#region
/* -----------------------------------------------------------------------
*
*
* 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
* copyright notice, this list of conditions and the following
* 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
* provided with the distribution.
*
*
* 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
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* -----------------------------------------------------------------------
*/
#endregion
using System.Collections.Concurrent;
using System.ComponentModel.Composition;
using System.Diagnostics;
using System.Diagnostics.Contracts;
using System.IO;
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
{
using System;
using System.Collections.Generic;
using System.Linq;
///
/// PollAgent periodically polls the server to detect object changes. The agent retrieves a listing of all
/// objects and compares it with a previously cached version to detect differences.
/// New files are downloaded, missing files are deleted from the local file system and common files are compared
/// to determine the appropriate action
///
[Export]
public class PollAgent
{
private static readonly ILog Log = LogManager.GetLogger(MethodBase.GetCurrentMethod().DeclaringType);
[System.ComponentModel.Composition.Import]
public IStatusKeeper StatusKeeper { get; set; }
[System.ComponentModel.Composition.Import]
public IPithosSettings Settings { get; set; }
[System.ComponentModel.Composition.Import]
public NetworkAgent NetworkAgent { get; set; }
[System.ComponentModel.Composition.Import]
public Selectives Selectives { get; set; }
public IStatusNotification StatusNotification { get; set; }
public bool Pause
{
get {
return _pause;
}
set {
_pause = value;
if (!_pause)
_unPauseEvent.Set();
else
{
_unPauseEvent.Reset();
}
}
}
private bool _firstPoll = true;
//The Sync Event signals a manual synchronisation
private readonly AsyncManualResetEvent _syncEvent = new AsyncManualResetEvent();
private readonly AsyncManualResetEvent _unPauseEvent = new AsyncManualResetEvent(true);
private readonly ConcurrentDictionary _lastSeen = new ConcurrentDictionary();
private readonly ConcurrentDictionary _accounts = new ConcurrentDictionary();
///
/// Start a manual synchronization
///
public void SynchNow()
{
_syncEvent.Set();
}
///
/// Remote files are polled periodically. Any changes are processed
///
///
///
public async Task PollRemoteFiles(DateTime? since = null)
{
if (Log.IsDebugEnabled)
Log.DebugFormat("Polling changes after [{0}]",since);
Debug.Assert(Thread.CurrentThread.IsBackground, "Polling Ended up in the main thread!");
GC.Collect();
using (ThreadContext.Stacks["Retrieve Remote"].Push("All accounts"))
{
//If this poll fails, we will retry with the same since value
var nextSince = since;
try
{
await _unPauseEvent.WaitAsync();
UpdateStatus(PithosStatus.PollSyncing);
var tasks = from accountInfo in _accounts.Values
select ProcessAccountFiles(accountInfo, since);
var nextTimes=await TaskEx.WhenAll(tasks.ToList());
_firstPoll = false;
//Reschedule the poll with the current timestamp as a "since" value
if (nextTimes.Length>0)
nextSince = nextTimes.Min();
if (Log.IsDebugEnabled)
Log.DebugFormat("Next Poll at [{0}]",nextSince);
}
catch (Exception ex)
{
Log.ErrorFormat("Error while processing accounts\r\n{0}", ex);
//In case of failure retry with the same "since" value
}
UpdateStatus(PithosStatus.PollComplete);
//The multiple try blocks are required because we can't have an await call
//inside a finally block
//TODO: Find a more elegant solution for reschedulling in the event of an exception
try
{
//Wait for the polling interval to pass or the Sync event to be signalled
nextSince = await WaitForScheduledOrManualPoll(nextSince);
}
finally
{
//Ensure polling is scheduled even in case of error
TaskEx.Run(() => PollRemoteFiles(nextSince));
}
}
}
///
/// Wait for the polling period to expire or a manual sync request
///
///
///
private async Task WaitForScheduledOrManualPoll(DateTime? since)
{
var sync = _syncEvent.WaitAsync();
var wait = TaskEx.Delay(TimeSpan.FromSeconds(Settings.PollingInterval), NetworkAgent.CancellationToken);
var signaledTask = await TaskEx.WhenAny(sync, wait);
//Pausing takes precedence over manual sync or awaiting
_unPauseEvent.Wait();
//Wait for network processing to finish before polling
var pauseTask=NetworkAgent.ProceedEvent.WaitAsync();
await TaskEx.WhenAll(signaledTask, pauseTask);
//If polling is signalled by SynchNow, ignore the since tag
if (sync.IsCompleted)
{
//TODO: Must convert to AutoReset
_syncEvent.Reset();
return null;
}
return since;
}
public async Task ProcessAccountFiles(AccountInfo accountInfo, DateTime? since = null)
{
if (accountInfo == null)
throw new ArgumentNullException("accountInfo");
if (String.IsNullOrWhiteSpace(accountInfo.AccountPath))
throw new ArgumentException("The AccountInfo.AccountPath is empty", "accountInfo");
Contract.EndContractBlock();
using (ThreadContext.Stacks["Retrieve Remote"].Push(accountInfo.UserName))
{
await NetworkAgent.GetDeleteAwaiter();
Log.Info("Scheduled");
var client = new CloudFilesClient(accountInfo);
//We don't need to check the trash container
var containers = client.ListContainers(accountInfo.UserName)
.Where(c=>c.Name!="trash")
.ToList();
CreateContainerFolders(accountInfo, containers);
//The nextSince time fallback time is the same as the current.
//If polling succeeds, the next Since time will be the smallest of the maximum modification times
//of the shared and account objects
var nextSince = since;
try
{
//Wait for any deletions to finish
await NetworkAgent.GetDeleteAwaiter();
//Get the poll time now. We may miss some deletions but it's better to keep a file that was deleted
//than delete a file that was created while we were executing the poll
//Get the list of server objects changed since the last check
//The name of the container is passed as state in order to create a dictionary of tasks in a subsequent step
var listObjects = (from container in containers
select Task>.Factory.StartNew(_ =>
client.ListObjects(accountInfo.UserName, container.Name, since), container.Name)).ToList();
var listShared = Task>.Factory.StartNew(_ =>
client.ListSharedObjects(since), "shared");
listObjects.Add(listShared);
var listTasks = await Task.Factory.WhenAll(listObjects.ToArray());
using (ThreadContext.Stacks["SCHEDULE"].Push("Process Results"))
{
var dict = listTasks.ToDictionary(t => t.AsyncState);
//Get all non-trash objects. Remember, the container name is stored in AsyncState
var remoteObjects = (from objectList in listTasks
where (string)objectList.AsyncState != "trash"
from obj in objectList.Result
select obj).ToList();
//Get the latest remote object modification date, only if it is after
//the original since date
nextSince = GetLatestDateAfter(nextSince, remoteObjects);
var sharedObjects = dict["shared"].Result;
nextSince = GetLatestDateBefore(nextSince, sharedObjects);
//DON'T process trashed files
//If some files are deleted and added again to a folder, they will be deleted
//even though they are new.
//We would have to check file dates and hashes to ensure that a trashed file
//can be deleted safely from the local hard drive.
/*
//Items with the same name, hash may be both in the container and the trash
//Don't delete items that exist in the container
var realTrash = from trash in trashObjects
where
!remoteObjects.Any(
info => info.Name == trash.Name && info.Hash == trash.Hash)
select trash;
ProcessTrashedFiles(accountInfo, realTrash);
*/
var cleanRemotes = (from info in remoteObjects.Union(sharedObjects)
let name = info.Name??""
where !name.EndsWith(".ignore", StringComparison.InvariantCultureIgnoreCase) &&
!name.StartsWith(FolderConstants.CacheFolder + "/",
StringComparison.InvariantCultureIgnoreCase)
select info).ToList();
if (_firstPoll)
StatusKeeper.CleanupOrphanStates();
StatusKeeper.CleanupStaleStates(accountInfo, cleanRemotes);
var differencer = _differencer.PostSnapshot(accountInfo, cleanRemotes);
var filterUris = Selectives.SelectiveUris[accountInfo.AccountKey];
//On the first run
if (_firstPoll)
{
MarkSuspectedDeletes(accountInfo, cleanRemotes);
}
ProcessDeletedFiles(accountInfo, differencer.Deleted.FilterDirectlyBelow(filterUris));
// @@@ NEED To add previous state here as well, To compare with previous hash
//Create a list of actions from the remote files
var allActions = MovesToActions(accountInfo,differencer.Moved.FilterDirectlyBelow(filterUris))
.Union(
ChangesToActions(accountInfo, differencer.Changed.FilterDirectlyBelow(filterUris)))
.Union(
CreatesToActions(accountInfo, differencer.Created.FilterDirectlyBelow(filterUris)));
//And remove those that are already being processed by the agent
var distinctActions = allActions
.Except(NetworkAgent.GetEnumerable(), new LocalFileComparer())
.ToList();
await _unPauseEvent.WaitAsync();
//Queue all the actions
foreach (var message in distinctActions)
{
NetworkAgent.Post(message);
}
Log.Info("[LISTENER] End Processing");
}
}
catch (Exception ex)
{
Log.ErrorFormat("[FAIL] ListObjects for{0} in ProcessRemoteFiles with {1}", accountInfo.UserName, ex);
return nextSince;
}
Log.Info("[LISTENER] Finished");
return nextSince;
}
}
///
/// Returns the latest LastModified date from the list of objects, but only if it is before
/// than the threshold value
///
///
///
///
private static DateTime? GetLatestDateBefore(DateTime? threshold, IList cloudObjects)
{
DateTime? maxDate = null;
if (cloudObjects!=null && cloudObjects.Count > 0)
maxDate = cloudObjects.Max(obj => obj.Last_Modified);
if (maxDate == null || maxDate == DateTime.MinValue)
return threshold;
if (threshold == null || threshold == DateTime.MinValue || threshold > maxDate)
return maxDate;
return threshold;
}
///
/// Returns the latest LastModified date from the list of objects, but only if it is after
/// the threshold value
///
///
///
///
private static DateTime? GetLatestDateAfter(DateTime? threshold, IList cloudObjects)
{
DateTime? maxDate = null;
if (cloudObjects!=null && cloudObjects.Count > 0)
maxDate = cloudObjects.Max(obj => obj.Last_Modified);
if (maxDate == null || maxDate == DateTime.MinValue)
return threshold;
if (threshold == null || threshold == DateTime.MinValue || threshold < maxDate)
return maxDate;
return threshold;
}
readonly AccountsDifferencer _differencer = new AccountsDifferencer();
private Dictionary> _selectiveUris = new Dictionary>();
private bool _pause;
///
/// Deletes local files that are not found in the list of cloud files
///
///
///
private void ProcessDeletedFiles(AccountInfo accountInfo, IEnumerable cloudFiles)
{
if (accountInfo == null)
throw new ArgumentNullException("accountInfo");
if (String.IsNullOrWhiteSpace(accountInfo.AccountPath))
throw new ArgumentException("The AccountInfo.AccountPath is empty", "accountInfo");
if (cloudFiles == null)
throw new ArgumentNullException("cloudFiles");
Contract.EndContractBlock();
var deletedFiles = new List();
foreach (var objectInfo in cloudFiles)
{
if (Log.IsDebugEnabled)
Log.DebugFormat("Handle deleted [{0}]", objectInfo.Uri);
var relativePath = objectInfo.RelativeUrlToFilePath(accountInfo.UserName);
var item = FileAgent.GetFileAgent(accountInfo).GetFileSystemInfo(relativePath);
if (Log.IsDebugEnabled)
Log.DebugFormat("Will delete [{0}] for [{1}]", item.FullName, objectInfo.Uri);
if (item.Exists)
{
if ((item.Attributes & FileAttributes.ReadOnly) == FileAttributes.ReadOnly)
{
item.Attributes = item.Attributes & ~FileAttributes.ReadOnly;
}
Log.DebugFormat("Deleting {0}", item.FullName);
var directory = item as DirectoryInfo;
if (directory != null)
directory.Delete(true);
else
item.Delete();
Log.DebugFormat("Deleted [{0}] for [{1}]", item.FullName, objectInfo.Uri);
DateTime lastDate;
_lastSeen.TryRemove(item.FullName, out lastDate);
deletedFiles.Add(item);
}
StatusKeeper.SetFileState(item.FullName, FileStatus.Deleted, FileOverlayStatus.Deleted, "File Deleted");
}
Log.InfoFormat("[{0}] files were deleted", deletedFiles.Count);
StatusNotification.NotifyForFiles(deletedFiles, String.Format("{0} files were deleted", deletedFiles.Count),
TraceLevel.Info);
}
private void MarkSuspectedDeletes(AccountInfo accountInfo, IEnumerable cloudFiles)
{
//Only consider files that are not being modified, ie they are in the Unchanged state
var deleteCandidates = FileState.Queryable.Where(state =>
state.FilePath.StartsWith(accountInfo.AccountPath)
&& state.FileStatus == FileStatus.Unchanged).ToList();
//TODO: filesToDelete must take into account the Others container
var filesToDelete = (from deleteCandidate in deleteCandidates
let localFile = FileInfoExtensions.FromPath(deleteCandidate.FilePath)
let relativeFilePath = localFile.AsRelativeTo(accountInfo.AccountPath)
where
!cloudFiles.Any(r => r.RelativeUrlToFilePath(accountInfo.UserName) == relativeFilePath)
select localFile).ToList();
//Set the status of missing files to Conflict
foreach (var item in filesToDelete)
{
//Try to acquire a gate on the file, to take into account files that have been dequeued
//and are being processed
using (var gate = NetworkGate.Acquire(item.FullName, NetworkOperation.Deleting))
{
if (gate.Failed)
continue;
StatusKeeper.SetFileState(item.FullName, FileStatus.Conflict, FileOverlayStatus.Deleted,
"Local file missing from server");
}
}
UpdateStatus(PithosStatus.HasConflicts);
StatusNotification.NotifyConflicts(filesToDelete,
String.Format(
"{0} local files are missing from Pithos, possibly because they were deleted",
filesToDelete.Count));
StatusNotification.NotifyForFiles(filesToDelete, String.Format("{0} files were deleted", filesToDelete.Count),
TraceLevel.Info);
}
///
/// Creates a Sync action for each changed server file
///
///
///
///
private IEnumerable ChangesToActions(AccountInfo accountInfo, IEnumerable changes)
{
if (changes == null)
throw new ArgumentNullException();
Contract.EndContractBlock();
var fileAgent = FileAgent.GetFileAgent(accountInfo);
//In order to avoid multiple iterations over the files, we iterate only once
//over the remote files
foreach (var objectInfo in changes)
{
var relativePath = objectInfo.RelativeUrlToFilePath(accountInfo.UserName);
//If a directory object already exists, we may need to sync it
if (fileAgent.Exists(relativePath))
{
var localFile = fileAgent.GetFileSystemInfo(relativePath);
//We don't need to sync directories
if (objectInfo.IsDirectory && localFile is DirectoryInfo)
continue;
using (new SessionScope(FlushAction.Never))
{
var state = StatusKeeper.GetStateByFilePath(localFile.FullName);
_lastSeen[localFile.FullName] = DateTime.Now;
//Common files should be checked on a per-case basis to detect differences, which is newer
yield return new CloudAction(accountInfo, CloudActionType.MustSynch,
localFile, objectInfo, state, accountInfo.BlockSize,
accountInfo.BlockHash,"Poll Changes");
}
}
else
{
//Remote files should be downloaded
yield return new CloudDownloadAction(accountInfo, objectInfo,"Poll Changes");
}
}
}
///
/// Creates a Local Move action for each moved server file
///
///
///
///
private IEnumerable MovesToActions(AccountInfo accountInfo, IEnumerable moves)
{
if (moves == null)
throw new ArgumentNullException();
Contract.EndContractBlock();
var fileAgent = FileAgent.GetFileAgent(accountInfo);
//In order to avoid multiple iterations over the files, we iterate only once
//over the remote files
foreach (var objectInfo in moves)
{
var previousRelativepath = objectInfo.Previous.RelativeUrlToFilePath(accountInfo.UserName);
//If the previous file already exists, we can execute a Move operation
if (fileAgent.Exists(previousRelativepath))
{
var previousFile = fileAgent.GetFileSystemInfo(previousRelativepath);
using (new SessionScope(FlushAction.Never))
{
var state = StatusKeeper.GetStateByFilePath(previousFile.FullName);
_lastSeen[previousFile.FullName] = DateTime.Now;
//For each moved object we need to move both the local file and update
yield return new CloudAction(accountInfo, CloudActionType.RenameLocal,
previousFile, objectInfo, state, accountInfo.BlockSize,
accountInfo.BlockHash,"Poll Moves");
//For modified files, we need to download the changes as well
if (objectInfo.Hash!=objectInfo.PreviousHash)
yield return new CloudDownloadAction(accountInfo,objectInfo, "Poll Moves");
}
}
//If the previous file does not exist, we need to download it in the new location
else
{
//Remote files should be downloaded
yield return new CloudDownloadAction(accountInfo, objectInfo, "Poll Moves");
}
}
}
///
/// Creates a download action for each new server file
///
///
///
///
private IEnumerable CreatesToActions(AccountInfo accountInfo, IEnumerable creates)
{
if (creates == null)
throw new ArgumentNullException();
Contract.EndContractBlock();
var fileAgent = FileAgent.GetFileAgent(accountInfo);
//In order to avoid multiple iterations over the files, we iterate only once
//over the remote files
foreach (var objectInfo in creates)
{
if (Log.IsDebugEnabled)
Log.DebugFormat("[NEW INFO] {0}",objectInfo.Uri);
var relativePath = objectInfo.RelativeUrlToFilePath(accountInfo.UserName);
//If the object already exists, we should check before uploading or downloading
if (fileAgent.Exists(relativePath))
{
var localFile= fileAgent.GetFileSystemInfo(relativePath);
var state = StatusKeeper.GetStateByFilePath(localFile.WithProperCapitalization().FullName);
yield return new CloudAction(accountInfo, CloudActionType.MustSynch,
localFile, objectInfo, state, accountInfo.BlockSize,
accountInfo.BlockHash,"Poll Creates");
}
else
{
//Remote files should be downloaded
yield return new CloudDownloadAction(accountInfo, objectInfo,"Poll Creates");
}
}
}
///
/// Notify the UI to update the visual status
///
///
private void UpdateStatus(PithosStatus status)
{
try
{
StatusNotification.SetPithosStatus(status);
//StatusNotification.Notify(new Notification());
}
catch (Exception exc)
{
//Failure is not critical, just log it
Log.Warn("Error while updating status", exc);
}
}
private static void CreateContainerFolders(AccountInfo accountInfo, IEnumerable containers)
{
var containerPaths = from container in containers
let containerPath = Path.Combine(accountInfo.AccountPath, container.Name)
where container.Name != FolderConstants.TrashContainer && !Directory.Exists(containerPath)
select containerPath;
foreach (var path in containerPaths)
{
Directory.CreateDirectory(path);
}
}
public void AddAccount(AccountInfo accountInfo)
{
//Avoid adding a duplicate accountInfo
_accounts.TryAdd(accountInfo.AccountKey, accountInfo);
}
public void RemoveAccount(AccountInfo accountInfo)
{
AccountInfo account;
_accounts.TryRemove(accountInfo.AccountKey, out account);
SnapshotDifferencer differencer;
_differencer.Differencers.TryRemove(accountInfo.AccountKey, out differencer);
}
public void SetSelectivePaths(AccountInfo accountInfo,Uri[] added, Uri[] removed)
{
AbortRemovedPaths(accountInfo,removed);
DownloadNewPaths(accountInfo,added);
}
private void DownloadNewPaths(AccountInfo accountInfo, Uri[] added)
{
var client = new CloudFilesClient(accountInfo);
foreach (var folderUri in added)
{
try
{
string account;
string container;
var segmentsCount = folderUri.Segments.Length;
//Is this an account URL?
if (segmentsCount < 3)
continue;
//Is this a container or folder URL?
if (segmentsCount == 3)
{
account = folderUri.Segments[1].TrimEnd('/');
container = folderUri.Segments[2].TrimEnd('/');
}
else
{
account = folderUri.Segments[2].TrimEnd('/');
container = folderUri.Segments[3].TrimEnd('/');
}
IList items;
if (segmentsCount > 3)
{
//List folder
var folder = String.Join("", folderUri.Segments.Splice(4));
items = client.ListObjects(account, container, folder);
}
else
{
//List container
items = client.ListObjects(account, container);
}
var actions = CreatesToActions(accountInfo, items);
foreach (var action in actions)
{
NetworkAgent.Post(action);
}
}
catch (Exception exc)
{
Log.WarnFormat("Listing of new selective path [{0}] failed with \r\n{1}", folderUri, exc);
}
}
//Need to get a listing of each of the URLs, then post them to the NetworkAgent
//CreatesToActions(accountInfo,)
/* NetworkAgent.Post();*/
}
private void AbortRemovedPaths(AccountInfo accountInfo, Uri[] removed)
{
/*this.NetworkAgent.*/
}
}
}