third_party/grpc/src/core/iomgr/exec_ctx.h

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#ifndef GRPC_INTERNAL_CORE_IOMGR_EXEC_CTX_H
#define GRPC_INTERNAL_CORE_IOMGR_EXEC_CTX_H

#include "src/core/iomgr/closure.h"

/** 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)
 *
 *  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;
};

/** A workqueue represents a list of work to be executed asynchronously.
    Forward declared here to avoid a circular dependency with workqueue.h. */
struct grpc_workqueue;
typedef struct grpc_workqueue grpc_workqueue;

#define GRPC_EXEC_CTX_INIT \
  { GRPC_CLOSURE_LIST_INIT }

/** 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);
/** Add a closure to be executed at the next flush/finish point */
void grpc_exec_ctx_enqueue(grpc_exec_ctx *exec_ctx, grpc_closure *closure,
                           bool success,
                           grpc_workqueue *offload_target_or_null);
/** Add a list of closures to be executed at the next flush/finish point.
 *  Leaves \a list empty. */
void grpc_exec_ctx_enqueue_list(grpc_exec_ctx *exec_ctx,
                                grpc_closure_list *list,
                                grpc_workqueue *offload_target_or_null);

#endif