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 /*

  * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  *

  */

 #include "precompiled.hpp"

 #include "classfile/symbolTable.hpp"

 #include "classfile/systemDictionary.hpp"

 #include "code/codeCache.hpp"

 #include "gc_implementation/g1/bufferingOopClosure.hpp"

 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"

 #include "gc_implementation/g1/g1CollectorPolicy.hpp"

 #include "gc_implementation/g1/g1GCPhaseTimes.hpp"

 #include "gc_implementation/g1/g1RemSet.inline.hpp"

 #include "gc_implementation/g1/g1RootProcessor.hpp"

 #include "memory/allocation.inline.hpp"

 #include "runtime/fprofiler.hpp"

 #include "runtime/mutex.hpp"

 #include "services/management.hpp"

 class G1CodeBlobClosure : public CodeBlobClosure {

   class HeapRegionGatheringOopClosure : public OopClosure {

     G1CollectedHeap* _g1h;

     OopClosure* _work;

     nmethod* _nm;

     template <typename T>

     void do_oop_work(T* p) {

       _work->do_oop(p);

       T oop_or_narrowoop = oopDesc::load_heap_oop(p);

       if (!oopDesc::is_null(oop_or_narrowoop)) {

         oop o = oopDesc::decode_heap_oop_not_null(oop_or_narrowoop);

         HeapRegion* hr = _g1h->heap_region_containing_raw(o);

         assert(!_g1h->obj_in_cs(o) || hr->rem_set()->strong_code_roots_list_contains(_nm), "if o still in CS then evacuation failed and nm must already be in the remset");

         hr->add_strong_code_root(_nm);

       }

     }

   public:

     HeapRegionGatheringOopClosure(OopClosure* oc) : _g1h(G1CollectedHeap::heap()), _work(oc), _nm(NULL) {}

     void do_oop(oop* o) {

       do_oop_work(o);

     }

     void do_oop(narrowOop* o) {

       do_oop_work(o);

     }

     void set_nm(nmethod* nm) {

       _nm = nm;

     }

   };

   HeapRegionGatheringOopClosure _oc;

 public:

   G1CodeBlobClosure(OopClosure* oc) : _oc(oc) {}

   void do_code_blob(CodeBlob* cb) {

     nmethod* nm = cb->as_nmethod_or_null();

     if (nm != NULL) {

       if (!nm->test_set_oops_do_mark()) {

         _oc.set_nm(nm);

         nm->oops_do(&_oc);

         nm->fix_oop_relocations();

       }

     }

   }

 };

 void G1RootProcessor::worker_has_discovered_all_strong_classes() {

   uint n_workers = _g1h->n_par_threads();

   assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading");

   uint new_value = (uint)Atomic::add(1, &_n_workers_discovered_strong_classes);

   if (new_value == n_workers) {

     // This thread is last. Notify the others.

     MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag);

     _lock.notify_all();

   }

 }

 void G1RootProcessor::wait_until_all_strong_classes_discovered() {

   uint n_workers = _g1h->n_par_threads();

   assert(ClassUnloadingWithConcurrentMark, "Currently only needed when doing G1 Class Unloading");

   if ((uint)_n_workers_discovered_strong_classes != n_workers) {

     MonitorLockerEx ml(&_lock, Mutex::_no_safepoint_check_flag);

     while ((uint)_n_workers_discovered_strong_classes != n_workers) {

       _lock.wait(Mutex::_no_safepoint_check_flag, 0, false);

     }

   }

 }

 G1RootProcessor::G1RootProcessor(G1CollectedHeap* g1h) :

     _g1h(g1h),

     _process_strong_tasks(new SubTasksDone(G1RP_PS_NumElements)),

     _srs(g1h),

     _lock(Mutex::leaf, "G1 Root Scanning barrier lock", false),

     _n_workers_discovered_strong_classes(0) {}

 void G1RootProcessor::evacuate_roots(OopClosure* scan_non_heap_roots,

                                      OopClosure* scan_non_heap_weak_roots,

                                      CLDClosure* scan_strong_clds,

                                      CLDClosure* scan_weak_clds,

                                      bool trace_metadata,

                                      uint worker_i) {

   // First scan the shared roots.

   double ext_roots_start = os::elapsedTime();

   BufferingOopClosure buf_scan_non_heap_roots(scan_non_heap_roots);

   BufferingOopClosure buf_scan_non_heap_weak_roots(scan_non_heap_weak_roots);

   OopClosure* const weak_roots = &buf_scan_non_heap_weak_roots;

   OopClosure* const strong_roots = &buf_scan_non_heap_roots;

   // CodeBlobClosures are not interoperable with BufferingOopClosures

   G1CodeBlobClosure root_code_blobs(scan_non_heap_roots);

   process_java_roots(strong_roots,

                      trace_metadata ? scan_strong_clds : NULL,

                      scan_strong_clds,

                      trace_metadata ? NULL : scan_weak_clds,

                      &root_code_blobs);

   // This is the point where this worker thread will not find more strong CLDs/nmethods.

   // Report this so G1 can synchronize the strong and weak CLDs/nmethods processing.

   if (trace_metadata) {

     worker_has_discovered_all_strong_classes();

   }

   process_vm_roots(strong_roots, weak_roots);

   // Now the CM ref_processor roots.

   if (!_process_strong_tasks->is_task_claimed(G1RP_PS_refProcessor_oops_do)) {

     // We need to treat the discovered reference lists of the

     // concurrent mark ref processor as roots and keep entries

     // (which are added by the marking threads) on them live

     // until they can be processed at the end of marking.

     _g1h->ref_processor_cm()->weak_oops_do(&buf_scan_non_heap_roots);

   }

   if (trace_metadata) {

     // Barrier to make sure all workers passed

     // the strong CLD and strong nmethods phases.

     wait_until_all_strong_classes_discovered();

     // Now take the complement of the strong CLDs.

     ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);

   }

   // Finish up any enqueued closure apps (attributed as object copy time).

   buf_scan_non_heap_roots.done();

   buf_scan_non_heap_weak_roots.done();

   double obj_copy_time_sec = buf_scan_non_heap_roots.closure_app_seconds()

       + buf_scan_non_heap_weak_roots.closure_app_seconds();

   G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();

   phase_times->record_time_secs(G1GCPhaseTimes::ObjCopy, worker_i, obj_copy_time_sec);

   double ext_root_time_sec = os::elapsedTime() - ext_roots_start - obj_copy_time_sec;

   phase_times->record_time_secs(G1GCPhaseTimes::ExtRootScan, worker_i, ext_root_time_sec);

   // During conc marking we have to filter the per-thread SATB buffers

   // to make sure we remove any oops into the CSet (which will show up

   // as implicitly live).

   {

     G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::SATBFiltering, worker_i);

     if (!_process_strong_tasks->is_task_claimed(G1RP_PS_filter_satb_buffers) && _g1h->mark_in_progress()) {

       JavaThread::satb_mark_queue_set().filter_thread_buffers();

     }

   }

   _process_strong_tasks->all_tasks_completed();

 }

 void G1RootProcessor::process_strong_roots(OopClosure* oops,

                                            CLDClosure* clds,

                                            CodeBlobClosure* blobs) {

   process_java_roots(oops, clds, clds, NULL, blobs);

   process_vm_roots(oops, NULL);

   _process_strong_tasks->all_tasks_completed();

 }

 void G1RootProcessor::process_all_roots(OopClosure* oops,

                                         CLDClosure* clds,

                                         CodeBlobClosure* blobs) {

   process_java_roots(oops, NULL, clds, clds, NULL);

   process_vm_roots(oops, oops);

   if (!_process_strong_tasks->is_task_claimed(G1RP_PS_CodeCache_oops_do)) {

     CodeCache::blobs_do(blobs);

   }

   _process_strong_tasks->all_tasks_completed();

 }

 void G1RootProcessor::process_java_roots(OopClosure* strong_roots,

                                          CLDClosure* thread_stack_clds,

                                          CLDClosure* strong_clds,

                                          CLDClosure* weak_clds,

                                          CodeBlobClosure* strong_code) {

   assert(thread_stack_clds == NULL || weak_clds == NULL, "There is overlap between those, only one may be set");

   // Iterating over the CLDG and the Threads are done early to allow us to

   // first process the strong CLDs and nmethods and then, after a barrier,

   // let the thread process the weak CLDs and nmethods.

   if (!_process_strong_tasks->is_task_claimed(G1RP_PS_ClassLoaderDataGraph_oops_do)) {

     ClassLoaderDataGraph::roots_cld_do(strong_clds, weak_clds);

   }

   Threads::possibly_parallel_oops_do(strong_roots, thread_stack_clds, strong_code);

 }

 void G1RootProcessor::process_vm_roots(OopClosure* strong_roots,

                                        OopClosure* weak_roots) {

   if (!_process_strong_tasks->is_task_claimed(G1RP_PS_Universe_oops_do)) {

     Universe::oops_do(strong_roots);

   }

   if (!_process_strong_tasks->is_task_claimed(G1RP_PS_JNIHandles_oops_do)) {

     JNIHandles::oops_do(strong_roots);

   }

   if (!_process_strong_tasks-> is_task_claimed(G1RP_PS_ObjectSynchronizer_oops_do)) {

     ObjectSynchronizer::oops_do(strong_roots);

   }

   if (!_process_strong_tasks->is_task_claimed(G1RP_PS_FlatProfiler_oops_do)) {

     FlatProfiler::oops_do(strong_roots);

   }

   if (!_process_strong_tasks->is_task_claimed(G1RP_PS_Management_oops_do)) {

     Management::oops_do(strong_roots);

   }

   if (!_process_strong_tasks->is_task_claimed(G1RP_PS_jvmti_oops_do)) {

     JvmtiExport::oops_do(strong_roots);

   }

   if (!_process_strong_tasks->is_task_claimed(G1RP_PS_SystemDictionary_oops_do)) {

     SystemDictionary::roots_oops_do(strong_roots, weak_roots);

   }

   // All threads execute the following. A specific chunk of buckets

   // from the StringTable are the individual tasks.

   if (weak_roots != NULL) {

     StringTable::possibly_parallel_oops_do(weak_roots);

   }

 }

 void G1RootProcessor::scan_remembered_sets(G1ParPushHeapRSClosure* scan_rs,

                                            OopClosure* scan_non_heap_weak_roots,

                                            uint worker_i) {

   // Now scan the complement of the collection set.

   G1CodeBlobClosure scavenge_cs_nmethods(scan_non_heap_weak_roots);

   _g1h->g1_rem_set()->oops_into_collection_set_do(scan_rs, &scavenge_cs_nmethods, worker_i);

 }

 void G1RootProcessor::set_num_workers(int active_workers) {

   _process_strong_tasks->set_n_threads(active_workers);

 }