/*

 * Copyright (c) 2015, 2019, 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/shared/gcId.hpp"

#include "gc/shared/gcLocker.hpp"

#include "gc/shared/isGCActiveMark.hpp"

#include "gc/z/zCollectedHeap.hpp"

#include "gc/z/zDriver.hpp"

#include "gc/z/zHeap.inline.hpp"

#include "gc/z/zMessagePort.inline.hpp"

#include "gc/z/zServiceability.hpp"

#include "gc/z/zStat.hpp"

#include "logging/log.hpp"

#include "memory/universe.hpp"

#include "runtime/vmOperations.hpp"

#include "runtime/vmThread.hpp"

static const ZStatPhaseCycle      ZPhaseCycle("Garbage Collection Cycle");

static const ZStatPhasePause      ZPhasePauseMarkStart("Pause Mark Start");

static const ZStatPhaseConcurrent ZPhaseConcurrentMark("Concurrent Mark");

static const ZStatPhaseConcurrent ZPhaseConcurrentMarkContinue("Concurrent Mark Continue");

static const ZStatPhasePause      ZPhasePauseMarkEnd("Pause Mark End");

static const ZStatPhaseConcurrent ZPhaseConcurrentProcessNonStrongReferences("Concurrent Process Non-Strong References");

static const ZStatPhaseConcurrent ZPhaseConcurrentResetRelocationSet("Concurrent Reset Relocation Set");

static const ZStatPhaseConcurrent ZPhaseConcurrentSelectRelocationSet("Concurrent Select Relocation Set");

static const ZStatPhasePause      ZPhasePauseRelocateStart("Pause Relocate Start");

static const ZStatPhaseConcurrent ZPhaseConcurrentRelocated("Concurrent Relocate");

static const ZStatCriticalPhase   ZCriticalPhaseGCLockerStall("GC Locker Stall", false /* verbose */);

static const ZStatSampler         ZSamplerJavaThreads("System", "Java Threads", ZStatUnitThreads);

class VM_ZOperation : public VM_Operation {

private:

  const uint _gc_id;

  bool       _gc_locked;

  bool       _success;

public:

  VM_ZOperation() :

      _gc_id(GCId::current()),

      _gc_locked(false),

      _success(false) {}

  virtual bool needs_inactive_gc_locker() const {

    // An inactive GC locker is needed in operations where we change the bad

    // mask or move objects. Changing the bad mask will invalidate all oops,

    // which makes it conceptually the same thing as moving all objects.

    return false;

  }

  virtual bool do_operation() = 0;

  virtual bool doit_prologue() {

    Heap_lock->lock();

    return true;

  }

  virtual void doit() {

    // Abort if GC locker state is incompatible

    if (needs_inactive_gc_locker() && GCLocker::check_active_before_gc()) {

      _gc_locked = true;

      return;

    }

    // Setup GC id and active marker

    GCIdMark gc_id_mark(_gc_id);

    IsGCActiveMark gc_active_mark;

    // Execute operation

    _success = do_operation();

    // Update statistics

    ZStatSample(ZSamplerJavaThreads, Threads::number_of_threads());

  }

  virtual void doit_epilogue() {

    Heap_lock->unlock();

  }

  bool gc_locked() const {

    return _gc_locked;

  }

  bool success() const {

    return _success;

  }

};

static bool should_clear_soft_references() {

  // Clear if one or more allocations have stalled

  const bool stalled = ZHeap::heap()->is_alloc_stalled();

  if (stalled) {

    // Clear

    return true;

  }

  // Clear if implied by the GC cause

  const GCCause::Cause cause = ZCollectedHeap::heap()->gc_cause();

  if (cause == GCCause::_wb_full_gc ||

      cause == GCCause::_metadata_GC_clear_soft_refs) {

    // Clear

    return true;

  }

  // Don't clear

  return false;

}

static bool should_boost_worker_threads() {

  // Boost worker threads if one or more allocations have stalled

  const bool stalled = ZHeap::heap()->is_alloc_stalled();

  if (stalled) {

    // Boost

    return true;

  }

  // Boost worker threads if implied by the GC cause

  const GCCause::Cause cause = ZCollectedHeap::heap()->gc_cause();

  if (cause == GCCause::_wb_full_gc ||

      cause == GCCause::_java_lang_system_gc ||

      cause == GCCause::_metadata_GC_clear_soft_refs) {

    // Boost

    return true;

  }

  // Don't boost

  return false;

}

class VM_ZMarkStart : public VM_ZOperation {

public:

  virtual VMOp_Type type() const {

    return VMOp_ZMarkStart;

  }

  virtual bool needs_inactive_gc_locker() const {

    return true;

  }

  virtual bool do_operation() {

    ZStatTimer timer(ZPhasePauseMarkStart);

    ZServiceabilityMarkStartTracer tracer;

    // Set up soft reference policy

    const bool clear = should_clear_soft_references();

    ZHeap::heap()->set_soft_reference_policy(clear);

    // Set up boost mode

    const bool boost = should_boost_worker_threads();

    ZHeap::heap()->set_boost_worker_threads(boost);

    ZCollectedHeap::heap()->increment_total_collections(true /* full */);

    ZHeap::heap()->mark_start();

    return true;

  }

};

class VM_ZMarkEnd : public VM_ZOperation {

public:

  virtual VMOp_Type type() const {

    return VMOp_ZMarkEnd;

  }

  virtual bool do_operation() {

    ZStatTimer timer(ZPhasePauseMarkEnd);

    ZServiceabilityMarkEndTracer tracer;

    return ZHeap::heap()->mark_end();

  }

};

class VM_ZRelocateStart : public VM_ZOperation {

public:

  virtual VMOp_Type type() const {

    return VMOp_ZRelocateStart;

  }

  virtual bool needs_inactive_gc_locker() const {

    return true;

  }

  virtual bool do_operation() {

    ZStatTimer timer(ZPhasePauseRelocateStart);

    ZServiceabilityRelocateStartTracer tracer;

    ZHeap::heap()->relocate_start();

    return true;

  }

};

ZDriver::ZDriver() :

    _gc_cycle_port(),

    _gc_locker_port() {

  set_name("ZDriver");

  create_and_start();

}

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

  switch (cause) {

  case GCCause::_wb_young_gc:

  case GCCause::_wb_conc_mark:

  case GCCause::_wb_full_gc:

  case GCCause::_dcmd_gc_run:

  case GCCause::_java_lang_system_gc:

  case GCCause::_full_gc_alot:

  case GCCause::_scavenge_alot:

  case GCCause::_jvmti_force_gc:

  case GCCause::_metadata_GC_clear_soft_refs:

    // Start synchronous GC

    _gc_cycle_port.send_sync(cause);

    break;

  case GCCause::_z_timer:

  case GCCause::_z_warmup:

  case GCCause::_z_allocation_rate:

  case GCCause::_z_allocation_stall:

  case GCCause::_z_proactive:

  case GCCause::_metadata_GC_threshold:

    // Start asynchronous GC

    _gc_cycle_port.send_async(cause);

    break;

  case GCCause::_gc_locker:

    // Restart VM operation previously blocked by the GC locker

    _gc_locker_port.signal();

    break;

  default:

    // Other causes not supported

    fatal("Unsupported GC cause (%s)", GCCause::to_string(cause));

    break;

  }

}

template <typename T>

bool ZDriver::pause() {

  for (;;) {

    T op;

    VMThread::execute(&op);

    if (op.gc_locked()) {

      // Wait for GC to become unlocked and restart the VM operation

      ZStatTimer timer(ZCriticalPhaseGCLockerStall);

      _gc_locker_port.wait();

      continue;

    }

    // Notify VM operation completed

    _gc_locker_port.ack();

    return op.success();

  }

}

void ZDriver::pause_mark_start() {

  pause<VM_ZMarkStart>();

}

void ZDriver::concurrent_mark() {

  ZStatTimer timer(ZPhaseConcurrentMark);

  ZHeap::heap()->mark(true /* initial */);

}

bool ZDriver::pause_mark_end() {

  return pause<VM_ZMarkEnd>();

}

void ZDriver::concurrent_mark_continue() {

  ZStatTimer timer(ZPhaseConcurrentMarkContinue);

  ZHeap::heap()->mark(false /* initial */);

}

void ZDriver::concurrent_process_non_strong_references() {

  ZStatTimer timer(ZPhaseConcurrentProcessNonStrongReferences);

  ZHeap::heap()->process_non_strong_references();

}

void ZDriver::concurrent_reset_relocation_set() {

  ZStatTimer timer(ZPhaseConcurrentResetRelocationSet);

  ZHeap::heap()->reset_relocation_set();

}

void ZDriver::pause_verify() {

  if (VerifyBeforeGC || VerifyDuringGC || VerifyAfterGC) {

    VM_Verify op;

    VMThread::execute(&op);

  }

}

void ZDriver::concurrent_select_relocation_set() {

  ZStatTimer timer(ZPhaseConcurrentSelectRelocationSet);

  ZHeap::heap()->select_relocation_set();

}

void ZDriver::pause_relocate_start() {

  pause<VM_ZRelocateStart>();

}

void ZDriver::concurrent_relocate() {

  ZStatTimer timer(ZPhaseConcurrentRelocated);

  ZHeap::heap()->relocate();

}

void ZDriver::check_out_of_memory() {

  ZHeap::heap()->check_out_of_memory();

}

class ZDriverGCScope : public StackObj {

private:

  GCIdMark      _gc_id;

  GCCauseSetter _gc_cause_setter;

  ZStatTimer    _timer;

public:

  ZDriverGCScope(GCCause::Cause cause) :

      _gc_id(),

      _gc_cause_setter(ZCollectedHeap::heap(), cause),

      _timer(ZPhaseCycle) {

    // Update statistics

    ZStatCycle::at_start();

  }

  ~ZDriverGCScope() {

    // Calculate boost factor

    const double boost_factor = (double)ZHeap::heap()->nconcurrent_worker_threads() /

                                (double)ZHeap::heap()->nconcurrent_no_boost_worker_threads();

    // Update statistics

    ZStatCycle::at_end(boost_factor);

    // Update data used by soft reference policy

    Universe::update_heap_info_at_gc();

  }

};

void ZDriver::gc(GCCause::Cause cause) {

  ZDriverGCScope scope(cause);

  // Phase 1: Pause Mark Start

  pause_mark_start();

  // Phase 2: Concurrent Mark

  concurrent_mark();

  // Phase 3: Pause Mark End

  while (!pause_mark_end()) {

    // Phase 3.5: Concurrent Mark Continue

    concurrent_mark_continue();

  }

  // Phase 4: Concurrent Process Non-Strong References

  concurrent_process_non_strong_references();

  // Phase 5: Concurrent Reset Relocation Set

  concurrent_reset_relocation_set();

  pause_verify();

  concurrent_select_relocation_set();

  pause_relocate_start();

  concurrent_relocate();

}

void ZDriver::run_service() {

  // Main loop

  while (!should_terminate()) {

    // Wait for GC request

    const GCCause::Cause cause = _gc_cycle_port.receive();

    if (cause == GCCause::_no_gc) {

      continue;

    }

    // Run GC

    gc(cause);

    // Notify GC completed

    _gc_cycle_port.ack();

    // Check for out of memory condition

    check_out_of_memory();

  }

}

void ZDriver::stop_service() {

  _gc_cycle_port.send_async(GCCause::_no_gc);

}