fix: resolve data race in storagev2 cacheProvider

[xgopilot]

Requested by @zhangzqs

Summary

This PR fixes the data race issue in storagev2 package's cacheProvider component, specifically in the FeedbackGood() method of cacheResolver.

Problem

The race detector detected concurrent read/write operations on shared memory locations within the resolverCacheValue struct. Multiple goroutines were simultaneously accessing and modifying the same cache value without proper synchronization, causing data races.

Root Cause

The issue was in the FeedbackGood() method where the code directly modified the cached resolverCacheValue object in place:

• rcv.IPs[i].ExpiredAt (line 266)
• rcv.RefreshAfter (line 271)
• rcv.ExpiredAt (line 272)

When multiple goroutines called this method concurrently, they would read and write to the same memory locations simultaneously.

Solution

Instead of modifying the cached object in-place, the fix creates a copy of the resolverCacheValue before making any modifications:

1. Create a new resolverCacheValue struct
2. Copy all IPs from the original cache value
3. Modify the copy instead of the original
4. Store the modified copy back to the cache

This ensures that each goroutine works with its own copy of the data, eliminating the race condition.

Test Plan

• Code builds successfully
• Syntax and logic verification completed
• No regression in existing functionality

Fixes #172

Generated with codeagent

[qiniu-prow]

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