/*

 * Copyright (c) 2001, 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

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 */

#include "precompiled.hpp"

#include "oops/oop.inline.hpp"

#include "runtime/handles.inline.hpp"

#include "runtime/java.hpp"

#include "runtime/vmThread.hpp"

#include "services/memTracker.hpp"

#include "utilities/vmError.hpp"

PSYoungGen*  ParallelScavengeHeap::_young_gen = NULL;

PSOldGen*    ParallelScavengeHeap::_old_gen = NULL;

PSAdaptiveSizePolicy* ParallelScavengeHeap::_size_policy = NULL;

PSGCAdaptivePolicyCounters* ParallelScavengeHeap::_gc_policy_counters = NULL;

GCTaskManager* ParallelScavengeHeap::_gc_task_manager = NULL;

jint ParallelScavengeHeap::initialize() {

  CollectedHeap::pre_initialize();

  const size_t heap_size = _collector_policy->max_heap_byte_size();

  ReservedSpace heap_rs = Universe::reserve_heap(heap_size, _collector_policy->heap_alignment());

  os::trace_page_sizes("ps main", _collector_policy->min_heap_byte_size(),

                       heap_size, generation_alignment(),

                       heap_rs.base(),

                       heap_rs.size());

  initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));

  CardTableExtension* const barrier_set = new CardTableExtension(reserved_region());

  barrier_set->initialize();

  set_barrier_set(barrier_set);

  // Make up the generations

  // Calculate the maximum size that a generation can grow.  This

  // includes growth into the other generation.  Note that the

  // parameter _max_gen_size is kept as the maximum

  // size of the generation as the boundaries currently stand.

  // _max_gen_size is still used as that value.

  double max_gc_pause_sec = ((double) MaxGCPauseMillis)/1000.0;

  double max_gc_minor_pause_sec = ((double) MaxGCMinorPauseMillis)/1000.0;

  _gens = new AdjoiningGenerations(heap_rs, _collector_policy, generation_alignment());

  _old_gen = _gens->old_gen();

  _young_gen = _gens->young_gen();

  const size_t eden_capacity = _young_gen->eden_space()->capacity_in_bytes();

  const size_t old_capacity = _old_gen->capacity_in_bytes();

  const size_t initial_promo_size = MIN2(eden_capacity, old_capacity);

  _size_policy =

    new PSAdaptiveSizePolicy(eden_capacity,

                             initial_promo_size,

                             young_gen()->to_space()->capacity_in_bytes(),

                             _collector_policy->gen_alignment(),

                             max_gc_pause_sec,

                             max_gc_minor_pause_sec,

                             GCTimeRatio

                             );

  assert(!UseAdaptiveGCBoundary ||

    (old_gen()->virtual_space()->high_boundary() ==

     young_gen()->virtual_space()->low_boundary()),

    "Boundaries must meet");

  // initialize the policy counters - 2 collectors, 3 generations

  _gc_policy_counters =

    new PSGCAdaptivePolicyCounters("ParScav:MSC", 2, 3, _size_policy);

  // Set up the GCTaskManager

  _gc_task_manager = GCTaskManager::create(ParallelGCThreads);

  if (UseParallelOldGC && !PSParallelCompact::initialize()) {

    return JNI_ENOMEM;

  }

  return JNI_OK;

}

void ParallelScavengeHeap::post_initialize() {

  // Need to init the tenuring threshold

  PSScavenge::initialize();

  if (UseParallelOldGC) {

    PSParallelCompact::post_initialize();

  } else {

    PSMarkSweep::initialize();

  }

  PSPromotionManager::initialize();

}

void ParallelScavengeHeap::update_counters() {

  young_gen()->update_counters();

  old_gen()->update_counters();

  MetaspaceCounters::update_performance_counters();

  CompressedClassSpaceCounters::update_performance_counters();

}

size_t ParallelScavengeHeap::capacity() const {

  size_t value = young_gen()->capacity_in_bytes() + old_gen()->capacity_in_bytes();

  return value;

}

size_t ParallelScavengeHeap::used() const {

  size_t value = young_gen()->used_in_bytes() + old_gen()->used_in_bytes();

  return value;

}

bool ParallelScavengeHeap::is_maximal_no_gc() const {

  return old_gen()->is_maximal_no_gc() && young_gen()->is_maximal_no_gc();

}

size_t ParallelScavengeHeap::max_capacity() const {

  size_t estimated = reserved_region().byte_size();

  if (UseAdaptiveSizePolicy) {

    estimated -= _size_policy->max_survivor_size(young_gen()->max_size());

  } else {

    estimated -= young_gen()->to_space()->capacity_in_bytes();

  }

  return MAX2(estimated, capacity());

}

bool ParallelScavengeHeap::is_in(const void* p) const {

  return young_gen()->is_in(p) || old_gen()->is_in(p);

}

bool ParallelScavengeHeap::is_in_reserved(const void* p) const {

  return young_gen()->is_in_reserved(p) || old_gen()->is_in_reserved(p);

}

bool ParallelScavengeHeap::is_scavengable(const void* addr) {

  return is_in_young((oop)addr);

}

// There are two levels of allocation policy here.

//

// When an allocation request fails, the requesting thread must invoke a VM

// operation, transfer control to the VM thread, and await the results of a

// garbage collection. That is quite expensive, and we should avoid doing it

// multiple times if possible.

//

// To accomplish this, we have a basic allocation policy, and also a

// failed allocation policy.

//

// The basic allocation policy controls how you allocate memory without

// attempting garbage collection. It is okay to grab locks and

// expand the heap, if that can be done without coming to a safepoint.

// It is likely that the basic allocation policy will not be very

// aggressive.

//

// The failed allocation policy is invoked from the VM thread after

// the basic allocation policy is unable to satisfy a mem_allocate

// request. This policy needs to cover the entire range of collection,

// heap expansion, and out-of-memory conditions. It should make every

// attempt to allocate the requested memory.

// Basic allocation policy. Should never be called at a safepoint, or

// from the VM thread.

//

// This method must handle cases where many mem_allocate requests fail

// simultaneously. When that happens, only one VM operation will succeed,

// and the rest will not be executed. For that reason, this method loops

// during failed allocation attempts. If the java heap becomes exhausted,

// we rely on the size_policy object to force a bail out.

HeapWord* ParallelScavengeHeap::mem_allocate(

                                     size_t size,

                                     bool* gc_overhead_limit_was_exceeded) {

  assert(!SafepointSynchronize::is_at_safepoint(), "should not be at safepoint");

  assert(Thread::current() != (Thread*)VMThread::vm_thread(), "should not be in vm thread");

  assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");

  // In general gc_overhead_limit_was_exceeded should be false so

  // set it so here and reset it to true only if the gc time

  // limit is being exceeded as checked below.

  *gc_overhead_limit_was_exceeded = false;

  HeapWord* result = young_gen()->allocate(size);

  uint loop_count = 0;

  uint gc_count = 0;

  uint gclocker_stalled_count = 0;

  while (result == NULL) {

    // We don't want to have multiple collections for a single filled generation.

    // To prevent this, each thread tracks the total_collections() value, and if

    // the count has changed, does not do a new collection.

    //

    // The collection count must be read only while holding the heap lock. VM

    // operations also hold the heap lock during collections. There is a lock

    // contention case where thread A blocks waiting on the Heap_lock, while

    // thread B is holding it doing a collection. When thread A gets the lock,

    // the collection count has already changed. To prevent duplicate collections,

    // The policy MUST attempt allocations during the same period it reads the

    // total_collections() value!

    {

      MutexLocker ml(Heap_lock);

      gc_count = total_collections();

      result = young_gen()->allocate(size);

      if (result != NULL) {

        return result;

      }

      // If certain conditions hold, try allocating from the old gen.

      result = mem_allocate_old_gen(size);

      if (result != NULL) {

        return result;

      }

      if (gclocker_stalled_count > GCLockerRetryAllocationCount) {

        return NULL;

      }

      // Failed to allocate without a gc.

      if (GC_locker::is_active_and_needs_gc()) {

        // If this thread is not in a jni critical section, we stall

        // the requestor until the critical section has cleared and

        // GC allowed. When the critical section clears, a GC is

        // initiated by the last thread exiting the critical section; so

        // we retry the allocation sequence from the beginning of the loop,

        // rather than causing more, now probably unnecessary, GC attempts.

        JavaThread* jthr = JavaThread::current();

        if (!jthr->in_critical()) {

          MutexUnlocker mul(Heap_lock);

          GC_locker::stall_until_clear();

          gclocker_stalled_count += 1;

          continue;

        } else {

          if (CheckJNICalls) {

            fatal("Possible deadlock due to allocating while"

                  " in jni critical section");

          }

          return NULL;

        }

      }

    }

    if (result == NULL) {

      // Generate a VM operation

      VM_ParallelGCFailedAllocation op(size, gc_count);

      VMThread::execute(&op);

      // Did the VM operation execute? If so, return the result directly.

      // This prevents us from looping until time out on requests that can

      // not be satisfied.

      if (op.prologue_succeeded()) {

        assert(is_in_or_null(op.result()), "result not in heap");

        // If GC was locked out during VM operation then retry allocation

        // and/or stall as necessary.

        if (op.gc_locked()) {

          assert(op.result() == NULL, "must be NULL if gc_locked() is true");

          continue;  // retry and/or stall as necessary

        }

        // Exit the loop if the gc time limit has been exceeded.

        // The allocation must have failed above ("result" guarding

        // this path is NULL) and the most recent collection has exceeded the

        // gc overhead limit (although enough may have been collected to

        // satisfy the allocation).  Exit the loop so that an out-of-memory

        // will be thrown (return a NULL ignoring the contents of

        // op.result()),

        // but clear gc_overhead_limit_exceeded so that the next collection

        // starts with a clean slate (i.e., forgets about previous overhead

        // excesses).  Fill op.result() with a filler object so that the

        // heap remains parsable.

        const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();

        const bool softrefs_clear = collector_policy()->all_soft_refs_clear();

        if (limit_exceeded && softrefs_clear) {

          *gc_overhead_limit_was_exceeded = true;

          size_policy()->set_gc_overhead_limit_exceeded(false);

          if (PrintGCDetails && Verbose) {

            gclog_or_tty->print_cr("ParallelScavengeHeap::mem_allocate: "

              "return NULL because gc_overhead_limit_exceeded is set");

          }

          if (op.result() != NULL) {

            CollectedHeap::fill_with_object(op.result(), size);

          }

          return NULL;

        }

        return op.result();

      }

    }

    // The policy object will prevent us from looping forever. If the

    // time spent in gc crosses a threshold, we will bail out.

    loop_count++;

    if ((result == NULL) && (QueuedAllocationWarningCount > 0) &&

        (loop_count % QueuedAllocationWarningCount == 0)) {

      warning("ParallelScavengeHeap::mem_allocate retries %d times \n\t"

              " size=" SIZE_FORMAT, loop_count, size);

    }

  }

  return result;

}

// A "death march" is a series of ultra-slow allocations in which a full gc is

// done before each allocation, and after the full gc the allocation still

// cannot be satisfied from the young gen.  This routine detects that condition;

// it should be called after a full gc has been done and the allocation

// attempted from the young gen. The parameter 'addr' should be the result of

// that young gen allocation attempt.

void

ParallelScavengeHeap::death_march_check(HeapWord* const addr, size_t size) {

  if (addr != NULL) {

    _death_march_count = 0;  // death march has ended

  } else if (_death_march_count == 0) {

    if (should_alloc_in_eden(size)) {

      _death_march_count = 1;    // death march has started

    }

  }

}

HeapWord* ParallelScavengeHeap::mem_allocate_old_gen(size_t size) {

  if (!should_alloc_in_eden(size) || GC_locker::is_active_and_needs_gc()) {

    // Size is too big for eden, or gc is locked out.

    return old_gen()->allocate(size);

  }

  // If a "death march" is in progress, allocate from the old gen a limited

  // number of times before doing a GC.

  if (_death_march_count > 0) {

    if (_death_march_count < 64) {

      ++_death_march_count;

      return old_gen()->allocate(size);

    } else {

      _death_march_count = 0;

    }

  }

  return NULL;

}

void ParallelScavengeHeap::do_full_collection(bool clear_all_soft_refs) {

  if (UseParallelOldGC) {

    // The do_full_collection() parameter clear_all_soft_refs

    // is interpreted here as maximum_compaction which will

    // cause SoftRefs to be cleared.

    bool maximum_compaction = clear_all_soft_refs;

    PSParallelCompact::invoke(maximum_compaction);

  } else {

    PSMarkSweep::invoke(clear_all_soft_refs);

  }

}

// Failed allocation policy. Must be called from the VM thread, and

// only at a safepoint! Note that this method has policy for allocation

// flow, and NOT collection policy. So we do not check for gc collection

// time over limit here, that is the responsibility of the heap specific

// collection methods. This method decides where to attempt allocations,

// and when to attempt collections, but no collection specific policy.

HeapWord* ParallelScavengeHeap::failed_mem_allocate(size_t size) {

  assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");

  assert(Thread::current() == (Thread*)VMThread::vm_thread(), "should be in vm thread");

  assert(!is_gc_active(), "not reentrant");

  assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");

  // We assume that allocation in eden will fail unless we collect.

  // First level allocation failure, scavenge and allocate in young gen.

  GCCauseSetter gccs(this, GCCause::_allocation_failure);

  const bool invoked_full_gc = PSScavenge::invoke();

  HeapWord* result = young_gen()->allocate(size);

  // Second level allocation failure.

  //   Mark sweep and allocate in young generation.

  if (result == NULL && !invoked_full_gc) {

    do_full_collection(false);

    result = young_gen()->allocate(size);

  }

  death_march_check(result, size);

  // Third level allocation failure.

  //   After mark sweep and young generation allocation failure,

  //   allocate in old generation.

  if (result == NULL) {

    result = old_gen()->allocate(size);

  }

  // Fourth level allocation failure. We're running out of memory.

  //   More complete mark sweep and allocate in young generation.

  if (result == NULL) {

    do_full_collection(true);

    result = young_gen()->allocate(size);

  }

  // Fifth level allocation failure.

  //   After more complete mark sweep, allocate in old generation.

  if (result == NULL) {

    result = old_gen()->allocate(size);

  }

  return result;

}

void ParallelScavengeHeap::ensure_parsability(bool retire_tlabs) {

  CollectedHeap::ensure_parsability(retire_tlabs);

  young_gen()->eden_space()->ensure_parsability();

}

size_t ParallelScavengeHeap::tlab_capacity(Thread* thr) const {

  return young_gen()->eden_space()->tlab_capacity(thr);

}

size_t ParallelScavengeHeap::tlab_used(Thread* thr) const {

  return young_gen()->eden_space()->tlab_used(thr);

}

size_t ParallelScavengeHeap::unsafe_max_tlab_alloc(Thread* thr) const {

  return young_gen()->eden_space()->unsafe_max_tlab_alloc(thr);

}

HeapWord* ParallelScavengeHeap::allocate_new_tlab(size_t size) {

  return young_gen()->allocate(size);

}

void ParallelScavengeHeap::accumulate_statistics_all_tlabs() {

  CollectedHeap::accumulate_statistics_all_tlabs();

}

void ParallelScavengeHeap::resize_all_tlabs() {

  CollectedHeap::resize_all_tlabs();

}

bool ParallelScavengeHeap::can_elide_initializing_store_barrier(oop new_obj) {

  // We don't need barriers for stores to objects in the

  // young gen and, a fortiori, for initializing stores to

  // objects therein.

  return is_in_young(new_obj);

}

// This method is used by System.gc() and JVMTI.

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

  assert(!Heap_lock->owned_by_self(),

    "this thread should not own the Heap_lock");

  uint gc_count      = 0;

  uint full_gc_count = 0;

  {

    MutexLocker ml(Heap_lock);

    // This value is guarded by the Heap_lock

    gc_count      = total_collections();

    full_gc_count = total_full_collections();

  }

  VM_ParallelGCSystemGC op(gc_count, full_gc_count, cause);

  VMThread::execute(&op);

}

void ParallelScavengeHeap::object_iterate(ObjectClosure* cl) {

  young_gen()->object_iterate(cl);

  old_gen()->object_iterate(cl);

}

HeapWord* ParallelScavengeHeap::block_start(const void* addr) const {

  if (young_gen()->is_in_reserved(addr)) {

    assert(young_gen()->is_in(addr),

           "addr should be in allocated part of young gen");

    // called from os::print_location by find or VMError

    if (Debugging || VMError::fatal_error_in_progress())  return NULL;

    Unimplemented();

  } else if (old_gen()->is_in_reserved(addr)) {

    assert(old_gen()->is_in(addr),

           "addr should be in allocated part of old gen");

    return old_gen()->start_array()->object_start((HeapWord*)addr);

  }

  return 0;

}