1/*
2 * Copyright (c) 2012, 2015, 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
38ServiceThread* ServiceThread::_instance = NULL;
39
40void ServiceThread::initialize() {
41  EXCEPTION_MARK;
42
43  instanceKlassHandle klass (THREAD,  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
85void 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
142bool ServiceThread::is_service_thread(Thread* thread) {
143  return thread == _instance;
144}
145