Switch audio synchronization from sleep() based to select() based.

base/sync_socket_posix.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/sync_socket.h"
 
 #include <errno.h>
 #include <limits.h>
 #include <fcntl.h>
 #include <stdio.h>
@@ skipping 90 matching lines @@
 }
 
 size_t SyncSocket::Receive(void* buffer, size_t length) {
   DCHECK_LE(length, kMaxMessageLength);
   char* charbuffer = static_cast<char*>(buffer);
   if (file_util::ReadFromFD(handle_, charbuffer, length))
     return length;
   return 0;
 }
 
+size_t SyncSocket::Receive(void* buffer, size_t length,
+                           base::TimeDelta timeout) {
+  // TODO(dalecurtis): Build fd_set during construction?

[tommi (sloooow) - chröme, 2013/08/20 10:55:57]

would this make a measurable difference?

[DaleCurtis, 2013/09/11 01:16:03]

Probably not. Comment removed. 

+  fd_set rfds;
+  FD_ZERO(&rfds);
+  FD_SET(handle_, &rfds);
+
+  // TODO(dalecurtis): Fill out seconds.  Can't use Time::ToTimeVal since it
+  // expects time relative to 1970.
+  struct timeval timeout_struct = { 0, timeout.InMicroseconds() };

[miu, 2013/08/17 02:39:13]

Since you're not populating the "seconds" part, consider adding:

  DCHECK_LT(timeout, base::TimeDelta::FromSeconds(1));

[DaleCurtis, 2013/09/11 01:16:03]

Done.

+  int select_result = HANDLE_EINTR(
+      select(handle_ + 1, &rfds, NULL, NULL, &timeout_struct));
+  if (select_result <= 0)
+    return 0;
+
+  DCHECK_LE(length, kMaxMessageLength);
+  char* charbuffer = static_cast<char*>(buffer);
+  if (file_util::ReadFromFD(handle_, charbuffer, length))

[tommi (sloooow) - chröme, 2013/08/20 10:55:57]

don't you first have to check if handle_ is in rfds after the select operation?

[DaleCurtis, 2013/08/20 18:27:51]

Not if we only have one descriptor since select() returns the number of matched
descriptors.  I'll add a DCHECK() for it though.

[tommi (sloooow) - chröme, 2013/08/21 12:33:26]

sgtm

+    return length;
+  return 0;
+}
+
 size_t SyncSocket::Peek() {
   int number_chars;
   if (-1 == ioctl(handle_, FIONREAD, &number_chars)) {
     // If there is an error in ioctl, signal that the channel would block.
     return 0;
   }
   return (size_t) number_chars;
 }
 
 CancelableSyncSocket::CancelableSyncSocket() {}
@@ skipping 24 matching lines @@
   return len;
 }
 
 // static
 bool CancelableSyncSocket::CreatePair(CancelableSyncSocket* socket_a,
                                       CancelableSyncSocket* socket_b) {
   return SyncSocket::CreatePair(socket_a, socket_b);
 }
 
 }  // namespace base