Synnefo » Pithos MS Client

#region

/* -----------------------------------------------------------------------

 * <copyright file="NetworkAgent.cs" company="GRNet">

 * 

 * Copyright 2011-2012 GRNET S.A. All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or

 * without modification, are permitted provided that the following

 * conditions are met:

 *

 *   1. Redistributions of source code must retain the above

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 *      disclaimer.

 *

 *   2. Redistributions in binary form must reproduce the above

 *      copyright notice, this list of conditions and the following

 *      disclaimer in the documentation and/or other materials

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 *

 * THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS

 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR

 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF

 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED

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 * The views and conclusions contained in the software and

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 * </copyright>

 * -----------------------------------------------------------------------

 */

#endregion

using System;

using System.Collections.Generic;

using System.ComponentModel.Composition;

using System.Diagnostics;

using System.Diagnostics.Contracts;

using System.IO;

using System.Linq;

using System.Net;

using System.Reflection;

using System.Threading;

using System.Threading.Tasks;

using Castle.ActiveRecord;

using Pithos.Interfaces;

using Pithos.Network;

using log4net;

namespace Pithos.Core.Agents

{

    [Export]

    public class NetworkAgent

    {

        private static readonly ILog Log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);

        private Agent<CloudAction> _agent;

        [System.ComponentModel.Composition.Import]

        private DeleteAgent DeleteAgent { get; set; }

        [System.ComponentModel.Composition.Import]

        public IStatusKeeper StatusKeeper { get; set; }

        private IStatusNotification _statusNotification;

        public IStatusNotification StatusNotification

        {

            get { return _statusNotification; }

            set

            {

                _statusNotification = value;

                DeleteAgent.StatusNotification = value;

                Uploader.StatusNotification = value;

                Downloader.StatusNotification = value;

            }

        }

        [System.ComponentModel.Composition.Import]

        public IPithosSettings Settings { get; set; }

        private Uploader _uploader;

        [System.ComponentModel.Composition.Import]

        public Uploader Uploader

        {

            get { return _uploader; }

            set

            {

                _uploader = value;

                _uploader.UnpauseEvent = _unPauseEvent;                

            }

        }

        private Downloader _downloader;

        [System.ComponentModel.Composition.Import]

        public Downloader Downloader

        {

            get { return _downloader; }

            set

            {

                _downloader = value;

                _downloader.UnpauseEvent = _unPauseEvent;

            }

        }

        [System.ComponentModel.Composition.Import]

        public Selectives Selectives { get; set; }

        //The Proceed signals the poll agent that it can proceed with polling. 

        //Essentially it stops the poll agent to give priority to the network agent

        //Initially the event is signalled because we don't need to pause

        private readonly AsyncManualResetEvent _proceedEvent = new AsyncManualResetEvent(true);

        private Agents.Selectives _selectives;

        private bool _pause;

        public AsyncManualResetEvent ProceedEvent

        {

            get { return _proceedEvent; }

        }

        private readonly AsyncManualResetEvent _unPauseEvent = new AsyncManualResetEvent(true);

        private CancellationTokenSource _currentOperationCancellation=new CancellationTokenSource();

        public void CancelCurrentOperation()

        {

            //What does it mean to cancel the current upload/download?

            //Obviously, the current operation will be cancelled by throwing

            //a cancellation exception.

            //

            //The default behavior is to retry any operations that throw.

            //Obviously this is not what we want in this situation.

            //The cancelled operation should NOT bea retried. 

            //

            //This can be done by catching the cancellation exception

            //and avoiding the retry.

            //

            //Have to reset the cancellation source - it is not possible to reset the source

            //Have to prevent a case where an operation requests a token from the old source

            var oldSource = Interlocked.Exchange(ref _currentOperationCancellation, new CancellationTokenSource());

            oldSource.Cancel();

        }

        public void Start()

        {

            if (_agent != null)

                return;

            if (Log.IsDebugEnabled)

                Log.Debug("Starting Network Agent");

            _agent = Agent<CloudAction>.Start(inbox =>

            {

                Action loop = null;

                loop = () =>

                {

                    DeleteAgent.ProceedEvent.Wait();

                    _unPauseEvent.Wait();

                    var message = inbox.Receive();

                    var process=message.Then(Process,inbox.CancellationToken);

                    inbox.LoopAsync(process, loop);

                };

                loop();

            });

        }

        private async Task Process(CloudAction action)

        {

            if (action == null)

                throw new ArgumentNullException("action");

            if (action.AccountInfo==null)

                throw new ArgumentException("The action.AccountInfo is empty","action");

            Contract.EndContractBlock();

            using (ThreadContext.Stacks["Operation"].Push(action.ToString()))

            {                

                var cloudFile = action.CloudFile;

                var downloadPath = action.GetDownloadPath();

                try

                {

                    StatusNotification.SetPithosStatus(PithosStatus.LocalSyncing,"Processing");

                    _proceedEvent.Reset();

                    var accountInfo = action.AccountInfo;

                    if (action.Action == CloudActionType.DeleteCloud)

                    {                        

                        //Redirect deletes to the delete agent 

                        DeleteAgent.Post((CloudDeleteAction)action);

                    }

                    if (DeleteAgent.IsDeletedFile(action))

                    {

                        //Clear the status of already deleted files to avoid reprocessing

                        if (action.LocalFile != null)

                            StatusKeeper.ClearFileStatus(action.LocalFile.FullName);

                    }

                    else

                    {

                        switch (action.Action)

                        {

                            case CloudActionType.UploadUnconditional:

                                //Abort if the file was deleted before we reached this point

                                await Uploader.UploadCloudFile(action,CurrentOperationCancelToken);

                                break;

                            case CloudActionType.DownloadUnconditional:

                                await Downloader.DownloadCloudFile(accountInfo, cloudFile, downloadPath, CurrentOperationCancelToken);

                                break;

                            case CloudActionType.RenameCloud:

                                var moveAction = (CloudMoveAction)action;

                                RenameCloudFile(accountInfo, moveAction);

                                break;

                            case CloudActionType.RenameLocal:

                                RenameLocalFile(accountInfo, action);

                                break;

                            case CloudActionType.MustSynch:

                                if (!File.Exists(downloadPath) && !Directory.Exists(downloadPath))

                                {

                                    await Downloader.DownloadCloudFile(accountInfo, cloudFile, downloadPath, CurrentOperationCancelToken);

                                }

                                else

                                {

                                    await SyncFiles(accountInfo, action);

                                }

                                break;

                        }

                    }

                    Log.InfoFormat("End Processing {0}:{1}->{2}", action.Action, action.LocalFile,

                                           action.CloudFile.Name);

                }

/*

                catch (WebException exc)

                {                    

                    Log.ErrorFormat("[WEB ERROR] {0} : {1} -> {2} due to exception\r\n{3}", action.Action, action.LocalFile, action.CloudFile, exc);

                    //Actions that resulted in server errors should be retried                    

                    var response = exc.Response as HttpWebResponse;

                    if (response != null && response.StatusCode >= HttpStatusCode.InternalServerError)

                    {

                        _agent.Post(action);

                        Log.WarnFormat("[REQUEUE] {0} : {1} -> {2}", action.Action, action.LocalFile, action.CloudFile);

                    }

                }

*/

                catch (OperationCanceledException ex)

                {                    

                    Log.WarnFormat("Cancelling [{0}]",ex);

                }

                catch (DirectoryNotFoundException)

                {

                    Log.ErrorFormat("{0} : {1} -> {2}  failed because the directory was not found.\n Rescheduling a delete",

                        action.Action, action.LocalFile, action.CloudFile);

                    //Post a delete action for the missing file

                    Post(new CloudDeleteAction(action));

                }

                catch (FileNotFoundException)

                {

                    Log.ErrorFormat("{0} : {1} -> {2}  failed because the file was not found.\n Rescheduling a delete",

                        action.Action, action.LocalFile, action.CloudFile);

                    //Post a delete action for the missing file

                    Post(new CloudDeleteAction(action));

                }

                catch (Exception exc)

                {

                    Log.ErrorFormat("[REQUEUE] {0} : {1} -> {2} due to exception\r\n{3}",

                                     action.Action, action.LocalFile, action.CloudFile, exc);

                    _agent.Post(action);

                }

                finally

                {

                    if (_agent.IsEmpty)

                        _proceedEvent.Set();

                    UpdateStatus(PithosStatus.LocalComplete);                                        

                }

            }

        }

        private CancellationToken CurrentOperationCancelToken

        {

            get { return _currentOperationCancellation.Token; }

        }

        private void UpdateStatus(PithosStatus status)

        {

            StatusNotification.SetPithosStatus(status);

            //StatusNotification.Notify(new Notification());

        }

        private void RenameLocalFile(AccountInfo accountInfo, CloudAction action)

        {

            if (accountInfo == null)

                throw new ArgumentNullException("accountInfo");

            if (action == null)

                throw new ArgumentNullException("action");

            if (action.LocalFile == null)

                throw new ArgumentException("The action's local file is not specified", "action");

            if (!Path.IsPathRooted(action.LocalFile.FullName))

                throw new ArgumentException("The action's local file path must be absolute", "action");

            if (action.CloudFile == null)

                throw new ArgumentException("The action's cloud file is not specified", "action");

            Contract.EndContractBlock();

            using (ThreadContext.Stacks["Operation"].Push("RenameLocalFile"))

            {

                //We assume that the local file already exists, otherwise the poll agent

                //would have issued a download request

                var currentInfo = action.CloudFile;

                var previousInfo = action.CloudFile.Previous;

                var fileAgent = FileAgent.GetFileAgent(accountInfo);

                var previousRelativepath = previousInfo.RelativeUrlToFilePath(accountInfo.UserName);

                var previousFile = fileAgent.GetFileSystemInfo(previousRelativepath);

                //In every case we need to move the local file first

                MoveLocalFile(accountInfo, previousFile, fileAgent, currentInfo);

            }

        }

        private void MoveLocalFile(AccountInfo accountInfo, FileSystemInfo previousFile, FileAgent fileAgent,

                                   ObjectInfo currentInfo)

        {

            var currentRelativepath = currentInfo.RelativeUrlToFilePath(accountInfo.UserName);

            var newPath = Path.Combine(fileAgent.RootPath, currentRelativepath);

            var isFile= (previousFile is FileInfo);

            var previousFullPath = isFile? 

                FileInfoExtensions.GetProperFilePathCapitalization(previousFile.FullName):

                FileInfoExtensions.GetProperDirectoryCapitalization(previousFile.FullName);                

            using (NetworkGate.Acquire(previousFullPath, NetworkOperation.Renaming))

            using (NetworkGate.Acquire(newPath,NetworkOperation.Renaming)) 

            using (new SessionScope(FlushAction.Auto))

            {

                if (isFile)

                    (previousFile as FileInfo).MoveTo(newPath);

                else

                {

                    (previousFile as DirectoryInfo).MoveTo(newPath);

                }

                var state = StatusKeeper.GetStateByFilePath(previousFullPath);

                state.FilePath = newPath;

                state.SaveCopy();

                StatusKeeper.SetFileState(previousFullPath,FileStatus.Deleted,FileOverlayStatus.Deleted, "Deleted");

            }            

        }

        private async Task SyncFiles(AccountInfo accountInfo,CloudAction action)

        {

            if (accountInfo == null)

                throw new ArgumentNullException("accountInfo");

            if (action==null)

                throw new ArgumentNullException("action");

            if (action.LocalFile==null)

                throw new ArgumentException("The action's local file is not specified","action");

            if (!Path.IsPathRooted(action.LocalFile.FullName))

                throw new ArgumentException("The action's local file path must be absolute","action");

            if (action.CloudFile== null)

                throw new ArgumentException("The action's cloud file is not specified", "action");

            Contract.EndContractBlock();

            using (ThreadContext.Stacks["Operation"].Push("SyncFiles"))

            {

                //var localFile = action.LocalFile;

                var cloudFile = action.CloudFile;

                var downloadPath = action.LocalFile.GetProperCapitalization();

                var cloudHash = cloudFile.Hash.ToLower();

                var previousCloudHash = cloudFile.PreviousHash == null?null: cloudFile.PreviousHash.ToLower();

                var localHash = action.TreeHash.Value.TopHash.ToHashString();// LocalHash.Value.ToLower();

                //var topHash = action.TopHash.Value.ToLower();

                if(cloudFile.IsDirectory && action.LocalFile is DirectoryInfo)

                {

                    Log.InfoFormat("Skipping folder {0} , exists in server", downloadPath);

                    return;

                }

                //At this point we know that an object has changed on the server and that a local

                //file already exists. We need to decide whether the file has only changed on 

                //the server or there is a conflicting change on the client.

                //

                //If the hashes match, we are done

                if (cloudFile != ObjectInfo.Empty && cloudHash == localHash)

                {

                    Log.InfoFormat("Skipping {0}, hashes match", downloadPath);

                    return;

                }

                //If the local and remote files have 0 length their hashes will not match

                if (!cloudFile.IsDirectory && cloudFile.Bytes==0 && action.LocalFile is FileInfo && (action.LocalFile as FileInfo).Length==0 )

                {

                    Log.InfoFormat("Skipping {0}, files are empty", downloadPath);

                    return;

                }

                //The hashes DON'T match. We need to sync

                // If the previous tophash matches the local tophash, the file was only changed on the server. 

                if (localHash == previousCloudHash)

                {

                    await Downloader.DownloadCloudFile(accountInfo, cloudFile, downloadPath, CurrentOperationCancelToken);

                }

                else

                {

                    //If the previous and local hash don't match, there was a local conflict

                    //that was not uploaded to the server. We have a conflict

                    ReportConflictForMismatch(downloadPath);

                }

            }

        }

        private void ReportConflictForMismatch(string downloadPath)

        {

            if (String.IsNullOrWhiteSpace(downloadPath))

                throw new ArgumentNullException("downloadPath");

            Contract.EndContractBlock();

            StatusKeeper.SetFileState(downloadPath,FileStatus.Conflict, FileOverlayStatus.Conflict,"File changed at the server");

            UpdateStatus(PithosStatus.HasConflicts);

            var message = String.Format("Conflict detected for file {0}", downloadPath);

            Log.Warn(message);

            StatusNotification.NotifyChange(message, TraceLevel.Warning);

        }

        public void Post(CloudAction cloudAction)

        {

            if (cloudAction == null)

                throw new ArgumentNullException("cloudAction");

            if (cloudAction.AccountInfo==null)

                throw new ArgumentException("The CloudAction.AccountInfo is empty","cloudAction");

            Contract.EndContractBlock();

            DeleteAgent.ProceedEvent.Wait();

            if (cloudAction is CloudDeleteAction)

                DeleteAgent.Post((CloudDeleteAction)cloudAction);

            else

                _agent.Post(cloudAction);

        }

        public IEnumerable<CloudAction> GetEnumerable()

        {

            return _agent.GetEnumerable();

        }

        public Task GetDeleteAwaiter()

        {

            return DeleteAgent.ProceedEvent.WaitAsync();

        }

        public CancellationToken CancellationToken

        {

            get { return _agent.CancellationToken; }

        }

        public bool Pause

        {

            get {

                return _pause;

            }

            set {

                _pause = value;

                if (_pause)

                    _unPauseEvent.Reset();

                else

                {

                    _unPauseEvent.Set();

                }

            }

        }

        private void RenameCloudFile(AccountInfo accountInfo,CloudMoveAction action)

        {

            if (accountInfo==null)

                throw new ArgumentNullException("accountInfo");

            if (action==null)

                throw new ArgumentNullException("action");

            if (action.CloudFile==null)

                throw new ArgumentException("CloudFile","action");

            if (action.LocalFile==null)

                throw new ArgumentException("LocalFile","action");

            if (action.OldLocalFile==null)

                throw new ArgumentException("OldLocalFile","action");

            if (action.OldCloudFile==null)

                throw new ArgumentException("OldCloudFile","action");

            Contract.EndContractBlock();

            using (ThreadContext.Stacks["Operation"].Push("RenameCloudFile"))

            {

                var newFilePath = action.LocalFile.FullName;

                //How do we handle concurrent renames and deletes/uploads/downloads?

                //* A conflicting upload means that a file was renamed before it had a chance to finish uploading

                //  This should never happen as the network agent executes only one action at a time

                //* A conflicting download means that the file was modified on the cloud. While we can go on and complete

                //  the rename, there may be a problem if the file is downloaded in blocks, as subsequent block requests for the 

                //  same name will fail.

                //  This should never happen as the network agent executes only one action at a time.

                //* A conflicting delete can happen if the rename was followed by a delete action that didn't have the chance

                //  to remove the rename from the queue.

                //  We can probably ignore this case. It will result in an error which should be ignored            

                //The local file is already renamed

                StatusKeeper.SetFileOverlayStatus(newFilePath, FileOverlayStatus.Modified);

                var account = action.CloudFile.Account ?? accountInfo.UserName;

                var container = action.CloudFile.Container;

                var client = new CloudFilesClient(accountInfo);

                //TODO: What code is returned when the source file doesn't exist?

                client.MoveObject(account, container, action.OldCloudFile.Name, container, action.CloudFile.Name);

                StatusKeeper.SetFileStatus(newFilePath, FileStatus.Unchanged);

                StatusKeeper.SetFileOverlayStatus(newFilePath, FileOverlayStatus.Normal);

                NativeMethods.RaiseChangeNotification(newFilePath);

            }

        }

    }

}