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Wojciech's questions

Martin Hope
Wojciech
Asked: 2025-04-10 01:01:23 +0800 CST
  • 5

源代码ConcurrentDictionary提到了使用的可能性TAlternateKey，这是一个 ref 结构。https ://github.com/dotnet/runtime/blob/main/src/libraries/System.Collections.Concurrent/src/System/Collections/Concurrent/ConcurrentDictionary.cs

另外，经过一番搜索，我还发现了其他有趣的例子。例如： https ://github.com/dotnet/runtime/blob/main/src/libraries/Microsoft.Extensions.Caching.Memory/src/MemoryCache.cs

#if NET9_0_OR_GREATER
            private readonly ConcurrentDictionary<string, CacheEntry>.AlternateLookup<ReadOnlySpan<char>> _stringAltLookup;

            public CoherentState()
            {
                _stringAltLookup = _stringEntries.GetAlternateLookup<ReadOnlySpan<char>>();
            }
#endif
//...
#if NET9_0_OR_GREATER
            internal bool TryGetValue(ReadOnlySpan<char> key, [NotNullWhen(true)] out CacheEntry? entry)
                => _stringAltLookup.TryGetValue(key, out entry);
#endif

#if NET9_0_OR_GREATER
            private readonly ConcurrentDictionary<string, CacheEntry>.AlternateLookup<ReadOnlySpan<char>> _stringAltLookup;

            public CoherentState()
            {
                _stringAltLookup = _stringEntries.GetAlternateLookup<ReadOnlySpan<char>>();
            }
#endif

为了获得更好的性能，我是否应该使用ReadOnlySpan<char>作为 Key，而ConcurrentDictionary不是string？

c#