59 lines
1.9 KiB
C#
59 lines
1.9 KiB
C#
// Copyright (c) .NET Foundation. All rights reserved.
|
|
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
|
|
|
|
using System;
|
|
using System.Collections.Generic;
|
|
using System.Threading;
|
|
|
|
namespace Microsoft.AspNetCore.Routing
|
|
{
|
|
internal class DataSourceDependentCache<T> where T : class
|
|
{
|
|
private readonly EndpointDataSource _dataSource;
|
|
private readonly Func<IReadOnlyList<Endpoint>, T> _initializeCore;
|
|
private readonly Func<T> _initializer;
|
|
private readonly Action<object> _initializerWithState;
|
|
|
|
private object _lock;
|
|
private bool _initialized;
|
|
private T _value;
|
|
|
|
public DataSourceDependentCache(EndpointDataSource dataSource, Func<IReadOnlyList<Endpoint>, T> initialize)
|
|
{
|
|
if (dataSource == null)
|
|
{
|
|
throw new ArgumentNullException(nameof(dataSource));
|
|
}
|
|
|
|
_dataSource = dataSource;
|
|
_initializeCore = initialize;
|
|
|
|
_initializer = Initialize;
|
|
_initializerWithState = (state) => Initialize();
|
|
_lock = new object();
|
|
}
|
|
|
|
// Note that we don't lock here, and think about that in the context of a 'push'. So when data gets 'pushed'
|
|
// we start computing a new state, but we're still able to perform operations on the old state until we've
|
|
// processed the update.
|
|
public T Value => _value;
|
|
|
|
public T EnsureInitialized()
|
|
{
|
|
return LazyInitializer.EnsureInitialized<T>(ref _value, ref _initialized, ref _lock, _initializer);
|
|
}
|
|
|
|
private T Initialize()
|
|
{
|
|
lock (_lock)
|
|
{
|
|
var changeToken = _dataSource.ChangeToken;
|
|
_value = _initializeCore(_dataSource.Endpoints);
|
|
|
|
changeToken.RegisterChangeCallback(_initializerWithState, null);
|
|
return _value;
|
|
}
|
|
}
|
|
}
|
|
}
|