1 /*
   2  * Copyright (c) 2001, 2009, 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 "incls/_precompiled.incl"
  26 #include "incls/_vm_operations_g1.cpp.incl"
  27 
  28 void VM_G1CollectForAllocation::doit() {
  29   JvmtiGCForAllocationMarker jgcm;
  30   G1CollectedHeap* g1h = G1CollectedHeap::heap();
  31   _res = g1h->satisfy_failed_allocation(_size);
  32   assert(g1h->is_in_or_null(_res), "result not in heap");
  33 }
  34 
  35 void VM_G1CollectFull::doit() {
  36   JvmtiGCFullMarker jgcm;
  37   G1CollectedHeap* g1h = G1CollectedHeap::heap();
  38   GCCauseSetter x(g1h, _gc_cause);
  39   g1h->do_full_collection(false /* clear_all_soft_refs */);
  40 }
  41 
  42 void VM_G1IncCollectionPause::doit() {
  43   JvmtiGCForAllocationMarker jgcm;
  44   G1CollectedHeap* g1h = G1CollectedHeap::heap();
  45   assert(!_should_initiate_conc_mark ||
  46   ((_gc_cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
  47    (_gc_cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent)),
  48          "only a GC locker or a System.gc() induced GC should start a cycle");
  49 
  50   GCCauseSetter x(g1h, _gc_cause);
  51   if (_should_initiate_conc_mark) {
  52     // It's safer to read full_collections_completed() here, given
  53     // that noone else will be updating it concurrently. Since we'll
  54     // only need it if we're initiating a marking cycle, no point in
  55     // setting it earlier.
  56     _full_collections_completed_before = g1h->full_collections_completed();
  57 
  58     // At this point we are supposed to start a concurrent cycle. We
  59     // will do so if one is not already in progress.
  60     bool res = g1h->g1_policy()->force_initial_mark_if_outside_cycle();
  61   }
  62   g1h->do_collection_pause_at_safepoint(_target_pause_time_ms);
  63 }
  64 
  65 void VM_G1IncCollectionPause::doit_epilogue() {
  66   VM_GC_Operation::doit_epilogue();
  67 
  68   // If the pause was initiated by a System.gc() and
  69   // +ExplicitGCInvokesConcurrent, we have to wait here for the cycle
  70   // that just started (or maybe one that was already in progress) to
  71   // finish.
  72   if (_gc_cause == GCCause::_java_lang_system_gc &&
  73       _should_initiate_conc_mark) {
  74     assert(ExplicitGCInvokesConcurrent,
  75            "the only way to be here is if ExplicitGCInvokesConcurrent is set");
  76 
  77     G1CollectedHeap* g1h = G1CollectedHeap::heap();
  78 
  79     // In the doit() method we saved g1h->full_collections_completed()
  80     // in the _full_collections_completed_before field. We have to
  81     // wait until we observe that g1h->full_collections_completed()
  82     // has increased by at least one. This can happen if a) we started
  83     // a cycle and it completes, b) a cycle already in progress
  84     // completes, or c) a Full GC happens.
  85 
  86     // If the condition has already been reached, there's no point in
  87     // actually taking the lock and doing the wait.
  88     if (g1h->full_collections_completed() <=
  89                                           _full_collections_completed_before) {
  90       // The following is largely copied from CMS
  91 
  92       Thread* thr = Thread::current();
  93       assert(thr->is_Java_thread(), "invariant");
  94       JavaThread* jt = (JavaThread*)thr;
  95       ThreadToNativeFromVM native(jt);
  96 
  97       MutexLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
  98       while (g1h->full_collections_completed() <=
  99                                           _full_collections_completed_before) {
 100         FullGCCount_lock->wait(Mutex::_no_safepoint_check_flag);
 101       }
 102     }
 103   }
 104 }
 105 
 106 void VM_CGC_Operation::doit() {
 107   gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
 108   TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
 109   TraceTime t(_printGCMessage, PrintGC, true, gclog_or_tty);
 110   SharedHeap* sh = SharedHeap::heap();
 111   // This could go away if CollectedHeap gave access to _gc_is_active...
 112   if (sh != NULL) {
 113     IsGCActiveMark x;
 114     _cl->do_void();
 115   } else {
 116     _cl->do_void();
 117   }
 118 }
 119 
 120 bool VM_CGC_Operation::doit_prologue() {
 121   Heap_lock->lock();
 122   SharedHeap::heap()->_thread_holds_heap_lock_for_gc = true;
 123   return true;
 124 }
 125 
 126 void VM_CGC_Operation::doit_epilogue() {
 127   SharedHeap::heap()->_thread_holds_heap_lock_for_gc = false;
 128   Heap_lock->unlock();
 129 }