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https://issues.apache.org/jira/browse/IGNITE-20127?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17772570#comment-17772570
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Alexander Lapin commented on IGNITE-20127:
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[~ascherbakov] LGTM!
> Implement 1rtt RW transaction await logic in pre commit
> -------------------------------------------------------
>
> Key: IGNITE-20127
> URL: https://issues.apache.org/jira/browse/IGNITE-20127
> Project: Ignite
> Issue Type: Improvement
> Reporter: Alexander Lapin
> Assignee: Alexey Scherbakov
> Priority: Major
> Labels: ignite-3, transactions
> Time Spent: 8h 10m
> Remaining Estimate: 0h
>
> h3. Motivation
> Our transaction protocol assumes that all required request validations, lock
> acquisitions and similar activities are performed on a primary replica prior
> to command replication, meaning that it's not necessary to await replication
> for every request one by one rather it's required to await them all at once
> in pre-commit phase. Most of what is required for such all at once await has
> already been implemented.
> h3. Definition of Done
> * It's required to do the command replication in an async manner, meaning
> that it's necessary to return the result to the client right after
> replication is triggered. Currently, we return replication result in
> PartitionReplicaListener#applyCmdWithExceptionHandling and await it in
> ReplicaManager#onReplicaMessageReceive
> {code:java}
> CompletableFuture<?> result = replica.processRequest(request);
> result.handle((res, ex) -> {
> ...
> msg = prepareReplicaResponse(requestTimestamp, res);
> ...
> clusterNetSvc.messagingService().respond(senderConsistentId, msg,
> correlationId); {code}
> * And of course it's required to await all commands replication at once in
> pre-commit. We already have such logic in ReadWriteTransactionImpl#finish
> {code:java}
> protected CompletableFuture<Void> finish(boolean commit) {
> ...
> CompletableFuture<Void> mainFinishFut = CompletableFuture
> .allOf(enlistedResults.toArray(new CompletableFuture[0]))
> .thenCompose(
> ...
> return txManager.finish(
> ...{code}
> however, it should use not the result from primary, but the replication
> completion one.
> h3. Implementation Notes
> I believe it's possible to implement it in a following way:
> * ReplicaManager should await only primary related actions like lock
> acquisition and store the replication future in a sort of map. It's possible
> to use safeTime as request Id.
> * Transaction should send replicationAwaitRequest in an async manner right
> after replicationResponse from primary was achieved.
> * enlistedResults should be switched to replicationAwaitResponse.
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