Built motion from commit 6a09e18b.|2.6.11

[motion2.git] / legacy-libs / grpc / deps / grpc / src / core / lib / iomgr / wakeup_fd_posix.h

diff --git a/legacy-libs/grpc/deps/grpc/src/core/lib/iomgr/wakeup_fd_posix.h b/legacy-libs/grpc/deps/grpc/src/core/lib/iomgr/wakeup_fd_posix.h
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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 <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);
+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 */