1 /*
   2  * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "gc/shared/concurrentGCThread.hpp"
  27 #include "runtime/init.hpp"
  28 #include "runtime/mutexLocker.hpp"
  29 #include "runtime/orderAccess.hpp"
  30 #include "runtime/os.hpp"
  31 
  32 ConcurrentGCThread::ConcurrentGCThread() :
  33     _monitor(Monitor::leaf, "ConcurrentGCThread"),
  34     _should_terminate(false),
  35     _has_terminated(false) {}
  36 
  37 void ConcurrentGCThread::create_and_start(ThreadPriority prio) {
  38   if (os::create_thread(this, os::cgc_thread)) {
  39     os::set_priority(this, prio);
  40     os::start_thread(this);
  41   }
  42 }
  43 
  44 void ConcurrentGCThread::run() {
  45   // Setup handle area
  46   set_active_handles(JNIHandleBlock::allocate_block());
  47 
  48   // Wait for initialization to complete
  49   wait_init_completed();
  50 
  51   run_service();
  52 
  53   // Signal thread has terminated
  54   MonitorLockerEx ml(&_monitor);
  55   OrderAccess::release_store(&_has_terminated, true);
  56   ml.notify_all();
  57 }
  58 
  59 void ConcurrentGCThread::stop() {
  60   assert(!should_terminate(), "Invalid state");
  61   assert(!has_terminated(), "Invalid state");
  62 
  63   // Signal thread to terminate
  64   OrderAccess::release_store(&_should_terminate, true);
  65 
  66   stop_service();
  67 
  68   // Wait for thread to terminate
  69   MonitorLockerEx ml(&_monitor);
  70   while (!_has_terminated) {
  71     ml.wait();
  72   }
  73 }
  74 
  75 bool ConcurrentGCThread::should_terminate() {
  76   return OrderAccess::load_acquire(&_should_terminate);
  77 }
  78 
  79 bool ConcurrentGCThread::has_terminated() {
  80   return OrderAccess::load_acquire(&_has_terminated);
  81 }