1 // This source code is dual-licensed under the Apache License, version
2 // 2.0, and the Mozilla Public License, version 1.1.
6 //---------------------------------------------------------------------------
7 // Copyright (C) 2007-2009 LShift Ltd., Cohesive Financial
8 // Technologies LLC., and Rabbit Technologies Ltd.
10 // Licensed under the Apache License, Version 2.0 (the "License");
11 // you may not use this file except in compliance with the License.
12 // You may obtain a copy of the License at
14 // http://www.apache.org/licenses/LICENSE-2.0
16 // Unless required by applicable law or agreed to in writing, software
17 // distributed under the License is distributed on an "AS IS" BASIS,
18 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
19 // See the License for the specific language governing permissions and
20 // limitations under the License.
21 //---------------------------------------------------------------------------
25 //---------------------------------------------------------------------------
26 // The contents of this file are subject to the Mozilla Public License
27 // Version 1.1 (the "License"); you may not use this file except in
28 // compliance with the License. You may obtain a copy of the License at
29 // http://www.rabbitmq.com/mpl.html
31 // Software distributed under the License is distributed on an "AS IS"
32 // basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
33 // License for the specific language governing rights and limitations
36 // The Original Code is The RabbitMQ .NET Client.
38 // The Initial Developers of the Original Code are LShift Ltd,
39 // Cohesive Financial Technologies LLC, and Rabbit Technologies Ltd.
41 // Portions created before 22-Nov-2008 00:00:00 GMT by LShift Ltd,
42 // Cohesive Financial Technologies LLC, or Rabbit Technologies Ltd
43 // are Copyright (C) 2007-2008 LShift Ltd, Cohesive Financial
44 // Technologies LLC, and Rabbit Technologies Ltd.
46 // Portions created by LShift Ltd are Copyright (C) 2007-2009 LShift
47 // Ltd. Portions created by Cohesive Financial Technologies LLC are
48 // Copyright (C) 2007-2009 Cohesive Financial Technologies
49 // LLC. Portions created by Rabbit Technologies Ltd are Copyright
50 // (C) 2007-2009 Rabbit Technologies Ltd.
52 // All Rights Reserved.
54 // Contributor(s): ______________________________________.
56 //---------------------------------------------------------------------------
58 using System.Collections;
59 using System.Threading;
61 namespace RabbitMQ.Util {
62 ///<summary>A thread-safe single-assignment reference cell.</summary>
64 ///A fresh BlockingCell holds no value (is empty). Any thread
65 ///reading the Value property when the cell is empty will block
66 ///until a value is made available by some other thread. The Value
67 ///property can only be set once - on the first call, the
68 ///BlockingCell is considered full, and made immutable. Further
69 ///attempts to set Value result in a thrown
70 ///InvalidOperationException.
72 public class BlockingCell {
73 private bool m_valueSet = false;
74 private object m_value = null;
76 ///<summary>Construct an empty BlockingCell.</summary>
77 public BlockingCell() {}
79 ///<summary>Retrieve the cell's value, blocking if none exists
80 ///at present, or supply a value to an empty cell, thereby
81 ///filling it.</summary>
82 /// <exception cref="InvalidOperationException" />
96 throw new InvalidOperationException("Setting BlockingCell value twice forbidden");
100 Monitor.PulseAll(this);
105 ///<summary>Retrieve the cell's value, waiting for the given
106 ///timeout if no value is immediately available.</summary>
109 /// If a value is present in the cell at the time the call is
110 /// made, the call will return immediately. Otherwise, the
111 /// calling thread blocks until either a value appears, or
112 /// millisecondsTimeout milliseconds have elapsed.
115 /// Returns true in the case that the value was available
116 /// before the timeout, in which case the out parameter
117 /// "result" is set to the value itself.
120 /// If no value was available before the timeout, returns
121 /// false, and sets "result" to null.
124 /// A timeout of -1 (i.e. System.Threading.Timeout.Infinite)
125 /// will be interpreted as a command to wait for an
126 /// indefinitely long period of time for the cell's value to
127 /// become available. See the MSDN documentation for
128 /// System.Threading.Monitor.Wait(object,int).
131 public bool GetValue(int millisecondsTimeout, out object result)
137 Monitor.Wait(this, validatedTimeout(millisecondsTimeout));
148 ///<summary>Return valid timeout value</summary>
149 ///<remarks>If value of the parameter is less then zero, return 0
150 ///to mean infinity</remarks>
151 public static int validatedTimeout(int timeout)
153 return (timeout != Timeout.Infinite)
154 && (timeout < 0) ? 0 : timeout;