00001 #ifndef __SYS_XSLOCK_HH__ 00002 #define __SYS_XSLOCK_HH__ 00003 /******************************************************************************/ 00004 /* */ 00005 /* X r d S y s X S L o c k . h h */ 00006 /* */ 00007 /* (c) 2003 by the Board of Trustees of the Leland Stanford, Jr., University */ 00008 /* All Rights Reserved */ 00009 /* Produced by Andrew Hanushevsky for Stanford University under contract */ 00010 /* DE-AC02-76-SFO0515 with the Department of Energy */ 00011 /* */ 00012 /* This file is part of the XRootD software suite. */ 00013 /* */ 00014 /* XRootD is free software: you can redistribute it and/or modify it under */ 00015 /* the terms of the GNU Lesser General Public License as published by the */ 00016 /* Free Software Foundation, either version 3 of the License, or (at your */ 00017 /* option) any later version. */ 00018 /* */ 00019 /* XRootD is distributed in the hope that it will be useful, but WITHOUT */ 00020 /* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or */ 00021 /* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public */ 00022 /* License for more details. */ 00023 /* */ 00024 /* You should have received a copy of the GNU Lesser General Public License */ 00025 /* along with XRootD in a file called COPYING.LESSER (LGPL license) and file */ 00026 /* COPYING (GPL license). If not, see <http://www.gnu.org/licenses/>. */ 00027 /* */ 00028 /* The copyright holder's institutional names and contributor's names may not */ 00029 /* be used to endorse or promote products derived from this software without */ 00030 /* specific prior written permission of the institution or contributor. */ 00031 /******************************************************************************/ 00032 00033 #include <errno.h> 00034 #include "XrdSys/XrdSysPthread.hh" 00035 00036 // These are valid usage options 00037 // 00038 enum XrdSysXS_Type {xs_None = 0, xs_Shared = 1, xs_Exclusive = 2}; 00039 00040 // This class implements the shared lock. Any number of readers are allowed 00041 // by requesting a shared lock. Only one exclusive writer is allowed by 00042 // requesting an exclusive lock. Up/downgrading is not supported. 00043 // 00044 class XrdSysXSLock 00045 { 00046 public: 00047 00048 void Lock(const XrdSysXS_Type usage); 00049 00050 void UnLock(const XrdSysXS_Type usage=xs_None); 00051 00052 XrdSysXSLock() : cur_usage(xs_None), cur_count(0), exc_wait(0), 00053 shr_wait(0), toggle(0), WantShr(0), WantExc(0) {} 00054 ~XrdSysXSLock(); 00055 00056 private: 00057 00058 XrdSysXS_Type cur_usage; 00059 int cur_count; 00060 int exc_wait; 00061 int shr_wait; 00062 int toggle; 00063 00064 XrdSysMutex LockContext; 00065 XrdSysSemaphore WantShr; 00066 XrdSysSemaphore WantExc; 00067 }; 00068 #endif