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/*
*
* 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.
*
*/
#ifndef GRPC_CORE_LIB_IOMGR_EXEC_CTX_H
#define GRPC_CORE_LIB_IOMGR_EXEC_CTX_H
#include "src/core/lib/iomgr/closure.h"
/* #define GRPC_EXECUTION_CONTEXT_SANITIZER 1 */
/** A workqueue represents a list of work to be executed asynchronously.
Forward declared here to avoid a circular dependency with workqueue.h. */
typedef struct grpc_workqueue grpc_workqueue;
typedef struct grpc_combiner grpc_combiner;
/* This exec_ctx is ready to return: either pre-populated, or cached as soon as
the finish_check returns true */
#define GRPC_EXEC_CTX_FLAG_IS_FINISHED 1
/* The exec_ctx's thread is (potentially) owned by a call or channel: care
should be given to not delete said call/channel from this exec_ctx */
#define GRPC_EXEC_CTX_FLAG_THREAD_RESOURCE_LOOP 2
/** Execution context.
* A bag of data that collects information along a callstack.
* Generally created at public API entry points, and passed down as
* pointer to child functions that manipulate it.
*
* Specific responsibilities (this may grow in the future):
* - track a list of work that needs to be delayed until the top of the
* call stack (this provides a convenient mechanism to run callbacks
* without worrying about locking issues)
* - provide a decision maker (via grpc_exec_ctx_ready_to_finish) that provides
* signal as to whether a borrowed thread should continue to do work or
* should actively try to finish up and get this thread back to its owner
*
* CONVENTIONS:
* - Instance of this must ALWAYS be constructed on the stack, never
* heap allocated.
* - Instances and pointers to them must always be called exec_ctx.
* - Instances are always passed as the first argument to a function that
* takes it, and always as a pointer (grpc_exec_ctx is never copied).
*/
struct grpc_exec_ctx {
grpc_closure_list closure_list;
/** currently active combiner: updated only via combiner.c */
grpc_combiner *active_combiner;
/** last active combiner in the active combiner list */
grpc_combiner *last_combiner;
uintptr_t flags;
void *check_ready_to_finish_arg;
bool (*check_ready_to_finish)(grpc_exec_ctx *exec_ctx, void *arg);
};
/* initializer for grpc_exec_ctx:
prefer to use GRPC_EXEC_CTX_INIT whenever possible */
#define GRPC_EXEC_CTX_INITIALIZER(flags, finish_check, finish_check_arg) \
{ GRPC_CLOSURE_LIST_INIT, NULL, NULL, flags, finish_check_arg, finish_check }
/* initialize an execution context at the top level of an API call into grpc
(this is safe to use elsewhere, though possibly not as efficient) */
#define GRPC_EXEC_CTX_INIT \
GRPC_EXEC_CTX_INITIALIZER(GRPC_EXEC_CTX_FLAG_IS_FINISHED, NULL, NULL)
extern grpc_closure_scheduler *grpc_schedule_on_exec_ctx;
bool grpc_exec_ctx_has_work(grpc_exec_ctx *exec_ctx);
/** Flush any work that has been enqueued onto this grpc_exec_ctx.
* Caller must guarantee that no interfering locks are held.
* Returns true if work was performed, false otherwise. */
bool grpc_exec_ctx_flush(grpc_exec_ctx *exec_ctx);
/** Finish any pending work for a grpc_exec_ctx. Must be called before
* the instance is destroyed, or work may be lost. */
void grpc_exec_ctx_finish(grpc_exec_ctx *exec_ctx);
/** Returns true if we'd like to leave this execution context as soon as
possible: useful for deciding whether to do something more or not depending
on outside context */
bool grpc_exec_ctx_ready_to_finish(grpc_exec_ctx *exec_ctx);
/** A finish check that is never ready to finish */
bool grpc_never_ready_to_finish(grpc_exec_ctx *exec_ctx, void *arg_ignored);
/** A finish check that is always ready to finish */
bool grpc_always_ready_to_finish(grpc_exec_ctx *exec_ctx, void *arg_ignored);
void grpc_exec_ctx_global_init(void);
void grpc_exec_ctx_global_init(void);
void grpc_exec_ctx_global_shutdown(void);
#endif /* GRPC_CORE_LIB_IOMGR_EXEC_CTX_H */
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