Reproduce safety error in Fast-HotStuff with Twins #55
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This makes Propose() continue even if the QC block could not be found. There is no reason why the proposal should be aborted if this happens.
This disables the check of the proposer's identity in OnPropose. By disabling this, we can perform the HighQC update in AdvanceView
This enables the GetLeader function to work correctly with the absence of an early HighQC update.
Broadcast and strict mode are on by default, which should be consistent with the old behavior.
This advances the node to the next view in the network when a timeout occurs, which should help prevent nodes from becoming "stuck".
This reverts commit e704f4a.
Not needed anymore
Codecov Report
@@ Coverage Diff @@
## master #55 +/- ##
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+ Coverage 53.72% 54.97% +1.25%
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Files 70 70
Lines 6362 6437 +75
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+ Hits 3418 3539 +121
+ Misses 2670 2626 -44
+ Partials 274 272 -2
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This reverts commit a556c47.
This reverts commit 1b1198b.
This changes the way the executor uses rounds. In a round, each replica is allowed to process all of its pending events. Any messages that are sent are held by the network until the start of the next round. A timeout mananger module sends a timeout every 5 rounds unless a view change happens.
We need a working view context to send the timeout messages
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This PR adds a test case showing that our Twins implementation can detect the safety violation in Fast-HotStuff that was found in the Twins paper.
The main problem I encountered is this:
Because our view synchronizer requires a timeout certificate created from a quorum of timeout messages, All nodes become stuck because they cannot gather a quorum of timeout messages:
At round 5, node B timeouts. It is prevented from sending timeout messages to the other nodes due to the firewall of round 5.
At round 6, nodes A and D timeout. They are prevented from communicating with node B due to the firewall of round 6.
At round 7, node C timeouts. It is prevented from communicating with the other nodes due to the firewall of round 7.
Several changes were made to the Twins executor to get it working:
Each node now runs concurrently.EDIT: I figured out how to run the event loops in turns.Each scenario is executed for a fixed amount of time with fixed timeout durations and message delays.EDIT: now, the executor runs for some number of "rounds" in which all replicas are allowed to process eventsThe test scenario results in the following commits, where node 2 disagrees with all other nodes at height 4: