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src/hotspot/share/utilities/waitBarrier_generic.hpp

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rev 53038 : 8214271: Fast primitive to wake many threads
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rev 53039 : [mq]: 8214271-3


  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_UTILITIES_WAITBARRIER_GENERIC_HPP
  26 #define SHARE_UTILITIES_WAITBARRIER_GENERIC_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "runtime/semaphore.hpp"
  30 
  31 // Except for the barrier tag it self, it uses two counter to keep the semaphore
  32 // count correct and not leave any late thread hanging.
  33 class GenericWaitBarrier : public CHeapObj<mtInternal> {
  34   volatile int _barrier_tag;
  35   // The number of threads waiting on or about to wait on the semaphore.
  36   volatile int _waiters;
  37   // The number of threads in the wait path, before or after the tag check.
  38   // Which means it can become a waiter.
  39   volatile int _barrier_threads;
  40   Semaphore _sem_barrier;
  41 
  42   // Prevent copying and assignment of GenericWaitBarrier instances.
  43   GenericWaitBarrier(const GenericWaitBarrier&);
  44   GenericWaitBarrier& operator=(const GenericWaitBarrier&);
  45 
  46   int wake_if_needed();
  47 
  48  public:
  49   GenericWaitBarrier() : _barrier_tag(0), _waiters(0), _barrier_threads(0), _sem_barrier(0) {}
  50   ~GenericWaitBarrier() {}
  51 
  52   const char* description() { return "semaphore"; }
  53 
  54   void arm(int barrier_tag);
  55   void disarm();
  56   void wake();
  57   void wait(int barrier_tag);
  58 };


  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #ifndef SHARE_UTILITIES_WAITBARRIER_GENERIC_HPP
  26 #define SHARE_UTILITIES_WAITBARRIER_GENERIC_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "runtime/semaphore.hpp"
  30 
  31 // Except for the barrier tag itself, it uses two counters to keep the semaphore
  32 // count correct and not leave any late thread waiting.
  33 class GenericWaitBarrier : public CHeapObj<mtInternal> {
  34   volatile int _barrier_tag;
  35   // The number of threads waiting on or about to wait on the semaphore.
  36   volatile int _waiters;
  37   // The number of threads in the wait path, before or after the tag check.
  38   // These threads can become waiters.
  39   volatile int _barrier_threads;
  40   Semaphore _sem_barrier;
  41 
  42   // Prevent copying and assignment of GenericWaitBarrier instances.
  43   GenericWaitBarrier(const GenericWaitBarrier&);
  44   GenericWaitBarrier& operator=(const GenericWaitBarrier&);
  45 
  46   int wake_if_needed();
  47 
  48  public:
  49   GenericWaitBarrier() : _barrier_tag(0), _waiters(0), _barrier_threads(0), _sem_barrier(0) {}
  50   ~GenericWaitBarrier() {}
  51 
  52   const char* description() { return "semaphore"; }
  53 
  54   void arm(int barrier_tag);
  55   void disarm();
  56   void wake();
  57   void wait(int barrier_tag);
  58 };
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