Retry when poll_read_ready immediately succeeds in AsyncChannel#592
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BenchmarksComparisonBenchmark execution time: 2024-08-22 16:40:57 Comparing candidate commit 82edf70 in PR branch Found 3 performance improvements and 0 performance regressions! Performance is the same for 47 metrics, 2 unstable metrics. scenario:normalization/normalize_service/normalize_service/[empty string]
scenario:normalization/normalize_trace/test_trace
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Codecov ReportAttention: Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## main #592 +/- ##
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- Coverage 72.90% 72.84% -0.07%
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Files 241 241
Lines 34364 34366 +2
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- Hits 25054 25034 -20
- Misses 9310 9332 +22
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iamluc
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bantonsson
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UnixStream::poll_read_ready may return Poll::Ready(Ok(())), which incidentally, when returned by an AsyncRead::poll_read function without further modification of buf, means that the channel was closed. The intended meaning is "immediately available", and thus we need to re-read. This only can happen when epoll() is resumed between a recvmsg() call and the poll_ready_ready function being invoked, which may only happen in a multithreaded environment, which we recently switched to. Signed-off-by: Bob Weinand <bob.weinand@datadoghq.com>
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UnixStream::poll_read_ready may return Poll::Ready(Ok(())), which incidentally, when returned by an AsyncRead::poll_read function without further modification of buf, means that the channel was closed. The intended meaning is "immediately available", and thus we need to re-read.
This only can happen when epoll() is resumed between a recvmsg() call and the poll_ready_ready function being invoked, which may only happen in a multithreaded environment, which we recently switched to.
This PR reminded me why race conditions are so much fun.