100 lines
2.9 KiB
C++
100 lines
2.9 KiB
C++
/*
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* Copyright (c) 2017, 2019, Red Hat, Inc. All rights reserved.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#ifndef SHARE_GC_SHENANDOAH_SHENANDOAHLOCK_HPP
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#define SHARE_GC_SHENANDOAH_SHENANDOAHLOCK_HPP
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#include "memory/allocation.hpp"
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#include "runtime/thread.hpp"
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class ShenandoahLock {
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private:
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enum LockState { unlocked = 0, locked = 1 };
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DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile int));
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volatile int _state;
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DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile Thread*));
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volatile Thread* _owner;
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DEFINE_PAD_MINUS_SIZE(2, DEFAULT_CACHE_LINE_SIZE, 0);
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public:
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ShenandoahLock() : _state(unlocked), _owner(NULL) {};
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void lock() {
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#ifdef ASSERT
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assert(_owner != Thread::current(), "reentrant locking attempt, would deadlock");
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#endif
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Thread::SpinAcquire(&_state, "Shenandoah Heap Lock");
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#ifdef ASSERT
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assert(_state == locked, "must be locked");
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assert(_owner == NULL, "must not be owned");
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_owner = Thread::current();
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#endif
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}
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void unlock() {
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#ifdef ASSERT
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assert (_owner == Thread::current(), "sanity");
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_owner = NULL;
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#endif
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Thread::SpinRelease(&_state);
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}
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#ifdef ASSERT
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void assert_owned_by_current_thread() {
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assert(_state == locked, "must be locked");
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assert(_owner == Thread::current(), "must be owned by current thread");
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}
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void assert_not_owned_by_current_thread() {
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assert(_owner != Thread::current(), "must be not owned by current thread");
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}
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void assert_owned_by_current_thread_or_safepoint() {
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Thread* thr = Thread::current();
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assert((_state == locked && _owner == thr) ||
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(SafepointSynchronize::is_at_safepoint() && thr->is_VM_thread()),
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"must own heap lock or by VM thread at safepoint");
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}
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#endif
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};
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class ShenandoahLocker : public StackObj {
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private:
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ShenandoahLock* const _lock;
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public:
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ShenandoahLocker(ShenandoahLock* lock) : _lock(lock) {
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if (_lock != NULL) {
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_lock->lock();
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}
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}
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~ShenandoahLocker() {
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if (_lock != NULL) {
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_lock->unlock();
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}
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}
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};
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#endif // SHARE_GC_SHENANDOAH_SHENANDOAHLOCK_HPP
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