1 /*
   2  * Copyright (c) 2000, 2012, 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/symbolTable.hpp"
  27 #include "classfile/systemDictionary.hpp"
  28 #include "code/codeCache.hpp"
  29 #include "gc_interface/collectedHeap.inline.hpp"
  30 #include "memory/sharedHeap.hpp"
  31 #include "oops/oop.inline.hpp"
  32 #include "runtime/fprofiler.hpp"
  33 #include "runtime/java.hpp"
  34 #include "services/management.hpp"
  35 #include "utilities/copy.hpp"
  36 #include "utilities/workgroup.hpp"
  37 
  38 SharedHeap* SharedHeap::_sh;
  39 
  40 // The set of potentially parallel tasks in strong root scanning.
  41 enum SH_process_strong_roots_tasks {
  42   SH_PS_Universe_oops_do,
  43   SH_PS_JNIHandles_oops_do,
  44   SH_PS_ObjectSynchronizer_oops_do,
  45   SH_PS_FlatProfiler_oops_do,
  46   SH_PS_Management_oops_do,
  47   SH_PS_SystemDictionary_oops_do,

  48   SH_PS_jvmti_oops_do,
  49   SH_PS_StringTable_oops_do,
  50   SH_PS_CodeCache_oops_do,
  51   // Leave this one last.
  52   SH_PS_NumElements
  53 };
  54 
  55 SharedHeap::SharedHeap(CollectorPolicy* policy_) :
  56   CollectedHeap(),
  57   _collector_policy(policy_),
  58   _rem_set(NULL),
  59   _strong_roots_parity(0),
  60   _process_strong_tasks(new SubTasksDone(SH_PS_NumElements)),
  61   _workers(NULL)
  62 {
  63   if (_process_strong_tasks == NULL || !_process_strong_tasks->valid()) {
  64     vm_exit_during_initialization("Failed necessary allocation.");
  65   }
  66   _sh = this;  // ch is static, should be set only once.
  67   if ((UseParNewGC ||
  68       (UseConcMarkSweepGC && CMSParallelRemarkEnabled) ||
  69        UseG1GC) &&
  70       ParallelGCThreads > 0) {
  71     _workers = new FlexibleWorkGang("Parallel GC Threads", ParallelGCThreads,
  72                             /* are_GC_task_threads */true,
  73                             /* are_ConcurrentGC_threads */false);
  74     if (_workers == NULL) {
  75       vm_exit_during_initialization("Failed necessary allocation.");
  76     } else {
  77       _workers->initialize_workers();
  78     }
  79   }
  80 }
  81 
  82 int SharedHeap::n_termination() {
  83   return _process_strong_tasks->n_threads();
  84 }
  85 
  86 void SharedHeap::set_n_termination(int t) {
  87   _process_strong_tasks->set_n_threads(t);
  88 }
  89 
  90 bool SharedHeap::heap_lock_held_for_gc() {
  91   Thread* t = Thread::current();
  92   return    Heap_lock->owned_by_self()
  93          || (   (t->is_GC_task_thread() ||  t->is_VM_thread())
  94              && _thread_holds_heap_lock_for_gc);
  95 }
  96 
  97 void SharedHeap::set_par_threads(uint t) {
  98   assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");
  99   _n_par_threads = t;
 100   _process_strong_tasks->set_n_threads(t);
 101 }
 102 
 103 #ifdef ASSERT
 104 class AssertNonScavengableClosure: public OopClosure {
 105 public:
 106   virtual void do_oop(oop* p) {
 107     assert(!Universe::heap()->is_in_partial_collection(*p),
 108       "Referent should not be scavengable.");  }
 109   virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
 110 };
 111 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
 112 #endif
 113 
 114 void SharedHeap::change_strong_roots_parity() {
 115   // Also set the new collection parity.
 116   assert(_strong_roots_parity >= 0 && _strong_roots_parity <= 2,
 117          "Not in range.");
 118   _strong_roots_parity++;
 119   if (_strong_roots_parity == 3) _strong_roots_parity = 1;
 120   assert(_strong_roots_parity >= 1 && _strong_roots_parity <= 2,
 121          "Not in range.");
 122 }
 123 
 124 SharedHeap::StrongRootsScope::StrongRootsScope(SharedHeap* outer, bool activate)
 125   : MarkScope(activate)
 126 {
 127   if (_active) {
 128     outer->change_strong_roots_parity();
 129   }
 130 }
 131 
 132 SharedHeap::StrongRootsScope::~StrongRootsScope() {
 133   // nothing particular
 134 }
 135 
 136 void SharedHeap::process_strong_roots(bool activate_scope,
 137                                       bool is_scavenging,
 138                                       ScanningOption so,
 139                                       OopClosure* roots,
 140                                       CodeBlobClosure* code_roots,
 141                                       KlassClosure* klass_closure) {
 142   StrongRootsScope srs(this, activate_scope);
 143 
 144   // General strong roots.
 145   assert(_strong_roots_parity != 0, "must have called prologue code");
 146   // _n_termination for _process_strong_tasks should be set up stream
 147   // in a method not running in a GC worker.  Otherwise the GC worker
 148   // could be trying to change the termination condition while the task
 149   // is executing in another GC worker.
 150   if (!_process_strong_tasks->is_task_claimed(SH_PS_Universe_oops_do)) {
 151     Universe::oops_do(roots);
 152   }
 153   // Global (strong) JNI handles
 154   if (!_process_strong_tasks->is_task_claimed(SH_PS_JNIHandles_oops_do))
 155     JNIHandles::oops_do(roots);
 156   // All threads execute this; the individual threads are task groups.
 157   CLDToOopClosure roots_from_clds(roots);
 158   CLDToOopClosure* roots_from_clds_p = (is_scavenging ? NULL : &roots_from_clds);
 159   if (ParallelGCThreads > 0) {
 160     Threads::possibly_parallel_oops_do(roots, roots_from_clds_p ,code_roots);
 161   } else {
 162     Threads::oops_do(roots, roots_from_clds_p, code_roots);
 163   }
 164   if (!_process_strong_tasks-> is_task_claimed(SH_PS_ObjectSynchronizer_oops_do))
 165     ObjectSynchronizer::oops_do(roots);
 166   if (!_process_strong_tasks->is_task_claimed(SH_PS_FlatProfiler_oops_do))
 167     FlatProfiler::oops_do(roots);
 168   if (!_process_strong_tasks->is_task_claimed(SH_PS_Management_oops_do))
 169     Management::oops_do(roots);
 170   if (!_process_strong_tasks->is_task_claimed(SH_PS_jvmti_oops_do))
 171     JvmtiExport::oops_do(roots);
 172 
 173   if (!_process_strong_tasks->is_task_claimed(SH_PS_SystemDictionary_oops_do)) {
 174     if (so & SO_AllClasses) {
 175       SystemDictionary::oops_do(roots);
 176       ClassLoaderDataGraph::oops_do(roots, klass_closure, !is_scavenging);
 177     } else if (so & SO_SystemClasses) {
 178       SystemDictionary::always_strong_oops_do(roots);
 179       ClassLoaderDataGraph::always_strong_oops_do(roots, klass_closure, !is_scavenging);
 180     } else {
 181       fatal("We should always have selected either SO_AllClasses or SO_SystemClasses");








 182     }
 183   }
 184 
 185   if (!_process_strong_tasks->is_task_claimed(SH_PS_StringTable_oops_do)) {
 186     if (so & SO_Strings) {
 187       StringTable::oops_do(roots);
 188     }
 189   }
 190 
 191   if (!_process_strong_tasks->is_task_claimed(SH_PS_CodeCache_oops_do)) {
 192     if (so & SO_CodeCache) {
 193       assert(code_roots != NULL, "must supply closure for code cache");
 194 
 195       if (is_scavenging) {
 196         // We only visit parts of the CodeCache when scavenging.
 197         CodeCache::scavenge_root_nmethods_do(code_roots);
 198       } else {
 199         // CMSCollector uses this to do intermediate-strength collections.
 200         // We scan the entire code cache, since CodeCache::do_unloading is not called.
 201         CodeCache::blobs_do(code_roots);
 202       }
 203     }
 204     // Verify that the code cache contents are not subject to
 205     // movement by a scavenging collection.
 206     DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, /*do_marking=*/ false));
 207     DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
 208   }
 209 
 210   _process_strong_tasks->all_tasks_completed();
 211 }
 212 
 213 class AlwaysTrueClosure: public BoolObjectClosure {
 214 public:
 215   bool do_object_b(oop p) { return true; }
 216 };
 217 static AlwaysTrueClosure always_true;
 218 
 219 void SharedHeap::process_weak_roots(OopClosure* root_closure,
 220                                     CodeBlobClosure* code_roots) {
 221   // Global (weak) JNI handles
 222   JNIHandles::weak_oops_do(&always_true, root_closure);
 223 
 224   CodeCache::blobs_do(code_roots);
 225   StringTable::oops_do(root_closure);
 226 }
 227 
 228 void SharedHeap::set_barrier_set(BarrierSet* bs) {
 229   _barrier_set = bs;
 230   // Cached barrier set for fast access in oops
 231   oopDesc::set_bs(bs);
 232 }
 233 
 234 void SharedHeap::post_initialize() {
 235   ref_processing_init();
 236 }
 237 
 238 void SharedHeap::ref_processing_init() {}
 239 
 240 // Some utilities.
 241 void SharedHeap::print_size_transition(outputStream* out,
 242                                        size_t bytes_before,
 243                                        size_t bytes_after,
 244                                        size_t capacity) {
 245   out->print(" %d%s->%d%s(%d%s)",
 246              byte_size_in_proper_unit(bytes_before),
 247              proper_unit_for_byte_size(bytes_before),
 248              byte_size_in_proper_unit(bytes_after),
 249              proper_unit_for_byte_size(bytes_after),
 250              byte_size_in_proper_unit(capacity),
 251              proper_unit_for_byte_size(capacity));
 252 }
--- EOF ---