CDRIVER-748 fix mock server for TSAN #620
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mock_server_hangs_up and mock_server_resets were closing a request stream directly from the main thread. But a request stream should only be accessed by the worker thread. This now adds a special reply to the worker thread's queue to signal a hangup or reset.
kevinAlbs
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May 25, 2020
| mongoc_stream_close (request->client); | ||
| reply = bson_malloc0 (sizeof (reply_t)); | ||
| reply->type = HANGUP; | ||
| q_put (request->replies, reply); |
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The behavior of mock_server_hangs_up was to close the server side stream from the main thread. TSan flags a data race because in the process of closing, it overwrites the stream's file descriptor with an invalid one, causing a write/read race.
The mock server maintains a worker thread for each server-side connection. And each worker thread maintains a thread-safe queue for sending replies back. So instead of closing the stream directly, this pushes a special reply onto the queue to signal the worker thread to close the stream.
kevinAlbs
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May 29, 2020
mock_server_hangs_up and mock_server_resets were closing a request stream directly from the main thread. But a request stream should only be accessed by the worker thread. This now adds a special reply to the worker thread's queue to signal a hangup or reset.
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This is not urgent. This, and some other test fixes from #607 are prerequisites for adding a thread-sanitizer task to evergreen to automatically check for thread related bugs.
mock_server_hangs_up and mock_server_resets were closing a request stream directly from the main thread. But a request stream should only be accessed by the worker thread. This now adds a special reply to the worker thread's queue to signal a hangup or reset.