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/*
*
* Copyright 2015-2016, Google Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* 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
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
/*
* wakeup_fd abstracts the concept of a file descriptor for the purpose of
* waking up a thread in select()/poll()/epoll_wait()/etc.
* The poll() family of system calls provide a way for a thread to block until
* there is activity on one (or more) of a set of file descriptors. An
* application may wish to wake up this thread to do non file related work. The
* typical way to do this is to add a pipe to the set of file descriptors, then
* write to the pipe to wake up the thread in poll().
*
* Linux has a lighter weight eventfd specifically designed for this purpose.
* wakeup_fd abstracts the difference between the two.
*
* Setup:
* 1. Before calling anything, call global_init() at least once.
* 1. Call grpc_wakeup_fd_create() to get a wakeup_fd.
* 2. Add the result of GRPC_WAKEUP_FD_FD to the set of monitored file
* descriptors for the poll() style API you are using. Monitor the file
* descriptor for readability.
* 3. To tear down, call grpc_wakeup_fd_destroy(). This closes the underlying
* file descriptor.
*
* Usage:
* 1. To wake up a polling thread, call grpc_wakeup_fd_wakeup() on a wakeup_fd
* it is monitoring.
* 2. If the polling thread was awakened by a wakeup_fd event, call
* grpc_wakeup_fd_consume_wakeup() on it.
*/
#ifndef GRPC_CORE_LIB_IOMGR_WAKEUP_FD_POSIX_H
#define GRPC_CORE_LIB_IOMGR_WAKEUP_FD_POSIX_H
void grpc_wakeup_fd_global_init(void);
void grpc_wakeup_fd_global_destroy(void);
/* Force using the fallback implementation. This is intended for testing
* purposes only.*/
void grpc_wakeup_fd_global_init_force_fallback(void);
typedef struct grpc_wakeup_fd grpc_wakeup_fd;
typedef struct grpc_wakeup_fd_vtable {
void (*init)(grpc_wakeup_fd* fd_info);
void (*consume)(grpc_wakeup_fd* fd_info);
void (*wakeup)(grpc_wakeup_fd* fd_info);
void (*destroy)(grpc_wakeup_fd* fd_info);
/* Must be called before calling any other functions */
int (*check_availability)(void);
} grpc_wakeup_fd_vtable;
struct grpc_wakeup_fd {
int read_fd;
int write_fd;
};
extern int grpc_allow_specialized_wakeup_fd;
#define GRPC_WAKEUP_FD_GET_READ_FD(fd_info) ((fd_info)->read_fd)
void grpc_wakeup_fd_init(grpc_wakeup_fd* fd_info);
void grpc_wakeup_fd_consume_wakeup(grpc_wakeup_fd* fd_info);
void grpc_wakeup_fd_wakeup(grpc_wakeup_fd* fd_info);
void grpc_wakeup_fd_destroy(grpc_wakeup_fd* fd_info);
/* Defined in some specialized implementation's .c file, or by
* wakeup_fd_nospecial.c if no such implementation exists. */
extern const grpc_wakeup_fd_vtable grpc_specialized_wakeup_fd_vtable;
#endif /* GRPC_CORE_LIB_IOMGR_WAKEUP_FD_POSIX_H */
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