/*

* Copyright (c) 2014-2015, Facebook, Inc.

* All rights reserved.

*

* This source code is licensed under the BSD-style license found in the

* LICENSE file in the root directory of this source tree. An additional grant

* of patent rights can be found in the PATENTS file in the same directory.

*/

using System;

using System.Collections.Generic;

using System.Linq;

using System.Runtime.Caching;

namespace React

{

/// <summary>

/// Memory cache implementation for React.ICache. Uses System.Runtime.Caching.

/// </summary>

public class MemoryFileCache : ICache

{

private readonly ObjectCache _cache;

/// <summary>

/// Initializes a new instance of the <see cref="MemoryFileCache"/> class.

/// </summary>

public MemoryFileCache()

{

_cache = MemoryCache.Default;

}

/// <summary>

/// Get an item from the cache. Returns <paramref name="fallback"/> if the item does

/// not exist.

/// </summary>

/// <typeparam name="T">Type of data</typeparam>

/// <param name="key">The cache key</param>

/// <param name="fallback">Value to return if item is not in the cache</param>

/// <returns>Data from cache, otherwise <paramref name="fallback"/></returns>

public T Get<T>(string key, T fallback = default(T))

{

return (T)(_cache.Get(key) ?? fallback);

}

/// <summary>

/// Sets an item in the cache.

/// </summary>

/// <typeparam name="T">Type of data</typeparam>

/// <param name="key">The cache key</param>

/// <param name="data">Data to cache</param>

/// <param name="slidingExpiration">

/// Sliding expiration, if cache key is not accessed in this time period it will

/// automatically be removed from the cache

/// </param>

/// <param name="cacheDependencyFiles">

/// Filenames this cached item is dependent on. If any of these files change, the cache

/// will be cleared automatically

/// </param>

/// <param name="cacheDependencyKeys">

/// Other cache keys this cached item is dependent on. If any of these keys change, the

/// cache will be cleared automatically

/// </param>

public void Set<T>(string key, T data, TimeSpan slidingExpiration, IEnumerable<string> cacheDependencyFiles = null, IEnumerable<string> cacheDependencyKeys = null)

{

if (data == null)

{

_cache.Remove(key);

return;

}

var policy = new CacheItemPolicy { SlidingExpiration = slidingExpiration };

if (cacheDependencyFiles != null && cacheDependencyFiles.Any())

policy.ChangeMonitors.Add(new HostFileChangeMonitor(cacheDependencyFiles.ToList()));

if (cacheDependencyKeys != null && cacheDependencyKeys.Any())

policy.ChangeMonitors.Add(_cache.CreateCacheEntryChangeMonitor(cacheDependencyKeys));

_cache.Set(key, data, policy);

}

}

}