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Fix an "unrecognized selector sent to instance" crash #79
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An app using `PocketSocket` crashes occasionally with this information: ``` Fatal Exception: NSInvalidArgumentException -[SomeDelegate webSocketDidFlushOutput:]: unrecognized selector sent to instance 0x123456789 0 CoreFoundation 0x88881ad8c __exceptionPreprocess … 5 PocketSocket 0x8888d5004 __43-[PSWebSocket notifyDelegateDidFlushOutput]_block_invoke (PSWebSocket.m:668) 6 libdispatch.dylib 0x88880caa0 _dispatch_call_block_and_release … ``` The `notifyDelegateDidFlushOutput` function checks if the delegate responds to the `webSocketDidFlushOutput:` selector before sending it. The only possible cause for the crash is when the delegate changes between the check and the call because the function is not atomic. Added `testChangingDelegateWhileFlushingOutputShouldNotCrashWithUnrecognizedSelector` can reproduce the crash very quickly and consistently. The fix here is to capture the delegate strongly while the function is running to work with the same instance. The patch fixes the crash in all similar places in `PSWebSocket`, as well as in `PSWebSocketServer`.
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An app using
PocketSocketcrashes occasionally with this information:The
notifyDelegateDidFlushOutputfunction checks if the delegateresponds to the
webSocketDidFlushOutput:selector before sending it.The only possible cause for the crash is when the delegate changes
between the check and the call because the function is not atomic. Added
testChangingDelegateWhileFlushingOutputShouldNotCrashWithUnrecognizedSelectorcan reproduce the crash very quickly and consistently.
The fix here is to capture the delegate strongly while the function is
running to work with the same instance. The patch fixes the crash in all
similar places in
PSWebSocket, as well as inPSWebSocketServer.