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Race condition in eventfd signaler fixed

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recv function on eventfd signaler could accidentally
grab two signals instead of one. Fixed.

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>
This commit is contained in:
Martin Sustrik
2011-07-03 15:30:31 +02:00
parent 9a9a0cf410
commit 6ae1be1a12
1 changed files with 10 additions and 2 deletions
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12
src/signaler.cpp
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@@ -206,8 +206,16 @@ void zmq::signaler_t::recv ()
uint64_t dummy;
ssize_t sz = read (r, &dummy, sizeof (dummy));
errno_assert (sz == sizeof (dummy));
if (dummy != 1)
printf ("dummy:%d\n", (int) dummy);
// If we accidentally grabbed the next signal along with the current
// one, return it back to the eventfd object.
if (unlikely (dummy == 2)) {
const uint64_t inc = 1;
ssize_t sz = write (w, &inc, sizeof (inc));
errno_assert (sz == sizeof (inc));
return;
}
zmq_assert (dummy == 1);
#else
unsigned char dummy;