/*
 * Copyright (c) 2013, 2015, Red Hat, Inc. and/or its affiliates.
 *
 * 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 "gc/shared/gcTraceTime.inline.hpp"
#include "gc/shenandoah/shenandoahConcurrentMark.inline.hpp"
#include "gc/shenandoah/shenandoahConcurrentThread.hpp"
#include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
#include "gc/shenandoah/shenandoahHeap.inline.hpp"
#include "gc/shenandoah/shenandoahMonitoringSupport.hpp"
#include "gc/shenandoah/vm_operations_shenandoah.hpp"
#include "memory/iterator.hpp"
#include "memory/universe.hpp"
#include "runtime/vmThread.hpp"

ShenandoahConcurrentThread::ShenandoahConcurrentThread() :
  ConcurrentGCThread(),
  _full_gc_lock(Mutex::leaf, "ShenandoahFullGC_lock", true, Monitor::_safepoint_check_always),
  _do_full_gc(false),
  _graceful_shutdown(0)
{
  create_and_start();
}

ShenandoahConcurrentThread::~ShenandoahConcurrentThread() {
  // This is here so that super is called.
}

void ShenandoahConcurrentThread::run_service() {
  ShenandoahHeap* heap = ShenandoahHeap::heap();

  while (!should_terminate()) {
    if (in_graceful_shutdown()) {
      break;
    } else if (is_full_gc()) {
      service_fullgc_cycle();
    } else if (heap->shenandoahPolicy()->should_start_partial_gc()) {
      service_partial_cycle();
    } else if (heap->shenandoahPolicy()->should_start_concurrent_mark(heap->used(), heap->capacity())) {
      service_normal_cycle();
      if (heap->is_evacuation_in_progress()) {
        heap->set_evacuation_in_progress_concurrently(false);
      }
    } else {
      Thread::current()->_ParkEvent->park(10);
    }
    heap->monitoring_support()->update_counters();

    // Make sure the _do_full_gc flag changes are seen.
    OrderAccess::storeload();
  }

  // Wait for the actual stop(), can't leave run_service() earlier.
  while (!should_terminate()) {
    Thread::current()->_ParkEvent->park(10);
  }
}

void ShenandoahConcurrentThread::service_partial_cycle() {
  GCIdMark gc_id_mark;
  VM_ShenandoahPartialGC partial_gc;
  VMThread::execute(&partial_gc);
}

void ShenandoahConcurrentThread::service_normal_cycle() {
  if (check_cancellation()) return;

  ShenandoahHeap* heap = ShenandoahHeap::heap();

  GCTimer* gc_timer = heap->gc_timer();

  gc_timer->register_gc_start();

  heap->shenandoahPolicy()->increase_cycle_counter();

  GCIdMark gc_id_mark;
  TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
  TraceMemoryManagerStats tmms(false, GCCause::_no_cause_specified);

  // Start initial mark under STW:
  {
    // Workers are setup by VM_ShenandoahInitMark
    TraceCollectorStats tcs(heap->monitoring_support()->stw_collection_counters());
    VM_ShenandoahInitMark initMark;
    heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::total_pause_gross);
    heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::init_mark_gross);
    VMThread::execute(&initMark);
    heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::init_mark_gross);
    heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::total_pause_gross);
  }

  if (check_cancellation()) return;

  // Continue concurrent mark:
  {
    // Setup workers for concurrent marking phase
    WorkGang* workers = heap->workers();
    uint n_workers = ShenandoahCollectorPolicy::calc_workers_for_conc_marking(workers->active_workers(),
      Threads::number_of_non_daemon_threads());
    ShenandoahWorkerScope scope(workers, n_workers);

    GCTraceTime(Info, gc) time("Concurrent marking", gc_timer, GCCause::_no_gc, true);
    TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
    ShenandoahHeap::heap()->concurrentMark()->mark_from_roots();
  }

  // Possibly hand over remaining marking work to final-mark phase.
  bool clear_full_gc = false;
  if (heap->cancelled_concgc()) {
    heap->shenandoahPolicy()->record_cm_cancelled();
    if (_full_gc_cause == GCCause::_allocation_failure &&
        heap->shenandoahPolicy()->handover_cancelled_marking()) {
      heap->set_cancelled_concgc(false);
      clear_full_gc = true;
      heap->shenandoahPolicy()->record_cm_degenerated();
    } else {
      heap->gc_timer()->register_gc_end();
      return;
    }
  } else {
    heap->shenandoahPolicy()->record_cm_success();
  }

  // Proceed to complete marking under STW, and start evacuation:
  {
    // Workers are setup by VM_ShenandoahStartEvacuation
    TraceCollectorStats tcs(heap->monitoring_support()->stw_collection_counters());
    VM_ShenandoahStartEvacuation finishMark;
    heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::total_pause_gross);
    heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::final_mark_gross);
    VMThread::execute(&finishMark);
    heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::final_mark_gross);
    heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::total_pause_gross);
  }

  if (check_cancellation()) return;

  // If we handed off remaining marking work above, we need to kick off waiting Java threads
  if (clear_full_gc) {
    reset_full_gc();
  }

  // Continue concurrent evacuation:
  {
    // Setup workers for concurrent evacuation phase
    WorkGang* workers = heap->workers();
    uint n_workers = ShenandoahCollectorPolicy::calc_workers_for_conc_evacuation(workers->active_workers(),
      Threads::number_of_non_daemon_threads());
    ShenandoahWorkerScope scope(workers, n_workers);

    GCTraceTime(Info, gc) time("Concurrent evacuation ", gc_timer, GCCause::_no_gc, true);
    TraceCollectorStats tcs(heap->monitoring_support()->concurrent_collection_counters());
    heap->do_evacuation();
  }

  // Prepare for the next normal cycle:
  if (check_cancellation()) return;

  {
    GCTraceTime(Info, gc) time("Concurrent reset bitmaps", gc_timer, GCCause::_no_gc);
    heap->shenandoahPolicy()->record_phase_start(ShenandoahCollectorPolicy::reset_bitmaps);
    WorkGang* workers = heap->workers();
    ShenandoahPushWorkerScope scope(workers, heap->max_workers());
    heap->reset_next_mark_bitmap(workers);
    heap->shenandoahPolicy()->record_phase_end(ShenandoahCollectorPolicy::reset_bitmaps);
  }

  gc_timer->register_gc_end();
}

bool ShenandoahConcurrentThread::check_cancellation() {
  ShenandoahHeap* heap = ShenandoahHeap::heap();
  if (heap->cancelled_concgc()) {
    assert (is_full_gc() || in_graceful_shutdown(), "Cancel GC either for Full GC, or gracefully exiting");
    heap->gc_timer()->register_gc_end();
    return true;
  }
  return false;
}


void ShenandoahConcurrentThread::stop_service() {
  // Nothing to do here.
}

void ShenandoahConcurrentThread::service_fullgc_cycle() {
  GCIdMark gc_id_mark;
  ShenandoahHeap* heap = ShenandoahHeap::heap();

  {
    if (_full_gc_cause == GCCause::_allocation_failure) {
      heap->shenandoahPolicy()->record_allocation_failure_gc();
    } else {
      heap->shenandoahPolicy()->record_user_requested_gc();
    }

    TraceCollectorStats tcs(heap->monitoring_support()->full_collection_counters());
    TraceMemoryManagerStats tmms(true, _full_gc_cause);
    VM_ShenandoahFullGC full_gc(_full_gc_cause);
    VMThread::execute(&full_gc);
  }

  reset_full_gc();
}

void ShenandoahConcurrentThread::do_full_gc(GCCause::Cause cause) {
  assert(Thread::current()->is_Java_thread(), "expect Java thread here");

  if (try_set_full_gc()) {
    _full_gc_cause = cause;

    // Now that full GC is scheduled, we can abort everything else
    ShenandoahHeap::heap()->cancel_concgc(cause);
  } else {
    if (_full_gc_cause != cause) {
      log_info(gc)("Full GC is already pending with cause: %s; new cause is %s",
                   GCCause::to_string(_full_gc_cause),
                   GCCause::to_string(cause));
    }
  }

  MonitorLockerEx ml(&_full_gc_lock);
  while (is_full_gc()) {
    ml.wait();
  }
  assert(!is_full_gc(), "expect full GC to have completed");
}

void ShenandoahConcurrentThread::reset_full_gc() {
  OrderAccess::release_store_fence(&_do_full_gc, 0);
  MonitorLockerEx ml(&_full_gc_lock);
  ml.notify_all();
}

bool ShenandoahConcurrentThread::try_set_full_gc() {
  jbyte old = Atomic::cmpxchg(1, &_do_full_gc, 0);
  return old == 0; // success
}

bool ShenandoahConcurrentThread::is_full_gc() {
  return OrderAccess::load_acquire(&_do_full_gc) == 1;
}

void ShenandoahConcurrentThread::print() const {
  print_on(tty);
}

void ShenandoahConcurrentThread::print_on(outputStream* st) const {
  st->print("Shenandoah Concurrent Thread");
  Thread::print_on(st);
  st->cr();
}

void ShenandoahConcurrentThread::sleepBeforeNextCycle() {
  assert(false, "Wake up in the GC thread that never sleeps :-)");
}

void ShenandoahConcurrentThread::start() {
  create_and_start();
}

void ShenandoahConcurrentThread::prepare_for_graceful_shutdown() {
  OrderAccess::release_store_fence(&_graceful_shutdown, 1);
}

bool ShenandoahConcurrentThread::in_graceful_shutdown() {
  return OrderAccess::load_acquire(&_graceful_shutdown) == 1;
}