1 /*
   2  * Copyright (c) 2012, 2018, 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 "classfile/protectionDomainCache.hpp"
  27 #include "classfile/stringTable.hpp"
  28 #include "classfile/symbolTable.hpp"
  29 #include "classfile/systemDictionary.hpp"
  30 #include "runtime/interfaceSupport.inline.hpp"
  31 #include "runtime/javaCalls.hpp"
  32 #include "runtime/serviceThread.hpp"
  33 #include "runtime/mutexLocker.hpp"
  34 #include "runtime/os.hpp"
  35 #include "prims/jvmtiImpl.hpp"
  36 #include "prims/resolvedMethodTable.hpp"
  37 #include "services/diagnosticArgument.hpp"
  38 #include "services/diagnosticFramework.hpp"
  39 #include "services/gcNotifier.hpp"
  40 #include "services/lowMemoryDetector.hpp"
  41 
  42 ServiceThread* ServiceThread::_instance = NULL;
  43 
  44 void ServiceThread::initialize() {
  45   EXCEPTION_MARK;
  46 
  47   const char* name = "Service Thread";
  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   Handle thread_oop = JavaCalls::construct_new_instance(
  53                           SystemDictionary::Thread_klass(),
  54                           vmSymbols::threadgroup_string_void_signature(),
  55                           thread_group,
  56                           string,
  57                           CHECK);
  58 
  59   {
  60     MutexLocker mu(Threads_lock);
  61     ServiceThread* thread =  new ServiceThread(&service_thread_entry);
  62 
  63     // At this point it may be possible that no osthread was created for the
  64     // JavaThread due to lack of memory. We would have to throw an exception
  65     // in that case. However, since this must work and we do not allow
  66     // exceptions anyway, check and abort if this fails.
  67     if (thread == NULL || thread->osthread() == NULL) {
  68       vm_exit_during_initialization("java.lang.OutOfMemoryError",
  69                                     os::native_thread_creation_failed_msg());
  70     }
  71 
  72     java_lang_Thread::set_thread(thread_oop(), thread);
  73     java_lang_Thread::set_priority(thread_oop(), NearMaxPriority);
  74     java_lang_Thread::set_daemon(thread_oop());
  75     thread->set_threadObj(thread_oop());
  76     _instance = thread;
  77 
  78     Threads::add(thread);
  79     Thread::start(thread);
  80   }
  81 }
  82 
  83 void ServiceThread::service_thread_entry(JavaThread* jt, TRAPS) {
  84   while (true) {
  85     bool sensors_changed = false;
  86     bool has_jvmti_events = false;
  87     bool has_gc_notification_event = false;
  88     bool has_dcmd_notification_event = false;
  89     bool acs_notify = false;
  90     bool stringtable_work = false;
  91     bool symboltable_work = false;
  92     bool resolved_method_table_work = false;
  93     bool protection_domain_table_work = false;
  94     JvmtiDeferredEvent jvmti_event;
  95     {
  96       // Need state transition ThreadBlockInVM so that this thread
  97       // will be handled by safepoint correctly when this thread is
  98       // notified at a safepoint.
  99 
 100       // This ThreadBlockInVM object is not also considered to be
 101       // suspend-equivalent because ServiceThread is not visible to
 102       // external suspension.
 103 
 104       ThreadBlockInVM tbivm(jt);
 105 
 106       MutexLockerEx ml(Service_lock, Mutex::_no_safepoint_check_flag);
 107       while (!(sensors_changed = LowMemoryDetector::has_pending_requests()) &&
 108              !(has_jvmti_events = JvmtiDeferredEventQueue::has_events()) &&
 109               !(has_gc_notification_event = GCNotifier::has_event()) &&
 110               !(has_dcmd_notification_event = DCmdFactory::has_pending_jmx_notification()) &&
 111               !(stringtable_work = StringTable::has_work()) &&
 112               !(symboltable_work = SymbolTable::has_work()) &&
 113               !(resolved_method_table_work = ResolvedMethodTable::has_work()) &&
 114               !(protection_domain_table_work = SystemDictionary::pd_cache_table()->has_work())) {
 115         // wait until one of the sensors has pending requests, or there is a
 116         // pending JVMTI event or JMX GC notification to post
 117         Service_lock->wait(Mutex::_no_safepoint_check_flag);
 118       }
 119 
 120       if (has_jvmti_events) {
 121         jvmti_event = JvmtiDeferredEventQueue::dequeue();
 122       }
 123     }
 124 
 125     if (stringtable_work) {
 126       StringTable::do_concurrent_work(jt);
 127     }
 128 
 129     if (symboltable_work) {
 130       SymbolTable::do_concurrent_work(jt);
 131     }
 132 
 133     if (has_jvmti_events) {
 134       jvmti_event.post();
 135     }
 136 
 137     if (sensors_changed) {
 138       LowMemoryDetector::process_sensor_changes(jt);
 139     }
 140 
 141     if(has_gc_notification_event) {
 142       GCNotifier::sendNotification(CHECK);
 143     }
 144 
 145     if(has_dcmd_notification_event) {
 146       DCmdFactory::send_notification(CHECK);
 147     }
 148 
 149     if (resolved_method_table_work) {
 150       ResolvedMethodTable::unlink();
 151     }
 152 
 153     if (protection_domain_table_work) {
 154       SystemDictionary::pd_cache_table()->unlink();
 155     }
 156   }
 157 }
 158 
 159 bool ServiceThread::is_service_thread(Thread* thread) {
 160   return thread == _instance;
 161 }