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Diffstat (limited to 'src/core/lib/iomgr/wakeup_fd_posix.h')
| -rw-r--r-- | src/core/lib/iomgr/wakeup_fd_posix.h | 101 |
1 files changed, 101 insertions, 0 deletions
diff --git a/src/core/lib/iomgr/wakeup_fd_posix.h b/src/core/lib/iomgr/wakeup_fd_posix.h new file mode 100644 index 0000000000..20988d5fd3 --- /dev/null +++ b/src/core/lib/iomgr/wakeup_fd_posix.h @@ -0,0 +1,101 @@ +/* + * + * 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 */ |