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using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Collections.Specialized;
using System.Diagnostics;
using System.Web.Resources;
using System.Globalization;
using System.Web.Caching;
using System.Web.Hosting;
namespace System.Web.DynamicData {
delegate void FileChangedCallback(string path);
class FileChangeNotifier {
private static VirtualPathProvider _vpp;
internal static VirtualPathProvider VirtualPathProvider {
private get {
if (_vpp == null) {
_vpp = HostingEnvironment.VirtualPathProvider;
}
return _vpp;
}
// For unit test purpose
set {
_vpp = value;
}
}
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA1806:DoNotIgnoreMethodResults",
MessageId = "System.Web.DynamicData.FileChangeNotifier",
Justification="The object deals with file change notifications and we don't need to hold on to it")]
internal static void Register(string virtualPath, FileChangedCallback onFileChanged) {
new FileChangeNotifier(virtualPath, onFileChanged);
}
private FileChangedCallback _onFileChanged;
private FileChangeNotifier(string virtualPath, FileChangedCallback onFileChanged) {
_onFileChanged = onFileChanged;
RegisterForNextNotification(virtualPath);
}
private void RegisterForNextNotification(string virtualPath) {
// Get a CacheDependency from the BuildProvider, so that we know anytime something changes
var virtualPathDependencies = new List<string>();
virtualPathDependencies.Add(virtualPath);
CacheDependency cacheDependency = VirtualPathProvider.GetCacheDependency(
virtualPath, virtualPathDependencies, DateTime.UtcNow);
// Rely on the ASP.NET cache for file change notifications, since FileSystemWatcher
// doesn't work in medium trust
HttpRuntime.Cache.Insert(virtualPath /*key*/, virtualPath /*value*/, cacheDependency,
Cache.NoAbsoluteExpiration, Cache.NoSlidingExpiration,
CacheItemPriority.NotRemovable, new CacheItemRemovedCallback(OnCacheItemRemoved));
}
private void OnCacheItemRemoved(string key, object value, CacheItemRemovedReason reason) {
// We only care about dependency changes
if (reason != CacheItemRemovedReason.DependencyChanged)
return;
_onFileChanged(key);
// We need to register again to get the next notification
RegisterForNextNotification(key);
}
}
}
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