aws_websocket_close() #48
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dislogical
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May 14, 2019
graebm
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Aug 16, 2024
The bug was introduced in [PR #474](https://github.com/awslabs/aws-c-http/pull/474/files#diff-ee776c7576cfff50a64158d59a6173ab9a0aa373150574aa9987b4f8726b58e3) - `is_writing_stopped = true` shouldn't be set directly, there's a helper function `s_stop_writing()` that ensures subsequent calls to `aws_websocket_send_frame()` will fail. Let's take a whole new approach these channel-shutdown-window-deadlock issues: - add `s_stop_reading_and_dont_block_shutdown()` function that sets `is_reading_stopped = true`, but also increments the read window so that channel shutdown won't deadlock. - Most places that were setting `is_reading_stopped = true` now use this helper instead - Revamp how `aws_channel_shutdown()` is called. Lots of channel behavior has changed since [this websocket code was written](#48). - If on the channel-thread, just call `aws_channel_shutdown()` - now that [aws_channel_shutdown()](awslabs/aws-c-io#172) is always async, we don't need to defensively schedule a task to call it - If off-thread, use `s_schedule_channel_shutdown_from_offthead()` - now that this is only called from `aws_websocket_close()`, or when the refcount goes to zero, we can assume the user is OK if reading stops, and it can call `s_stop_reading_and_dont_block_shutdown()` on the way to shutting down. - Add the test to verify that send after close should fail Co-authored-by: Michael Graeb <graebm@amazon.com>
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TLDR; Implemented
aws_websocket_close(). Also added return values to many callbacks, which allow the user to stop read/write processing by returning false.Details:
This is different than HTTP, where callbacks don't have return values, but a call to _close() from within a callback is guaranteed to stop read/write processing. It was too complex trying to get this working in websockets, whose shutdown procedure is more complex. Therefore I did the simple and direct thing. If a user realizes in a callback that something has gone wrong and processing cannot succeed, they return false.
I'll do a consistency pass eventually on the HTTP layer once websockets is done, making it work like this as well.
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.