[feat][broker] PIP-264: Add replication subscription stats

[dragosvictor]

PIP-264

Motivation

Adds replicated subscription metrics, defined here and here, to the OpenTelemetry pipeline.

Modifications

• Added metrics, as described by [feat][doc] PIP-264: Add replication subscription metrics reference pulsar-site#941, to the OpenTelemetry pipeline. Since these metrics expose no high-cardinality attributes, they can be stored as synchronous OpenTelemetry instruments.
• Instead of the existing Prometheus pulsar_replicated_subscriptions_pending_snapshots counter, opted to expose the number of snapshot operations attempted. The snapshot duration histogram maintains the number of operations completed. Using these values, the number of pending snapshots can be computed at any time.

Verifying this change

• Make sure that the change passes the CI checks.

This change added tests and can be verified as follows:

• Updated test ReplicatedSubscriptionTest#testReplicatedSubscriptionAcrossTwoRegions to cover the new metric values.

Does this pull request potentially affect one of the following parts:

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics: As described in [feat][doc] PIP-264: Add replication subscription metrics reference pulsar-site#941
• Anything that affects deployment

Documentation

• doc
• doc-required [feat][doc] PIP-264: Add replication subscription metrics reference pulsar-site#941
• doc-not-needed
• doc-complete

Matching PR in forked repository

PR in forked repository: dragosvictor#40

[lhotari]

LGTM, good work @dragosvictor

[lhotari]

I'll close and re-open to get a fresh run that runs with latest changes from master branch.

[dragosvictor]

/pulsarbot rerun-failure-checks

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 89.74359% with 4 lines in your changes missing coverage. Please review.

Project coverage is 74.50%. Comparing base (bbc6224) to head (59c7230).
Report is 556 commits behind head on master.

Files with missing lines	Patch %	Lines
.../persistent/ReplicatedSubscriptionsController.java	81.81%	2 Missing ⚠️
...tats/OpenTelemetryReplicatedSubscriptionStats.java	91.30%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #23026      +/-   ##
============================================
+ Coverage     73.57%   74.50%   +0.92%     
- Complexity    32624    33727    +1103     
============================================
  Files          1877     1925      +48     
  Lines        139502   144927    +5425     
  Branches      15299    15843     +544     
============================================
+ Hits         102638   107976    +5338     
+ Misses        28908    28683     -225     
- Partials       7956     8268     +312     

Flag	Coverage Δ
inttests	27.69% <35.89%> (+3.11%)	⬆️
systests	24.66% <35.89%> (+0.33%)	⬆️
unittests	73.86% <89.74%> (+1.02%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...n/java/org/apache/pulsar/broker/PulsarService.java	83.42% <100.00%> (+1.05%)	⬆️
...istent/ReplicatedSubscriptionsSnapshotBuilder.java	80.85% <100.00%> (-0.40%)	⬇️
.../persistent/ReplicatedSubscriptionsController.java	70.21% <81.81%> (-2.38%)	⬇️
...tats/OpenTelemetryReplicatedSubscriptionStats.java	91.30% <91.30%> (ø)

... and 544 files with indirect coverage changes

[dragosvictor]

/pulsarbot rerun-failure-checks