Quelle threadCritical_windows.cpp Sprache: C

/*
* Copyright (c) 2001, 2016, 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 "runtime/atomic.hpp"
#include "runtime/javaThread.hpp"
#include "runtime/threadCritical.hpp"

// OS-includes here
# include <windows.h>
# include <winbase.h>

//
// See threadCritical.hpp for details of this class.
//

static INIT_ONCE initialized = INIT_ONCE_STATIC_INIT;
static int lock_count = 0;
static HANDLE lock_event;
static DWORD lock_owner = 0;

//
// Note that Microsoft's critical region code contains a race
// condition, and is not suitable for use. A thread holding the
// critical section cannot safely suspend a thread attempting
// to enter the critical region. The failure mode is that both
// threads are permanently suspended.
//
// I experiemented with the use of ordinary windows mutex objects
// and found them ~30 times slower than the critical region code.
//

static BOOL WINAPI initialize(PINIT_ONCE InitOnce, PVOID Parameter, PVOID *Context) {
  lock_event = CreateEvent(NULL, false, true, NULL);
  assert(lock_event != NULL, "unexpected return value from CreateEvent");
  return true;
}

ThreadCritical::ThreadCritical() {
  InitOnceExecuteOnce(&initialized, &initialize, NULL, NULL);

  DWORD current_thread = GetCurrentThreadId();
  if (lock_owner != current_thread) {
    // Grab the lock before doing anything.
    DWORD ret = WaitForSingleObject(lock_event,  INFINITE);
    assert(ret == WAIT_OBJECT_0, "unexpected return value from WaitForSingleObject");
    lock_owner = current_thread;
  }
  // Atomicity isn't required. Bump the recursion count.
  lock_count++;
}

ThreadCritical::~ThreadCritical() {
  assert(lock_owner == GetCurrentThreadId(), "unlock attempt by wrong thread");
  assert(lock_count >= 0, "Attempt to unlock when already unlocked");

  lock_count--;
  if (lock_count == 0) {
    // We're going to unlock
    lock_owner = 0;
    // No lost wakeups, lock_event stays signaled until reset.
    DWORD ret = SetEvent(lock_event);
    assert(ret != 0, "unexpected return value from SetEvent");
  }
}

quality100%

¤ Dauer der Verarbeitung: 0.11 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.