1/* 2 * Copyright (c) 2013 The WebRTC project authors. All Rights Reserved. 3 * 4 * Use of this source code is governed by a BSD-style license 5 * that can be found in the LICENSE file in the root of the source 6 * tree. An additional intellectual property rights grant can be found 7 * in the file PATENTS. All contributing project authors may 8 * be found in the AUTHORS file in the root of the source tree. 9 */ 10 11#include "webrtc/modules/audio_device/android/low_latency_event.h" 12 13#include <assert.h> 14 15#define HANDLE_EINTR(x) ({ \ 16 typeof(x) eintr_wrapper_result; \ 17 do { \ 18 eintr_wrapper_result = (x); \ 19 } while (eintr_wrapper_result == -1 && errno == EINTR); \ 20 eintr_wrapper_result; \ 21 }) 22 23#define IGNORE_EINTR(x) ({ \ 24 typeof(x) eintr_wrapper_result; \ 25 do { \ 26 eintr_wrapper_result = (x); \ 27 if (eintr_wrapper_result == -1 && errno == EINTR) { \ 28 eintr_wrapper_result = 0; \ 29 } \ 30 } while (0); \ 31 eintr_wrapper_result; \ 32 }) 33 34namespace webrtc { 35 36const LowLatencyEvent::Handle LowLatencyEvent::kInvalidHandle = -1; 37const int LowLatencyEvent::kReadHandle = 0; 38const int LowLatencyEvent::kWriteHandle = 1; 39 40LowLatencyEvent::LowLatencyEvent() { 41 handles_[kReadHandle] = kInvalidHandle; 42 handles_[kWriteHandle] = kInvalidHandle; 43} 44 45LowLatencyEvent::~LowLatencyEvent() { 46 Stop(); 47} 48 49bool LowLatencyEvent::Start() { 50 assert(handles_[kReadHandle] == kInvalidHandle); 51 assert(handles_[kWriteHandle] == kInvalidHandle); 52 53 return socketpair(AF_UNIX, SOCK_STREAM, 0, handles_) == 0; 54} 55 56bool LowLatencyEvent::Stop() { 57 bool ret = Close(&handles_[kReadHandle]) && Close(&handles_[kWriteHandle]); 58 handles_[kReadHandle] = kInvalidHandle; 59 handles_[kWriteHandle] = kInvalidHandle; 60 return ret; 61} 62 63void LowLatencyEvent::SignalEvent(int event_id, int event_msg) { 64 WriteFd(event_id, event_msg); 65} 66 67void LowLatencyEvent::WaitOnEvent(int* event_id, int* event_msg) { 68 ReadFd(event_id, event_msg); 69} 70 71bool LowLatencyEvent::Close(Handle* handle) { 72 if (*handle == kInvalidHandle) { 73 return false; 74 } 75 int retval = IGNORE_EINTR(close(*handle)); 76 *handle = kInvalidHandle; 77 return retval == 0; 78} 79 80void LowLatencyEvent::WriteFd(int message_id, int message) { 81 char buffer[sizeof(message_id) + sizeof(message)]; 82 size_t bytes = sizeof(buffer); 83 memcpy(buffer, &message_id, sizeof(message_id)); 84 memcpy(&buffer[sizeof(message_id)], &message, sizeof(message)); 85 ssize_t bytes_written = HANDLE_EINTR(write(handles_[kWriteHandle], buffer, 86 bytes)); 87 if (bytes_written != static_cast<ssize_t>(bytes)) { 88 assert(false); 89 } 90} 91 92void LowLatencyEvent::ReadFd(int* message_id, int* message) { 93 char buffer[sizeof(message_id) + sizeof(message)]; 94 size_t bytes = sizeof(buffer); 95 ssize_t bytes_read = HANDLE_EINTR(read(handles_[kReadHandle], buffer, bytes)); 96 if (bytes_read == 0) { 97 *message_id = 0; 98 *message = 0; 99 return; 100 } else if (bytes_read == static_cast<ssize_t>(bytes)) { 101 memcpy(message_id, buffer, sizeof(*message_id)); 102 memcpy(message, &buffer[sizeof(*message_id)], sizeof(*message)); 103 } else { 104 assert(false); 105 } 106} 107 108} // namespace webrtc 109