fix(pool): Pool ReAuth should not interfere with handoff

[ndyakov]

This branch implements support for streaming credentials with automatic re-authentication of pooled Redis connections. The implementation adds a new pool hook system for background re-authentication, introduces a Used flag to prevent concurrent command execution on connections, and integrates with the existing maintenance notifications system.

[Copilot]

Pull Request Overview

This PR addresses a concurrency issue where pool re-authentication could interfere with connection handoff operations during maintenance notifications. The fix introduces connection state management using Usable and Used flags to coordinate between background operations (re-authentication) and handoff processes.

Key changes:

• Added connection-level credentials listener caching to prevent duplicate listeners per connection
• Introduced Used flag alongside existing Usable flag to prevent concurrent command execution on connections
• Modified re-authentication flow to wait for connections to be available before proceeding

Reviewed Changes

Copilot reviewed 11 out of 12 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
redis.go	Added credentials listener management with caching per connection and modified re-authentication callbacks to accept connection parameter
internal/pool/conn.go	Added Used flag and reorganized connection state fields, modified handoff marking logic to acquire connection before state changes
internal/pool/pool.go	Updated connection usage tracking with Used flag in pool operations
internal/pool/pool_single.go	Added Used flag management for single connection pools
auth/conn_reauth_credentials_listener.go	New file implementing connection-aware credentials listener with timeout-based waiting for connection availability
error.go	Added ErrConnUnusableTimeout to bad connection error handling
redis_test.go	Added mutex protection to mock streaming provider
sentinel_test.go	Renamed test function for clarity
internal/pool/pool_test.go	Adjusted test expectations for dial retry behavior
maintnotifications/handoff_worker.go	Added formatting and clarifying comments
internal/pool/buffer_size_test.go	Updated unsafe pointer field layout to match new connection structure

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[Copilot]

Pull Request Overview

Copilot reviewed 12 out of 13 changed files in this pull request and generated 4 comments.

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[Copilot]

Pull Request Overview

Copilot reviewed 12 out of 13 changed files in this pull request and generated 1 comment.

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[Copilot]

Pull Request Overview

Copilot reviewed 22 out of 23 changed files in this pull request and generated 4 comments.

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[Copilot]

Pull Request Overview

Copilot reviewed 22 out of 23 changed files in this pull request and generated 3 comments.

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[Copilot]

Pull Request Overview

Copilot reviewed 22 out of 23 changed files in this pull request and generated 2 comments.

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[Copilot]

Pull Request Overview

Copilot reviewed 22 out of 23 changed files in this pull request and generated 4 comments.

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[jit-ci]

❌ Jit has detected 4 important findings in this PR that you should review.
The findings are detailed below as separate comments.
It’s highly recommended that you fix these security issues before merge.

Repository Risks:

• Database Integration: Connects to a database, often involving sensitive data that must be securely managed.
• High Severity Findings: Indicates that the resource has high severity security findings that need attention.

Repository Context:

graph LR
    GitHub$Repository_U23_redis/go_U2D_redis["GitHub Repository<br/>redis/go-redis"]:::GitHub$Repository
    Team_U23_client_U2D_developers["Team<br/>client-developers"]:::Team
    Team_U23_client_U2D_docs["Team<br/>client-docs"]:::Team
    DBIntegration_U23_redis["DBIntegration<br/>redis"]:::DBIntegration
    Team_U23_client_U2D_developers -- "Owns" --> GitHub$Repository_U23_redis/go_U2D_redis
    Team_U23_client_U2D_docs -- "Owns" --> GitHub$Repository_U23_redis/go_U2D_redis
    GitHub$Repository_U23_redis/go_U2D_redis -- "Is accessible to" --> DBIntegration_U23_redis

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[jit-ci]

❌ Jit has detected 4 important findings in this PR that you should review.
The findings are detailed as separate comments.
It’s highly recommended that you fix these security issues before merge.

Until now, you ignored/fixed 2 findings.

[jit-ci]

❌ Jit has detected 4 important findings in this PR that you should review.
The findings are detailed as separate comments.
It’s highly recommended that you fix these security issues before merge.

Until now, you ignored/fixed 6 findings.

[Copilot]

Pull Request Overview

Copilot reviewed 22 out of 23 changed files in this pull request and generated 1 comment.

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[Copilot]

This TODO indicates a known issue with the current connection acquisition approach. The release-and-retry pattern could lead to starvation if the connection is continuously used. Consider implementing a wait mechanism (e.g., using a condition variable or channel) to be notified when the connection becomes available instead of polling with exponential backoff.

Suggested change

	// Release Usable and retry with exponential backoff
	// todo(ndyakov): think of a better way to do this without the need
	// to release the connection, but just wait till it is not used
	conn.SetUsable(true)
	}
	}
	if !acquired {
	// Exponential backoff: 10, 20, 40, 80... up to 5120 microseconds
	delay := baseDelay * time.Duration(1<<uint(attempt%10)) // Cap exponential growth
	time.Sleep(delay)
	attempt++
	}
	// Release Usable and wait for notification
	conn.SetUsable(true)
	// Wait for the connection to become unused or timeout
	usedWaitCh := make(chan struct{})
	go func() {
	// Poll at a reasonable interval, but not busy-wait
	ticker := time.NewTicker(100 * time.Microsecond)
	defer ticker.Stop()
	for {
	if !conn.IsUsed() {
	close(usedWaitCh)
	return
	}
	select {
	case <-ticker.C:
	// continue
	case <-timeout:
	// timeout, exit
	return
	}
	}
	}()
	select {
	case <-usedWaitCh:
	// Try again to acquire
	case <-timeout:
	// Timeout occurred, cannot acquire connection
	err = pool.ErrConnUnusableTimeout
	reAuthFn(err)
	return
	}
	}
	}