70 lines
2.5 KiB
C#
70 lines
2.5 KiB
C#
/*
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Copyright 2017 Google Inc
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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using System.Threading.Tasks;
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namespace Google.Apis.Util.Store
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{
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/// <summary>
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/// A null datastore. Nothing is stored, nothing is retrievable.
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/// </summary>
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public class NullDataStore : IDataStore
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{
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private static readonly Task s_completedTask = CompletedTask<int>();
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private static Task<T> CompletedTask<T>()
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{
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var tcs = new TaskCompletionSource<T>();
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tcs.SetResult(default(T));
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return tcs.Task;
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}
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/// <summary>
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/// Construct a new null datastore, that stores nothing.
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/// </summary>
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public NullDataStore()
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{
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}
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/// <inheritdoc/>
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public Task ClearAsync() => s_completedTask;
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/// <inheritdoc/>
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public Task DeleteAsync<T>(string key) => s_completedTask;
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/// <summary>
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/// Asynchronously returns the stored value for the given key or <c>null</c> if not found.
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/// This implementation of <see cref="IDataStore"/> will always return a completed task
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/// with a result of <c>null</c>.
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/// </summary>
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/// <typeparam name="T">The type to retrieve from the data store.</typeparam>
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/// <param name="key">The key to retrieve its value.</param>
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/// <returns>Always <c>null</c>.</returns>
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public Task<T> GetAsync<T>(string key) => CompletedTask<T>();
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/// <summary>
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/// Asynchronously stores the given value for the given key (replacing any existing value).
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/// This implementation of <see cref="IDataStore"/> does not store the value,
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/// and will not return it in future calls to <see cref="GetAsync{T}(string)"/>.
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/// </summary>
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/// <typeparam name="T">The type to store in the data store.</typeparam>
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/// <param name="key">The key.</param>
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/// <param name="value">The value.</param>
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/// <returns>A task that completes immediately.</returns>
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public Task StoreAsync<T>(string key, T value) => s_completedTask;
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}
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}
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