Integer overflow in `bufferTimeout`

[qrpnxz]

Through FluxBufferTimeout through BufferTimeoutWithBackpressureSubscriber:

reactor-core/reactor-core/src/main/java/reactor/core/publisher/FluxBufferTimeout.java

Lines 215 to 216 in c431f54

	this.prefetch = batchSize << 2;
	this.replenishMark = batchSize << 1;

If batchSize (maxSize in bufferTimeout) is very big, prefetch and replenishMark can become negative. In my experience, this can cause a thread to silently hang. I would expect a large input to gracefully saturate these internal variables or at least signal an error.

Integer.MAX_VALUE would work well for ‘unbounded’ buffering if not for this; the brittle-looking Integer.MAX_VALUE >> 2 will do for now.

Versions affected: commits since PR #3332 as far as I know. Link above represents main as of time of writing.