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/*
* Copyright (c) 2010, 2022, 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.
*
*/
#ifndef OS_POSIX_PARK_POSIX_HPP
#define OS_POSIX_PARK_POSIX_HPP
#include "memory/allocation.hpp"
#include "utilities/debug.hpp"
#include "utilities/globalDefinitions.hpp"
#include <pthread.h>
/*
* This is the platform-specific implementation underpinning
* the ParkEvent class, which itself underpins Java-level monitor
* operations. See park.hpp for details.
* These event objects are type-stable and immortal - we never delete them.
* Events are associated with a thread for the lifetime of the thread.
*/
class PlatformEvent : public CHeapObj<mtSynchronizer> {
private:
double cachePad[4]; // Increase odds that _mutex is sole occupant of cache line
volatile int _event; // Event count/permit: -1, 0 or 1
volatile int _nParked; // Indicates if associated thread is blocked: 0 or 1
pthread_mutex_t _mutex[1]; // Native mutex for locking
pthread_cond_t _cond[1]; // Native condition variable for blocking
double postPad[2];
protected: // TODO-FIXME: make dtor private
~PlatformEvent() { guarantee(false, "invariant"); } // immortal so can't delete
public:
PlatformEvent();
void park();
int park(jlong millis);
void unpark();
// Use caution with reset() and fired() -- they may require MEMBARs
void reset() { _event = 0; }
int fired() { return _event; }
};
// JSR166 support
// PlatformParker provides the platform dependent base class for the
// Parker class. It basically provides the internal data structures:
// - mutex and convars
// which are then used directly by the Parker methods defined in the OS
// specific implementation files.
// There is significant overlap between the funcionality supported in the
// combination of Parker+PlatformParker and PlatformEvent (above). If Parker
// were more like ObjectMonitor we could use PlatformEvent in both (with some
// API updates of course). But Parker methods use fastpaths that break that
// level of encapsulation - so combining the two remains a future project.
class PlatformParker {
NONCOPYABLE(PlatformParker);
protected:
enum {
REL_INDEX = 0,
ABS_INDEX = 1
};
volatile int _counter;
int _cur_index; // which cond is in use: -1, 0, 1
pthread_mutex_t _mutex[1];
pthread_cond_t _cond[2]; // one for relative times and one for absolute
public:
PlatformParker();
~PlatformParker();
};
#endif // OS_POSIX_PARK_POSIX_HPP
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