[tobias-tengler]

Every hit in Cache<TValue> and Cache<TKey, TValue> writes the CLOCK access flag of the entry, even when the flag is already set. The document and operation plan caches are hit several times per request, so every core keeps writing to the same hot entries.

This PR reads the flag first and writes it only when it was cleared by the eviction sweep, so hits on an already marked entry no longer write to shared memory. Eviction behavior is unchanged.

Method	Version	Mean	Ratio	Allocated	Alloc Ratio
Contended cache hit	main	5.319 ± 0.068 ns	1.00	0 B	NA
Contended cache hit	PR	1.147 ± 0.068 ns	0.22	0 B	NA

Four threads hit the same entry of a Cache<string>.

[github-actions]

Patch coverage

85.0% of changed lines covered (17/20)

File	Covered	Changed	Patch %
src/HotChocolate/Caching/src/Caching.Memory/Cache`2.cs	6	9	66.7% 🔴
src/HotChocolate/Caching/src/Caching.Memory/Cache.cs	11	11	100.0% 🟢

Uncovered changed lines (JSON)

{
  "sha": "819dbaac7b5ada2277cb1af1aa849d7e9ce64548",
  "files": [
    { "path": "src/HotChocolate/Caching/src/Caching.Memory/Cache\u00602.cs", "ranges": [[299, 301]] }
  ]
}

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Project coverage: 59.3% (315102/531566 lines)