3 * Copyright 2015 gRPC authors.
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
9 * http://www.apache.org/licenses/LICENSE-2.0
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
19 #ifndef GRPC_CORE_LIB_CHANNEL_CHANNEL_STACK_H
20 #define GRPC_CORE_LIB_CHANNEL_CHANNEL_STACK_H
22 //////////////////////////////////////////////////////////////////////////////
25 // When you update this API, please make the corresponding changes to
26 // the C++ API in src/cpp/common/channel_filter.{h,cc}
27 //////////////////////////////////////////////////////////////////////////////
29 /* A channel filter defines how operations on a channel are implemented.
30 Channel filters are chained together to create full channels, and if those
31 chains are linear, then channel stacks provide a mechanism to minimize
32 allocations for that chain.
33 Call stacks are created by channel stacks and represent the per-call data
36 #include <grpc/support/port_platform.h>
40 #include <grpc/grpc.h>
41 #include <grpc/support/log.h>
42 #include <grpc/support/time.h>
44 #include "src/core/lib/debug/trace.h"
45 #include "src/core/lib/gpr/time_precise.h"
46 #include "src/core/lib/gprpp/arena.h"
47 #include "src/core/lib/iomgr/call_combiner.h"
48 #include "src/core/lib/iomgr/polling_entity.h"
49 #include "src/core/lib/transport/transport.h"
51 typedef struct grpc_channel_element grpc_channel_element;
52 typedef struct grpc_call_element grpc_call_element;
54 typedef struct grpc_channel_stack grpc_channel_stack;
55 typedef struct grpc_call_stack grpc_call_stack;
58 grpc_channel_stack* channel_stack;
59 const grpc_channel_args* channel_args;
60 /** Transport, iff it is known */
61 grpc_transport* optional_transport;
64 } grpc_channel_element_args;
67 grpc_call_stack* call_stack;
68 const void* server_transport_data;
69 grpc_call_context_element* context;
70 const grpc_slice& path;
71 gpr_cycle_counter start_time;
73 grpc_core::Arena* arena;
74 grpc_core::CallCombiner* call_combiner;
75 } grpc_call_element_args;
78 grpc_transport_stream_stats transport_stream_stats;
79 gpr_timespec latency; /* From call creating to enqueing of received status */
82 /** Information about the call upon completion. */
83 struct grpc_call_final_info {
84 grpc_call_stats stats;
85 grpc_status_code final_status = GRPC_STATUS_OK;
86 const char* error_string = nullptr;
89 /* Channel filters specify:
90 1. the amount of memory needed in the channel & call (via the sizeof_XXX
92 2. functions to initialize and destroy channel & call data
93 (init_XXX, destroy_XXX)
94 3. functions to implement call operations and channel operations (call_op,
96 4. a name, which is useful when debugging
98 Members are laid out in approximate frequency of use order. */
100 /* Called to eg. send/receive data on a call.
101 See grpc_call_next_op on how to call the next element in the stack */
102 void (*start_transport_stream_op_batch)(grpc_call_element* elem,
103 grpc_transport_stream_op_batch* op);
104 /* Called to handle channel level operations - e.g. new calls, or transport
106 See grpc_channel_next_op on how to call the next element in the stack */
107 void (*start_transport_op)(grpc_channel_element* elem, grpc_transport_op* op);
109 /* sizeof(per call data) */
110 size_t sizeof_call_data;
111 /* Initialize per call data.
112 elem is initialized at the start of the call, and elem->call_data is what
114 The filter does not need to do any chaining.
115 server_transport_data is an opaque pointer. If it is NULL, this call is
116 on a client; if it is non-NULL, then it points to memory owned by the
117 transport and is on the server. Most filters want to ignore this
119 Implementations may assume that elem->call_data is all zeros. */
120 grpc_error* (*init_call_elem)(grpc_call_element* elem,
121 const grpc_call_element_args* args);
122 void (*set_pollset_or_pollset_set)(grpc_call_element* elem,
123 grpc_polling_entity* pollent);
124 /* Destroy per call data.
125 The filter does not need to do any chaining.
126 The bottom filter of a stack will be passed a non-NULL pointer to
127 \a then_schedule_closure that should be passed to GRPC_CLOSURE_SCHED when
128 destruction is complete. \a final_info contains data about the completed
129 call, mainly for reporting purposes. */
130 void (*destroy_call_elem)(grpc_call_element* elem,
131 const grpc_call_final_info* final_info,
132 grpc_closure* then_schedule_closure);
134 /* sizeof(per channel data) */
135 size_t sizeof_channel_data;
136 /* Initialize per-channel data.
137 elem is initialized at the creating of the channel, and elem->channel_data
138 is what needs initializing.
139 is_first, is_last designate this elements position in the stack, and are
140 useful for asserting correct configuration by upper layer code.
141 The filter does not need to do any chaining.
142 Implementations may assume that elem->channel_data is all zeros. */
143 grpc_error* (*init_channel_elem)(grpc_channel_element* elem,
144 grpc_channel_element_args* args);
145 /* Destroy per channel data.
146 The filter does not need to do any chaining */
147 void (*destroy_channel_elem)(grpc_channel_element* elem);
149 /* Implement grpc_channel_get_info() */
150 void (*get_channel_info)(grpc_channel_element* elem,
151 const grpc_channel_info* channel_info);
153 /* The name of this filter */
155 } grpc_channel_filter;
157 /* A channel_element tracks its filter and the filter requested memory within
158 a channel allocation */
159 struct grpc_channel_element {
160 const grpc_channel_filter* filter;
164 /* A call_element tracks its filter, the filter requested memory within
165 a channel allocation, and the filter requested memory within a call
167 struct grpc_call_element {
168 const grpc_channel_filter* filter;
173 /* A channel stack tracks a set of related filters for one channel, and
174 guarantees they live within a single malloc() allocation */
175 struct grpc_channel_stack {
176 grpc_stream_refcount refcount;
178 /* Memory required for a call stack (computed at channel stack
180 size_t call_stack_size;
183 /* A call stack tracks a set of related filters for one call, and guarantees
184 they live within a single malloc() allocation */
185 struct grpc_call_stack {
186 /* shared refcount for this channel stack.
187 MUST be the first element: the underlying code calls destroy
188 with the address of the refcount, but higher layers prefer to think
189 about the address of the call stack itself. */
190 grpc_stream_refcount refcount;
194 /* Get a channel element given a channel stack and its index */
195 grpc_channel_element* grpc_channel_stack_element(grpc_channel_stack* stack,
197 /* Get the last channel element in a channel stack */
198 grpc_channel_element* grpc_channel_stack_last_element(
199 grpc_channel_stack* stack);
200 /* Get a call stack element given a call stack and an index */
201 grpc_call_element* grpc_call_stack_element(grpc_call_stack* stack, size_t i);
203 /* Determine memory required for a channel stack containing a set of filters */
204 size_t grpc_channel_stack_size(const grpc_channel_filter** filters,
205 size_t filter_count);
206 /* Initialize a channel stack given some filters */
207 grpc_error* grpc_channel_stack_init(
208 int initial_refs, grpc_iomgr_cb_func destroy, void* destroy_arg,
209 const grpc_channel_filter** filters, size_t filter_count,
210 const grpc_channel_args* args, grpc_transport* optional_transport,
211 const char* name, grpc_channel_stack* stack);
212 /* Destroy a channel stack */
213 void grpc_channel_stack_destroy(grpc_channel_stack* stack);
215 /* Initialize a call stack given a channel stack. transport_server_data is
216 expected to be NULL on a client, or an opaque transport owned pointer on the
218 grpc_error* grpc_call_stack_init(grpc_channel_stack* channel_stack,
219 int initial_refs, grpc_iomgr_cb_func destroy,
221 const grpc_call_element_args* elem_args);
222 /* Set a pollset or a pollset_set for a call stack: must occur before the first
224 void grpc_call_stack_set_pollset_or_pollset_set(grpc_call_stack* call_stack,
225 grpc_polling_entity* pollent);
228 #define GRPC_CALL_STACK_REF(call_stack, reason) \
229 grpc_stream_ref(&(call_stack)->refcount, reason)
230 #define GRPC_CALL_STACK_UNREF(call_stack, reason) \
231 grpc_stream_unref(&(call_stack)->refcount, reason)
232 #define GRPC_CHANNEL_STACK_REF(channel_stack, reason) \
233 grpc_stream_ref(&(channel_stack)->refcount, reason)
234 #define GRPC_CHANNEL_STACK_UNREF(channel_stack, reason) \
235 grpc_stream_unref(&(channel_stack)->refcount, reason)
237 #define GRPC_CALL_STACK_REF(call_stack, reason) \
238 grpc_stream_ref(&(call_stack)->refcount)
239 #define GRPC_CALL_STACK_UNREF(call_stack, reason) \
240 grpc_stream_unref(&(call_stack)->refcount)
241 #define GRPC_CHANNEL_STACK_REF(channel_stack, reason) \
242 grpc_stream_ref(&(channel_stack)->refcount)
243 #define GRPC_CHANNEL_STACK_UNREF(channel_stack, reason) \
244 grpc_stream_unref(&(channel_stack)->refcount)
247 /* Destroy a call stack */
248 void grpc_call_stack_destroy(grpc_call_stack* stack,
249 const grpc_call_final_info* final_info,
250 grpc_closure* then_schedule_closure);
252 /* Ignore set pollset{_set} - used by filters if they don't care about pollsets
253 * at all. Does nothing. */
254 void grpc_call_stack_ignore_set_pollset_or_pollset_set(
255 grpc_call_element* elem, grpc_polling_entity* pollent);
256 /* Call the next operation in a call stack */
257 void grpc_call_next_op(grpc_call_element* elem,
258 grpc_transport_stream_op_batch* op);
259 /* Call the next operation (depending on call directionality) in a channel
261 void grpc_channel_next_op(grpc_channel_element* elem, grpc_transport_op* op);
262 /* Pass through a request to get_channel_info() to the next child element */
263 void grpc_channel_next_get_info(grpc_channel_element* elem,
264 const grpc_channel_info* channel_info);
266 /* Given the top element of a channel stack, get the channel stack itself */
267 grpc_channel_stack* grpc_channel_stack_from_top_element(
268 grpc_channel_element* elem);
269 /* Given the top element of a call stack, get the call stack itself */
270 grpc_call_stack* grpc_call_stack_from_top_element(grpc_call_element* elem);
272 void grpc_call_log_op(const char* file, int line, gpr_log_severity severity,
273 grpc_call_element* elem,
274 grpc_transport_stream_op_batch* op);
276 extern grpc_core::TraceFlag grpc_trace_channel;
278 #define GRPC_CALL_LOG_OP(sev, elem, op) \
280 if (GRPC_TRACE_FLAG_ENABLED(grpc_trace_channel)) { \
281 grpc_call_log_op(sev, elem, op); \
285 #endif /* GRPC_CORE_LIB_CHANNEL_CHANNEL_STACK_H */