--- /dev/null
+/*
+ *
+ * Copyright 2015 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.
+ *
+ */
+
+#include <grpc/support/port_platform.h>
+
+#include "src/core/ext/filters/client_channel/resolving_lb_policy.h"
+
+#include <inttypes.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/log.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/sync.h>
+
+#include "src/core/ext/filters/client_channel/backup_poller.h"
+#include "src/core/ext/filters/client_channel/http_connect_handshaker.h"
+#include "src/core/ext/filters/client_channel/lb_policy_registry.h"
+#include "src/core/ext/filters/client_channel/proxy_mapper_registry.h"
+#include "src/core/ext/filters/client_channel/resolver_registry.h"
+#include "src/core/ext/filters/client_channel/retry_throttle.h"
+#include "src/core/ext/filters/client_channel/server_address.h"
+#include "src/core/ext/filters/client_channel/service_config.h"
+#include "src/core/ext/filters/client_channel/subchannel.h"
+#include "src/core/ext/filters/deadline/deadline_filter.h"
+#include "src/core/lib/backoff/backoff.h"
+#include "src/core/lib/channel/channel_args.h"
+#include "src/core/lib/channel/connected_channel.h"
+#include "src/core/lib/channel/status_util.h"
+#include "src/core/lib/gpr/string.h"
+#include "src/core/lib/gprpp/inlined_vector.h"
+#include "src/core/lib/gprpp/manual_constructor.h"
+#include "src/core/lib/gprpp/sync.h"
+#include "src/core/lib/iomgr/combiner.h"
+#include "src/core/lib/iomgr/iomgr.h"
+#include "src/core/lib/iomgr/polling_entity.h"
+#include "src/core/lib/profiling/timers.h"
+#include "src/core/lib/slice/slice_internal.h"
+#include "src/core/lib/slice/slice_string_helpers.h"
+#include "src/core/lib/surface/channel.h"
+#include "src/core/lib/transport/connectivity_state.h"
+#include "src/core/lib/transport/error_utils.h"
+#include "src/core/lib/transport/metadata.h"
+#include "src/core/lib/transport/metadata_batch.h"
+#include "src/core/lib/transport/static_metadata.h"
+#include "src/core/lib/transport/status_metadata.h"
+
+namespace grpc_core {
+
+//
+// ResolvingLoadBalancingPolicy::ResolverResultHandler
+//
+
+class ResolvingLoadBalancingPolicy::ResolverResultHandler
+ : public Resolver::ResultHandler {
+ public:
+ explicit ResolverResultHandler(
+ RefCountedPtr<ResolvingLoadBalancingPolicy> parent)
+ : parent_(std::move(parent)) {}
+
+ ~ResolverResultHandler() {
+ if (GRPC_TRACE_FLAG_ENABLED(*(parent_->tracer_))) {
+ gpr_log(GPR_INFO, "resolving_lb=%p: resolver shutdown complete",
+ parent_.get());
+ }
+ }
+
+ void ReturnResult(Resolver::Result result) override {
+ parent_->OnResolverResultChangedLocked(std::move(result));
+ }
+
+ void ReturnError(grpc_error* error) override {
+ parent_->OnResolverError(error);
+ }
+
+ private:
+ RefCountedPtr<ResolvingLoadBalancingPolicy> parent_;
+};
+
+//
+// ResolvingLoadBalancingPolicy::ResolvingControlHelper
+//
+
+class ResolvingLoadBalancingPolicy::ResolvingControlHelper
+ : public LoadBalancingPolicy::ChannelControlHelper {
+ public:
+ explicit ResolvingControlHelper(
+ RefCountedPtr<ResolvingLoadBalancingPolicy> parent)
+ : parent_(std::move(parent)) {}
+
+ RefCountedPtr<SubchannelInterface> CreateSubchannel(
+ const grpc_channel_args& args) override {
+ if (parent_->resolver_ == nullptr) return nullptr; // Shutting down.
+ if (!CalledByCurrentChild() && !CalledByPendingChild()) return nullptr;
+ return parent_->channel_control_helper()->CreateSubchannel(args);
+ }
+
+ void UpdateState(grpc_connectivity_state state,
+ UniquePtr<SubchannelPicker> picker) override {
+ if (parent_->resolver_ == nullptr) return; // Shutting down.
+ // 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(*(parent_->tracer_))) {
+ gpr_log(GPR_INFO,
+ "resolving_lb=%p helper=%p: pending child policy %p reports "
+ "state=%s",
+ parent_.get(), this, child_,
+ grpc_connectivity_state_name(state));
+ }
+ if (state != GRPC_CHANNEL_READY) return;
+ grpc_pollset_set_del_pollset_set(
+ parent_->lb_policy_->interested_parties(),
+ parent_->interested_parties());
+ parent_->lb_policy_ = std::move(parent_->pending_lb_policy_);
+ } else if (!CalledByCurrentChild()) {
+ // This request is from an outdated child, so ignore it.
+ return;
+ }
+ parent_->channel_control_helper()->UpdateState(state, std::move(picker));
+ }
+
+ void RequestReresolution() override {
+ // If there is a pending child policy, ignore re-resolution requests
+ // from the current child policy (or any outdated child).
+ if (parent_->pending_lb_policy_ != nullptr && !CalledByPendingChild()) {
+ return;
+ }
+ if (GRPC_TRACE_FLAG_ENABLED(*(parent_->tracer_))) {
+ gpr_log(GPR_INFO, "resolving_lb=%p: started name re-resolving",
+ parent_.get());
+ }
+ if (parent_->resolver_ != nullptr) {
+ parent_->resolver_->RequestReresolutionLocked();
+ }
+ }
+
+ void AddTraceEvent(TraceSeverity severity, StringView message) override {}
+
+ void set_child(LoadBalancingPolicy* child) { child_ = child; }
+
+ private:
+ bool CalledByPendingChild() const {
+ GPR_ASSERT(child_ != nullptr);
+ return child_ == parent_->pending_lb_policy_.get();
+ }
+
+ bool CalledByCurrentChild() const {
+ GPR_ASSERT(child_ != nullptr);
+ return child_ == parent_->lb_policy_.get();
+ };
+
+ RefCountedPtr<ResolvingLoadBalancingPolicy> parent_;
+ LoadBalancingPolicy* child_ = nullptr;
+};
+
+//
+// ResolvingLoadBalancingPolicy
+//
+
+ResolvingLoadBalancingPolicy::ResolvingLoadBalancingPolicy(
+ Args args, TraceFlag* tracer, UniquePtr<char> target_uri,
+ ProcessResolverResultCallback process_resolver_result,
+ void* process_resolver_result_user_data)
+ : LoadBalancingPolicy(std::move(args)),
+ tracer_(tracer),
+ target_uri_(std::move(target_uri)),
+ process_resolver_result_(process_resolver_result),
+ process_resolver_result_user_data_(process_resolver_result_user_data) {
+ GPR_ASSERT(process_resolver_result != nullptr);
+ resolver_ = ResolverRegistry::CreateResolver(
+ target_uri_.get(), args.args, interested_parties(), combiner(),
+ UniquePtr<Resolver::ResultHandler>(New<ResolverResultHandler>(Ref())));
+ // Since the validity of args has been checked when create the channel,
+ // CreateResolver() must return a non-null result.
+ GPR_ASSERT(resolver_ != nullptr);
+ if (GRPC_TRACE_FLAG_ENABLED(*tracer_)) {
+ gpr_log(GPR_INFO, "resolving_lb=%p: starting name resolution", this);
+ }
+ channel_control_helper()->UpdateState(
+ GRPC_CHANNEL_CONNECTING,
+ UniquePtr<SubchannelPicker>(New<QueuePicker>(Ref())));
+ resolver_->StartLocked();
+}
+
+ResolvingLoadBalancingPolicy::~ResolvingLoadBalancingPolicy() {
+ GPR_ASSERT(resolver_ == nullptr);
+ GPR_ASSERT(lb_policy_ == nullptr);
+}
+
+void ResolvingLoadBalancingPolicy::ShutdownLocked() {
+ if (resolver_ != nullptr) {
+ resolver_.reset();
+ if (lb_policy_ != nullptr) {
+ if (GRPC_TRACE_FLAG_ENABLED(*tracer_)) {
+ gpr_log(GPR_INFO, "resolving_lb=%p: shutting down lb_policy=%p", this,
+ lb_policy_.get());
+ }
+ grpc_pollset_set_del_pollset_set(lb_policy_->interested_parties(),
+ interested_parties());
+ lb_policy_.reset();
+ }
+ if (pending_lb_policy_ != nullptr) {
+ if (GRPC_TRACE_FLAG_ENABLED(*tracer_)) {
+ gpr_log(GPR_INFO, "resolving_lb=%p: shutting down pending lb_policy=%p",
+ this, pending_lb_policy_.get());
+ }
+ grpc_pollset_set_del_pollset_set(pending_lb_policy_->interested_parties(),
+ interested_parties());
+ pending_lb_policy_.reset();
+ }
+ }
+}
+
+void ResolvingLoadBalancingPolicy::ExitIdleLocked() {
+ if (lb_policy_ != nullptr) {
+ lb_policy_->ExitIdleLocked();
+ if (pending_lb_policy_ != nullptr) pending_lb_policy_->ExitIdleLocked();
+ }
+}
+
+void ResolvingLoadBalancingPolicy::ResetBackoffLocked() {
+ if (resolver_ != nullptr) {
+ resolver_->ResetBackoffLocked();
+ resolver_->RequestReresolutionLocked();
+ }
+ if (lb_policy_ != nullptr) lb_policy_->ResetBackoffLocked();
+ if (pending_lb_policy_ != nullptr) pending_lb_policy_->ResetBackoffLocked();
+}
+
+void ResolvingLoadBalancingPolicy::OnResolverError(grpc_error* error) {
+ if (resolver_ == nullptr) {
+ GRPC_ERROR_UNREF(error);
+ return;
+ }
+ if (GRPC_TRACE_FLAG_ENABLED(*tracer_)) {
+ gpr_log(GPR_INFO, "resolving_lb=%p: resolver transient failure: %s", this,
+ grpc_error_string(error));
+ }
+ // If we already have an LB policy from a previous resolution
+ // result, then we continue to let it set the connectivity state.
+ // Otherwise, we go into TRANSIENT_FAILURE.
+ if (lb_policy_ == nullptr) {
+ grpc_error* state_error = GRPC_ERROR_CREATE_REFERENCING_FROM_STATIC_STRING(
+ "Resolver transient failure", &error, 1);
+ channel_control_helper()->UpdateState(
+ GRPC_CHANNEL_TRANSIENT_FAILURE,
+ UniquePtr<SubchannelPicker>(New<TransientFailurePicker>(state_error)));
+ }
+ GRPC_ERROR_UNREF(error);
+}
+
+void ResolvingLoadBalancingPolicy::CreateOrUpdateLbPolicyLocked(
+ const char* lb_policy_name,
+ RefCountedPtr<LoadBalancingPolicy::Config> lb_policy_config,
+ Resolver::Result result, TraceStringVector* trace_strings) {
+ // 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 bool create_policy =
+ // case 1
+ lb_policy_ == nullptr ||
+ // case 2b
+ (pending_lb_policy_ == nullptr &&
+ strcmp(lb_policy_->name(), lb_policy_name) != 0) ||
+ // case 3b
+ (pending_lb_policy_ != nullptr &&
+ strcmp(pending_lb_policy_->name(), lb_policy_name) != 0);
+ LoadBalancingPolicy* policy_to_update = nullptr;
+ if (create_policy) {
+ // Cases 1, 2b, and 3b: create a new child policy.
+ // If lb_policy_ is null, we set it (case 1), else we set
+ // pending_lb_policy_ (cases 2b and 3b).
+ if (GRPC_TRACE_FLAG_ENABLED(*tracer_)) {
+ gpr_log(GPR_INFO, "resolving_lb=%p: Creating new %schild policy %s", this,
+ lb_policy_ == nullptr ? "" : "pending ", lb_policy_name);
+ }
+ auto& lb_policy = lb_policy_ == nullptr ? lb_policy_ : pending_lb_policy_;
+ lb_policy =
+ CreateLbPolicyLocked(lb_policy_name, *result.args, trace_strings);
+ 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_lb_policy_ != nullptr ? pending_lb_policy_.get()
+ : lb_policy_.get();
+ }
+ GPR_ASSERT(policy_to_update != nullptr);
+ // Update the policy.
+ if (GRPC_TRACE_FLAG_ENABLED(*tracer_)) {
+ gpr_log(GPR_INFO, "resolving_lb=%p: Updating %schild policy %p", this,
+ policy_to_update == pending_lb_policy_.get() ? "pending " : "",
+ policy_to_update);
+ }
+ UpdateArgs update_args;
+ update_args.addresses = std::move(result.addresses);
+ update_args.config = std::move(lb_policy_config);
+ // TODO(roth): Once channel args is converted to C++, use std::move() here.
+ update_args.args = result.args;
+ result.args = nullptr;
+ policy_to_update->UpdateLocked(std::move(update_args));
+}
+
+// Creates a new LB policy.
+// Updates trace_strings to indicate what was done.
+OrphanablePtr<LoadBalancingPolicy>
+ResolvingLoadBalancingPolicy::CreateLbPolicyLocked(
+ const char* lb_policy_name, const grpc_channel_args& args,
+ TraceStringVector* trace_strings) {
+ ResolvingControlHelper* helper = New<ResolvingControlHelper>(Ref());
+ LoadBalancingPolicy::Args lb_policy_args;
+ lb_policy_args.combiner = combiner();
+ lb_policy_args.channel_control_helper =
+ UniquePtr<ChannelControlHelper>(helper);
+ lb_policy_args.args = &args;
+ OrphanablePtr<LoadBalancingPolicy> lb_policy =
+ LoadBalancingPolicyRegistry::CreateLoadBalancingPolicy(
+ lb_policy_name, std::move(lb_policy_args));
+ if (GPR_UNLIKELY(lb_policy == nullptr)) {
+ gpr_log(GPR_ERROR, "could not create LB policy \"%s\"", lb_policy_name);
+ char* str;
+ gpr_asprintf(&str, "Could not create LB policy \"%s\"", lb_policy_name);
+ trace_strings->push_back(str);
+ return nullptr;
+ }
+ helper->set_child(lb_policy.get());
+ if (GRPC_TRACE_FLAG_ENABLED(*tracer_)) {
+ gpr_log(GPR_INFO, "resolving_lb=%p: created new LB policy \"%s\" (%p)",
+ this, lb_policy_name, lb_policy.get());
+ }
+ char* str;
+ gpr_asprintf(&str, "Created new LB policy \"%s\"", lb_policy_name);
+ trace_strings->push_back(str);
+ grpc_pollset_set_add_pollset_set(lb_policy->interested_parties(),
+ interested_parties());
+ return lb_policy;
+}
+
+void ResolvingLoadBalancingPolicy::MaybeAddTraceMessagesForAddressChangesLocked(
+ bool resolution_contains_addresses, TraceStringVector* trace_strings) {
+ if (!resolution_contains_addresses &&
+ previous_resolution_contained_addresses_) {
+ trace_strings->push_back(gpr_strdup("Address list became empty"));
+ } else if (resolution_contains_addresses &&
+ !previous_resolution_contained_addresses_) {
+ trace_strings->push_back(gpr_strdup("Address list became non-empty"));
+ }
+ previous_resolution_contained_addresses_ = resolution_contains_addresses;
+}
+
+void ResolvingLoadBalancingPolicy::ConcatenateAndAddChannelTraceLocked(
+ TraceStringVector* trace_strings) const {
+ if (!trace_strings->empty()) {
+ gpr_strvec v;
+ gpr_strvec_init(&v);
+ gpr_strvec_add(&v, gpr_strdup("Resolution event: "));
+ bool is_first = 1;
+ for (size_t i = 0; i < trace_strings->size(); ++i) {
+ if (!is_first) gpr_strvec_add(&v, gpr_strdup(", "));
+ is_first = false;
+ gpr_strvec_add(&v, (*trace_strings)[i]);
+ }
+ size_t len = 0;
+ UniquePtr<char> message(gpr_strvec_flatten(&v, &len));
+ channel_control_helper()->AddTraceEvent(ChannelControlHelper::TRACE_INFO,
+ StringView(message.get()));
+ gpr_strvec_destroy(&v);
+ }
+}
+
+void ResolvingLoadBalancingPolicy::OnResolverResultChangedLocked(
+ Resolver::Result result) {
+ // Handle race conditions.
+ if (resolver_ == nullptr) return;
+ if (GRPC_TRACE_FLAG_ENABLED(*tracer_)) {
+ gpr_log(GPR_INFO, "resolving_lb=%p: got resolver result", this);
+ }
+ // We only want to trace the address resolution in the follow cases:
+ // (a) Address resolution resulted in service config change.
+ // (b) Address resolution that causes number of backends to go from
+ // zero to non-zero.
+ // (c) Address resolution that causes number of backends to go from
+ // non-zero to zero.
+ // (d) Address resolution that causes a new LB policy to be created.
+ //
+ // We track a list of strings to eventually be concatenated and traced.
+ TraceStringVector trace_strings;
+ const bool resolution_contains_addresses = result.addresses.size() > 0;
+ // Process the resolver result.
+ const char* lb_policy_name = nullptr;
+ RefCountedPtr<LoadBalancingPolicy::Config> lb_policy_config;
+ bool service_config_changed = false;
+ char* service_config_error_string = nullptr;
+ if (process_resolver_result_ != nullptr) {
+ grpc_error* service_config_error = GRPC_ERROR_NONE;
+ service_config_changed = process_resolver_result_(
+ process_resolver_result_user_data_, result, &lb_policy_name,
+ &lb_policy_config, &service_config_error);
+ if (service_config_error != GRPC_ERROR_NONE) {
+ service_config_error_string =
+ gpr_strdup(grpc_error_string(service_config_error));
+ if (lb_policy_name == nullptr) {
+ // Use an empty lb_policy_name as an indicator that we received an
+ // invalid service config and we don't have a fallback service config.
+ OnResolverError(service_config_error);
+ } else {
+ GRPC_ERROR_UNREF(service_config_error);
+ }
+ }
+ } else {
+ lb_policy_name = child_policy_name_.get();
+ lb_policy_config = child_lb_config_;
+ }
+ if (lb_policy_name != nullptr) {
+ // Create or update LB policy, as needed.
+ CreateOrUpdateLbPolicyLocked(lb_policy_name, lb_policy_config,
+ std::move(result), &trace_strings);
+ }
+ // Add channel trace event.
+ if (service_config_changed) {
+ // TODO(ncteisen): might be worth somehow including a snippet of the
+ // config in the trace, at the risk of bloating the trace logs.
+ trace_strings.push_back(gpr_strdup("Service config changed"));
+ }
+ if (service_config_error_string != nullptr) {
+ trace_strings.push_back(service_config_error_string);
+ service_config_error_string = nullptr;
+ }
+ MaybeAddTraceMessagesForAddressChangesLocked(resolution_contains_addresses,
+ &trace_strings);
+ ConcatenateAndAddChannelTraceLocked(&trace_strings);
+}
+
+} // namespace grpc_core
git://repos.xcallymotion.com / motion2.git / blobdiff