Improve push lock wakeup behavior under contention - #38
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The current implementation doesn't record whether a waiter requested shared or exclusive ownership, so every release wakes only one waiter. As a result, shared waiters queued behind an exclusive owner are effectively serialized.
This change records waiter mode and wakes the waiter chain when the oldest waiter is shared, while preserving retry-after-wake semantics. Also removes hard coded push lock masks/alignment values.
Queued 4 reader case:
max-active=1, ~83 msmax-active=4, ~21-22 ms