2020-11-06 12:26:18 +08:00
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// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
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// See the LICENCE file in the repository root for full licence text.
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2022-06-17 15:37:17 +08:00
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#nullable disable
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2022-06-24 17:39:44 +08:00
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using System;
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2020-11-06 12:26:18 +08:00
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using System.Collections.Concurrent;
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2020-11-06 12:50:51 +08:00
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using System.Threading;
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using System.Threading.Tasks;
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using JetBrains.Annotations;
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2020-11-06 12:26:18 +08:00
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using osu.Framework.Graphics;
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namespace osu.Game.Database
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{
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/// <summary>
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/// A component which performs lookups (or calculations) and caches the results.
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/// Currently not persisted between game sessions.
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/// </summary>
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public abstract class MemoryCachingComponent<TLookup, TValue> : Component
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{
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2020-11-06 12:50:51 +08:00
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private readonly ConcurrentDictionary<TLookup, TValue> cache = new ConcurrentDictionary<TLookup, TValue>();
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protected virtual bool CacheNullValues => true;
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/// <summary>
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2020-11-06 13:31:21 +08:00
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/// Retrieve the cached value for the given lookup.
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2020-11-06 12:50:51 +08:00
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/// </summary>
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/// <param name="lookup">The lookup to retrieve.</param>
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/// <param name="token">An optional <see cref="CancellationToken"/> to cancel the operation.</param>
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protected async Task<TValue> GetAsync([NotNull] TLookup lookup, CancellationToken token = default)
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{
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2020-11-06 15:57:09 +08:00
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if (CheckExists(lookup, out TValue performance))
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return performance;
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2021-03-08 11:57:16 +08:00
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var computed = await ComputeValueAsync(lookup, token).ConfigureAwait(false);
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2020-11-06 12:50:51 +08:00
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if (computed != null || CacheNullValues)
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cache[lookup] = computed;
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return computed;
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}
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2022-06-30 16:17:06 +08:00
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/// <summary>
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/// Invalidate all entries matching a provided predicate.
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/// </summary>
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/// <param name="matchKeyPredicate">The predicate to decide which keys should be invalidated.</param>
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protected void Invalidate(Func<TLookup, bool> matchKeyPredicate)
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{
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foreach (var kvp in cache)
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{
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if (matchKeyPredicate(kvp.Key))
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cache.TryRemove(kvp.Key, out _);
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}
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}
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2020-11-06 13:31:21 +08:00
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protected bool CheckExists([NotNull] TLookup lookup, out TValue value) =>
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cache.TryGetValue(lookup, out value);
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2020-11-06 12:50:51 +08:00
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/// <summary>
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/// Called on cache miss to compute the value for the specified lookup.
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/// </summary>
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/// <param name="lookup">The lookup to retrieve.</param>
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/// <param name="token">An optional <see cref="CancellationToken"/> to cancel the operation.</param>
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/// <returns>The computed value.</returns>
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protected abstract Task<TValue> ComputeValueAsync(TLookup lookup, CancellationToken token = default);
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2020-11-06 12:26:18 +08:00
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}
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}
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