Reduce unnecessary watch events in the work-status-controller

[XiShanYongYe-Chang]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

The work-status-controller only needs to watch the creation events of work objects and the updates of the WorkApplied status of work objects. It does not need to watch updates events for other fields of the work objects or deletion events.

Additionally, for the karmada-agent, it only needs to be concerned with the work of the current cluster.

Which issue(s) this PR fixes:

Part of #6780

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

[karmada-bot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[gemini-code-assist]

Summary of Changes

Hello @XiShanYongYe-Chang, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request optimizes the work-status-controller by introducing specialized predicate functions to filter unnecessary watch events. New predicates, NewWorkStatusPredicate for the controller-manager and NewWorkStatusPredicateOnAgent for the agent, ensure that Work objects are only processed if they match specific criteria (e.g., push-mode clusters, current agent's cluster) and, for updates, only when their status transitions from 'not applied' to 'applied'. This reduces controller load and improves efficiency. The changes include updates to controller initialization, predicate definitions, and new unit tests.

Highlights

• Intent: This PR aims to reduce unnecessary watch events processed by the work-status-controller in both the karmada-controller-manager and karmada-agent components. This is a cleanup effort to optimize controller performance by filtering out irrelevant events.
• Key Changes: The primary change involves introducing new, more specific predicate functions for the work-status-controller:

1. NewWorkStatusPredicate: Used by the karmada-controller-manager, this predicate filters Work objects to only process those belonging to clusters with Push synchronization mode. Crucially, for update events, it only triggers reconciliation when a Work object transitions from a 'not applied' state to an 'applied' state.
2. NewWorkStatusPredicateOnAgent: Used by the karmada-agent, this predicate filters Work objects to only process those relevant to the current agent's cluster. Similar to the controller-manager's predicate, it only triggers update events when a Work object transitions from 'not applied' to 'applied'.

Both new predicates explicitly ignore Delete and Generic events for Work objects.

Supporting changes include:

• Updating cmd/agent/app/agent.go and cmd/controller-manager/app/controllermanager.go to integrate these new predicates into the WorkStatusController setup.
• Refactoring pkg/controllers/status/work_status_controller.go to simplify the predicate integration logic.
• Updating comments in pkg/util/helper/predicate.go to clarify the usage of WorkWithinPushClusterPredicate.
• Adding comprehensive unit tests for the new predicate functions in pkg/util/helper/predicate_test.go.
• Impact: These changes are expected to significantly reduce the number of Work watch events that the work-status-controller needs to process, leading to improved performance and reduced resource consumption for both the karmada-controller-manager and karmada-agent.

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[gemini-code-assist]

Code Review

This pull request effectively reduces unnecessary watch events in the work-status-controller by introducing more specific predicates. The changes are clear, and the addition of comprehensive tests is commendable. I have one suggestion to improve code maintainability by reducing duplication.

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

❌ Patch coverage is 86.53846% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 45.87%. Comparing base (070927d) to head (cc75a1b).
⚠️ Report is 2 commits behind head on master.

Files with missing lines	Patch %	Lines
pkg/controllers/status/work_status_controller.go	0.00%	5 Missing ⚠️
cmd/agent/app/agent.go	0.00%	1 Missing ⚠️
cmd/controller-manager/app/controllermanager.go	0.00%	1 Missing ⚠️
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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6813      +/-   ##
==========================================
+ Coverage   45.84%   45.87%   +0.02%     
==========================================
  Files         690      690              
  Lines       57300    57342      +42     
==========================================
+ Hits        26271    26303      +32     
- Misses      29399    29406       +7     
- Partials     1630     1633       +3     

Flag	Coverage Δ
unittests	45.87% <86.53%> (+0.02%)	⬆️

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[XiShanYongYe-Chang]

/cc @zhzhuang-zju