src/core/lib/iomgr/pollset.h

/*
 *
 * Copyright 2015-2016, Google Inc.
 * All rights reserved.
 *
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 * modification, are permitted provided that the following conditions are
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 *
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 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
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 * this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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#ifndef GRPC_CORE_LIB_IOMGR_POLLSET_H
#define GRPC_CORE_LIB_IOMGR_POLLSET_H

#include <grpc/support/port_platform.h>
#include <grpc/support/sync.h>
#include <grpc/support/time.h>

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

#define GRPC_POLLSET_KICK_BROADCAST ((grpc_pollset_worker *)1)

/* A grpc_pollset is a set of file descriptors that a higher level item is
   interested in. For example:
    - a server will typically keep a pollset containing all connected channels,
      so that it can find new calls to service
    - a completion queue might keep a pollset with an entry for each transport
      that is servicing a call that it's tracking */

typedef struct grpc_pollset grpc_pollset;
typedef struct grpc_pollset_worker grpc_pollset_worker;

size_t grpc_pollset_size(void);
void grpc_pollset_init(grpc_pollset *pollset, gpr_mu **mu);
/* Begin shutting down the pollset, and call closure when done.
 * pollset's mutex must be held */
void grpc_pollset_shutdown(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
                           grpc_closure *closure);
/** Reset the pollset to its initial state (perhaps with some cached objects);
 *  must have been previously shutdown */
void grpc_pollset_reset(grpc_pollset *pollset);
void grpc_pollset_destroy(grpc_pollset *pollset);

/* Do some work on a pollset.
   May involve invoking asynchronous callbacks, or actually polling file
   descriptors.
   Requires pollset's mutex locked.
   May unlock its mutex during its execution.

   worker is a (platform-specific) handle that can be used to wake up
   from grpc_pollset_work before any events are received and before the timeout
   has expired. It is both initialized and destroyed by grpc_pollset_work.
   Initialization of worker is guaranteed to occur BEFORE the
   pollset's mutex is released for the first time by grpc_pollset_work
   and it is guaranteed that it will not be released by grpc_pollset_work
   AFTER worker has been destroyed.

   Tries not to block past deadline.
   May call grpc_closure_list_run on grpc_closure_list, without holding the
   pollset
   lock */
void grpc_pollset_work(grpc_exec_ctx *exec_ctx, grpc_pollset *pollset,
                       grpc_pollset_worker **worker, gpr_timespec now,
                       gpr_timespec deadline);

/* Break one polling thread out of polling work for this pollset.
   If specific_worker is GRPC_POLLSET_KICK_BROADCAST, kick ALL the workers.
   Otherwise, if specific_worker is non-NULL, then kick that worker. */
void grpc_pollset_kick(grpc_pollset *pollset,
                       grpc_pollset_worker *specific_worker);

#endif /* GRPC_CORE_LIB_IOMGR_POLLSET_H */