[automatic failover] Add dual thresholds (min num of failures + failure rate) capabililty to circuit breaker

[atakavci]

Summary

Add dual-threshold failover to Jedis multi-cluster: failover occurs only when both minimum failures and failure-rate thresholds are exceeded. Simplify configuration, adapt thresholds cleanly to resilience4j, and update docs/tests.

Key changes

• CircuitBreakerCommandExecutor: enforce dual thresholds using CB metrics; raise JedisFailoverThresholdsExceededException on exceed.
• CircuitBreakerThresholdsAdapter (new): maps MultiClusterClientConfig to resilience4j CB config, handling 0.0% rate and min calls robustly.
• MultiClusterClientConfig simplified:
  • Defaults: failureRate=10%, windowSize=2, minFailures=1000
  • Removed slow-call and window-type/min-calls knobs
  • Added thresholdMinNumOfFailures and validation (disallow 0 failures + 0.0% rate)
  • Added JedisFailoverThresholdsExceededException to fallback list
• MultiClusterPooledConnectionProvider: build CB via adapter; cluster exposes getThresholdMinNumOfFailures
• Docs: updated defaults and examples; clarified simpler CB model
• Tests: added/updated parameterized and integration tests, including 0.0% rate and large min-failures

Behavior

• Failover triggers when:
  • failures >= thresholdMinNumOfFailures AND
  • (failed / total) × 100 >= failureRateThreshold
• For configured 0.0% rate: adapter maps to 100% and sets very large minimumNumberOfCalls to prevent CB from self-opening; executor still applies dual thresholds.

Migration

• Prefer:
  • thresholdMinNumOfFailures(int)
  • circuitBreakerFailureRateThreshold(float)
  • circuitBreakerSlidingWindowSize(int)
• Removed: slidingWindowType, slidingWindowMinCalls, slowCallDurationThreshold, slowCallRateThreshold. Adjust configs accordingly.

Validation

• Unit and parameterized tests cover edge thresholds (0%, 100%), small/large sample sizes.
• Integration tests updated; docs aligned with new defaults and API.

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[Copilot]

Pull Request Overview

This PR adds dual-threshold failover capability to Jedis multi-cluster circuit breaker functionality. The circuit breaker now requires both a minimum number of failures AND a failure rate threshold to be exceeded before triggering failover, providing more robust failover control.

Key changes:

• Introduces dual threshold logic requiring both minimum failures and failure rate criteria to be met
• Simplifies configuration by removing deprecated circuit breaker settings and updating defaults
• Adds new adapter class to handle threshold mapping to resilience4j configuration

Reviewed Changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
MultiClusterClientConfig.java	Updated configuration with new dual threshold properties and simplified circuit breaker settings
CircuitBreakerThresholdsAdapter.java	New adapter class for mapping configuration to resilience4j circuit breaker settings
CircuitBreakerCommandExecutor.java	Added dual threshold checking logic before triggering failover
CircuitBreakerFailoverBase.java	Base class with shared threshold validation logic
JedisFailoverThresholdsExceededException.java	New exception type for threshold-based failover
Various test files	Updated tests to remove deprecated configuration options and add threshold testing
docs/failover.md	Updated documentation with new defaults and simplified configuration

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[Copilot]

The calculation appears incorrect. The formula failures * rate * 100 doesn't represent the minimum number of total calls needed. For example, if you need 3 failures at 50% rate, you'd need at least 6 total calls, but this formula gives 150. The correct formula should be (int) Math.ceil(failures / (rate / 100.0)) or (int) Math.ceil(failures * 100.0 / rate).

Suggested change

	int minCalls = (int) (failures * rate * 100);
	int minCalls = (int) Math.ceil(failures * 100.0 / rate);