1 /*

     2  * Copyright (c) 2019, Red Hat, Inc. All rights reserved.

     3  *

     4  * This code is free software; you can redistribute it and/or modify it

     5  * under the terms of the GNU General Public License version 2 only, as

     6  * published by the Free Software Foundation.

     7  *

     8  * This code is distributed in the hope that it will be useful, but WITHOUT

     9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    11  * version 2 for more details (a copy is included in the LICENSE file that

    12  * accompanied this code).

    13  *

    14  * You should have received a copy of the GNU General Public License version

    15  * 2 along with this work; if not, write to the Free Software Foundation,

    16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    17  *

    18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    19  * or visit www.oracle.com if you need additional information or have any

    20  * questions.

    21  *

    22  */

    23 

    24 #include "precompiled.hpp"

    25 

    26 #include "runtime/os.hpp"

    27 

    28 #include "gc/shenandoah/shenandoahLock.hpp"

    29 #include "runtime/atomic.hpp"

    30 #include "runtime/os.inline.hpp"

    31 #include "runtime/thread.hpp"

    32 

    33 ShenandoahSimpleLock::ShenandoahSimpleLock() {

    34   assert(os::mutex_init_done(), "Too early!");

    35 }

    36 

    37 void ShenandoahSimpleLock::lock() {

    38   _lock.lock();

    39 }

    40 

    41 void ShenandoahSimpleLock::unlock() {

    42   _lock.unlock();

    43 }

    44 

    45 ShenandoahReentrantLock::ShenandoahReentrantLock() :

    46   ShenandoahSimpleLock(), _owner(NULL), _count(0) {

    47   assert(os::mutex_init_done(), "Too early!");

    48 }

    49 

    50 ShenandoahReentrantLock::~ShenandoahReentrantLock() {

    51   assert(_count == 0, "Unbalance");

    52 }

    53 

    54 void ShenandoahReentrantLock::lock() {

    55   Thread* const thread = Thread::current();

    56   Thread* const owner = Atomic::load(&_owner);

    57 

    58   if (owner != thread) {

    59     ShenandoahSimpleLock::lock();

    60     Atomic::store(&_owner, thread);

    61   }

    62 

    63   _count++;

    64 }

    65 

    66 void ShenandoahReentrantLock::unlock() {

    67   assert(owned_by_self(), "Invalid owner");

    68   assert(_count > 0, "Invalid count");

    69 

    70   _count--;

    71 

    72   if (_count == 0) {

    73     Atomic::store(&_owner, (Thread*)NULL);

    74     ShenandoahSimpleLock::unlock();

    75   }

    76 }

    77 

    78 bool ShenandoahReentrantLock::owned_by_self() const {

    79   Thread* const thread = Thread::current();

    80   Thread* const owner = Atomic::load(&_owner);

    81   return owner == thread;

    82 }