root / trunk / Pithos.Core / NetworkGate.cs @ e6faf02b
History | View | Annotate | Download (6.5 kB)
1 |
#region |
---|---|
2 |
/* ----------------------------------------------------------------------- |
3 |
* <copyright file="NetworkGate.cs" company="GRNet"> |
4 |
* |
5 |
* Copyright 2011-2012 GRNET S.A. All rights reserved. |
6 |
* |
7 |
* Redistribution and use in source and binary forms, with or |
8 |
* without modification, are permitted provided that the following |
9 |
* conditions are met: |
10 |
* |
11 |
* 1. Redistributions of source code must retain the above |
12 |
* copyright notice, this list of conditions and the following |
13 |
* disclaimer. |
14 |
* |
15 |
* 2. Redistributions in binary form must reproduce the above |
16 |
* copyright notice, this list of conditions and the following |
17 |
* disclaimer in the documentation and/or other materials |
18 |
* provided with the distribution. |
19 |
* |
20 |
* |
21 |
* THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS |
22 |
* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED |
23 |
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
24 |
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR |
25 |
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
26 |
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
27 |
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF |
28 |
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
29 |
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
30 |
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
31 |
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
32 |
* POSSIBILITY OF SUCH DAMAGE. |
33 |
* |
34 |
* The views and conclusions contained in the software and |
35 |
* documentation are those of the authors and should not be |
36 |
* interpreted as representing official policies, either expressed |
37 |
* or implied, of GRNET S.A. |
38 |
* </copyright> |
39 |
* ----------------------------------------------------------------------- |
40 |
*/ |
41 |
#endregion |
42 |
using System; |
43 |
using System.Collections.Concurrent; |
44 |
using System.Collections.Generic; |
45 |
using System.Diagnostics.Contracts; |
46 |
using System.IO; |
47 |
|
48 |
namespace Pithos.Core |
49 |
{ |
50 |
public enum NetworkOperation |
51 |
{ |
52 |
None, |
53 |
Uploading, |
54 |
Downloading, |
55 |
Deleting, |
56 |
Renaming |
57 |
} |
58 |
|
59 |
//The NetworkGate prevents starting download/uploads for files that are already in the process of downloading, |
60 |
//uploading. |
61 |
public class NetworkGate:IDisposable |
62 |
{ |
63 |
public string FilePath { get; private set; } |
64 |
public NetworkOperation Operation { get; private set; } |
65 |
|
66 |
[ContractInvariantMethod] |
67 |
private void Invariants() |
68 |
{ |
69 |
Contract.Invariant(!String.IsNullOrWhiteSpace(FilePath)); |
70 |
Contract.Invariant(Path.IsPathRooted(FilePath)); |
71 |
} |
72 |
|
73 |
//The state of each file is stored in a thread-safe dictionary |
74 |
static readonly ConcurrentDictionary<string, NetworkOperation> NetworkState = new ConcurrentDictionary<string, NetworkOperation>(); |
75 |
|
76 |
public static NetworkOperation GetNetworkState(string path) |
77 |
{ |
78 |
if (String.IsNullOrWhiteSpace(path)) |
79 |
throw new ArgumentNullException("path"); |
80 |
if (!Path.IsPathRooted(path)) |
81 |
throw new ArgumentException("path must be a rooted path", "path"); |
82 |
Contract.EndContractBlock(); |
83 |
|
84 |
NetworkOperation operation; |
85 |
var lower = path.ToLower(); |
86 |
if (NetworkState.TryGetValue(lower, out operation)) |
87 |
return operation; |
88 |
return NetworkOperation.None; |
89 |
} |
90 |
|
91 |
//Store a network operation for the specified path |
92 |
public static void SetNetworkState(string path, NetworkOperation operation) |
93 |
{ |
94 |
if (String.IsNullOrWhiteSpace(path)) |
95 |
throw new ArgumentNullException("path"); |
96 |
if (!Path.IsPathRooted(path)) |
97 |
throw new ArgumentException("path must be a rooted path", "path"); |
98 |
Contract.EndContractBlock(); |
99 |
|
100 |
var lower = path.ToLower(); |
101 |
NetworkState[lower] = operation; |
102 |
//By default, None values don't need to be stored. They are stored anyway |
103 |
//because TryRemove may fail. |
104 |
if (operation == NetworkOperation.None) |
105 |
{ |
106 |
NetworkOperation oldOperation; |
107 |
NetworkState.TryRemove(lower, out oldOperation); |
108 |
} |
109 |
} |
110 |
|
111 |
//Clients should acquire a NetworkGate before starting any network operation. |
112 |
//If Acquire fails, another network operation is already in progress |
113 |
public static NetworkGate Acquire(string path, NetworkOperation operation) |
114 |
{ |
115 |
if (String.IsNullOrWhiteSpace(path)) |
116 |
throw new ArgumentNullException("path"); |
117 |
if (!Path.IsPathRooted(path)) |
118 |
throw new ArgumentException("path must be a rooted path", "path"); |
119 |
Contract.EndContractBlock(); |
120 |
|
121 |
var lower = path.ToLower(); |
122 |
var state = GetNetworkState(lower); |
123 |
//If no operation is in progress, return a NetworkGate |
124 |
return (state == NetworkOperation.None) |
125 |
? new NetworkGate(lower, operation) |
126 |
//otherwise return a gate with Fail flagged |
127 |
: new NetworkGate(lower, NetworkOperation.None); |
128 |
} |
129 |
|
130 |
|
131 |
|
132 |
|
133 |
|
134 |
|
135 |
private NetworkGate(string path,NetworkOperation operation) |
136 |
{ |
137 |
if (String.IsNullOrWhiteSpace(path)) |
138 |
throw new ArgumentNullException("path"); |
139 |
if (!Path.IsPathRooted(path)) |
140 |
throw new ArgumentException("path must be rooted","path"); |
141 |
Contract.EndContractBlock(); |
142 |
|
143 |
Operation = operation; |
144 |
FilePath = path.ToLower(); |
145 |
|
146 |
//Skip dummy operations (those with Operation == None) |
147 |
if (Operation != NetworkOperation.None) |
148 |
//and store the file's operation |
149 |
SetNetworkState(FilePath, operation); |
150 |
} |
151 |
|
152 |
//A NetworkGate has Failed if its operation is None |
153 |
public bool Failed { get { return Operation == NetworkOperation.None; } } |
154 |
|
155 |
//Release a gate by setting the NetworkOperation to None |
156 |
public void Release() |
157 |
{ |
158 |
//Skip Failed flags |
159 |
if (!Failed) |
160 |
//And reset the operation state for the file |
161 |
SetNetworkState(FilePath,NetworkOperation.None); |
162 |
} |
163 |
|
164 |
|
165 |
public void Dispose() |
166 |
{ |
167 |
Dispose(true); |
168 |
GC.SuppressFinalize(this); |
169 |
} |
170 |
|
171 |
protected void Dispose(bool disposing) |
172 |
{ |
173 |
if (disposing) |
174 |
{ |
175 |
Release(); |
176 |
} |
177 |
} |
178 |
|
179 |
} |
180 |
} |