Fix concurrent search NPE with track_total_hits, size=0, and terminate_after

[jed326]

Description

Change EmptyTopDocsCollectorContext::createManager to not return a null manager.

Same query no longer returns NPE:

curl -X GET "localhost:9200/_search?size=0&track_total_hits=true&pretty&terminate_after=1000000" -H 'Content-Type: application/json' -d'
{
    "query": {                        
        "match_all": {}                         
    }      
}                  
'  
{
  "took" : 889,
  "timed_out" : false,
  "terminated_early" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "skipped" : 0,
    "failed" : 0
  },
  "hits" : {
    "total" : {
      "value" : 4,
      "relation" : "eq"
    },
    "max_score" : null,
    "hits" : [ ]
  }
}

Related Issues

Resolves #10054

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Commits are signed per the DCO using --signoff
• Commit changes are listed out in CHANGELOG.md file (See: Changelog)

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
For more information on following Developer Certificate of Origin and signing off your commits, please check here.

[github-actions]

Compatibility status:

Checks if related components are compatible with change 0e6d29e

Incompatible components

Incompatible components: [https://github.com/opensearch-project/k-nn.git]

Skipped components

Compatible components

Compatible components: [https://github.com/opensearch-project/security-analytics.git, https://github.com/opensearch-project/security.git, https://github.com/opensearch-project/custom-codecs.git, https://github.com/opensearch-project/opensearch-oci-object-storage.git, https://github.com/opensearch-project/index-management.git, https://github.com/opensearch-project/geospatial.git, https://github.com/opensearch-project/sql.git, https://github.com/opensearch-project/job-scheduler.git, https://github.com/opensearch-project/notifications.git, https://github.com/opensearch-project/observability.git, https://github.com/opensearch-project/neural-search.git, https://github.com/opensearch-project/cross-cluster-replication.git, https://github.com/opensearch-project/alerting.git, https://github.com/opensearch-project/performance-analyzer.git, https://github.com/opensearch-project/anomaly-detection.git, https://github.com/opensearch-project/asynchronous-search.git, https://github.com/opensearch-project/ml-commons.git, https://github.com/opensearch-project/performance-analyzer-rca.git, https://github.com/opensearch-project/common-utils.git, https://github.com/opensearch-project/reporting.git]

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.client.PitIT.testDeleteAllAndListAllPits

• URL: https://build.ci.opensearch.org/job/gradle-check/25728/
• CommitID: f6a97ed
  Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[codecov]

Codecov Report

Merging #10082 (0e6d29e) into main (9b5bf5f) will increase coverage by 0.02%.
Report is 2 commits behind head on main.
The diff coverage is 0.00%.

@@             Coverage Diff              @@
##               main   #10082      +/-   ##
============================================
+ Coverage     71.04%   71.06%   +0.02%     
- Complexity    58090    58094       +4     
============================================
  Files          4825     4825              
  Lines        274101   274102       +1     
  Branches      39945    39945              
============================================
+ Hits         194741   194797      +56     
+ Misses        63026    62974      -52     
+ Partials      16334    16331       -3     

Files Changed	Coverage Δ
...ensearch/search/query/TopDocsCollectorContext.java	88.28% <0.00%> (+0.33%)	⬆️

... and 448 files with indirect coverage changes

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/25729/
• CommitID: 279db49
  Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green.
  Is the failure a flaky test unrelated to your change?

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: FAILURE ❌
• URL: https://build.ci.opensearch.org/job/gradle-check/25947/
• CommitID: 773e7b7
  Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green.
  Is the failure a flaky test unrelated to your change?

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.remotestore.SegmentReplicationUsingRemoteStoreIT.testMultipleShards

• URL: https://build.ci.opensearch.org/job/gradle-check/25948/
• CommitID: 1c84cec
  Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: SUCCESS ✅
• URL: https://build.ci.opensearch.org/job/gradle-check/25980/
• CommitID: 0e6d29e

[jed326]

@reta @sohami could you help review this PR? Thanks!