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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.
*
*/
/*
* 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_init() to set up 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
#include "src/core/lib/iomgr/error.h"
#ifdef __cplusplus
extern "C" {
#endif
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);
int grpc_has_wakeup_fd(void);
int grpc_cv_wakeup_fds_enabled(void);
void grpc_enable_cv_wakeup_fds(int enable);
typedef struct grpc_wakeup_fd grpc_wakeup_fd;
typedef struct grpc_wakeup_fd_vtable {
grpc_error* (*init)(grpc_wakeup_fd* fd_info);
grpc_error* (*consume)(grpc_wakeup_fd* fd_info);
grpc_error* (*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;
extern int grpc_allow_pipe_wakeup_fd;
#define GRPC_WAKEUP_FD_GET_READ_FD(fd_info) ((fd_info)->read_fd)
grpc_error* grpc_wakeup_fd_init(grpc_wakeup_fd* fd_info) GRPC_MUST_USE_RESULT;
grpc_error* grpc_wakeup_fd_consume_wakeup(grpc_wakeup_fd* fd_info)
GRPC_MUST_USE_RESULT;
grpc_error* grpc_wakeup_fd_wakeup(grpc_wakeup_fd* fd_info) GRPC_MUST_USE_RESULT;
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;
#ifdef __cplusplus
}
#endif
#endif /* GRPC_CORE_LIB_IOMGR_WAKEUP_FD_POSIX_H */
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