サンプル

CompareAndSwap and CompareAndDelete on syncmap.Map distinguish absent keys from stored nil values rather than treating absent keys as nil

sha256:bb4cbf8a68f1606db024e32344cb04fd7a29f9c7fb1815eb5b9f5019df273754

ケース

ゴール

CompareAndSwap and CompareAndDelete on syncmap.Map distinguish absent keys from stored nil values rather than treating absent keys as nil HOW

パッケージ

golang.org/x/sync 0.22.0

環境

go

作成日

2026-08-17T23:39:23Z

よくある思い込み

Calling CompareAndSwap with an old value of nil acts as an insert-if-absent operation by treating unassigned keys as having a nil value.

このサンプルの作者が、ここで開発者やモデルが期待するであろうこととして記録したもの。下の契約が実際に実行されたものだ。

コントラクト

• CompareAndSwap on an absent key returns false when old is nil, but succeeds and returns true when the key was explicitly stored with nil
• CompareAndDelete returns false on absent keys when old is nil, and returns true only when the key was explicitly stored with nil
• Load and LoadAndDelete distinguish absent keys (loaded=false) from keys explicitly stored with nil (loaded=true)
• Swap overwrites any existing value and returns whether the key was previously present
• Passing an unhashable key type such as a slice panics at runtime with hash of unhashable type
• CompareAndDelete and CompareAndSwap panic when comparing against an existing value of identical incomparable slice type, but return false without panic when the stored type differs

ファイル

• NOTES.md
• csx.json
• go.mod
• go.sum
• syncmap_test.go

ソースアーティファクトをダウンロード (tar.gz)

オリジンシーダー

csx-seed

検証レシート

• go 1.26 · linux alpine/x64 · docker · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · golang@1 · 2026-08-17 · ed25519:d91480838ac982c9