task_scheduler_observer.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_task_scheduler_observer_H
#define __TBB_task_scheduler_observer_H

#include "atomic.h"
#if __TBB_ARENA_OBSERVER || __TBB_SLEEP_PERMISSION
#include "task_arena.h"
#endif

#if __TBB_SCHEDULER_OBSERVER

namespace tbb {
namespace interface6 {
class task_scheduler_observer;
}
namespace internal {

class observer_proxy;
class observer_list;

class task_scheduler_observer_v3 {
    friend class observer_proxy;
    friend class observer_list;
    friend class interface6::task_scheduler_observer;


    observer_proxy* my_proxy;


    atomic<intptr_t> my_busy_count;

public:

    void __TBB_EXPORTED_METHOD observe( bool state=true );

    bool is_observing() const {return my_proxy!=NULL;}

    task_scheduler_observer_v3() : my_proxy(NULL) { my_busy_count.store<relaxed>(0); }


    virtual void on_scheduler_entry( bool /*is_worker*/ ) {}


    virtual void on_scheduler_exit( bool /*is_worker*/ ) {}

    virtual ~task_scheduler_observer_v3() { if(my_proxy) observe(false);}
};

} // namespace internal

#if __TBB_ARENA_OBSERVER || __TBB_SLEEP_PERMISSION
namespace interface6 {
class task_scheduler_observer : public internal::task_scheduler_observer_v3 {
    friend class internal::task_scheduler_observer_v3;
    friend class internal::observer_proxy;
    friend class internal::observer_list;

    // TODO: take more high bits for version number
    static const intptr_t v6_trait = (intptr_t)((~(uintptr_t)0 >> 1) + 1);

    intptr_t my_context_tag;
    enum { global_tag = 0, implicit_tag = 1 };

public:

    task_scheduler_observer( bool local = false ) {
#if  __TBB_ARENA_OBSERVER
        my_context_tag = local? implicit_tag : global_tag;
#else
        __TBB_ASSERT_EX( !local, NULL );
        my_context_tag = global_tag;
#endif
    }

#if  __TBB_ARENA_OBSERVER

    task_scheduler_observer( task_arena & a) {
        my_context_tag = (intptr_t)&a;
    }
#endif /* __TBB_ARENA_OBSERVER */

    virtual ~task_scheduler_observer() { if(my_proxy) observe(false); }


    void observe( bool state=true ) {
        if( state && !my_proxy ) {
            __TBB_ASSERT( !my_busy_count, "Inconsistent state of task_scheduler_observer instance");
            my_busy_count.store<relaxed>(v6_trait);
        }
        internal::task_scheduler_observer_v3::observe(state);
    }

#if  __TBB_SLEEP_PERMISSION
    enum { keep_awake = false, allow_sleep = true };


    virtual bool may_sleep() { return allow_sleep; }
#endif /*__TBB_SLEEP_PERMISSION*/
};

} //namespace interface6
using interface6::task_scheduler_observer;
#else /*__TBB_ARENA_OBSERVER || __TBB_SLEEP_PERMISSION*/
typedef tbb::internal::task_scheduler_observer_v3 task_scheduler_observer;
#endif /*__TBB_ARENA_OBSERVER || __TBB_SLEEP_PERMISSION*/

} // namespace tbb

#endif /* __TBB_SCHEDULER_OBSERVER */

#endif /* __TBB_task_scheduler_observer_H */