root / trunk / Pithos.Core / Agents / SnapshotDifferencer.cs @ 64171b56
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#region |
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/* ----------------------------------------------------------------------- |
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* <copyright file="SnapshotDifferencer.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 Pithos.Interfaces; |
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using Pithos.Network; |
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using System; |
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using System.Collections.Generic; |
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using System.Linq; |
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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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/// Calculates the differences between two ObjectInfo snapshots. |
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/// </summary> |
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public class SnapshotDifferencer |
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{ |
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/// <summary> |
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/// Contains the previous and current listings. |
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/// Using a separate class for the state simplifies the Post method |
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/// which has to modify the listings |
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/// </summary> |
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private class State |
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{ |
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/// <summary> |
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/// The previous snapshot listing |
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/// </summary> |
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public readonly IEnumerable<ObjectInfo> Previous; |
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|
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/// <summary> |
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/// The current snapshot listing |
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/// </summary> |
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public readonly IEnumerable<ObjectInfo> Current; |
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|
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/// <summary> |
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/// Common objects, lazily evalueated. |
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/// The common objects are used to calculate both the Changed and Unchanged objects |
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/// </summary> |
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public readonly Lazy<IEnumerable<ObjectInfo>> Common; |
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|
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public State(IEnumerable<ObjectInfo> previous, IEnumerable<ObjectInfo> current) |
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{ |
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Previous = previous ?? new List<ObjectInfo>(); |
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Current = current ?? new List<ObjectInfo>(); |
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|
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Common=new Lazy<IEnumerable<ObjectInfo>>(() => |
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Current.Join(Previous, |
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outKey => new { outKey.Account, outKey.Container, outKey.Name }, |
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inKey => new { inKey.Account, inKey.Container, inKey.Name }, |
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(outer, inner) => |
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{ |
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outer.PreviousHash = inner.Hash; |
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return outer; |
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})); |
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} |
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} |
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|
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|
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private State _state; |
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|
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/// <summary> |
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/// The comparer used to identify common objects. |
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/// Objects are considered common when they have the same Account, Container and Name |
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/// </summary> |
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private readonly ObjectInfoComparer _comparer = new ObjectInfoComparer(); |
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|
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/// <summary> |
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/// Default constructor. Initializes the Current and Previous listings to empty lists |
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/// </summary> |
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public SnapshotDifferencer() |
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:this(new List<ObjectInfo>(),new List<ObjectInfo>()) |
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{ |
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} |
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|
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/// <summary> |
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/// Creates a new differencer using the specified previous and current list. Null lists |
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/// are replaced with empty lists |
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/// </summary> |
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/// <param name="previous"></param> |
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/// <param name="current"></param> |
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public SnapshotDifferencer(IEnumerable<ObjectInfo> previous,IEnumerable<ObjectInfo> current ) |
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{ |
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_state=new State(previous,current); |
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} |
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|
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/// <summary> |
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/// Posts a new listing |
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/// </summary> |
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/// <param name="list"></param> |
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/// <returns></returns> |
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public SnapshotDifferencer Post(IEnumerable<ObjectInfo> list) |
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{ |
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List<ObjectInfo> newCurrent=null; |
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if (list != null) |
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{ |
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//The state field holds the old state |
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var oldState = _state; |
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//Replace any NoModification entries with previous values that have |
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//the same account, container and possibly, folder |
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newCurrent = list.Replace( |
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info => info is NoModificationInfo, |
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noMod => oldState.Current.Where(noMod.CorrespondsTo)) |
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.ToList(); |
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} |
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//Set the new state |
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_state = new State(_state.Current, newCurrent); |
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|
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return this; |
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} |
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|
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public IEnumerable<ObjectInfo> Deleted |
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{ |
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get { return _state.Previous.Except(_state.Current,_comparer); } |
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} |
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public IEnumerable<ObjectInfo> Created |
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{ |
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get { return _state.Current.Except(_state.Previous,_comparer); } |
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} |
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|
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public IEnumerable<ObjectInfo> Common |
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{ |
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get { return _state.Common.Value; } |
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} |
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|
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public IEnumerable<ObjectInfo> Changed |
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{ |
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get{return Common.Where(i=>i.PreviousHash!=i.Hash);} |
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} |
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public IEnumerable<ObjectInfo> Unchanged |
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{ |
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get{ return Common.Where(i => i.PreviousHash == i.Hash);} |
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} |
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} |
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|
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public class AccountsDifferencer |
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{ |
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readonly ConcurrentDictionary<string, SnapshotDifferencer> _differencers = new ConcurrentDictionary<string, SnapshotDifferencer>(); |
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|
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public ConcurrentDictionary<string, SnapshotDifferencer> Differencers { get { return _differencers; } } |
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|
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public SnapshotDifferencer PostSnapshot(AccountInfo accountInfo, List<ObjectInfo> cleanRemotes) |
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{ |
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SnapshotDifferencer differencer; |
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if (!_differencers.TryGetValue(accountInfo.UserName, out differencer)) |
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{ |
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differencer = new SnapshotDifferencer(); |
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_differencers[accountInfo.UserName] = differencer; |
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} |
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differencer.Post(cleanRemotes); |
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return differencer; |
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} |
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|
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} |
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} |