Optimize select expression registration phase #1445
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There is no need for multi-word atomic performAtomicIfNotSelected operation when enqueuing select node for operation. We can simply enqueue (addLast) xxxSelect node (SendSelect, ReceiveSelect, LockSelect). If the coroutine that rendezvous with this node finds out that the select expression was already selected, then it'll try again. * Removed SelectInstance.performAtomicIfNotSelected function * Removed Mutex.TryEnqueueLockDesc class, simplified onLock * Removed AbstractSendChannel.TryEnqueueSendDesc class, simpler onSend * Removed AbstractChannel.TryEnqueueReceiveDesc class, simpler onReceive * Simplified SelectInstance.disposeOnSelect. It does not have to do atomic addLastIf operation. Can do a simple addLast.
It was hanging not being able to properly see that the channel was already closed at that send attempt should fail.
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Also fixed a bug with unlimited channel select onSend on closed channel. It was hanging not being able to properly see that the channel was already closed at that send attempt should fail. |
| if (prev is ReceiveOrClosed<*>) return@enqueueSend prev | ||
| true | ||
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| } |
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Line 220: return ENQUEUE_FAILED
Nobody checks for ENQUEUE_FAILED. It doesn't look like a bug because of the current state machine (null -> success, Closed -> closed, everything else -> retry), but kind of error-prone.
For example, null can become ENQUEUE_SUCCESS and ENQUEUE_FAILED will become null instead. Code flow will be more straightforward and explicit
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I've rewritten the corresponding when statements in a more explicit way, checking all possible outcomes and added error on unexpected result.
Now registerSelectSend and sendSuspend are more alike
Also removed describeRemove and the corresponding tests (not needed in prod code).
There is no need for multi-word atomic performAtomicIfNotSelected
operation when enqueuing select node for operation. We can simply
enqueue (addLast) xxxSelect node (SendSelect, ReceiveSelect, LockSelect).
If the coroutine that rendezvous with this node finds out that the
select expression was already selected, then it'll try again.