Fix type assertion panic in Cache.Get() when key not found#881
Merged
mattisonchao merged 3 commits intooxia-db:mainfrom Feb 6, 2026
Merged
Fix type assertion panic in Cache.Get() when key not found#881mattisonchao merged 3 commits intooxia-db:mainfrom
mattisonchao merged 3 commits intooxia-db:mainfrom
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When a key is not found in Oxia, the cache stores a negative cache entry using `empty[cachedResult[Value]]()`. However, since cachedResult[Value] is a type alias for Optional[valueVersion[Value]], this creates a double-wrapped optional type: *optional[Optional[valueVersion[Value]]]. When Cache.Get() later retrieves this entry and attempts the type assertion `cachedValue.(cachedResult[Value])`, it fails with: "interface conversion: *oxia.optional[cachedResult[...]] is not cachedResult[...]: missing method Get" The fix is to use `empty[valueVersion[Value]]()` instead, which creates *optional[valueVersion[Value]] - the same type structure as the non-empty case, ensuring type consistency.
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Hi @labuladong could you hellp add a test for it? |
mattisonchao
reviewed
Feb 5, 2026
TestCache_GetNotFoundTwice: Verifies that calling Get() twice on a non-existing key does not panic. The first call stores a negative cache entry via load(), the second call reads it from ristretto and performs a type assertion that would fail with the old code. TestCache_GetNotFoundThenPut: Verifies that a key can transition from "not found" (negative cache entry) to a valid value without issues.
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mattisonchao
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Feb 6, 2026
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Summary
Fix a type assertion panic that occurs when
Cache.Get()is called for a key that doesn't exist in Oxia.Problem
When a key is not found, the cache stores a negative cache entry using:
However,
cachedResult[Value]is a type alias forOptional[valueVersion[Value]], so this creates a double-wrapped optional type:When
Cache.Get()later retrieves this entry and attempts the type assertion:It fails with:
Solution
Use
empty[valueVersion[Value]]()instead, which creates*optional[valueVersion[Value]]- the same type structure as the non-empty case, ensuring type consistency.Type Analysis