Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright (c) 2011, 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/interfaceSupport.hpp"

 #include "runtime/javaCalls.hpp"

 #include "runtime/serviceThread.hpp"

 #include "runtime/mutexLocker.hpp"

 #include "prims/jvmtiImpl.hpp"

 ServiceThread* ServiceThread::_instance = NULL;

 void ServiceThread::initialize() {

   EXCEPTION_MARK;

   instanceKlassHandle klass (THREAD,  SystemDictionary::Thread_klass());

   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);

   const char* name = JDK_Version::is_gte_jdk17x_version() ?

       "Service Thread" : "Low Memory Detector";

   Handle string = java_lang_String::create_from_str(name, CHECK);

   // Initialize thread_oop to put it into the system threadGroup

   Handle thread_group (THREAD, Universe::system_thread_group());

   JavaValue result(T_VOID);

   JavaCalls::call_special(&result, thread_oop,

                           klass,

                           vmSymbols::object_initializer_name(),

                           vmSymbols::threadgroup_string_void_signature(),

                           thread_group,

                           string,

                           CHECK);

   {

     MutexLocker mu(Threads_lock);

     ServiceThread* thread =  new ServiceThread(&service_thread_entry);

     // At this point it may be possible that no osthread was created for the

     // JavaThread due to lack of memory. We would have to throw an exception

     // in that case. However, since this must work and we do not allow

     // exceptions anyway, check and abort if this fails.

     if (thread == NULL || thread->osthread() == NULL) {

       vm_exit_during_initialization("java.lang.OutOfMemoryError",

                                     "unable to create new native thread");

     }

     java_lang_Thread::set_thread(thread_oop(), thread);

     java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);

     java_lang_Thread::set_daemon(thread_oop());

     thread->set_threadObj(thread_oop());

     _instance = thread;

     Threads::add(thread);

     Thread::start(thread);

   }

 }

 void ServiceThread::service_thread_entry(JavaThread* jt, TRAPS) {

   while (true) {

     bool sensors_changed = false;

     bool has_jvmti_events = false;

     JvmtiDeferredEvent jvmti_event;

     {

       // Need state transition ThreadBlockInVM so that this thread

       // will be handled by safepoint correctly when this thread is

       // notified at a safepoint.

       // This ThreadBlockInVM object is not also considered to be

       // suspend-equivalent because ServiceThread is not visible to

       // external suspension.

       ThreadBlockInVM tbivm(jt);

       MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);

       while (!(sensors_changed = LowMemoryDetector::has_pending_requests()) &&

              !(has_jvmti_events = JvmtiDeferredEventQueue::has_events())) {

         // wait until one of the sensors has pending requests, or there is a

         // pending JVMTI event to post

         Service_lock->wait(Mutex::_no_safepoint_check_flag);

       }

       if (has_jvmti_events) {

         jvmti_event = JvmtiDeferredEventQueue::dequeue();

       }

     }

     if (has_jvmti_events) {

       jvmti_event.post();

     }

     if (sensors_changed) {

       LowMemoryDetector::process_sensor_changes(jt);

     }

   }

 }

 bool ServiceThread::is_service_thread(Thread* thread) {

   return thread == _instance;

 }