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

base/sync_socket_posix.cc

Index: base/sync_socket_posix.cc
diff --git a/base/sync_socket_posix.cc b/base/sync_socket_posix.cc
index 257916df3357a21962a4f6b9fe7561a09c286d50..df962fe525121321cd1251020e0b9265bdfc0ac7 100644
--- a/base/sync_socket_posix.cc
+++ b/base/sync_socket_posix.cc
@@ -108,6 +108,28 @@ size_t SyncSocket::Receive(void* buffer, size_t 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)) {