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https://issues.apache.org/jira/browse/CASSANDRA-20059?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17897689#comment-17897689
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David Capwell commented on CASSANDRA-20059:
-------------------------------------------
I gave the following examples in slack
{code}
org.apache.cassandra.tcm.PaxosBackedProcessor#fetchLogAndWait
org.apache.cassandra.tcm.RemoteProcessor#fetchLogAndWait(org.apache.cassandra.tcm.Epoch,
org.apache.cassandra.tcm.Retry.Deadline)
{code}
If you use "retryIndefinitely" in this code path we actually stop blocking
right away as we wait for "(0, NANOSECONDS)"... I asked for unbounded waiting
and I instead got no waiting....
Outside of logging these are the only 2 places on trunk that even care about
Retry.Deadline, everything else works off of Retry (but might call this method
so take a Retry.Deadline).
> TCM's Retry.Deadline#retryIndefinitely is dangerous if used with
> RemoteProcessor as the deadline does not impact message retries
> --------------------------------------------------------------------------------------------------------------------------------
>
> Key: CASSANDRA-20059
> URL: https://issues.apache.org/jira/browse/CASSANDRA-20059
> Project: Cassandra
> Issue Type: Bug
> Components: Transactional Cluster Metadata
> Reporter: David Capwell
> Assignee: David Capwell
> Priority: Normal
> Fix For: 5.x
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> {code}
> public static Deadline retryIndefinitely(long timeoutNanos, Meter retryMeter)
> {
> return new Deadline(Clock.Global.nanoTime() + timeoutNanos,
> new Retry.Jitter(Integer.MAX_VALUE,
> DEFAULT_BACKOFF_MS, new Random(), retryMeter))
> {
> @Override
> public boolean reachedMax()
> {
> return false;
> }
> @Override
> public long remainingNanos()
> {
> return timeoutNanos;
> }
> public String toString()
> {
> return String.format("RetryIndefinitely{tries=%d}",
> currentTries());
> }
> };
> }
> {code}
> Sample usage pattern (example is in Accord, but same pattern exists in
> RemoteProcessor.commit)
> {code}
> Promise<LogState> request = new AsyncPromise<>();
> List<InetAddressAndPort> candidates = new
> ArrayList<>(log.metadata().fullCMSMembers());
> sendWithCallbackAsync(request,
> Verb.TCM_RECONSTRUCT_EPOCH_REQ,
> new ReconstructLogState(lowEpoch, highEpoch,
> includeSnapshot),
> new CandidateIterator(candidates),
> retryPolicy);
> return request.get(retryPolicy.remainingNanos(), TimeUnit.NANOSECONDS);
> {code}
> The issue here is that the networking retry has no clue that we gave up
> waiting on the request, so we will keep retrying until success! The reason
> for this is “reachedMax” is used to see if its safe to run again, but it
> isn’t as the deadline has passed!
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