XRootD
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XrdSysXSLock.hh
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1#ifndef __SYS_XSLOCK_HH__
2#define __SYS_XSLOCK_HH__
3/******************************************************************************/
4/* */
5/* X r d S y s X S L o c k . h h */
6/* */
7/* (c) 2003 by the Board of Trustees of the Leland Stanford, Jr., University */
8/* All Rights Reserved */
9/* Produced by Andrew Hanushevsky for Stanford University under contract */
10/* DE-AC02-76-SFO0515 with the Department of Energy */
11/* */
12/* This file is part of the XRootD software suite. */
13/* */
14/* XRootD is free software: you can redistribute it and/or modify it under */
15/* the terms of the GNU Lesser General Public License as published by the */
16/* Free Software Foundation, either version 3 of the License, or (at your */
17/* option) any later version. */
18/* */
19/* XRootD is distributed in the hope that it will be useful, but WITHOUT */
20/* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or */
21/* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public */
22/* License for more details. */
23/* */
24/* You should have received a copy of the GNU Lesser General Public License */
25/* along with XRootD in a file called COPYING.LESSER (LGPL license) and file */
26/* COPYING (GPL license). If not, see <http://www.gnu.org/licenses/>. */
27/* */
28/* The copyright holder's institutional names and contributor's names may not */
29/* be used to endorse or promote products derived from this software without */
30/* specific prior written permission of the institution or contributor. */
31/******************************************************************************/
32
33#include <cerrno>
35
36// These are valid usage options
37//
39
40// This class implements the shared lock. Any number of readers are allowed
41// by requesting a shared lock. Only one exclusive writer is allowed by
42// requesting an exclusive lock. Up/downgrading is not supported.
43//
45{
46public:
47
48void Lock(const XrdSysXS_Type usage);
49
51
52 XrdSysXSLock() : cur_usage(xs_None), cur_count(0), exc_wait(0),
53 shr_wait(0), toggle(0), WantShr(0), WantExc(0) {}
55
56private:
57
58XrdSysXS_Type cur_usage;
59int cur_count;
60int exc_wait;
61int shr_wait;
62int toggle;
63
64XrdSysMutex LockContext;
65XrdSysSemaphore WantShr;
66XrdSysSemaphore WantExc;
67};
68#endif
void usage()
XrdSysXS_Type
@ xs_Exclusive
@ xs_None
@ xs_Shared
void Lock(const XrdSysXS_Type usage)
void UnLock(const XrdSysXS_Type usage=xs_None)