1 /* 2 * 3 * Copyright 2016 gRPC authors. 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 * 17 */ 18 19 /* 20 * wakeup_fd_cv uses condition variables to implement wakeup fds. 21 * 22 * It is intended for use only in cases when eventfd() and pipe() are not 23 * available. It can only be used with the "poll" engine. 24 * 25 * Implementation: 26 * A global table of cv wakeup fds is mantained. A cv wakeup fd is a negative 27 * file descriptor. poll() is then run in a background thread with only the 28 * real socket fds while we wait on a condition variable trigged by either the 29 * poll() completion or a wakeup_fd() call. 30 * 31 */ 32 33 #ifndef GRPC_CORE_LIB_IOMGR_WAKEUP_FD_CV_H 34 #define GRPC_CORE_LIB_IOMGR_WAKEUP_FD_CV_H 35 36 #include <grpc/support/port_platform.h> 37 38 #include <grpc/support/sync.h> 39 40 #include "src/core/lib/iomgr/ev_posix.h" 41 42 #define GRPC_FD_TO_IDX(fd) (-(fd)-1) 43 #define GRPC_IDX_TO_FD(idx) (-(idx)-1) 44 45 typedef struct grpc_cv_node { 46 gpr_cv* cv; 47 struct grpc_cv_node* next; 48 struct grpc_cv_node* prev; 49 } grpc_cv_node; 50 51 typedef struct grpc_fd_node { 52 int is_set; 53 grpc_cv_node* cvs; 54 struct grpc_fd_node* next_free; 55 } grpc_fd_node; 56 57 typedef struct grpc_cv_fd_table { 58 gpr_mu mu; 59 gpr_refcount pollcount; 60 gpr_cv shutdown_cv; 61 grpc_fd_node* cvfds; 62 grpc_fd_node* free_fds; 63 unsigned int size; 64 grpc_poll_function_type poll; 65 } grpc_cv_fd_table; 66 67 extern const grpc_wakeup_fd_vtable grpc_cv_wakeup_fd_vtable; 68 69 #endif /* GRPC_CORE_LIB_IOMGR_WAKEUP_FD_CV_H */ 70