TimeStampChecker.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / FX-1434 / FX-1434 / 1.0 / untmp / whidbey / REDBITS / ndp / fx / src / xsp / System / Web / Compilation / TimeStampChecker.cs / 1 / TimeStampChecker.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Web.Compilation { 
 
    using System;
    using System.Collections; 
    using System.IO;
    using System.Web;
    using System.Web.Hosting;
    using Debug = System.Web.Util.Debug; 

    internal class TimeStampChecker { 
        internal const String CallContextSlotName = "TSC"; 

        private Hashtable _timeStamps = new Hashtable(StringComparer.OrdinalIgnoreCase); 

        private static TimeStampChecker Current {
            get {
                TimeStampChecker tsc = (TimeStampChecker)System.Runtime.Remoting.Messaging.CallContext.GetData( 
                    CallContextSlotName) as TimeStampChecker;
 
                // Create it on demand 
                if (tsc == null) {
                    tsc = new TimeStampChecker(); 
                    Debug.Trace("TimeStampChecker", "Creating new TimeStampChecker");
                    System.Runtime.Remoting.Messaging.CallContext.SetData(CallContextSlotName, tsc);
                }
 
                return tsc;
            } 
        } 

        internal static void AddFile(string virtualPath, string path) { 
            Current.AddFileInternal(virtualPath, path);
        }

        private void AddFileInternal(string virtualPath, string path) { 
            DateTime lastWriteTimeUtc = File.GetLastWriteTimeUtc(path);
 
            if (_timeStamps.Contains(virtualPath)) { 
                DateTime storedValue = (DateTime)_timeStamps[virtualPath];
 
                // Already found to have changed before
                if (storedValue == DateTime.MaxValue) {
                    Debug.Trace("TimeStampChecker", "AddFileInternal: Same time stamp (" + path + ")");
                    return; 
                }
 
                // If it's different, set it to MaxValue as marker of being invalid 
                if (storedValue != lastWriteTimeUtc) {
                    _timeStamps[virtualPath] = DateTime.MaxValue; 
                    Debug.Trace("TimeStampChecker", "AddFileInternal: Changed time stamp (" + path + ")");
                }
            }
            else { 
                // New path: just add it
                _timeStamps[virtualPath] = lastWriteTimeUtc; 
                Debug.Trace("TimeStampChecker", "AddFileInternal: New path (" + path + ")"); 
            }
        } 

        internal static bool CheckFilesStillValid(string key, ICollection virtualPaths) {
            if (virtualPaths == null)
                return true; 

            return Current.CheckFilesStillValidInternal(key, virtualPaths); 
        } 

        private bool CheckFilesStillValidInternal(string key, ICollection virtualPaths) { 
            Debug.Trace("TimeStampChecker", "CheckFilesStillValidInternal (" + key + ")");

            foreach (string virtualPath in virtualPaths) {
 
                if (!_timeStamps.Contains(virtualPath))
                    continue; 
 
                string path = HostingEnvironment.MapPath(virtualPath);
 
                DateTime lastWriteTimeUtc = File.GetLastWriteTimeUtc(path);
                DateTime storedValue = (DateTime)_timeStamps[virtualPath];

                // If it changed, then it's not valid 
                if (lastWriteTimeUtc != storedValue) {
                    Debug.Trace("TimeStampChecker", "CheckFilesStillValidInternal: File (" + path + ") has changed!"); 
 
                    return false;
                } 
            }

            Debug.Trace("TimeStampChecker", "CheckFilesStillValidInternal (" + key + ") is still valid");
            return true; 
        }
    } 
}

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