Quelle globalCounter.cpp Sprache: C

/*
* Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code 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
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/

#include "precompiled.hpp"
#include "memory/iterator.hpp"
#include "runtime/atomic.hpp"
#include "runtime/javaThread.hpp"
#include "runtime/threadSMR.inline.hpp"
#include "runtime/vmThread.hpp"
#include "utilities/globalCounter.hpp"
#include "utilities/spinYield.hpp"

GlobalCounter::PaddedCounter GlobalCounter::_global_counter;

class GlobalCounter::CounterThreadCheck : public ThreadClosure {
private:
  uintx _gbl_cnt;
public:
  CounterThreadCheck(uintx gbl_cnt) : _gbl_cnt(gbl_cnt) {}
  void do_thread(Thread* thread) {
    SpinYield yield;
    // Loops on this thread until it has exited the critical read section.
    while(true) {
      uintx cnt = Atomic::load_acquire(thread->get_rcu_counter());
      // This checks if the thread's counter is active. And if so is the counter
      // for a pre-existing reader (belongs to this grace period). A pre-existing
      // reader will have a lower counter than the global counter version for this
      // generation. If the counter is larger than the global counter version this
      //  is a new reader and we can continue.
      if (((cnt & COUNTER_ACTIVE) != 0) && (cnt - _gbl_cnt) > (max_uintx / 2)) {
        yield.wait();
      } else {
        break;
      }
    }
  }
};

void GlobalCounter::write_synchronize() {
  assert((*Thread::current()->get_rcu_counter() & COUNTER_ACTIVE) == 0x0, "must be outside a critcal section");
  // Atomic::add must provide fence since we have storeload dependency.
  uintx gbl_cnt = Atomic::add(&_global_counter._counter, COUNTER_INCREMENT);

  // Do all RCU threads.
  CounterThreadCheck ctc(gbl_cnt);
  for (JavaThreadIteratorWithHandle jtiwh; JavaThread *thread = jtiwh.next(); ) {
    ctc.do_thread(thread);
  }
  for (NonJavaThread::Iterator njti; !njti.end(); njti.step()) {
    ctc.do_thread(njti.current());
  }
}

quality54%

¤ Dauer der Verarbeitung: 0.14 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.