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 4. Derivative works are permitted, but they must carry this notice 00027 in full and credit the original source. 00028 00029 00030 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 00031 00032 00033 @version Initial version, March 2004 00034 @author Kris 00035 00036 00037 *******************************************************************************/ 00038 00039 module mango.io.model.IResource; 00040 00041 /******************************************************************************* 00042 00043 Protocol for acquiring and releasing a resource such as a file, or 00044 socket. This isn't strictly necessary, but will aid migration to a 00045 multi-threaded runtime environment. 00046 00047 *******************************************************************************/ 00048 00049 interface IResource 00050 { 00051 /*********************************************************************** 00052 00053 Subclasses must implement closure mechanics. This is 00054 invoked when the number of close() invocations match 00055 that of aquire() -- the latter is typically called 00056 immediately following the successful construction of 00057 an IResource implementation; one should expect close 00058 to be required at least once. 00059 00060 ***********************************************************************/ 00061 00062 abstract protected void closure (); 00063 00064 /*********************************************************************** 00065 00066 Return the lock used by this resource 00067 00068 ***********************************************************************/ 00069 00070 Object getLock (); 00071 00072 /*********************************************************************** 00073 00074 Set an alternate lock. Typically one would use this to 00075 synchronize multiple different Resources via a common 00076 object. 00077 00078 ***********************************************************************/ 00079 00080 void setLock (Object lock); 00081 00082 /*********************************************************************** 00083 00084 hold a reference to this resource. The caller is now 00085 responsible for invoking close() upon this resource; 00086 00087 ***********************************************************************/ 00088 00089 void acquire (); 00090 00091 /*********************************************************************** 00092 00093 If this resource is still open, acquire it and return true. 00094 This is a threadsafe test-and-set mechanism that fails only 00095 if the resource is already closed, or was never opened. 00096 00097 Note that you are responsible for invoking close() whenever 00098 this method returns true. 00099 00100 ***********************************************************************/ 00101 00102 bool acquireIfOpen (); 00103 00104 /*********************************************************************** 00105 00106 release a reference to this resource 00107 00108 ***********************************************************************/ 00109 00110 void close (); 00111 } 00112