linux_common.h

/*
    Copyright 2005-2016 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 internal file directly; use public TBB headers instead.
#endif

#include <sched.h>
#define __TBB_Yield()  sched_yield()

#include <unistd.h>
/* 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 */