&ipport, &locality.serverlist[j].address(),
+ false);
+ gpr_log(GPR_INFO,
+ "[xdslb %p] Locality %" PRIuPTR
+ " %s, server address %" PRIuPTR ": %s",
+ xdslb_policy, i,
+ locality.locality_name->AsHumanReadableString(), j, ipport);
+ gpr_free(ipport);
+ }
+ }
+ for (size_t i = 0; i < update.drop_config->drop_category_list().size();
+ ++i) {
+ const XdsDropConfig::DropCategory& drop_category =
+ update.drop_config->drop_category_list()[i];
+ gpr_log(GPR_INFO,
+ "[xdslb %p] Drop category %s has drop rate %d per million",
+ xdslb_policy, drop_category.name.get(),
+ drop_category.parts_per_million);
+ }
+ }
+ // Pending LB channel receives a response; promote it.
+ // Note that this call can't be on a discarded pending channel, because
+ // such channels don't have any current call but we have checked this call
+ // is a current call.
+ if (!lb_chand->IsCurrentChannel()) {
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] Pending LB channel %p receives EDS response; "
+ "promoting it to replace current LB channel %p",
+ xdslb_policy, lb_chand, xdslb_policy->lb_chand_.get());
+ }
+ // TODO(juanlishen): Maybe promote the pending LB channel when the
+ // response results a READY locality map.
+ xdslb_policy->lb_chand_ = std::move(xdslb_policy->pending_lb_chand_);
+ }
+ // At this point, lb_chand must be the current LB channel, so try to start
+ // load reporting.
+ LrsCallState* lrs_calld = lb_chand->lrs_calld_->lb_calld();
+ if (lrs_calld != nullptr) lrs_calld->MaybeStartReportingLocked();
+ // If the balancer tells us to drop all the calls, we should exit fallback
+ // mode immediately.
+ if (update.drop_all) xdslb_policy->MaybeExitFallbackMode();
+ // Update the drop config.
+ const bool drop_config_changed =
+ xdslb_policy->drop_config_ == nullptr ||
+ *xdslb_policy->drop_config_ != *update.drop_config;
+ xdslb_policy->drop_config_ = std::move(update.drop_config);
+ // Ignore identical locality update.
+ if (xdslb_policy->locality_list_ == update.locality_list) {
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] Incoming locality list identical to current, "
+ "ignoring. (drop_config_changed=%d)",
+ xdslb_policy, drop_config_changed);
+ }
+ if (drop_config_changed) {
+ xdslb_policy->locality_map_.UpdateXdsPickerLocked();
+ }
+ return;
+ }
+ // Update the locality list.
+ xdslb_policy->locality_list_ = std::move(update.locality_list);
+ // Update the locality map.
+ xdslb_policy->locality_map_.UpdateLocked(
+ xdslb_policy->locality_list_, xdslb_policy->child_policy_config_.get(),
+ xdslb_policy->args_, xdslb_policy);
+ }();
+ grpc_slice_unref_internal(response_slice);
+ if (xdslb_policy->shutting_down_) {
+ eds_calld->Unref(DEBUG_LOCATION,
+ "EDS+OnResponseReceivedLocked+xds_shutdown");
+ return;
+ }
+ // Keep listening for serverlist updates.
+ grpc_op op;
+ memset(&op, 0, sizeof(op));
+ op.op = GRPC_OP_RECV_MESSAGE;
+ op.data.recv_message.recv_message = &eds_calld->recv_message_payload_;
+ op.flags = 0;
+ op.reserved = nullptr;
+ GPR_ASSERT(eds_calld->lb_call_ != nullptr);
+ // Reuse the "EDS+OnResponseReceivedLocked" ref taken in ctor.
+ const grpc_call_error call_error = grpc_call_start_batch_and_execute(
+ eds_calld->lb_call_, &op, 1, &eds_calld->on_response_received_);
+ GPR_ASSERT(GRPC_CALL_OK == call_error);
+}
+
+void XdsLb::LbChannelState::EdsCallState::OnStatusReceivedLocked(
+ void* arg, grpc_error* error) {
+ EdsCallState* eds_calld = static_cast<EdsCallState*>(arg);
+ LbChannelState* lb_chand = eds_calld->lb_chand();
+ XdsLb* xdslb_policy = eds_calld->xdslb_policy();
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ char* status_details = grpc_slice_to_c_string(eds_calld->status_details_);
+ gpr_log(GPR_INFO,
+ "[xdslb %p] EDS call status received. Status = %d, details "
+ "= '%s', (lb_chand: %p, eds_calld: %p, lb_call: %p), error '%s'",
+ xdslb_policy, eds_calld->status_code_, status_details, lb_chand,
+ eds_calld, eds_calld->lb_call_, grpc_error_string(error));
+ gpr_free(status_details);
+ }
+ // Ignore status from a stale call.
+ if (eds_calld->IsCurrentCallOnChannel()) {
+ // Because this call is the current one on the channel, the channel can't
+ // have been swapped out; otherwise, the call should have been reset.
+ GPR_ASSERT(lb_chand->IsCurrentChannel() || lb_chand->IsPendingChannel());
+ if (lb_chand != xdslb_policy->LatestLbChannel()) {
+ // This channel must be the current one and there is a pending one. Swap
+ // in the pending one and we are done.
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] Promoting pending LB channel %p to replace "
+ "current LB channel %p",
+ xdslb_policy, lb_chand, xdslb_policy->lb_chand_.get());
+ }
+ xdslb_policy->lb_chand_ = std::move(xdslb_policy->pending_lb_chand_);
+ } else {
+ // This channel is the most recently created one. Try to restart the call
+ // and reresolve.
+ eds_calld->parent_->OnCallFinishedLocked();
+ xdslb_policy->channel_control_helper()->RequestReresolution();
+ // If the fallback-at-startup checks are pending, go into fallback mode
+ // immediately. This short-circuits the timeout for the
+ // fallback-at-startup case.
+ if (xdslb_policy->fallback_at_startup_checks_pending_) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] Balancer call finished; entering fallback mode",
+ xdslb_policy);
+ xdslb_policy->fallback_at_startup_checks_pending_ = false;
+ grpc_timer_cancel(&xdslb_policy->lb_fallback_timer_);
+ lb_chand->CancelConnectivityWatchLocked();
+ xdslb_policy->UpdateFallbackPolicyLocked();
+ }
+ }
+ }
+ eds_calld->Unref(DEBUG_LOCATION, "EDS+OnStatusReceivedLocked");
+}
+
+bool XdsLb::LbChannelState::EdsCallState::IsCurrentCallOnChannel() const {
+ // If the retryable EDS call is null (which only happens when the LB channel
+ // is shutting down), all the EDS calls are stale.
+ if (lb_chand()->eds_calld_ == nullptr) return false;
+ return this == lb_chand()->eds_calld_->lb_calld();
+}
+
+//
+// XdsLb::LbChannelState::LrsCallState::Reporter
+//
+
+void XdsLb::LbChannelState::LrsCallState::Reporter::Orphan() {
+ if (next_report_timer_callback_pending_) {
+ grpc_timer_cancel(&next_report_timer_);
+ }
+}
+
+void XdsLb::LbChannelState::LrsCallState::Reporter::ScheduleNextReportLocked() {
+ const grpc_millis next_report_time = ExecCtx::Get()->Now() + report_interval_;
+ grpc_timer_init(&next_report_timer_, next_report_time,
+ &on_next_report_timer_);
+ next_report_timer_callback_pending_ = true;
+}
+
+void XdsLb::LbChannelState::LrsCallState::Reporter::OnNextReportTimerLocked(
+ void* arg, grpc_error* error) {
+ Reporter* self = static_cast<Reporter*>(arg);
+ self->next_report_timer_callback_pending_ = false;
+ if (error != GRPC_ERROR_NONE || !self->IsCurrentReporterOnCall()) {
+ self->Unref(DEBUG_LOCATION, "Reporter+timer");
+ return;
+ }
+ self->SendReportLocked();
+}
+
+void XdsLb::LbChannelState::LrsCallState::Reporter::SendReportLocked() {
+ // Create a request that contains the load report.
+ grpc_slice request_payload_slice = XdsLrsRequestCreateAndEncode(
+ xdslb_policy()->server_name_, &xdslb_policy()->client_stats_);
+ // Skip client load report if the counters were all zero in the last
+ // report and they are still zero in this one.
+ const bool old_val = last_report_counters_were_zero_;
+ last_report_counters_were_zero_ = static_cast<bool>(
+ grpc_slice_eq(request_payload_slice, grpc_empty_slice()));
+ if (old_val && last_report_counters_were_zero_) {
+ ScheduleNextReportLocked();
+ return;
+ }
+ parent_->send_message_payload_ =
+ grpc_raw_byte_buffer_create(&request_payload_slice, 1);
+ grpc_slice_unref_internal(request_payload_slice);
+ // Send the report.
+ grpc_op op;
+ memset(&op, 0, sizeof(op));
+ op.op = GRPC_OP_SEND_MESSAGE;
+ op.data.send_message.send_message = parent_->send_message_payload_;
+ grpc_call_error call_error = grpc_call_start_batch_and_execute(
+ parent_->lb_call_, &op, 1, &on_report_done_);
+ if (GPR_UNLIKELY(call_error != GRPC_CALL_OK)) {
+ gpr_log(GPR_ERROR,
+ "[xdslb %p] lb_calld=%p call_error=%d sending client load report",
+ xdslb_policy(), this, call_error);
+ GPR_ASSERT(GRPC_CALL_OK == call_error);
+ }
+}
+
+void XdsLb::LbChannelState::LrsCallState::Reporter::OnReportDoneLocked(
+ void* arg, grpc_error* error) {
+ Reporter* self = static_cast<Reporter*>(arg);
+ grpc_byte_buffer_destroy(self->parent_->send_message_payload_);
+ self->parent_->send_message_payload_ = nullptr;
+ if (error != GRPC_ERROR_NONE || !self->IsCurrentReporterOnCall()) {
+ // If this reporter is no longer the current one on the call, the reason
+ // might be that it was orphaned for a new one due to config update.
+ if (!self->IsCurrentReporterOnCall()) {
+ self->parent_->MaybeStartReportingLocked();
+ }
+ self->Unref(DEBUG_LOCATION, "Reporter+report_done");
+ return;
+ }
+ self->ScheduleNextReportLocked();
+}
+
+//
+// XdsLb::LbChannelState::LrsCallState
+//
+
+XdsLb::LbChannelState::LrsCallState::LrsCallState(
+ RefCountedPtr<RetryableLbCall<LrsCallState>> parent)
+ : InternallyRefCounted<LrsCallState>(&grpc_lb_xds_trace),
+ parent_(std::move(parent)) {
+ // Init the LB call. Note that the LB call will progress every time there's
+ // activity in xdslb_policy()->interested_parties(), which is comprised of
+ // the polling entities from client_channel.
+ GPR_ASSERT(xdslb_policy() != nullptr);
+ GPR_ASSERT(xdslb_policy()->server_name_ != nullptr);
+ GPR_ASSERT(xdslb_policy()->server_name_[0] != '\0');
+ const grpc_millis deadline =
+ xdslb_policy()->lb_call_timeout_ms_ == 0
+ ? GRPC_MILLIS_INF_FUTURE
+ : ExecCtx::Get()->Now() + xdslb_policy()->lb_call_timeout_ms_;
+ lb_call_ = grpc_channel_create_pollset_set_call(
+ lb_chand()->channel_, nullptr, GRPC_PROPAGATE_DEFAULTS,
+ xdslb_policy()->interested_parties(),
+ GRPC_MDSTR_SLASH_ENVOY_DOT_SERVICE_DOT_LOAD_STATS_DOT_V2_DOT_LOADREPORTINGSERVICE_SLASH_STREAMLOADSTATS,
+ nullptr, deadline, nullptr);
+ GPR_ASSERT(lb_call_ != nullptr);
+ // Init the LB call request payload.
+ grpc_slice request_payload_slice =
+ XdsLrsRequestCreateAndEncode(xdslb_policy()->server_name_);
+ send_message_payload_ =
+ grpc_raw_byte_buffer_create(&request_payload_slice, 1);
+ grpc_slice_unref_internal(request_payload_slice);
+ // Init other data associated with the LRS call.
+ grpc_metadata_array_init(&initial_metadata_recv_);
+ grpc_metadata_array_init(&trailing_metadata_recv_);
+ GRPC_CLOSURE_INIT(&on_initial_request_sent_, OnInitialRequestSentLocked, this,
+ grpc_combiner_scheduler(xdslb_policy()->combiner()));
+ GRPC_CLOSURE_INIT(&on_response_received_, OnResponseReceivedLocked, this,
+ grpc_combiner_scheduler(xdslb_policy()->combiner()));
+ GRPC_CLOSURE_INIT(&on_status_received_, OnStatusReceivedLocked, this,
+ grpc_combiner_scheduler(xdslb_policy()->combiner()));
+ // Start the call.
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] Starting LRS call (lb_chand: %p, lb_calld: %p, "
+ "lb_call: %p)",
+ xdslb_policy(), lb_chand(), this, lb_call_);
+ }
+ // Create the ops.
+ grpc_call_error call_error;
+ grpc_op ops[3];
+ memset(ops, 0, sizeof(ops));
+ // Op: send initial metadata.
+ grpc_op* op = ops;
+ op->op = GRPC_OP_SEND_INITIAL_METADATA;
+ op->data.send_initial_metadata.count = 0;
+ op->flags = 0;
+ op->reserved = nullptr;
+ op++;
+ // Op: send request message.
+ GPR_ASSERT(send_message_payload_ != nullptr);
+ op->op = GRPC_OP_SEND_MESSAGE;
+ op->data.send_message.send_message = send_message_payload_;
+ op->flags = 0;
+ op->reserved = nullptr;
+ op++;
+ Ref(DEBUG_LOCATION, "LRS+OnInitialRequestSentLocked").release();
+ call_error = grpc_call_start_batch_and_execute(
+ lb_call_, ops, (size_t)(op - ops), &on_initial_request_sent_);
+ GPR_ASSERT(GRPC_CALL_OK == call_error);
+ // Op: recv initial metadata.
+ op = ops;
+ op->op = GRPC_OP_RECV_INITIAL_METADATA;
+ op->data.recv_initial_metadata.recv_initial_metadata =
+ &initial_metadata_recv_;
+ op->flags = 0;
+ op->reserved = nullptr;
+ op++;
+ // Op: recv response.
+ op->op = GRPC_OP_RECV_MESSAGE;
+ op->data.recv_message.recv_message = &recv_message_payload_;
+ op->flags = 0;
+ op->reserved = nullptr;
+ op++;
+ Ref(DEBUG_LOCATION, "LRS+OnResponseReceivedLocked").release();
+ call_error = grpc_call_start_batch_and_execute(
+ lb_call_, ops, (size_t)(op - ops), &on_response_received_);
+ GPR_ASSERT(GRPC_CALL_OK == call_error);
+ // Op: recv server status.
+ op = ops;
+ op->op = GRPC_OP_RECV_STATUS_ON_CLIENT;
+ op->data.recv_status_on_client.trailing_metadata = &trailing_metadata_recv_;
+ op->data.recv_status_on_client.status = &status_code_;
+ op->data.recv_status_on_client.status_details = &status_details_;
+ op->flags = 0;
+ op->reserved = nullptr;
+ op++;
+ // This callback signals the end of the LB call, so it relies on the initial
+ // ref instead of a new ref. When it's invoked, it's the initial ref that is
+ // unreffed.
+ call_error = grpc_call_start_batch_and_execute(
+ lb_call_, ops, (size_t)(op - ops), &on_status_received_);
+ GPR_ASSERT(GRPC_CALL_OK == call_error);
+}
+
+XdsLb::LbChannelState::LrsCallState::~LrsCallState() {
+ grpc_metadata_array_destroy(&initial_metadata_recv_);
+ grpc_metadata_array_destroy(&trailing_metadata_recv_);
+ grpc_byte_buffer_destroy(send_message_payload_);
+ grpc_byte_buffer_destroy(recv_message_payload_);
+ grpc_slice_unref_internal(status_details_);
+ GPR_ASSERT(lb_call_ != nullptr);
+ grpc_call_unref(lb_call_);
+}
+
+void XdsLb::LbChannelState::LrsCallState::Orphan() {
+ reporter_.reset();
+ GPR_ASSERT(lb_call_ != nullptr);
+ // If we are here because xdslb_policy wants to cancel the call,
+ // on_status_received_ will complete the cancellation and clean up. Otherwise,
+ // we are here because xdslb_policy has to orphan a failed call, then the
+ // following cancellation will be a no-op.
+ grpc_call_cancel(lb_call_, nullptr);
+ // Note that the initial ref is hold by on_status_received_. So the
+ // corresponding unref happens in on_status_received_ instead of here.
+}
+
+void XdsLb::LbChannelState::LrsCallState::MaybeStartReportingLocked() {
+ // Don't start if this is not the current call on the current channel.
+ if (!IsCurrentCallOnChannel() || !lb_chand()->IsCurrentChannel()) return;
+ // Don't start again if already started.
+ if (reporter_ != nullptr) return;
+ // Don't start if the previous send_message op (of the initial request or the
+ // last report of the previous reporter) hasn't completed.
+ if (send_message_payload_ != nullptr) return;
+ // Don't start if no LRS response has arrived.
+ if (!seen_response()) return;
+ // Don't start if the EDS call hasn't received any valid response. Note that
+ // this must be the first channel because it is the current channel but its
+ // EDS call hasn't seen any response.
+ EdsCallState* eds_calld = lb_chand()->eds_calld_->lb_calld();
+ if (eds_calld == nullptr || !eds_calld->seen_response()) return;
+ // Start reporting.
+ lb_chand()->xdslb_policy_->client_stats_.MaybeInitLastReportTime();
+ reporter_ = MakeOrphanable<Reporter>(
+ Ref(DEBUG_LOCATION, "LRS+load_report+start"), load_reporting_interval_);
+}
+
+void XdsLb::LbChannelState::LrsCallState::OnInitialRequestSentLocked(
+ void* arg, grpc_error* error) {
+ LrsCallState* lrs_calld = static_cast<LrsCallState*>(arg);
+ // Clear the send_message_payload_.
+ grpc_byte_buffer_destroy(lrs_calld->send_message_payload_);
+ lrs_calld->send_message_payload_ = nullptr;
+ lrs_calld->MaybeStartReportingLocked();
+ lrs_calld->Unref(DEBUG_LOCATION, "LRS+OnInitialRequestSentLocked");
+}
+
+void XdsLb::LbChannelState::LrsCallState::OnResponseReceivedLocked(
+ void* arg, grpc_error* error) {
+ LrsCallState* lrs_calld = static_cast<LrsCallState*>(arg);
+ XdsLb* xdslb_policy = lrs_calld->xdslb_policy();
+ // Empty payload means the LB call was cancelled.
+ if (!lrs_calld->IsCurrentCallOnChannel() ||
+ lrs_calld->recv_message_payload_ == nullptr) {
+ lrs_calld->Unref(DEBUG_LOCATION, "LRS+OnResponseReceivedLocked");
+ return;
+ }
+ // Read the response.
+ grpc_byte_buffer_reader bbr;
+ grpc_byte_buffer_reader_init(&bbr, lrs_calld->recv_message_payload_);
+ grpc_slice response_slice = grpc_byte_buffer_reader_readall(&bbr);
+ grpc_byte_buffer_reader_destroy(&bbr);
+ grpc_byte_buffer_destroy(lrs_calld->recv_message_payload_);
+ lrs_calld->recv_message_payload_ = nullptr;
+ // This anonymous lambda is a hack to avoid the usage of goto.
+ [&]() {
+ // Parse the response.
+ grpc_millis new_load_reporting_interval;
+ grpc_error* parse_error = XdsLrsResponseDecodeAndParse(
+ response_slice, &new_load_reporting_interval,
+ xdslb_policy->server_name_);
+ if (parse_error != GRPC_ERROR_NONE) {
+ gpr_log(GPR_ERROR, "[xdslb %p] LRS response parsing failed. error=%s",
+ xdslb_policy, grpc_error_string(parse_error));
+ GRPC_ERROR_UNREF(parse_error);
+ return;
+ }
+ lrs_calld->seen_response_ = true;
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] LRS response received, load_report_interval=%" PRId64
+ "ms",
+ xdslb_policy, new_load_reporting_interval);
+ }
+ if (new_load_reporting_interval <
+ GRPC_XDS_MIN_CLIENT_LOAD_REPORTING_INTERVAL_MS) {
+ new_load_reporting_interval =
+ GRPC_XDS_MIN_CLIENT_LOAD_REPORTING_INTERVAL_MS;
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(
+ GPR_INFO,
+ "[xdslb %p] Increased load_report_interval to minimum value %dms",
+ xdslb_policy, GRPC_XDS_MIN_CLIENT_LOAD_REPORTING_INTERVAL_MS);
+ }
+ }
+ // Ignore identical update.
+ if (lrs_calld->load_reporting_interval_ == new_load_reporting_interval) {
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] Incoming LRS response identical to current, "
+ "ignoring.",
+ xdslb_policy);
+ }
+ return;
+ }
+ // Stop current load reporting (if any) to adopt the new reporting interval.
+ lrs_calld->reporter_.reset();
+ // Record the new config.
+ lrs_calld->load_reporting_interval_ = new_load_reporting_interval;
+ // Try starting sending load report.
+ lrs_calld->MaybeStartReportingLocked();
+ }();
+ grpc_slice_unref_internal(response_slice);
+ if (xdslb_policy->shutting_down_) {
+ lrs_calld->Unref(DEBUG_LOCATION,
+ "LRS+OnResponseReceivedLocked+xds_shutdown");
+ return;
+ }
+ // Keep listening for LRS config updates.
+ grpc_op op;
+ memset(&op, 0, sizeof(op));
+ op.op = GRPC_OP_RECV_MESSAGE;
+ op.data.recv_message.recv_message = &lrs_calld->recv_message_payload_;
+ op.flags = 0;
+ op.reserved = nullptr;
+ GPR_ASSERT(lrs_calld->lb_call_ != nullptr);
+ // Reuse the "OnResponseReceivedLocked" ref taken in ctor.
+ const grpc_call_error call_error = grpc_call_start_batch_and_execute(
+ lrs_calld->lb_call_, &op, 1, &lrs_calld->on_response_received_);
+ GPR_ASSERT(GRPC_CALL_OK == call_error);
+}
+
+void XdsLb::LbChannelState::LrsCallState::OnStatusReceivedLocked(
+ void* arg, grpc_error* error) {
+ LrsCallState* lrs_calld = static_cast<LrsCallState*>(arg);
+ XdsLb* xdslb_policy = lrs_calld->xdslb_policy();
+ LbChannelState* lb_chand = lrs_calld->lb_chand();
+ GPR_ASSERT(lrs_calld->lb_call_ != nullptr);
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ char* status_details = grpc_slice_to_c_string(lrs_calld->status_details_);
+ gpr_log(GPR_INFO,
+ "[xdslb %p] LRS call status received. Status = %d, details "
+ "= '%s', (lb_chand: %p, lb_calld: %p, lb_call: %p), error '%s'",
+ xdslb_policy, lrs_calld->status_code_, status_details, lb_chand,
+ lrs_calld, lrs_calld->lb_call_, grpc_error_string(error));
+ gpr_free(status_details);
+ }
+ // Ignore status from a stale call.
+ if (lrs_calld->IsCurrentCallOnChannel()) {
+ // Because this call is the current one on the channel, the channel can't
+ // have been swapped out; otherwise, the call should have been reset.
+ GPR_ASSERT(lb_chand->IsCurrentChannel() || lb_chand->IsPendingChannel());
+ GPR_ASSERT(!xdslb_policy->shutting_down_);
+ if (lb_chand == xdslb_policy->LatestLbChannel()) {
+ // This channel is the most recently created one. Try to restart the call
+ // and reresolve.
+ lrs_calld->parent_->OnCallFinishedLocked();
+ xdslb_policy->channel_control_helper()->RequestReresolution();
+ }
+ }
+ lrs_calld->Unref(DEBUG_LOCATION, "LRS+OnStatusReceivedLocked");
+}
+
+bool XdsLb::LbChannelState::LrsCallState::IsCurrentCallOnChannel() const {
+ // If the retryable LRS call is null (which only happens when the LB channel
+ // is shutting down), all the LRS calls are stale.
+ if (lb_chand()->lrs_calld_ == nullptr) return false;
+ return this == lb_chand()->lrs_calld_->lb_calld();
+}
+
+//
+// helper code for creating balancer channel
+//
+
+// Returns the channel args for the LB channel, used to create a bidirectional
+// stream for the reception of load balancing updates.
+grpc_channel_args* BuildBalancerChannelArgs(const grpc_channel_args* args) {
+ static const char* args_to_remove[] = {
+ // LB policy name, since we want to use the default (pick_first) in
+ // the LB channel.
+ GRPC_ARG_LB_POLICY_NAME,
+ // The service config that contains the LB config. We don't want to
+ // recursively use xds in the LB channel.
+ GRPC_ARG_SERVICE_CONFIG,
+ // The channel arg for the server URI, since that will be different for
+ // the LB channel than for the parent channel. The client channel
+ // factory will re-add this arg with the right value.
+ GRPC_ARG_SERVER_URI,
+ // The LB channel should use the authority indicated by the target
+ // authority table (see \a ModifyXdsBalancerChannelArgs),
+ // as opposed to the authority from the parent channel.
+ GRPC_ARG_DEFAULT_AUTHORITY,
+ // Just as for \a GRPC_ARG_DEFAULT_AUTHORITY, the LB channel should be
+ // treated as a stand-alone channel and not inherit this argument from the
+ // args of the parent channel.
+ GRPC_SSL_TARGET_NAME_OVERRIDE_ARG,
+ // Don't want to pass down channelz node from parent; the balancer
+ // channel will get its own.
+ GRPC_ARG_CHANNELZ_CHANNEL_NODE,
+ };
+ // Channel args to add.
+ InlinedVector<grpc_arg, 2> args_to_add;
+ // A channel arg indicating the target is a xds load balancer.
+ args_to_add.emplace_back(grpc_channel_arg_integer_create(
+ const_cast<char*>(GRPC_ARG_ADDRESS_IS_XDS_LOAD_BALANCER), 1));
+ // The parent channel's channelz uuid.
+ channelz::ChannelNode* channelz_node = nullptr;
+ const grpc_arg* arg =
+ grpc_channel_args_find(args, GRPC_ARG_CHANNELZ_CHANNEL_NODE);
+ if (arg != nullptr && arg->type == GRPC_ARG_POINTER &&
+ arg->value.pointer.p != nullptr) {
+ channelz_node = static_cast<channelz::ChannelNode*>(arg->value.pointer.p);
+ args_to_add.emplace_back(
+ channelz::MakeParentUuidArg(channelz_node->uuid()));
+ }
+ // Construct channel args.
+ grpc_channel_args* new_args = grpc_channel_args_copy_and_add_and_remove(
+ args, args_to_remove, GPR_ARRAY_SIZE(args_to_remove), args_to_add.data(),
+ args_to_add.size());
+ // Make any necessary modifications for security.
+ return ModifyXdsBalancerChannelArgs(new_args);
+}
+
+//
+// ctor and dtor
+//
+
+XdsLb::XdsLb(Args args)
+ : LoadBalancingPolicy(std::move(args)),
+ lb_call_timeout_ms_(grpc_channel_args_find_integer(
+ args.args, GRPC_ARG_GRPCLB_CALL_TIMEOUT_MS, {0, 0, INT_MAX})),
+ lb_fallback_timeout_ms_(grpc_channel_args_find_integer(
+ args.args, GRPC_ARG_XDS_FALLBACK_TIMEOUT_MS,
+ {GRPC_XDS_DEFAULT_FALLBACK_TIMEOUT_MS, 0, INT_MAX})),
+ locality_retention_interval_ms_(grpc_channel_args_find_integer(
+ args.args, GRPC_ARG_LOCALITY_RETENTION_INTERVAL_MS,
+ {GRPC_XDS_DEFAULT_LOCALITY_RETENTION_INTERVAL_MS, 0, INT_MAX})),
+ locality_map_(this) {
+ // Record server name.
+ const grpc_arg* arg = grpc_channel_args_find(args.args, GRPC_ARG_SERVER_URI);
+ const char* server_uri = grpc_channel_arg_get_string(arg);
+ GPR_ASSERT(server_uri != nullptr);
+ grpc_uri* uri = grpc_uri_parse(server_uri, true);
+ GPR_ASSERT(uri->path[0] != '\0');
+ server_name_ = gpr_strdup(uri->path[0] == '/' ? uri->path + 1 : uri->path);
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] Will use '%s' as the server name for LB request.", this,
+ server_name_);
+ }
+ grpc_uri_destroy(uri);
+}
+
+XdsLb::~XdsLb() {
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO, "[xdslb %p] destroying xds LB policy", this);
+ }
+ gpr_free((void*)server_name_);
+ grpc_channel_args_destroy(args_);
+ locality_list_.clear();
+}
+
+void XdsLb::ShutdownLocked() {
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO, "[xdslb %p] shutting down", this);
+ }
+ shutting_down_ = true;
+ if (fallback_at_startup_checks_pending_) {
+ grpc_timer_cancel(&lb_fallback_timer_);
+ }
+ locality_map_.ShutdownLocked();
+ if (fallback_policy_ != nullptr) {
+ grpc_pollset_set_del_pollset_set(fallback_policy_->interested_parties(),
+ interested_parties());
+ }
+ if (pending_fallback_policy_ != nullptr) {
+ grpc_pollset_set_del_pollset_set(
+ pending_fallback_policy_->interested_parties(), interested_parties());
+ }
+ fallback_policy_.reset();
+ pending_fallback_policy_.reset();
+ // We reset the LB channels here instead of in our destructor because they
+ // hold refs to XdsLb.
+ lb_chand_.reset();
+ pending_lb_chand_.reset();
+}
+
+//
+// public methods
+//
+
+void XdsLb::ResetBackoffLocked() {
+ if (lb_chand_ != nullptr) {
+ grpc_channel_reset_connect_backoff(lb_chand_->channel());
+ }
+ if (pending_lb_chand_ != nullptr) {
+ grpc_channel_reset_connect_backoff(pending_lb_chand_->channel());
+ }
+ locality_map_.ResetBackoffLocked();
+ if (fallback_policy_ != nullptr) {
+ fallback_policy_->ResetBackoffLocked();
+ }
+ if (pending_fallback_policy_ != nullptr) {
+ pending_fallback_policy_->ResetBackoffLocked();
+ }
+}
+
+void XdsLb::ProcessAddressesAndChannelArgsLocked(
+ ServerAddressList addresses, const grpc_channel_args& args) {
+ // Update fallback address list.
+ fallback_backend_addresses_ = std::move(addresses);
+ // Make sure that GRPC_ARG_LB_POLICY_NAME is set in channel args,
+ // since we use this to trigger the client_load_reporting filter.
+ static const char* args_to_remove[] = {GRPC_ARG_LB_POLICY_NAME};
+ grpc_arg new_arg = grpc_channel_arg_string_create(
+ (char*)GRPC_ARG_LB_POLICY_NAME, (char*)"xds");
+ grpc_channel_args_destroy(args_);
+ args_ = grpc_channel_args_copy_and_add_and_remove(
+ &args, args_to_remove, GPR_ARRAY_SIZE(args_to_remove), &new_arg, 1);
+ // Construct args for balancer channel.
+ grpc_channel_args* lb_channel_args = BuildBalancerChannelArgs(&args);
+ // Create an LB channel if we don't have one yet or the balancer name has
+ // changed from the last received one.
+ bool create_lb_channel = lb_chand_ == nullptr;
+ if (lb_chand_ != nullptr) {
+ UniquePtr<char> last_balancer_name(
+ grpc_channel_get_target(LatestLbChannel()->channel()));
+ create_lb_channel =
+ strcmp(last_balancer_name.get(), balancer_name_.get()) != 0;
+ }
+ if (create_lb_channel) {
+ OrphanablePtr<LbChannelState> lb_chand = MakeOrphanable<LbChannelState>(
+ Ref(DEBUG_LOCATION, "XdsLb+LbChannelState"), balancer_name_.get(),
+ *lb_channel_args);
+ if (lb_chand_ == nullptr || !lb_chand_->HasActiveEdsCall()) {
+ GPR_ASSERT(pending_lb_chand_ == nullptr);
+ // If we do not have a working LB channel yet, use the newly created one.
+ lb_chand_ = std::move(lb_chand);
+ } else {
+ // Otherwise, wait until the new LB channel to be ready to swap it in.
+ pending_lb_chand_ = std::move(lb_chand);
+ }
+ }
+ grpc_channel_args_destroy(lb_channel_args);
+}
+
+void XdsLb::ParseLbConfig(const ParsedXdsConfig* xds_config) {
+ if (xds_config == nullptr || xds_config->balancer_name() == nullptr) return;
+ // TODO(yashykt) : does this need to be a gpr_strdup
+ // TODO(juanlishen): Read balancer name from bootstrap file.
+ balancer_name_ = UniquePtr<char>(gpr_strdup(xds_config->balancer_name()));
+ child_policy_config_ = xds_config->child_policy();
+ fallback_policy_config_ = xds_config->fallback_policy();
+}
+
+void XdsLb::UpdateLocked(UpdateArgs args) {
+ const bool is_initial_update = lb_chand_ == nullptr;
+ ParseLbConfig(static_cast<const ParsedXdsConfig*>(args.config.get()));
+ if (balancer_name_ == nullptr) {
+ gpr_log(GPR_ERROR, "[xdslb %p] LB config parsing fails.", this);
+ return;
+ }
+ ProcessAddressesAndChannelArgsLocked(std::move(args.addresses), *args.args);
+ locality_map_.UpdateLocked(locality_list_, child_policy_config_.get(), args_,
+ this, is_initial_update);
+ // Update the existing fallback policy. The fallback policy config and/or the
+ // fallback addresses may be new.
+ if (fallback_policy_ != nullptr) UpdateFallbackPolicyLocked();
+ // If this is the initial update, start the fallback-at-startup checks.
+ if (is_initial_update) {
+ grpc_millis deadline = ExecCtx::Get()->Now() + lb_fallback_timeout_ms_;
+ Ref(DEBUG_LOCATION, "on_fallback_timer").release(); // Held by closure
+ GRPC_CLOSURE_INIT(&lb_on_fallback_, &XdsLb::OnFallbackTimerLocked, this,
+ grpc_combiner_scheduler(combiner()));
+ fallback_at_startup_checks_pending_ = true;
+ grpc_timer_init(&lb_fallback_timer_, deadline, &lb_on_fallback_);
+ // Start watching the channel's connectivity state. If the channel
+ // goes into state TRANSIENT_FAILURE, we go into fallback mode even if
+ // the fallback timeout has not elapsed.
+ lb_chand_->StartConnectivityWatchLocked();
+ }
+}
+
+//
+// fallback-related methods
+//
+
+void XdsLb::MaybeCancelFallbackAtStartupChecks() {
+ if (!fallback_at_startup_checks_pending_) return;
+ gpr_log(GPR_INFO,
+ "[xdslb %p] Cancelling fallback timer and LB channel connectivity "
+ "watch",
+ this);
+ grpc_timer_cancel(&lb_fallback_timer_);
+ lb_chand_->CancelConnectivityWatchLocked();
+ fallback_at_startup_checks_pending_ = false;
+}
+
+void XdsLb::OnFallbackTimerLocked(void* arg, grpc_error* error) {
+ XdsLb* xdslb_policy = static_cast<XdsLb*>(arg);
+ // If some fallback-at-startup check is done after the timer fires but before
+ // this callback actually runs, don't fall back.
+ if (xdslb_policy->fallback_at_startup_checks_pending_ &&
+ !xdslb_policy->shutting_down_ && error == GRPC_ERROR_NONE) {
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] Child policy not ready after fallback timeout; "
+ "entering fallback mode",
+ xdslb_policy);
+ }
+ xdslb_policy->fallback_at_startup_checks_pending_ = false;
+ xdslb_policy->UpdateFallbackPolicyLocked();
+ xdslb_policy->lb_chand_->CancelConnectivityWatchLocked();
+ }
+ xdslb_policy->Unref(DEBUG_LOCATION, "on_fallback_timer");
+}
+
+void XdsLb::UpdateFallbackPolicyLocked() {
+ if (shutting_down_) return;
+ // Construct update args.
+ UpdateArgs update_args;
+ update_args.addresses = fallback_backend_addresses_;
+ update_args.config = fallback_policy_config_ == nullptr
+ ? nullptr
+ : fallback_policy_config_->Ref();
+ update_args.args = grpc_channel_args_copy(args_);
+ // If the child policy name changes, we need to create a new child
+ // policy. When this happens, we leave child_policy_ as-is and store
+ // the new child policy in pending_child_policy_. Once the new child
+ // policy transitions into state READY, we swap it into child_policy_,
+ // replacing the original child policy. So pending_child_policy_ is
+ // non-null only between when we apply an update that changes the child
+ // policy name and when the new child reports state READY.
+ //
+ // Updates can arrive at any point during this transition. We always
+ // apply updates relative to the most recently created child policy,
+ // even if the most recent one is still in pending_child_policy_. This
+ // is true both when applying the updates to an existing child policy
+ // and when determining whether we need to create a new policy.
+ //
+ // As a result of this, there are several cases to consider here:
+ //
+ // 1. We have no existing child policy (i.e., we have started up but
+ // have not yet received a serverlist from the balancer or gone
+ // into fallback mode; in this case, both child_policy_ and
+ // pending_child_policy_ are null). In this case, we create a
+ // new child policy and store it in child_policy_.
+ //
+ // 2. We have an existing child policy and have no pending child policy
+ // from a previous update (i.e., either there has not been a
+ // previous update that changed the policy name, or we have already
+ // finished swapping in the new policy; in this case, child_policy_
+ // is non-null but pending_child_policy_ is null). In this case:
+ // a. If child_policy_->name() equals child_policy_name, then we
+ // update the existing child policy.
+ // b. If child_policy_->name() does not equal child_policy_name,
+ // we create a new policy. The policy will be stored in
+ // pending_child_policy_ and will later be swapped into
+ // child_policy_ by the helper when the new child transitions
+ // into state READY.
+ //
+ // 3. We have an existing child policy and have a pending child policy
+ // from a previous update (i.e., a previous update set
+ // pending_child_policy_ as per case 2b above and that policy has
+ // not yet transitioned into state READY and been swapped into
+ // child_policy_; in this case, both child_policy_ and
+ // pending_child_policy_ are non-null). In this case:
+ // a. If pending_child_policy_->name() equals child_policy_name,
+ // then we update the existing pending child policy.
+ // b. If pending_child_policy->name() does not equal
+ // child_policy_name, then we create a new policy. The new
+ // policy is stored in pending_child_policy_ (replacing the one
+ // that was there before, which will be immediately shut down)
+ // and will later be swapped into child_policy_ by the helper
+ // when the new child transitions into state READY.
+ const char* fallback_policy_name = fallback_policy_config_ == nullptr
+ ? "round_robin"
+ : fallback_policy_config_->name();
+ const bool create_policy =
+ // case 1
+ fallback_policy_ == nullptr ||
+ // case 2b
+ (pending_fallback_policy_ == nullptr &&
+ strcmp(fallback_policy_->name(), fallback_policy_name) != 0) ||
+ // case 3b
+ (pending_fallback_policy_ != nullptr &&
+ strcmp(pending_fallback_policy_->name(), fallback_policy_name) != 0);
+ LoadBalancingPolicy* policy_to_update = nullptr;
+ if (create_policy) {
+ // Cases 1, 2b, and 3b: create a new child policy.
+ // If child_policy_ is null, we set it (case 1), else we set
+ // pending_child_policy_ (cases 2b and 3b).
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO, "[xdslb %p] Creating new %sfallback policy %s", this,
+ fallback_policy_ == nullptr ? "" : "pending ",
+ fallback_policy_name);
+ }
+ auto& lb_policy = fallback_policy_ == nullptr ? fallback_policy_
+ : pending_fallback_policy_;
+ lb_policy =
+ CreateFallbackPolicyLocked(fallback_policy_name, update_args.args);
+ policy_to_update = lb_policy.get();
+ } else {
+ // Cases 2a and 3a: update an existing policy.
+ // If we have a pending child policy, send the update to the pending
+ // policy (case 3a), else send it to the current policy (case 2a).
+ policy_to_update = pending_fallback_policy_ != nullptr
+ ? pending_fallback_policy_.get()
+ : fallback_policy_.get();
+ }
+ GPR_ASSERT(policy_to_update != nullptr);
+ // Update the policy.
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(
+ GPR_INFO, "[xdslb %p] Updating %sfallback policy %p", this,
+ policy_to_update == pending_fallback_policy_.get() ? "pending " : "",
+ policy_to_update);
+ }
+ policy_to_update->UpdateLocked(std::move(update_args));
+}
+
+OrphanablePtr<LoadBalancingPolicy> XdsLb::CreateFallbackPolicyLocked(
+ const char* name, const grpc_channel_args* args) {
+ FallbackHelper* helper =
+ New<FallbackHelper>(Ref(DEBUG_LOCATION, "FallbackHelper"));
+ LoadBalancingPolicy::Args lb_policy_args;
+ lb_policy_args.combiner = combiner();
+ lb_policy_args.args = args;
+ lb_policy_args.channel_control_helper =
+ UniquePtr<ChannelControlHelper>(helper);
+ OrphanablePtr<LoadBalancingPolicy> lb_policy =
+ LoadBalancingPolicyRegistry::CreateLoadBalancingPolicy(
+ name, std::move(lb_policy_args));
+ if (GPR_UNLIKELY(lb_policy == nullptr)) {
+ gpr_log(GPR_ERROR, "[xdslb %p] Failure creating fallback policy %s", this,
+ name);
+ return nullptr;
+ }
+ helper->set_child(lb_policy.get());
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO, "[xdslb %p] Created new fallback policy %s (%p)", this,
+ name, lb_policy.get());
+ }
+ // Add the xDS's interested_parties pollset_set to that of the newly created
+ // child policy. This will make the child policy progress upon activity on xDS
+ // LB, which in turn is tied to the application's call.
+ grpc_pollset_set_add_pollset_set(lb_policy->interested_parties(),
+ interested_parties());
+ return lb_policy;
+}
+
+void XdsLb::MaybeExitFallbackMode() {
+ if (fallback_policy_ == nullptr) return;
+ gpr_log(GPR_INFO, "[xdslb %p] Exiting fallback mode", this);
+ fallback_policy_.reset();
+ pending_fallback_policy_.reset();
+}
+
+//
+// XdsLb::LocalityMap
+//
+
+void XdsLb::LocalityMap::UpdateLocked(
+ const XdsLocalityList& locality_list,
+ LoadBalancingPolicy::Config* child_policy_config,
+ const grpc_channel_args* args, XdsLb* parent, bool is_initial_update) {
+ if (parent->shutting_down_) return;
+ // Add or update the localities in locality_list.
+ for (size_t i = 0; i < locality_list.size(); i++) {
+ auto& locality_name = locality_list[i].locality_name;
+ auto iter = map_.find(locality_name);
+ // Add a new entry in the locality map if a new locality is received in the
+ // locality list.
+ if (iter == map_.end()) {
+ OrphanablePtr<LocalityEntry> new_entry = MakeOrphanable<LocalityEntry>(
+ parent->Ref(DEBUG_LOCATION, "LocalityEntry"), locality_name);
+ iter = map_.emplace(locality_name, std::move(new_entry)).first;
+ }
+ // Keep a copy of serverlist in locality_list_ so that we can compare it
+ // with the future ones.
+ iter->second->UpdateLocked(locality_list[i].lb_weight,
+ locality_list[i].serverlist, child_policy_config,
+ args);
+ }
+ // Remove (later) the localities not in locality_list.
+ for (auto& p : map_) {
+ const XdsLocalityName* locality_name = p.first.get();
+ LocalityEntry* locality_entry = p.second.get();
+ bool in_locality_list = false;
+ for (size_t i = 0; i < locality_list.size(); ++i) {
+ if (*locality_list[i].locality_name == *locality_name) {
+ in_locality_list = true;
+ break;
+ }
+ }
+ if (!in_locality_list) locality_entry->DeactivateLocked();
+ }
+ // Generate a new xds picker immediately.
+ if (!is_initial_update) UpdateXdsPickerLocked();
+}
+
+void XdsLb::LocalityMap::UpdateXdsPickerLocked() {
+ // If we are in fallback mode, don't generate an xds picker from localities.
+ if (xds_policy_->fallback_policy_ != nullptr) return;
+ // Construct a new xds picker which maintains a map of all locality pickers
+ // that are ready. Each locality is represented by a portion of the range
+ // proportional to its weight, such that the total range is the sum of the
+ // weights of all localities.
+ uint32_t end = 0;
+ size_t num_connecting = 0;
+ size_t num_idle = 0;
+ size_t num_transient_failures = 0;
+ Picker::PickerList pickers;
+ for (auto& p : map_) {
+ const LocalityEntry* entry = p.second.get();
+ if (entry->locality_weight() == 0) continue;
+ switch (entry->connectivity_state()) {
+ case GRPC_CHANNEL_READY: {
+ end += entry->locality_weight();
+ pickers.push_back(MakePair(end, entry->picker_wrapper()));
+ break;
+ }
+ case GRPC_CHANNEL_CONNECTING: {
+ num_connecting++;
+ break;
+ }
+ case GRPC_CHANNEL_IDLE: {
+ num_idle++;
+ break;
+ }
+ case GRPC_CHANNEL_TRANSIENT_FAILURE: {
+ num_transient_failures++;
+ break;
+ }
+ default:
+ GPR_UNREACHABLE_CODE(return );
+ }
+ }
+ // Pass on the constructed xds picker if it has any ready pickers in their map
+ // otherwise pass a QueuePicker if any of the locality pickers are in a
+ // connecting or idle state, finally return a transient failure picker if all
+ // locality pickers are in transient failure.
+ if (!pickers.empty()) {
+ xds_policy_->channel_control_helper()->UpdateState(
+ GRPC_CHANNEL_READY,
+ UniquePtr<LoadBalancingPolicy::SubchannelPicker>(
+ New<Picker>(xds_policy_->Ref(DEBUG_LOCATION, "XdsLb+Picker"),
+ std::move(pickers))));
+ } else if (num_connecting > 0) {
+ xds_policy_->channel_control_helper()->UpdateState(
+ GRPC_CHANNEL_CONNECTING,
+ UniquePtr<SubchannelPicker>(
+ New<QueuePicker>(xds_policy_->Ref(DEBUG_LOCATION, "QueuePicker"))));
+ } else if (num_idle > 0) {
+ xds_policy_->channel_control_helper()->UpdateState(
+ GRPC_CHANNEL_IDLE,
+ UniquePtr<SubchannelPicker>(
+ New<QueuePicker>(xds_policy_->Ref(DEBUG_LOCATION, "QueuePicker"))));
+ } else {
+ grpc_error* error =
+ grpc_error_set_int(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+ "connections to all active localities failing"),
+ GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_UNAVAILABLE);
+ xds_policy_->channel_control_helper()->UpdateState(
+ GRPC_CHANNEL_TRANSIENT_FAILURE,
+ UniquePtr<SubchannelPicker>(New<TransientFailurePicker>(error)));
+ }
+}
+
+void XdsLb::LocalityMap::ShutdownLocked() { map_.clear(); }
+
+void XdsLb::LocalityMap::ResetBackoffLocked() {
+ for (auto& p : map_) {
+ p.second->ResetBackoffLocked();
+ }
+}
+
+//
+// XdsLb::LocalityMap::LocalityEntry
+//
+
+XdsLb::LocalityMap::LocalityEntry::LocalityEntry(
+ RefCountedPtr<XdsLb> parent, RefCountedPtr<XdsLocalityName> name)
+ : parent_(std::move(parent)), name_(std::move(name)) {
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO, "[xdslb %p] created LocalityEntry %p for %s",
+ parent_.get(), this, name_->AsHumanReadableString());
+ }
+ GRPC_CLOSURE_INIT(&on_delayed_removal_timer_, OnDelayedRemovalTimerLocked,
+ this, grpc_combiner_scheduler(parent_->combiner()));
+}
+
+XdsLb::LocalityMap::LocalityEntry::~LocalityEntry() {
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] LocalityEntry %p %s: destroying locality entry",
+ parent_.get(), this, name_->AsHumanReadableString());
+ }
+ parent_.reset(DEBUG_LOCATION, "LocalityEntry");
+}
+
+grpc_channel_args*
+XdsLb::LocalityMap::LocalityEntry::CreateChildPolicyArgsLocked(
+ const grpc_channel_args* args_in) {
+ const grpc_arg args_to_add[] = {
+ // A channel arg indicating if the target is a backend inferred from a
+ // grpclb load balancer.
+ grpc_channel_arg_integer_create(
+ const_cast<char*>(GRPC_ARG_ADDRESS_IS_BACKEND_FROM_XDS_LOAD_BALANCER),
+ 1),
+ // Inhibit client-side health checking, since the balancer does
+ // this for us.
+ grpc_channel_arg_integer_create(
+ const_cast<char*>(GRPC_ARG_INHIBIT_HEALTH_CHECKING), 1),
+ };
+ return grpc_channel_args_copy_and_add(args_in, args_to_add,
+ GPR_ARRAY_SIZE(args_to_add));
+}
+
+OrphanablePtr<LoadBalancingPolicy>
+XdsLb::LocalityMap::LocalityEntry::CreateChildPolicyLocked(
+ const char* name, const grpc_channel_args* args) {
+ Helper* helper = New<Helper>(this->Ref(DEBUG_LOCATION, "Helper"));
+ LoadBalancingPolicy::Args lb_policy_args;
+ lb_policy_args.combiner = parent_->combiner();
+ lb_policy_args.args = args;
+ lb_policy_args.channel_control_helper =
+ UniquePtr<ChannelControlHelper>(helper);
+ OrphanablePtr<LoadBalancingPolicy> lb_policy =
+ LoadBalancingPolicyRegistry::CreateLoadBalancingPolicy(
+ name, std::move(lb_policy_args));
+ if (GPR_UNLIKELY(lb_policy == nullptr)) {
+ gpr_log(GPR_ERROR,
+ "[xdslb %p] LocalityEntry %p %s: failure creating child policy %s",
+ parent_.get(), this, name_->AsHumanReadableString(), name);
+ return nullptr;
+ }
+ helper->set_child(lb_policy.get());
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] LocalityEntry %p %s: Created new child policy %s (%p)",
+ parent_.get(), this, name_->AsHumanReadableString(), name,
+ lb_policy.get());
+ }
+ // Add the xDS's interested_parties pollset_set to that of the newly created
+ // child policy. This will make the child policy progress upon activity on xDS
+ // LB, which in turn is tied to the application's call.
+ grpc_pollset_set_add_pollset_set(lb_policy->interested_parties(),
+ parent_->interested_parties());
+ return lb_policy;
+}
+
+void XdsLb::LocalityMap::LocalityEntry::UpdateLocked(
+ uint32_t locality_weight, ServerAddressList serverlist,
+ LoadBalancingPolicy::Config* child_policy_config,
+ const grpc_channel_args* args_in) {
+ if (parent_->shutting_down_) return;
+ // Update locality weight.
+ locality_weight_ = locality_weight;
+ if (delayed_removal_timer_callback_pending_) {
+ grpc_timer_cancel(&delayed_removal_timer_);
+ }
+ // Construct update args.
+ UpdateArgs update_args;
+ update_args.addresses = std::move(serverlist);
+ update_args.config =
+ child_policy_config == nullptr ? nullptr : child_policy_config->Ref();
+ update_args.args = CreateChildPolicyArgsLocked(args_in);
+ // If the child policy name changes, we need to create a new child
+ // policy. When this happens, we leave child_policy_ as-is and store
+ // the new child policy in pending_child_policy_. Once the new child
+ // policy transitions into state READY, we swap it into child_policy_,
+ // replacing the original child policy. So pending_child_policy_ is
+ // non-null only between when we apply an update that changes the child
+ // policy name and when the new child reports state READY.
+ //
+ // Updates can arrive at any point during this transition. We always
+ // apply updates relative to the most recently created child policy,
+ // even if the most recent one is still in pending_child_policy_. This
+ // is true both when applying the updates to an existing child policy
+ // and when determining whether we need to create a new policy.
+ //
+ // As a result of this, there are several cases to consider here:
+ //
+ // 1. We have no existing child policy (i.e., we have started up but
+ // have not yet received a serverlist from the balancer or gone
+ // into fallback mode; in this case, both child_policy_ and
+ // pending_child_policy_ are null). In this case, we create a
+ // new child policy and store it in child_policy_.
+ //
+ // 2. We have an existing child policy and have no pending child policy
+ // from a previous update (i.e., either there has not been a
+ // previous update that changed the policy name, or we have already
+ // finished swapping in the new policy; in this case, child_policy_
+ // is non-null but pending_child_policy_ is null). In this case:
+ // a. If child_policy_->name() equals child_policy_name, then we
+ // update the existing child policy.
+ // b. If child_policy_->name() does not equal child_policy_name,
+ // we create a new policy. The policy will be stored in
+ // pending_child_policy_ and will later be swapped into
+ // child_policy_ by the helper when the new child transitions
+ // into state READY.
+ //
+ // 3. We have an existing child policy and have a pending child policy
+ // from a previous update (i.e., a previous update set
+ // pending_child_policy_ as per case 2b above and that policy has
+ // not yet transitioned into state READY and been swapped into
+ // child_policy_; in this case, both child_policy_ and
+ // pending_child_policy_ are non-null). In this case:
+ // a. If pending_child_policy_->name() equals child_policy_name,
+ // then we update the existing pending child policy.
+ // b. If pending_child_policy->name() does not equal
+ // child_policy_name, then we create a new policy. The new
+ // policy is stored in pending_child_policy_ (replacing the one
+ // that was there before, which will be immediately shut down)
+ // and will later be swapped into child_policy_ by the helper
+ // when the new child transitions into state READY.
+ // TODO(juanlishen): If the child policy is not configured via service config,
+ // use whatever algorithm is specified by the balancer.
+ const char* child_policy_name = child_policy_config == nullptr
+ ? "round_robin"
+ : child_policy_config->name();
+ const bool create_policy =
+ // case 1
+ child_policy_ == nullptr ||
+ // case 2b
+ (pending_child_policy_ == nullptr &&
+ strcmp(child_policy_->name(), child_policy_name) != 0) ||
+ // case 3b
+ (pending_child_policy_ != nullptr &&
+ strcmp(pending_child_policy_->name(), child_policy_name) != 0);
+ LoadBalancingPolicy* policy_to_update = nullptr;
+ if (create_policy) {
+ // Cases 1, 2b, and 3b: create a new child policy.
+ // If child_policy_ is null, we set it (case 1), else we set
+ // pending_child_policy_ (cases 2b and 3b).
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] LocalityEntry %p %s: Creating new %schild policy %s",
+ parent_.get(), this, name_->AsHumanReadableString(),
+ child_policy_ == nullptr ? "" : "pending ", child_policy_name);
+ }
+ auto& lb_policy =
+ child_policy_ == nullptr ? child_policy_ : pending_child_policy_;
+ lb_policy = CreateChildPolicyLocked(child_policy_name, update_args.args);
+ policy_to_update = lb_policy.get();
+ } else {
+ // Cases 2a and 3a: update an existing policy.
+ // If we have a pending child policy, send the update to the pending
+ // policy (case 3a), else send it to the current policy (case 2a).
+ policy_to_update = pending_child_policy_ != nullptr
+ ? pending_child_policy_.get()
+ : child_policy_.get();
+ }
+ GPR_ASSERT(policy_to_update != nullptr);
+ // Update the policy.
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] LocalityEntry %p %s: Updating %schild policy %p",
+ parent_.get(), this, name_->AsHumanReadableString(),
+ policy_to_update == pending_child_policy_.get() ? "pending " : "",
+ policy_to_update);
+ }
+ policy_to_update->UpdateLocked(std::move(update_args));
+}
+
+void XdsLb::LocalityMap::LocalityEntry::ShutdownLocked() {
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] LocalityEntry %p %s: shutting down locality entry",
+ parent_.get(), this, name_->AsHumanReadableString());
+ }
+ // Remove the child policy's interested_parties pollset_set from the
+ // xDS policy.
+ grpc_pollset_set_del_pollset_set(child_policy_->interested_parties(),
+ parent_->interested_parties());
+ child_policy_.reset();
+ if (pending_child_policy_ != nullptr) {
+ grpc_pollset_set_del_pollset_set(
+ pending_child_policy_->interested_parties(),
+ parent_->interested_parties());
+ pending_child_policy_.reset();
+ }
+ // Drop our ref to the child's picker, in case it's holding a ref to
+ // the child.
+ picker_wrapper_.reset();
+ if (delayed_removal_timer_callback_pending_) {
+ grpc_timer_cancel(&delayed_removal_timer_);
+ }
+}
+
+void XdsLb::LocalityMap::LocalityEntry::ResetBackoffLocked() {
+ child_policy_->ResetBackoffLocked();
+ if (pending_child_policy_ != nullptr) {
+ pending_child_policy_->ResetBackoffLocked();
+ }
+}
+
+void XdsLb::LocalityMap::LocalityEntry::Orphan() {
+ ShutdownLocked();
+ Unref();
+}
+
+void XdsLb::LocalityMap::LocalityEntry::DeactivateLocked() {
+ // If locality retaining is disabled, delete the locality immediately.
+ if (parent_->locality_retention_interval_ms_ == 0) {
+ parent_->locality_map_.map_.erase(name_);
+ return;
+ }
+ // If already deactivated, don't do that again.
+ if (locality_weight_ == 0) return;
+ // Set the locality weight to 0 so that future xds picker won't contain this
+ // locality.
+ locality_weight_ = 0;
+ // Start a timer to delete the locality.
+ Ref(DEBUG_LOCATION, "LocalityEntry+timer").release();
+ grpc_timer_init(
+ &delayed_removal_timer_,
+ ExecCtx::Get()->Now() + parent_->locality_retention_interval_ms_,
+ &on_delayed_removal_timer_);
+ delayed_removal_timer_callback_pending_ = true;
+}
+
+void XdsLb::LocalityMap::LocalityEntry::OnDelayedRemovalTimerLocked(
+ void* arg, grpc_error* error) {
+ LocalityEntry* self = static_cast<LocalityEntry*>(arg);
+ self->delayed_removal_timer_callback_pending_ = false;
+ if (error == GRPC_ERROR_NONE && self->locality_weight_ == 0) {
+ self->parent_->locality_map_.map_.erase(self->name_);
+ }
+ self->Unref(DEBUG_LOCATION, "LocalityEntry+timer");
+}
+
+//
+// XdsLb::LocalityEntry::Helper
+//
+
+bool XdsLb::LocalityMap::LocalityEntry::Helper::CalledByPendingChild() const {
+ GPR_ASSERT(child_ != nullptr);
+ return child_ == entry_->pending_child_policy_.get();
+}
+
+bool XdsLb::LocalityMap::LocalityEntry::Helper::CalledByCurrentChild() const {
+ GPR_ASSERT(child_ != nullptr);
+ return child_ == entry_->child_policy_.get();
+}
+
+RefCountedPtr<SubchannelInterface>
+XdsLb::LocalityMap::LocalityEntry::Helper::CreateSubchannel(
+ const grpc_channel_args& args) {
+ if (entry_->parent_->shutting_down_ ||
+ (!CalledByPendingChild() && !CalledByCurrentChild())) {
+ return nullptr;
+ }
+ return entry_->parent_->channel_control_helper()->CreateSubchannel(args);
+}
+
+void XdsLb::LocalityMap::LocalityEntry::Helper::UpdateState(
+ grpc_connectivity_state state, UniquePtr<SubchannelPicker> picker) {
+ if (entry_->parent_->shutting_down_) return;
+ // If this request is from the pending child policy, ignore it until
+ // it reports READY, at which point we swap it into place.
+ if (CalledByPendingChild()) {
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p helper %p] pending child policy %p reports state=%s",
+ entry_->parent_.get(), this, entry_->pending_child_policy_.get(),
+ grpc_connectivity_state_name(state));
+ }
+ if (state != GRPC_CHANNEL_READY) return;
+ grpc_pollset_set_del_pollset_set(
+ entry_->child_policy_->interested_parties(),
+ entry_->parent_->interested_parties());
+ entry_->child_policy_ = std::move(entry_->pending_child_policy_);
+ } else if (!CalledByCurrentChild()) {
+ // This request is from an outdated child, so ignore it.
+ return;
+ }
+ // At this point, child_ must be the current child policy.
+ if (state == GRPC_CHANNEL_READY) {
+ entry_->parent_->MaybeCancelFallbackAtStartupChecks();
+ entry_->parent_->MaybeExitFallbackMode();
+ }
+ GPR_ASSERT(entry_->parent_->lb_chand_ != nullptr);
+ // Cache the picker and its state in the entry.
+ entry_->picker_wrapper_ = MakeRefCounted<PickerWrapper>(
+ std::move(picker),
+ entry_->parent_->client_stats_.FindLocalityStats(entry_->name_));
+ entry_->connectivity_state_ = state;
+ // Construct a new xds picker and pass it to the channel.
+ entry_->parent_->locality_map_.UpdateXdsPickerLocked();
+}
+
+void XdsLb::LocalityMap::LocalityEntry::Helper::RequestReresolution() {
+ if (entry_->parent_->shutting_down_) return;
+ // If there is a pending child policy, ignore re-resolution requests
+ // from the current child policy (or any outdated child).
+ if (entry_->pending_child_policy_ != nullptr && !CalledByPendingChild()) {
+ return;
+ }
+ if (GRPC_TRACE_FLAG_ENABLED(grpc_lb_xds_trace)) {
+ gpr_log(GPR_INFO,
+ "[xdslb %p] Re-resolution requested from the internal RR policy "
+ "(%p).",
+ entry_->parent_.get(), entry_->child_policy_.get());
+ }
+ GPR_ASSERT(entry_->parent_->lb_chand_ != nullptr);
+ // If we are talking to a balancer, we expect to get updated addresses
+ // from the balancer, so we can ignore the re-resolution request from
+ // the child policy. Otherwise, pass the re-resolution request up to the
+ // channel.
+ if (entry_->parent_->lb_chand_->eds_calld() == nullptr ||
+ !entry_->parent_->lb_chand_->eds_calld()->seen_response()) {
+ entry_->parent_->channel_control_helper()->RequestReresolution();
+ }
+}
+
+void XdsLb::LocalityMap::LocalityEntry::Helper::AddTraceEvent(
+ TraceSeverity severity, StringView message) {
+ if (entry_->parent_->shutting_down_ ||
+ (!CalledByPendingChild() && !CalledByCurrentChild())) {
+ return;
+ }
+ entry_->parent_->channel_control_helper()->AddTraceEvent(severity, message);
+}
+
+//
+// factory
+//
+
+class XdsFactory : public LoadBalancingPolicyFactory {
+ public:
+ OrphanablePtr<LoadBalancingPolicy> CreateLoadBalancingPolicy(
+ LoadBalancingPolicy::Args args) const override {
+ return OrphanablePtr<LoadBalancingPolicy>(New<XdsLb>(std::move(args)));
+ }
+
+ const char* name() const override { return kXds; }
+
+ RefCountedPtr<LoadBalancingPolicy::Config> ParseLoadBalancingConfig(
+ const grpc_json* json, grpc_error** error) const override {
+ GPR_DEBUG_ASSERT(error != nullptr && *error == GRPC_ERROR_NONE);
+ if (json == nullptr) {
+ // xds was mentioned as a policy in the deprecated loadBalancingPolicy
+ // field or in the client API.
+ *error = GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+ "field:loadBalancingPolicy error:Xds Parser has required field - "
+ "balancerName. Please use loadBalancingConfig field of service "
+ "config instead.");
+ return nullptr;
+ }
+ GPR_DEBUG_ASSERT(strcmp(json->key, name()) == 0);
+
+ InlinedVector<grpc_error*, 3> error_list;
+ const char* balancer_name = nullptr;
+ RefCountedPtr<LoadBalancingPolicy::Config> child_policy;
+ RefCountedPtr<LoadBalancingPolicy::Config> fallback_policy;
+ for (const grpc_json* field = json->child; field != nullptr;
+ field = field->next) {
+ if (field->key == nullptr) continue;
+ if (strcmp(field->key, "balancerName") == 0) {
+ if (balancer_name != nullptr) {
+ error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+ "field:balancerName error:Duplicate entry"));
+ }
+ if (field->type != GRPC_JSON_STRING) {
+ error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+ "field:balancerName error:type should be string"));
+ continue;
+ }
+ balancer_name = field->value;
+ } else if (strcmp(field->key, "childPolicy") == 0) {
+ if (child_policy != nullptr) {
+ error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+ "field:childPolicy error:Duplicate entry"));
+ }
+ grpc_error* parse_error = GRPC_ERROR_NONE;
+ child_policy = LoadBalancingPolicyRegistry::ParseLoadBalancingConfig(
+ field, &parse_error);
+ if (child_policy == nullptr) {
+ GPR_DEBUG_ASSERT(parse_error != GRPC_ERROR_NONE);
+ error_list.push_back(parse_error);
+ }
+ } else if (strcmp(field->key, "fallbackPolicy") == 0) {
+ if (fallback_policy != nullptr) {
+ error_list.push_back(GRPC_ERROR_CREATE_FROM_STATIC_STRING(
+ "field:fallbackPolicy error:Duplicate entry"));
+ }
+ grpc_error* parse_error = GRPC_ERROR_NONE;
+ fallback_policy = LoadBalancingPolicyRegistry::ParseLoadBalancingConfig(
+ field, &parse_error);
+ if (fallback_policy == nullptr) {
+ GPR_DEBUG_ASSERT(parse_error != GRPC_ERROR_NONE);
+ error_list.push_back(parse_error);
+ }
+ }
+ }
+ if (error_list.empty()) {
+ return RefCountedPtr<LoadBalancingPolicy::Config>(New<ParsedXdsConfig>(
+ balancer_name, std::move(child_policy), std::move(fallback_policy)));
+ } else {
+ *error = GRPC_ERROR_CREATE_FROM_VECTOR("Xds Parser", &error_list);
+ return nullptr;
+ }
+ }
+};
+
+} // namespace
+
+} // namespace grpc_core
+
+//
+// Plugin registration
+//
+
+void grpc_lb_policy_xds_init() {
+ grpc_core::LoadBalancingPolicyRegistry::Builder::
+ RegisterLoadBalancingPolicyFactory(
+ grpc_core::UniquePtr<grpc_core::LoadBalancingPolicyFactory>(
+ grpc_core::New<grpc_core::XdsFactory>()));
+}
+
+void grpc_lb_policy_xds_shutdown() {}
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