Max Katz
3 years ago
committed by
GitHub
GitHub
23 changed files with 128 additions and 50 deletions
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// This file is imported from dotnet/runtime
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// Source Link: https://github.com/dotnet/runtime/blob/e63d21947e734db2da5093510a6636b5b7fb45b5/src/libraries/Common/src/System/Text/StringBuilderCache.cs
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// Commit: a9c5ead on Feb 10, 2021, https://github.com/dotnet/runtime/commit/a9c5eadd951dcba73167f72cc624eb790573663a
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//
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// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT license.
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using System; |
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using System.Text; |
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namespace Avalonia.Utilities; |
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// <summary>Provide a cached reusable instance of stringbuilder per thread.</summary>
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internal static class StringBuilderCache |
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{ |
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// The value 360 was chosen in discussion with performance experts as a compromise between using
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// as little memory per thread as possible and still covering a large part of short-lived
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// StringBuilder creations on the startup path of VS designers.
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internal const int MaxBuilderSize = 360; |
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private const int DefaultCapacity = 16; // == StringBuilder.DefaultCapacity
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// WARNING: We allow diagnostic tools to directly inspect this member (t_cachedInstance).
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// See https://github.com/dotnet/corert/blob/master/Documentation/design-docs/diagnostics/diagnostics-tools-contract.md for more details.
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// Please do not change the type, the name, or the semantic usage of this member without understanding the implication for tools.
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// Get in touch with the diagnostics team if you have questions.
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[ThreadStatic] |
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private static StringBuilder? t_cachedInstance; |
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/// <summary>Get a StringBuilder for the specified capacity.</summary>
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/// <remarks>If a StringBuilder of an appropriate size is cached, it will be returned and the cache emptied.</remarks>
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public static StringBuilder Acquire(int capacity = DefaultCapacity) |
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{ |
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if (capacity <= MaxBuilderSize) |
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{ |
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StringBuilder? sb = t_cachedInstance; |
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if (sb != null) |
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{ |
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// Avoid stringbuilder block fragmentation by getting a new StringBuilder
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// when the requested size is larger than the current capacity
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if (capacity <= sb.Capacity) |
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{ |
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t_cachedInstance = null; |
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sb.Clear(); |
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return sb; |
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} |
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} |
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} |
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return new StringBuilder(capacity); |
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} |
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/// <summary>Place the specified builder in the cache if it is not too big.</summary>
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public static void Release(StringBuilder sb) |
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{ |
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if (sb.Capacity <= MaxBuilderSize) |
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{ |
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t_cachedInstance = sb; |
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} |
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} |
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/// <summary>ToString() the stringbuilder, Release it to the cache, and return the resulting string.</summary>
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public static string GetStringAndRelease(StringBuilder sb) |
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{ |
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string result = sb.ToString(); |
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Release(sb); |
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return result; |
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} |
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} |
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