/*

 * Copyright (c) 2017, 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 "gc/cms/concurrentMarkSweepThread.hpp"

#include "gc/cms/cmsHeap.hpp"

#include "gc/cms/vmCMSOperations.hpp"

#include "gc/shared/genOopClosures.inline.hpp"

#include "gc/shared/strongRootsScope.hpp"

#include "gc/shared/workgroup.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/vmThread.hpp"

#include "utilities/stack.inline.hpp"

CMSHeap::CMSHeap(GenCollectorPolicy *policy) : GenCollectedHeap(policy) {

  _workers = new WorkGang("GC Thread", ParallelGCThreads,

                          /* are_GC_task_threads */true,

                          /* are_ConcurrentGC_threads */false);

  _workers->initialize_workers();

}

jint CMSHeap::initialize() {

  jint status = GenCollectedHeap::initialize();

  if (status != JNI_OK) return status;

  // If we are running CMS, create the collector responsible

  // for collecting the CMS generations.

  assert(collector_policy()->is_concurrent_mark_sweep_policy(), "must be CMS policy");

  create_cms_collector();

  return JNI_OK;

}

void CMSHeap::check_gen_kinds() {

  assert(young_gen()->kind() == Generation::ParNew,

         "Wrong youngest generation type");

  assert(old_gen()->kind() == Generation::ConcurrentMarkSweep,

         "Wrong generation kind");

}

CMSHeap* CMSHeap::heap() {

  CollectedHeap* heap = Universe::heap();

  assert(heap != NULL, "Uninitialized access to CMSHeap::heap()");

  assert(heap->kind() == CollectedHeap::CMSHeap, "Not a CMSHeap");

  return (CMSHeap*) heap;

}

void CMSHeap::gc_threads_do(ThreadClosure* tc) const {

  assert(workers() != NULL, "should have workers here");

  workers()->threads_do(tc);

  ConcurrentMarkSweepThread::threads_do(tc);

}

void CMSHeap::print_gc_threads_on(outputStream* st) const {

  assert(workers() != NULL, "should have workers here");

  workers()->print_worker_threads_on(st);

  ConcurrentMarkSweepThread::print_all_on(st);

}

void CMSHeap::print_on_error(outputStream* st) const {

  GenCollectedHeap::print_on_error(st);

  st->cr();

  CMSCollector::print_on_error(st);

}

void CMSHeap::create_cms_collector() {

  assert(old_gen()->kind() == Generation::ConcurrentMarkSweep,

         "Unexpected generation kinds");

  assert(gen_policy()->is_concurrent_mark_sweep_policy(), "Unexpected policy type");

  CMSCollector* collector =

    new CMSCollector((ConcurrentMarkSweepGeneration*) old_gen(),

                     rem_set(),

                     gen_policy()->as_concurrent_mark_sweep_policy());

  if (!collector->completed_initialization()) {

    vm_shutdown_during_initialization("Could not create CMS collector");

  }

}

void CMSHeap::collect(GCCause::Cause cause) {

  if (should_do_concurrent_full_gc(cause)) {

    // Mostly concurrent full collection.

    collect_mostly_concurrent(cause);

  } else {

    GenCollectedHeap::collect(cause);

  }

}

bool CMSHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {

  switch (cause) {

    case GCCause::_gc_locker:           return GCLockerInvokesConcurrent;

    case GCCause::_java_lang_system_gc:

    case GCCause::_dcmd_gc_run:         return ExplicitGCInvokesConcurrent;

    default:                            return false;

  }

}

void CMSHeap::collect_mostly_concurrent(GCCause::Cause cause) {

  assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");

  MutexLocker ml(Heap_lock);

  // Read the GC counts while holding the Heap_lock

  unsigned int full_gc_count_before = total_full_collections();

  unsigned int gc_count_before      = total_collections();

  {

    MutexUnlocker mu(Heap_lock);

    VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);

    VMThread::execute(&op);

  }

}

void CMSHeap::stop() {

  ConcurrentMarkSweepThread::cmst()->stop();

}

void CMSHeap::cms_process_roots(StrongRootsScope* scope,

                                bool young_gen_as_roots,

                                ScanningOption so,

                                bool only_strong_roots,

                                OopsInGenClosure* root_closure,

                                CLDClosure* cld_closure) {

  MarkingCodeBlobClosure mark_code_closure(root_closure, !CodeBlobToOopClosure::FixRelocations);

  OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure;

  CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;

  process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure);

  if (!only_strong_roots) {

    process_string_table_roots(scope, root_closure);

  }

  if (young_gen_as_roots &&

      !_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {

    root_closure->set_generation(young_gen());

    young_gen()->oop_iterate(root_closure);

    root_closure->reset_generation();

  }

  _process_strong_tasks->all_tasks_completed(scope->n_threads());

}

void CMSHeap::gc_prologue(bool full) {

  always_do_update_barrier = false;

  GenCollectedHeap::gc_prologue(full);

};

void CMSHeap::gc_epilogue(bool full) {

  GenCollectedHeap::gc_epilogue(full);

  always_do_update_barrier = true;

};