| // |
| // |
| // 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_SRC_CORE_LIB_IOMGR_WAKEUP_FD_POSIX_H |
| #define GRPC_SRC_CORE_LIB_IOMGR_WAKEUP_FD_POSIX_H |
| |
| #include <grpc/support/port_platform.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); |
| |
| typedef struct grpc_wakeup_fd grpc_wakeup_fd; |
| |
| typedef struct grpc_wakeup_fd_vtable { |
| grpc_error_handle (*init)(grpc_wakeup_fd* fd_info); |
| grpc_error_handle (*consume)(grpc_wakeup_fd* fd_info); |
| grpc_error_handle (*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_handle grpc_wakeup_fd_init(grpc_wakeup_fd* fd_info) |
| GRPC_MUST_USE_RESULT; |
| grpc_error_handle grpc_wakeup_fd_consume_wakeup(grpc_wakeup_fd* fd_info) |
| GRPC_MUST_USE_RESULT; |
| grpc_error_handle 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_SRC_CORE_LIB_IOMGR_WAKEUP_FD_POSIX_H |