00001 /******************************************************************************* 00002 00003 @file IResource.d 00004 00005 Copyright (C) 2004 Kris Bell 00006 00007 This software is provided 'as-is', without any express or implied 00008 warranty. In no event will the authors be held liable for damages 00009 of any kind arising from the use of this software. 00010 00011 Permission is hereby granted to anyone to use this software for any 00012 purpose, including commercial applications, and to alter it and/or 00013 redistribute it freely, subject to the following restrictions: 00014 00015 1. The origin of this software must not be misrepresented; you must 00016 not claim that you wrote the original software. If you use this 00017 software in a product, an acknowledgment within documentation of 00018 said product would be appreciated but is not required. 00019 00020 2. Altered source versions must be plainly marked as such, and must 00021 not be misrepresented as being the original software. 00022 00023 3. This notice may not be removed or altered from any distribution 00024 of the source. 00025 00026 00027 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 00028 00029 00030 @version Initial version, March 2004 00031 @author Kris 00032 00033 00034 *******************************************************************************/ 00035 00036 module mango.io.model.IResource; 00037 00038 /******************************************************************************* 00039 00040 Protocol for acquiring and releasing a resource such as a file, or 00041 socket. This isn't strictly necessary, but will aid migration to a 00042 multi-threaded runtime environment. 00043 00044 *******************************************************************************/ 00045 00046 interface IResource 00047 { 00048 /*********************************************************************** 00049 00050 Subclasses must implement closure mechanics. This is 00051 invoked when the number of close() invocations match 00052 that of aquire() -- the latter is typically called 00053 immediately following the successful construction of 00054 an IResource implementation; one should expect close 00055 to be required at least once. 00056 00057 ***********************************************************************/ 00058 00059 abstract protected void closure (); 00060 00061 /*********************************************************************** 00062 00063 Return the lock used by this resource 00064 00065 ***********************************************************************/ 00066 00067 Object getLock (); 00068 00069 /*********************************************************************** 00070 00071 Set an alternate lock. Typically one would use this to 00072 synchronize multiple different Resources via a common 00073 object. 00074 00075 ***********************************************************************/ 00076 00077 void setLock (Object lock); 00078 00079 /*********************************************************************** 00080 00081 hold a reference to this resource. The caller is now 00082 responsible for invoking close() upon this resource; 00083 00084 ***********************************************************************/ 00085 00086 void acquire (); 00087 00088 /*********************************************************************** 00089 00090 If this resource is still open, acquire it and return true. 00091 This is a threadsafe test-and-set mechanism that fails only 00092 if the resource is already closed, or was never opened. 00093 00094 Note that you are responsible for invoking close() whenever 00095 this method returns true. 00096 00097 ***********************************************************************/ 00098 00099 bool acquireIfOpen (); 00100 00101 /*********************************************************************** 00102 00103 release a reference to this resource 00104 00105 ***********************************************************************/ 00106 00107 void close (); 00108 } 00109