task_scheduler_observer.h

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/*
    Copyright (c) 2005-2019 Intel Corporation

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

        http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the 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:

    explicit 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

    explicit 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 */