[Bug] [Segment Replication] Fix isAheadOf logic for ReplicationCheckpoint comparison

[dreamer-89]

Signed-off-by: Suraj Singh [email protected]

Description

Coming from #3988 which relies on ReplicationCheckpoint ordering for correctly identifying the furthest ahead replica. The existing ReplicationCheckpoint#isAheadOf is not correct as it uses || b/w segmentInfosVersion (1st) & PrimaryTerm(2nd) terms; instead of relying on 2nd term (PrimaryTerm field) ONLY WHEN first field (segmentInfosVersion) is equal.

This PR also fixes, the comparison order i.e. PrimaryTerm first followed by segmentInfosVersion; this is to prioritize active primary over stale.

Issues Related

#3988

Related

#4041

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[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: ABORTED ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/1379/
• CommitID: c992024

[dreamer-89]

> Task :distribution:bwc:staged:buildBwcLinuxTar FAILED

> Task :distribution:bwc:minor:buildBwcLinuxTar
 [2.3.0] > Task :buildSrc:pluginUnderTestMetadata FAILED
 [2.3.0] 
 [2.3.0] 11 actionable tasks: 11 executed
 [2.3.0] FAILURE: Build failed with an exception.
 [2.3.0] 
 [2.3.0] * What went wrong:
 [2.3.0] Execution failed for task ':buildSrc:pluginUnderTestMetadata'.
 [2.3.0] > Timeout waiting to lock file hash cache (/home/ubuntu/.gradle/caches/7.5/fileHashes). It is currently in use by another Gradle instance.
 [2.3.0]   Owner PID: 28733
 [2.3.0]   Our PID: 32188
 [2.3.0]   Owner Operation: 
 [2.3.0]   Our operation: 
 [2.3.0]   Lock file: /home/ubuntu/.gradle/caches/7.5/fileHashes/fileHashes.lock
 [2.3.0] 
 [2.3.0] * Try:
 [2.3.0] > Run with --stacktrace option to get the stack trace.
 [2.3.0] > Run with --info or --debug option to get more log output.
 [2.3.0] 
 [2.3.0] * Get more help at https://help.gradle.org
 [2.3.0] 
 [2.3.0] BUILD FAILED in 2m 4s
Output for /var/jenkins/workspace/gradle-check/search/distribution/bwc/minor/build/bwc/checkout-2.x/gradlew:

> Task :distribution:bwc:minor:buildBwcLinuxTar FAILED

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: SUCCESS ✅
• URL: https://build.ci.opensearch.org/job/gradle-check/1395/
• CommitID: c992024

[codecov-commenter]

Codecov Report

Merging #4112 (c992024) into main (6f43dbc) will decrease coverage by 0.07%.
The diff coverage is 50.00%.

@@             Coverage Diff              @@
##               main    #4112      +/-   ##
============================================
- Coverage     70.61%   70.53%   -0.08%     
- Complexity    56983    57004      +21     
============================================
  Files          4595     4595              
  Lines        274234   274236       +2     
  Branches      40181    40183       +2     
============================================
- Hits         193638   193427     -211     
- Misses        64342    64564     +222     
+ Partials      16254    16245       -9     

Impacted Files	Coverage Δ
...pensearch/common/settings/IndexScopedSettings.java	100.00% <ø> (ø)
.../java/org/opensearch/snapshots/RestoreService.java	55.37% <0.00%> (ø)
.../replication/checkpoint/ReplicationCheckpoint.java	53.48% <33.33%> (-0.18%)	⬇️
...org/opensearch/cluster/metadata/IndexMetadata.java	83.85% <100.00%> (ø)
.../main/java/org/opensearch/index/IndexSettings.java	86.35% <100.00%> (ø)
...a/org/opensearch/client/cluster/SniffModeInfo.java	0.00% <0.00%> (-58.83%)	⬇️
...a/org/opensearch/tasks/TaskCancelledException.java	50.00% <0.00%> (-50.00%)	⬇️
...cluster/coordination/PendingClusterStateStats.java	20.00% <0.00%> (-48.00%)	⬇️
.../org/opensearch/client/indices/AnalyzeRequest.java	31.00% <0.00%> (-45.00%)	⬇️
...rch/client/transport/NoNodeAvailableException.java	28.57% <0.00%> (-42.86%)	⬇️
... and 470 more

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[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-2.x 2.x
# Navigate to the new working tree
cd .worktrees/backport-2.x
# Create a new branch
git switch --create backport/backport-4112-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 7af8e37f81c0a124712a8cf86dab973df26f906f
# Push it to GitHub
git push --set-upstream origin backport/backport-4112-to-2.x
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-4112-to-2.x.