1 /*
   2  * Copyright (c) 2012, 2017, 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 "runtime/interfaceSupport.hpp"
  27 #include "runtime/javaCalls.hpp"
  28 #include "runtime/serviceThread.hpp"
  29 #include "runtime/mutexLocker.hpp"
  30 #include "runtime/os.hpp"
  31 #include "prims/jvmtiImpl.hpp"
  32 #include "services/allocationContextService.hpp"
  33 #include "services/diagnosticArgument.hpp"
  34 #include "services/diagnosticFramework.hpp"
  35 #include "services/gcNotifier.hpp"
  36 #include "services/lowMemoryDetector.hpp"
  37 
  38 ServiceThread* ServiceThread::_instance = NULL;
  39 
  40 void ServiceThread::initialize() {
  41   EXCEPTION_MARK;
  42 
  43   InstanceKlass* klass = SystemDictionary::Thread_klass();
  44   instanceHandle thread_oop = klass->allocate_instance_handle(CHECK);
  45 
  46   const char* name = "Service Thread";
  47 
  48   Handle string = java_lang_String::create_from_str(name, CHECK);
  49 
  50   // Initialize thread_oop to put it into the system threadGroup
  51   Handle thread_group (THREAD, Universe::system_thread_group());
  52   JavaValue result(T_VOID);
  53   JavaCalls::call_special(&result, thread_oop,
  54                           klass,
  55                           vmSymbols::object_initializer_name(),
  56                           vmSymbols::threadgroup_string_void_signature(),
  57                           thread_group,
  58                           string,
  59                           CHECK);
  60 
  61   {
  62     MutexLocker mu(Threads_lock);
  63     ServiceThread* thread =  new ServiceThread(&service_thread_entry);
  64 
  65     // At this point it may be possible that no osthread was created for the
  66     // JavaThread due to lack of memory. We would have to throw an exception
  67     // in that case. However, since this must work and we do not allow
  68     // exceptions anyway, check and abort if this fails.
  69     if (thread == NULL || thread->osthread() == NULL) {
  70       vm_exit_during_initialization("java.lang.OutOfMemoryError",
  71                                     os::native_thread_creation_failed_msg());
  72     }
  73 
  74     java_lang_Thread::set_thread(thread_oop(), thread);
  75     java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
  76     java_lang_Thread::set_daemon(thread_oop());
  77     thread->set_threadObj(thread_oop());
  78     _instance = thread;
  79 
  80     Threads::add(thread);
  81     Thread::start(thread);
  82   }
  83 }
  84 
  85 void ServiceThread::service_thread_entry(JavaThread* jt, TRAPS) {
  86   while (true) {
  87     bool sensors_changed = false;
  88     bool has_jvmti_events = false;
  89     bool has_gc_notification_event = false;
  90     bool has_dcmd_notification_event = false;
  91     bool acs_notify = false;
  92     JvmtiDeferredEvent jvmti_event;
  93     {
  94       // Need state transition ThreadBlockInVM so that this thread
  95       // will be handled by safepoint correctly when this thread is
  96       // notified at a safepoint.
  97 
  98       // This ThreadBlockInVM object is not also considered to be
  99       // suspend-equivalent because ServiceThread is not visible to
 100       // external suspension.
 101 
 102       ThreadBlockInVM tbivm(jt);
 103 
 104       MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
 105       while (!(sensors_changed = LowMemoryDetector::has_pending_requests()) &&
 106              !(has_jvmti_events = JvmtiDeferredEventQueue::has_events()) &&
 107               !(has_gc_notification_event = GCNotifier::has_event()) &&
 108               !(has_dcmd_notification_event = DCmdFactory::has_pending_jmx_notification()) &&
 109              !(acs_notify = AllocationContextService::should_notify())) {
 110         // wait until one of the sensors has pending requests, or there is a
 111         // pending JVMTI event or JMX GC notification to post
 112         Service_lock->wait(Mutex::_no_safepoint_check_flag);
 113       }
 114 
 115       if (has_jvmti_events) {
 116         jvmti_event = JvmtiDeferredEventQueue::dequeue();
 117       }
 118     }
 119 
 120     if (has_jvmti_events) {
 121       jvmti_event.post();
 122     }
 123 
 124     if (sensors_changed) {
 125       LowMemoryDetector::process_sensor_changes(jt);
 126     }
 127 
 128     if(has_gc_notification_event) {
 129         GCNotifier::sendNotification(CHECK);
 130     }
 131 
 132     if(has_dcmd_notification_event) {
 133       DCmdFactory::send_notification(CHECK);
 134     }
 135 
 136     if (acs_notify) {
 137       AllocationContextService::notify(CHECK);
 138     }
 139   }
 140 }
 141 
 142 bool ServiceThread::is_service_thread(Thread* thread) {
 143   return thread == _instance;
 144 }