Fix deadlock on duplicate PooledTransactions response - #151
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damilolaedwards wants to merge 1 commit into
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Fix deadlock on duplicate PooledTransactions response#151damilolaedwards wants to merge 1 commit into
damilolaedwards wants to merge 1 commit into
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handlePooledTransactions sent to the per-request channel while holding pooledTransactionsMux. A peer that replied twice to the same request ID could make the second send block forever on an unbuffered, already drained channel, while still holding the mutex. That wedged the whole session read loop, and the original caller's deferred cleanup then blocked forever trying to acquire the same lock. Make the channel buffered so the first reply never has to wait for the receiver to be ready, and make the send non-blocking so any extra reply for a request that has already been answered is dropped instead of stalling the read loop. Adds a test that replays a duplicate response over a real handshake and confirms the mutex is still available afterward. Confirmed the test fails against the previous behavior and passes with the fix.
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Summary
handlePooledTransactions sent to the per-request channel while holding pooledTransactionsMux. A peer that replied twice to the same request ID could make the second send block forever on an unbuffered, already drained channel, while still holding the mutex. That wedged the whole session read loop, and the original caller's deferred cleanup then blocked forever trying to acquire the same lock.
Makes the channel buffered so the first reply never has to wait for the receiver to be ready, and makes the send non-blocking so any extra reply for a request that has already been answered is dropped instead of stalling the read loop. The map lookup and the send still happen under the same lock as before, so there is no window where a stale or closed channel could be sent to.
Test plan
go build ./...,go vet ./..., and the full package test suite all pass.