175 lines
6.8 KiB
C++
175 lines
6.8 KiB
C++
/*
|
|
Copyright (c) 2005-2017 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;
|
|
|
|
//! Pointer to the proxy holding this observer.
|
|
/** Observers are proxied by the scheduler to maintain persistent lists of them. **/
|
|
observer_proxy* my_proxy;
|
|
|
|
//! Counter preventing the observer from being destroyed while in use by the scheduler.
|
|
/** Valid only when observation is on. **/
|
|
atomic<intptr_t> my_busy_count;
|
|
|
|
public:
|
|
//! Enable or disable observation
|
|
/** For local observers the method can be used only when the current thread
|
|
has the task scheduler initialized or is attached to an arena.
|
|
|
|
Repeated calls with the same state are no-ops. **/
|
|
void __TBB_EXPORTED_METHOD observe( bool state=true );
|
|
|
|
//! Returns true if observation is enabled, false otherwise.
|
|
bool is_observing() const {return my_proxy!=NULL;}
|
|
|
|
//! Construct observer with observation disabled.
|
|
task_scheduler_observer_v3() : my_proxy(NULL) { my_busy_count.store<relaxed>(0); }
|
|
|
|
//! Entry notification
|
|
/** Invoked from inside observe(true) call and whenever a worker enters the arena
|
|
this observer is associated with. If a thread is already in the arena when
|
|
the observer is activated, the entry notification is called before it
|
|
executes the first stolen task.
|
|
|
|
Obsolete semantics. For global observers it is called by a thread before
|
|
the first steal since observation became enabled. **/
|
|
virtual void on_scheduler_entry( bool /*is_worker*/ ) {}
|
|
|
|
//! Exit notification
|
|
/** Invoked from inside observe(false) call and whenever a worker leaves the
|
|
arena this observer is associated with.
|
|
|
|
Obsolete semantics. For global observers it is called by a thread before
|
|
the first steal since observation became enabled. **/
|
|
virtual void on_scheduler_exit( bool /*is_worker*/ ) {}
|
|
|
|
//! Destructor automatically switches observation off if it is enabled.
|
|
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;
|
|
|
|
/** Negative numbers with the largest absolute value to minimize probability
|
|
of coincidence in case of a bug in busy count usage. **/
|
|
// TODO: take more high bits for version number
|
|
static const intptr_t v6_trait = (intptr_t)((~(uintptr_t)0 >> 1) + 1);
|
|
|
|
//! contains task_arena pointer or tag indicating local or global semantics of the observer
|
|
intptr_t my_context_tag;
|
|
enum { global_tag = 0, implicit_tag = 1 };
|
|
|
|
public:
|
|
//! Construct local or global observer in inactive state (observation disabled).
|
|
/** For a local observer entry/exit notifications are invoked whenever a worker
|
|
thread joins/leaves the arena of the observer's owner thread. If a thread is
|
|
already in the arena when the observer is activated, the entry notification is
|
|
called before it executes the first stolen task. **/
|
|
/** TODO: Obsolete.
|
|
Global observer semantics is obsolete as it violates master thread isolation
|
|
guarantees and is not composable. Thus the current default behavior of the
|
|
constructor is obsolete too and will be changed in one of the future versions
|
|
of the library. **/
|
|
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
|
|
//! Construct local observer for a given arena in inactive state (observation disabled).
|
|
/** entry/exit notifications are invoked whenever a thread joins/leaves arena.
|
|
If a thread is already in the arena when the observer is activated, the entry notification
|
|
is called before it executes the first stolen task. **/
|
|
explicit task_scheduler_observer( task_arena & a) {
|
|
my_context_tag = (intptr_t)&a;
|
|
}
|
|
#endif /* __TBB_ARENA_OBSERVER */
|
|
|
|
/** Destructor protects instance of the observer from concurrent notification.
|
|
It is recommended to disable observation before destructor of a derived class starts,
|
|
otherwise it can lead to concurrent notification callback on partly destroyed object **/
|
|
virtual ~task_scheduler_observer() { if(my_proxy) observe(false); }
|
|
|
|
//! Enable or disable observation
|
|
/** Warning: concurrent invocations of this method are not safe.
|
|
Repeated calls with the same state are no-ops. **/
|
|
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
|
|
//! Return commands for may_sleep()
|
|
enum { keep_awake = false, allow_sleep = true };
|
|
|
|
//! The callback can be invoked by a worker thread before it goes to sleep.
|
|
/** If it returns false ('keep_awake'), the thread will keep spinning and looking for work.
|
|
It will not be called for master threads. **/
|
|
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 */
|