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Problem: invoking the conditional variable for zero time is expensive

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Solution: for zero timeout, unlock and relock immediately instead of timedwait
This commit is contained in:
somdoron
2019-02-06 21:07:22 +02:00
parent 9b1627f041
commit 462dd36d0e
1 changed files with 13 additions and 5 deletions
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18
src/mailbox_safe.cpp
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@@ -99,11 +99,19 @@ int zmq::mailbox_safe_t::recv (command_t *cmd_, int timeout_)
if (_cpipe.read (cmd_))
return 0;
// Wait for signal from the command sender.
int rc = _cond_var.wait (_sync, timeout_);
if (rc == -1) {
errno_assert (errno == EAGAIN || errno == EINTR);
return -1;
// If the timeout is zero, it will be quicker to release the lock, giving other a chance to send a command
// and immediately relock it.
if (timeout_ == 0) {
_sync->unlock ();
_sync->lock ();
}
else {
// Wait for signal from the command sender.
int rc = _cond_var.wait (_sync, timeout_);
if (rc == -1) {
errno_assert (errno == EAGAIN || errno == EINTR);
return -1;
}
}
// Another thread may already fetch the command