linux_common.h

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/*
    Copyright 2005-2010 Intel Corporation.  All Rights Reserved.

    This file is part of Threading Building Blocks.

    Threading Building Blocks is free software; you can redistribute it
    and/or modify it under the terms of the GNU General Public License
    version 2 as published by the Free Software Foundation.

    Threading Building Blocks is distributed in the hope that it will be
    useful, but WITHOUT ANY WARRANTY; without even the implied warranty
    of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with Threading Building Blocks; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    As a special exception, you may use this file as part of a free software
    library without restriction.  Specifically, if other files instantiate
    templates or use macros or inline functions from this file, or you compile
    this file and link it with other files to produce an executable, this
    file does not by itself cause the resulting executable to be covered by
    the GNU General Public License.  This exception does not however
    invalidate any other reasons why the executable file might be covered by
    the GNU General Public License.
*/

#ifndef __TBB_machine_H
#error Do not include this file directly; include tbb_machine.h instead
#endif

#include <stdint.h>
#include <unistd.h>
#include <sched.h>

// Definition of __TBB_Yield()
#ifndef __TBB_Yield
#define __TBB_Yield()  sched_yield()
#endif

/* Futex definitions */
#include <sys/syscall.h>

#if defined(SYS_futex)

#define __TBB_USE_FUTEX 1
#include <limits.h>
#include <errno.h>
// Unfortunately, some versions of Linux do not have a header that defines FUTEX_WAIT and FUTEX_WAKE.

#ifdef FUTEX_WAIT
#define __TBB_FUTEX_WAIT FUTEX_WAIT
#else
#define __TBB_FUTEX_WAIT 0
#endif

#ifdef FUTEX_WAKE
#define __TBB_FUTEX_WAKE FUTEX_WAKE
#else
#define __TBB_FUTEX_WAKE 1
#endif

#ifndef __TBB_ASSERT
#error machine specific headers must be included after tbb_stddef.h
#endif

namespace tbb {

namespace internal {

inline int futex_wait( void *futex, int comparand ) {
    int r = ::syscall( SYS_futex,futex,__TBB_FUTEX_WAIT,comparand,NULL,NULL,0 );
#if TBB_USE_ASSERT
    int e = errno;
    __TBB_ASSERT( r==0||r==EWOULDBLOCK||(r==-1&&(e==EAGAIN||e==EINTR)), "futex_wait failed." );
#endif /* TBB_USE_ASSERT */
    return r;
}

inline int futex_wakeup_one( void *futex ) {
    int r = ::syscall( SYS_futex,futex,__TBB_FUTEX_WAKE,1,NULL,NULL,0 );
    __TBB_ASSERT( r==0||r==1, "futex_wakeup_one: more than one thread woken up?" );
    return r;
}

inline int futex_wakeup_all( void *futex ) {
    int r = ::syscall( SYS_futex,futex,__TBB_FUTEX_WAKE,INT_MAX,NULL,NULL,0 );
    __TBB_ASSERT( r>=0, "futex_wakeup_all: error in waking up threads" );
    return r;
}

} /* namespace internal */

} /* namespace tbb */

#endif /* SYS_futex */