Fix possible regression issue caused by ProposeWaitEmptyBlockTimer
#1774
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Possible scenario: * Schedule timeout for `ProposeWaitEmptyBlockTimer` on height: n * On timeout, timer loop queues a call to `Tendermint::on_timeout` on the timer worker * Blocks are imported at the same time with the timeout. * Block importer holds lock for Tendermint, calls `new_blocks` * The worker checks whether it is cancelled, but it is not cancelled yet. * The worker waits for the lock. * several `move_to_height`, `move_to_step` are called by new_blocks * height is not n anymore. * `move_to_step` clears timer, but the check is already passed and the worker waits for the lock. * It finally releases the lock. * The waiting worker calls Tendermint::on_timeout and the timeout for `ProposeWaitEmptyBlockTimer` calls `move_to_step(Prevote)` * The timeout was set for the height n, but the code in the timeout reads changed height.
majecty
approved these changes
Sep 18, 2019
remagpie
approved these changes
Sep 18, 2019
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Possible scenario:
ProposeWaitEmptyBlockTimeron height: nTendermint::on_timeouton thetimer worker
new_blocksmove_to_height,move_to_stepare called by new_blocksmove_to_stepclears timer, but the check is already passed and theworker waits for the lock.
ProposeWaitEmptyBlockTimercallsmove_to_step(Prevote)reads changed height.