| /* |
| * |
| * 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" |
| |
| 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; |
| |
| #endif /* GRPC_CORE_LIB_IOMGR_WAKEUP_FD_POSIX_H */ |