root / trunk / Pithos.Core / Agents / DeleteAgent.cs @ 255f5f86
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#region |
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/* ----------------------------------------------------------------------- |
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* <copyright file="DeleteAgent.cs" company="GRNet"> |
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* |
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* Copyright 2011-2012 GRNET S.A. All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or |
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* without modification, are permitted provided that the following |
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* conditions are met: |
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* |
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* 1. Redistributions of source code must retain the above |
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* copyright notice, this list of conditions and the following |
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* disclaimer. |
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* |
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* 2. Redistributions in binary form must reproduce the above |
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* copyright notice, this list of conditions and the following |
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* disclaimer in the documentation and/or other materials |
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* provided with the distribution. |
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* |
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* |
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* THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS |
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* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR |
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF |
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* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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* POSSIBILITY OF SUCH DAMAGE. |
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* |
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* The views and conclusions contained in the software and |
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* documentation are those of the authors and should not be |
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* interpreted as representing official policies, either expressed |
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* or implied, of GRNET S.A. |
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* </copyright> |
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* ----------------------------------------------------------------------- |
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*/ |
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#endregion |
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using System.Collections.Concurrent; |
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using System.ComponentModel.Composition; |
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using System.Diagnostics.Contracts; |
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using System.IO; |
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using System.Net; |
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using System.Threading.Tasks.Dataflow; |
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using Pithos.Interfaces; |
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using Pithos.Network; |
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using System; |
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using log4net; |
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|
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namespace Pithos.Core.Agents |
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{ |
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|
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/// <summary> |
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/// The Delete Agent is used to delete files from the Pithos server with high priority, |
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/// blocking the network agent through the PauseEvent until all pending deletions complete |
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/// </summary> |
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[Export] |
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public class DeleteAgent |
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{ |
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|
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[Import] |
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public IStatusKeeper StatusKeeper { get; set; } |
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|
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private static readonly ILog Log = LogManager.GetLogger("DeleteAgent"); |
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|
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//A separate agent is used to execute delete actions immediatelly; |
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private readonly ActionBlock<CloudDeleteAction> _deleteAgent; |
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|
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//The Pause event stops the network agent to give priority to the deletion agent |
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//Initially the event is signalled because we don't need to pause |
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private readonly AsyncManualResetEvent _pauseEvent = new AsyncManualResetEvent(true); |
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|
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public AsyncManualResetEvent PauseEvent |
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{ |
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get { return _pauseEvent; } |
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} |
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|
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//Deleted file names are stored in memory so we can check that a file has already been deleted. |
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//and avoid sending duplicate delete commands |
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readonly ConcurrentDictionary<string, DateTime> _deletedFiles = new ConcurrentDictionary<string, DateTime>(); |
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|
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public DeleteAgent() |
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{ |
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_deleteAgent = new ActionBlock<CloudDeleteAction>(message => ProcessDelete(message), new ExecutionDataflowBlockOptions { MaxDegreeOfParallelism = 4 }); |
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|
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} |
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|
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/// <summary> |
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/// Processes cloud delete actions |
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/// </summary> |
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/// <param name="action">The delete action to execute</param> |
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/// <returns></returns> |
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/// <remarks> |
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/// When a file/folder is deleted locally, we must delete it ASAP from the server and block any download |
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/// operations that may be in progress. |
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/// <para> |
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/// A separate agent is used to process deletes because the main agent may be busy with a long operation. |
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/// </para> |
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/// </remarks> |
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private void ProcessDelete(CloudDeleteAction action) |
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{ |
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if (action == null) |
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throw new ArgumentNullException("action"); |
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if (action.AccountInfo == null) |
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throw new ArgumentException("The action.AccountInfo is empty", "action"); |
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Contract.EndContractBlock(); |
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|
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var accountInfo = action.AccountInfo; |
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|
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using (log4net.ThreadContext.Stacks["NETWORK"].Push("PROCESS")) |
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{ |
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Log.InfoFormat("[ACTION] Start Processing {0}", action); |
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|
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var cloudFile = action.CloudFile; |
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|
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try |
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{ |
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//Acquire a lock on the deleted file to prevent uploading/downloading operations from the normal |
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//agent |
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using (NetworkGate.Acquire(action.LocalFile.FullName, NetworkOperation.Deleting)) |
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{ |
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|
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//Add the file URL to the deleted files list |
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var key = GetFileKey(action.CloudFile); |
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_deletedFiles[key] = DateTime.Now; |
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|
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_pauseEvent.Reset(); |
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// and then delete the file from the server |
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DeleteCloudFile(accountInfo, cloudFile); |
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|
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Log.InfoFormat("[ACTION] End Delete {0}:{1}->{2}", action.Action, action.LocalFile, |
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action.CloudFile.Name); |
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} |
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} |
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catch (WebException exc) |
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{ |
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Log.ErrorFormat("[WEB ERROR] {0} : {1} -> {2} due to exception\r\n{3}", action.Action, action.LocalFile, action.CloudFile, exc); |
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} |
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catch (OperationCanceledException) |
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{ |
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throw; |
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} |
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catch (DirectoryNotFoundException) |
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{ |
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Log.ErrorFormat("{0} : {1} -> {2} failed because the directory was not found.\n Rescheduling a delete", |
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action.Action, action.LocalFile, action.CloudFile); |
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//Repost a delete action for the missing file |
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_deleteAgent.Post(action); |
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} |
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catch (FileNotFoundException) |
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{ |
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Log.ErrorFormat("{0} : {1} -> {2} failed because the file was not found.\n Rescheduling a delete", |
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action.Action, action.LocalFile, action.CloudFile); |
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//Post a delete action for the missing file |
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_deleteAgent.Post(action); |
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} |
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catch (Exception exc) |
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{ |
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Log.ErrorFormat("[REQUEUE] {0} : {1} -> {2} due to exception\r\n{3}", |
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action.Action, action.LocalFile, action.CloudFile, exc); |
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|
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_deleteAgent.Post(action); |
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} |
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finally |
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{ |
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//Set the event when all delete actions are processed |
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if (_deleteAgent.InputCount == 0) |
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_pauseEvent.Set(); |
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|
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} |
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} |
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} |
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//Returns true if an action concerns a file that was deleted |
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public bool IsDeletedFile(CloudAction action) |
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{ |
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//Doesn't work for actions targeting shared files |
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if (action.IsShared) |
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return false; |
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var key = GetFileKey(action.CloudFile); |
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DateTime entryDate; |
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if (_deletedFiles.TryGetValue(key, out entryDate)) |
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{ |
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//If the delete entry was created after this action, abort the action |
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if (entryDate > action.Created) |
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return true; |
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//Otherwise, remove the stale entry |
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_deletedFiles.TryRemove(key, out entryDate); |
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} |
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return false; |
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} |
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|
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public void Post(CloudDeleteAction action) |
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{ |
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_deleteAgent.Post(action); |
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} |
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|
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private void DeleteCloudFile(AccountInfo accountInfo, ObjectInfo cloudFile) |
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{ |
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if (accountInfo == null) |
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throw new ArgumentNullException("accountInfo"); |
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if (cloudFile == null) |
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throw new ArgumentNullException("cloudFile"); |
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|
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if (String.IsNullOrWhiteSpace(cloudFile.Container)) |
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throw new ArgumentException("Invalid container", "cloudFile"); |
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Contract.EndContractBlock(); |
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var fileAgent = GetFileAgent(accountInfo); |
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using (ThreadContext.Stacks["DeleteCloudFile"].Push("Delete")) |
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{ |
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var fileName = cloudFile.RelativeUrlToFilePath(accountInfo.UserName); |
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var info = fileAgent.GetFileSystemInfo(fileName); |
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var fullPath = info.FullName.ToLower(); |
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StatusKeeper.SetFileOverlayStatus(fullPath, FileOverlayStatus.Modified); |
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var account = cloudFile.Account ?? accountInfo.UserName; |
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var container = cloudFile.Container;//?? FolderConstants.PithosContainer; |
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var client = new CloudFilesClient(accountInfo); |
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client.DeleteObject(account, container, cloudFile.Name); |
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StatusKeeper.ClearFileStatus(fullPath); |
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} |
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} |
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|
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private static string GetFileKey(ObjectInfo info) |
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{ |
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var key = String.Format("{0}/{1}/{2}", info.Account, info.Container, info.Name); |
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return key; |
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} |
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|
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private static FileAgent GetFileAgent(AccountInfo accountInfo) |
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{ |
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return AgentLocator<FileAgent>.Get(accountInfo.AccountPath); |
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} |
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|
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} |
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} |