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semaphore.cpp

/*
 *                         Sun Public License Notice
 *
 * The contents of this file are subject to the Sun Public License
 * Version 1.0 (the "License"); you may not use this file except
 * in compliance with the License. A copy of the License is available
 * at http://www.sun.com/
 *
 * The Original Code is the Java Profiler module.  The Initial Developers
 * of the Original Code are Jan Stola, Pavel Vacha, Michal Pise, Petr Luner,
 * Lukas Petru and Marek Przeczek.
 *
 * Portions created by Jan Stola are Copyright (C) 2000-2001.
 * All Rights Reserved.
 *
 * Portions created by Pavel Vacha are Copyright (C) 2000-2001.
 * All Rights Reserved.
 *
 * Portions created by Michal Pise are Copyright (C) 2000-2001.
 * All Rights Reserved.
 *
 * Portions created by Petr Luner are Copyright (C) 2000-2001.
 * All Rights Reserved.
 *
 * Portions created by Lukas Petru are Copyright (C) 2000-2001.
 * All Rights Reserved.
 *
 * Portions created by Marek Przeczek are Copyright (C) 2000-2001.
 * All Rights Reserved.
 *
 * Contributors: Jan Stola, Pavel Vacha, Michal Pise, Petr Luner,
 *               Lukas Petru and Marek Przeczek.
 */

#include "../commun3/semaphore.h"

Semaphore::Semaphore( const String& name) {

#ifdef WIN32
        _semid = CreateSemaphore( NULL, 0, 1, name);
#else
        _semid = semget( *(key_t*)(const char*)name, 1, 0666 | IPC_CREAT);
        reset();
#endif
}

Semaphore::~Semaphore() {
        
#ifdef WIN32
        CloseHandle( _semid);
#endif

        /* don't destroy semaphore on Unix, because
         * another process can be still using it !
         * semaphore stays in system as long as we
         * start profiling again or reboot the machine
         * (or remove it manually using 'ipcrm') */
}

void Semaphore::wait() {

#ifdef WIN32
        WaitForSingleObject( _semid, INFINITE);
#else
        static sembuf sop[2] = { 0, 0, 0, 0, 1, SEM_UNDO};
        semop( _semid, sop, 2);
#endif
}

void Semaphore::release() {

#ifdef WIN32
        ReleaseSemaphore( _semid, 1, NULL);
#else
        static sembuf sop = { 0, -1, SEM_UNDO | IPC_NOWAIT};
        semop( _semid, &sop, 1);
#endif
}

void Semaphore::reset() {

#ifndef WIN32
#ifdef LINUX
        // we define semun union ourselves on linux
        union {

                int val;
                semid_ds* buf;
                unsigned short int* array;
                seminfo* __buf;
        } arg;
#else
        // we define semun union ourselves on solaris
        union {

                int val;
                semid_ds* buf;
                ushort_t* array;
        } arg;
#endif
        arg.val = 1;
        semctl( _semid, 0, SETVAL, arg);
#endif

        /* not necessary to reset semaphore on Win32,
         * JVM goes well together with the system
         * and it seems there are no problems
         * with semaphore counter */
}

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