/*

 * 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/stringTable.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");

  if (n_workers > 0) {

    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 (n_workers > 0 && (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(),

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

    _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();

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

  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,

                     phase_times,

                     worker_i);

  // 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, phase_times, worker_i);

  {

    // Now the CM ref_processor roots.

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

    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) {

    {

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

      // 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.

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

    ClassLoaderDataGraph::roots_cld_do(NULL, scan_weak_clds);

  } else {

    phase_times->record_time_secs(G1GCPhaseTimes::WaitForStrongCLD, worker_i, 0.0);

    phase_times->record_time_secs(G1GCPhaseTimes::WeakCLDRoots, worker_i, 0.0);

  }

  // 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();

  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, NULL, 0);

  process_vm_roots(oops, NULL, NULL, 0);

  _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, NULL, 0);

  process_vm_roots(oops, oops, NULL, 0);

  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,

                                         G1GCPhaseTimes* phase_times,

                                         uint worker_i) {

  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.

  {

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

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

      ClassLoaderDataGraph::roots_cld_do(strong_clds, weak_clds);

    }

  }

  {

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

    bool is_par = _g1h->n_par_threads() > 0;

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

  }

}

void G1RootProcessor::process_vm_roots(OopClosure* strong_roots,

                                       OopClosure* weak_roots,

                                       G1GCPhaseTimes* phase_times,

                                       uint worker_i) {

  {

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

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

      Universe::oops_do(strong_roots);

    }

  }

  {

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

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

      JNIHandles::oops_do(strong_roots);

    }

  }

  {

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

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

      ObjectSynchronizer::oops_do(strong_roots);

    }

  }

  {

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

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

      FlatProfiler::oops_do(strong_roots);

    }

  }

  {

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

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

      Management::oops_do(strong_roots);

    }

  }

  {

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

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

      JvmtiExport::oops_do(strong_roots);

    }

  }

  {

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

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

      SystemDictionary::roots_oops_do(strong_roots, weak_roots);

    }

  }

  {

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

    // 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) {

  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);

}