sdk/runtime/vm/heap.cc

// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

#include "vm/heap.h"

#include "platform/assert.h"
#include "platform/utils.h"
#include "vm/flags.h"
#include "vm/isolate.h"
#include "vm/lockers.h"
#include "vm/object.h"
#include "vm/object_set.h"
#include "vm/os.h"
#include "vm/pages.h"
#include "vm/raw_object.h"
#include "vm/scavenger.h"
#include "vm/service.h"
#include "vm/service_event.h"
#include "vm/service_isolate.h"
#include "vm/stack_frame.h"
#include "vm/tags.h"
#include "vm/timeline.h"
#include "vm/verifier.h"
#include "vm/virtual_memory.h"
#include "vm/weak_table.h"

namespace dart {

Heap::Heap(Isolate* isolate,
           intptr_t max_new_gen_semi_words,
           intptr_t max_old_gen_words,
           intptr_t max_external_words)
    : isolate_(isolate),
      new_space_(this, max_new_gen_semi_words, kNewObjectAlignmentOffset),
      old_space_(this, max_old_gen_words, max_external_words),
      barrier_(new Monitor()),
      barrier_done_(new Monitor()),
      read_only_(false),
      gc_new_space_in_progress_(false),
      gc_old_space_in_progress_(false) {
  UpdateGlobalMaxUsed();
  for (int sel = 0; sel < kNumWeakSelectors; sel++) {
    new_weak_tables_[sel] = new WeakTable();
    old_weak_tables_[sel] = new WeakTable();
  }
  stats_.num_ = 0;
}


Heap::~Heap() {
  delete barrier_;
  delete barrier_done_;

  for (int sel = 0; sel < kNumWeakSelectors; sel++) {
    delete new_weak_tables_[sel];
    delete old_weak_tables_[sel];
  }
}


uword Heap::AllocateNew(intptr_t size) {
  ASSERT(Thread::Current()->no_safepoint_scope_depth() == 0);
  // Currently, only the Dart thread may allocate in new space.
  isolate()->AssertCurrentThreadIsMutator();
  uword addr = new_space_.TryAllocate(size);
  if (addr == 0) {
    // This call to CollectGarbage might end up "reusing" a collection spawned
    // from a different thread and will be racing to allocate the requested
    // memory with other threads being released after the collection.
    CollectGarbage(kNew);
    addr = new_space_.TryAllocate(size);
    if (addr == 0) {
      return AllocateOld(size, HeapPage::kData);
    }
  }
  return addr;
}


uword Heap::AllocateOld(intptr_t size, HeapPage::PageType type) {
  ASSERT(Thread::Current()->no_safepoint_scope_depth() == 0);
  uword addr = old_space_.TryAllocate(size, type);
  if (addr != 0) {
    return addr;
  }
  // If we are in the process of running a sweep, wait for the sweeper to free
  // memory.
  Thread* thread = Thread::Current();
  if (thread->CanCollectGarbage()) {
    // Wait for any GC tasks that are in progress.
    WaitForSweeperTasks(thread);
    addr = old_space_.TryAllocate(size, type);
    if (addr != 0) {
      return addr;
    }
    // All GC tasks finished without allocating successfully. Run a full GC.
    CollectAllGarbage();
    addr = old_space_.TryAllocate(size, type);
    if (addr != 0) {
      return addr;
    }
    // Wait for all of the concurrent tasks to finish before giving up.
    WaitForSweeperTasks(thread);
    addr = old_space_.TryAllocate(size, type);
    if (addr != 0) {
      return addr;
    }
    // Force growth before attempting another synchronous GC.
    addr = old_space_.TryAllocate(size, type, PageSpace::kForceGrowth);
    if (addr != 0) {
      return addr;
    }
    // Before throwing an out-of-memory error try a synchronous GC.
    CollectAllGarbage();
    WaitForSweeperTasks(thread);
  }
  addr = old_space_.TryAllocate(size, type, PageSpace::kForceGrowth);
  if (addr != 0) {
    return addr;
  }
  // Give up allocating this object.
  OS::PrintErr("Exhausted heap space, trying to allocate %" Pd " bytes.\n",
               size);
  return 0;
}


void Heap::AllocateExternal(intptr_t size, Space space) {
  ASSERT(Thread::Current()->no_safepoint_scope_depth() == 0);
  if (space == kNew) {
    isolate()->AssertCurrentThreadIsMutator();
    new_space_.AllocateExternal(size);
    if (new_space_.ExternalInWords() > (FLAG_new_gen_ext_limit * MBInWords)) {
      // Attempt to free some external allocation by a scavenge. (If the total
      // remains above the limit, next external alloc will trigger another.)
      CollectGarbage(kNew);
    }
  } else {
    ASSERT(space == kOld);
    old_space_.AllocateExternal(size);
    if (old_space_.NeedsGarbageCollection()) {
      CollectAllGarbage();
    }
  }
}

void Heap::FreeExternal(intptr_t size, Space space) {
  if (space == kNew) {
    new_space_.FreeExternal(size);
  } else {
    ASSERT(space == kOld);
    old_space_.FreeExternal(size);
  }
}

void Heap::PromoteExternal(intptr_t size) {
  new_space_.FreeExternal(size);
  old_space_.AllocateExternal(size);
}

bool Heap::Contains(uword addr) const {
  return new_space_.Contains(addr) || old_space_.Contains(addr);
}


bool Heap::NewContains(uword addr) const {
  return new_space_.Contains(addr);
}


bool Heap::OldContains(uword addr) const {
  return old_space_.Contains(addr);
}


bool Heap::CodeContains(uword addr) const {
  return old_space_.Contains(addr, HeapPage::kExecutable);
}


bool Heap::DataContains(uword addr) const {
  return old_space_.DataContains(addr);
}


void Heap::VisitObjects(ObjectVisitor* visitor) const {
  new_space_.VisitObjects(visitor);
  old_space_.VisitObjects(visitor);
}


void Heap::VisitObjectsNoImagePages(ObjectVisitor* visitor) const {
  new_space_.VisitObjects(visitor);
  old_space_.VisitObjectsNoImagePages(visitor);
}


void Heap::VisitObjectsImagePages(ObjectVisitor* visitor) const {
  old_space_.VisitObjectsImagePages(visitor);
}


HeapIterationScope::HeapIterationScope(bool writable)
    : StackResource(Thread::Current()),
      old_space_(isolate()->heap()->old_space()),
      writable_(writable) {
  {
    // It's not yet safe to iterate over a paged space while it's concurrently
    // sweeping, so wait for any such task to complete first.
    MonitorLocker ml(old_space_->tasks_lock());
#if defined(DEBUG)
    // We currently don't support nesting of HeapIterationScopes.
    ASSERT(old_space_->iterating_thread_ != thread());
#endif
    while (old_space_->tasks() > 0) {
      ml.WaitWithSafepointCheck(thread());
    }
#if defined(DEBUG)
    ASSERT(old_space_->iterating_thread_ == NULL);
    old_space_->iterating_thread_ = thread();
#endif
    old_space_->set_tasks(1);
  }

  if (writable_) {
    thread()->heap()->WriteProtectCode(false);
  }
}


HeapIterationScope::~HeapIterationScope() {
  if (writable_) {
    thread()->heap()->WriteProtectCode(true);
  }

  MonitorLocker ml(old_space_->tasks_lock());
#if defined(DEBUG)
  ASSERT(old_space_->iterating_thread_ == thread());
  old_space_->iterating_thread_ = NULL;
#endif
  ASSERT(old_space_->tasks() == 1);
  old_space_->set_tasks(0);
  ml.NotifyAll();
}


void Heap::IterateObjects(ObjectVisitor* visitor) const {
  // The visitor must not allocate from the heap.
  NoSafepointScope no_safepoint_scope_;
  new_space_.VisitObjects(visitor);
  IterateOldObjects(visitor);
}


void Heap::IterateOldObjects(ObjectVisitor* visitor) const {
  HeapIterationScope heap_iteration_scope;
  old_space_.VisitObjects(visitor);
}


void Heap::IterateOldObjectsNoImagePages(ObjectVisitor* visitor) const {
  HeapIterationScope heap_iteration_scope;
  old_space_.VisitObjectsNoImagePages(visitor);
}


void Heap::VisitObjectPointers(ObjectPointerVisitor* visitor) const {
  new_space_.VisitObjectPointers(visitor);
  old_space_.VisitObjectPointers(visitor);
}


RawInstructions* Heap::FindObjectInCodeSpace(FindObjectVisitor* visitor) const {
  // Only executable pages can have RawInstructions objects.
  RawObject* raw_obj = old_space_.FindObject(visitor, HeapPage::kExecutable);
  ASSERT((raw_obj == Object::null()) ||
         (raw_obj->GetClassId() == kInstructionsCid));
  return reinterpret_cast<RawInstructions*>(raw_obj);
}


RawObject* Heap::FindOldObject(FindObjectVisitor* visitor) const {
  HeapIterationScope heap_iteration_scope;
  return old_space_.FindObject(visitor, HeapPage::kData);
}


RawObject* Heap::FindNewObject(FindObjectVisitor* visitor) const {
  return new_space_.FindObject(visitor);
}


RawObject* Heap::FindObject(FindObjectVisitor* visitor) const {
  // The visitor must not allocate from the heap.
  NoSafepointScope no_safepoint_scope;
  RawObject* raw_obj = FindNewObject(visitor);
  if (raw_obj != Object::null()) {
    return raw_obj;
  }
  raw_obj = FindOldObject(visitor);
  if (raw_obj != Object::null()) {
    return raw_obj;
  }
  raw_obj = FindObjectInCodeSpace(visitor);
  return raw_obj;
}


bool Heap::BeginNewSpaceGC(Thread* thread) {
  MonitorLocker ml(&gc_in_progress_monitor_);
  bool start_gc_on_thread = true;
  while (gc_new_space_in_progress_ || gc_old_space_in_progress_) {
    start_gc_on_thread = !gc_new_space_in_progress_;
    ml.WaitWithSafepointCheck(thread);
  }
  if (start_gc_on_thread) {
    gc_new_space_in_progress_ = true;
    return true;
  }
  return false;
}


void Heap::EndNewSpaceGC() {
  MonitorLocker ml(&gc_in_progress_monitor_);
  ASSERT(gc_new_space_in_progress_);
  gc_new_space_in_progress_ = false;
  ml.NotifyAll();
}


bool Heap::BeginOldSpaceGC(Thread* thread) {
  MonitorLocker ml(&gc_in_progress_monitor_);
  bool start_gc_on_thread = true;
  while (gc_new_space_in_progress_ || gc_old_space_in_progress_) {
    start_gc_on_thread = !gc_old_space_in_progress_;
    ml.WaitWithSafepointCheck(thread);
  }
  if (start_gc_on_thread) {
    gc_old_space_in_progress_ = true;
    return true;
  }
  return false;
}


void Heap::EndOldSpaceGC() {
  MonitorLocker ml(&gc_in_progress_monitor_);
  ASSERT(gc_old_space_in_progress_);
  gc_old_space_in_progress_ = false;
  ml.NotifyAll();
}


#ifndef PRODUCT
void Heap::UpdateClassHeapStatsBeforeGC(Heap::Space space) {
  ClassTable* class_table = isolate()->class_table();
  if (space == kNew) {
    class_table->ResetCountersNew();
  } else {
    class_table->ResetCountersOld();
  }
}
#endif


void Heap::CollectNewSpaceGarbage(Thread* thread,
                                  ApiCallbacks api_callbacks,
                                  GCReason reason) {
  ASSERT((reason == kNewSpace) || (reason == kFull));
  if (BeginNewSpaceGC(thread)) {
    bool invoke_api_callbacks = (api_callbacks == kInvokeApiCallbacks);
    RecordBeforeGC(kNew, reason);
    VMTagScope tagScope(thread, VMTag::kGCNewSpaceTagId);
    TIMELINE_FUNCTION_GC_DURATION(thread, "CollectNewGeneration");
    NOT_IN_PRODUCT(UpdateClassHeapStatsBeforeGC(kNew));
    new_space_.Scavenge(invoke_api_callbacks);
    NOT_IN_PRODUCT(isolate()->class_table()->UpdatePromoted());
    RecordAfterGC(kNew);
    PrintStats();
    NOT_IN_PRODUCT(PrintStatsToTimeline(&tds));
    EndNewSpaceGC();
    if ((reason == kNewSpace) && old_space_.NeedsGarbageCollection()) {
      // Old collections should call the API callbacks.
      CollectOldSpaceGarbage(thread, kInvokeApiCallbacks, kPromotion);
    }
  }
}


void Heap::CollectOldSpaceGarbage(Thread* thread,
                                  ApiCallbacks api_callbacks,
                                  GCReason reason) {
  ASSERT((reason != kNewSpace));
  if (BeginOldSpaceGC(thread)) {
    bool invoke_api_callbacks = (api_callbacks == kInvokeApiCallbacks);
    RecordBeforeGC(kOld, reason);
    VMTagScope tagScope(thread, VMTag::kGCOldSpaceTagId);
    TIMELINE_FUNCTION_GC_DURATION(thread, "CollectOldGeneration");
    NOT_IN_PRODUCT(UpdateClassHeapStatsBeforeGC(kOld));
    old_space_.MarkSweep(invoke_api_callbacks);
    RecordAfterGC(kOld);
    PrintStats();
    NOT_IN_PRODUCT(PrintStatsToTimeline(&tds));
    // Some Code objects may have been collected so invalidate handler cache.
    thread->isolate()->handler_info_cache()->Clear();
    thread->isolate()->catch_entry_state_cache()->Clear();
    EndOldSpaceGC();
  }
}


void Heap::CollectGarbage(Space space,
                          ApiCallbacks api_callbacks,
                          GCReason reason) {
  Thread* thread = Thread::Current();
  switch (space) {
    case kNew: {
      CollectNewSpaceGarbage(thread, api_callbacks, reason);
      break;
    }
    case kOld:
    case kCode: {
      CollectOldSpaceGarbage(thread, api_callbacks, reason);
      break;
    }
    default:
      UNREACHABLE();
  }
}


void Heap::CollectGarbage(Space space) {
  Thread* thread = Thread::Current();
  if (space == kOld) {
    CollectOldSpaceGarbage(thread, kInvokeApiCallbacks, kOldSpace);
  } else {
    ASSERT(space == kNew);
    CollectNewSpaceGarbage(thread, kInvokeApiCallbacks, kNewSpace);
  }
}


void Heap::CollectAllGarbage() {
  Thread* thread = Thread::Current();
  CollectNewSpaceGarbage(thread, kInvokeApiCallbacks, kFull);
  CollectOldSpaceGarbage(thread, kInvokeApiCallbacks, kFull);
}


void Heap::WaitForSweeperTasks(Thread* thread) {
  MonitorLocker ml(old_space_.tasks_lock());
  while (old_space_.tasks() > 0) {
    ml.WaitWithSafepointCheck(thread);
  }
}


void Heap::UpdateGlobalMaxUsed() {
  ASSERT(isolate_ != NULL);
  // We are accessing the used in words count for both new and old space
  // without synchronizing. The value of this metric is approximate.
  isolate_->GetHeapGlobalUsedMaxMetric()->SetValue(
      (UsedInWords(Heap::kNew) * kWordSize) +
      (UsedInWords(Heap::kOld) * kWordSize));
}


void Heap::InitGrowthControl() {
  old_space_.InitGrowthControl();
}


void Heap::SetGrowthControlState(bool state) {
  old_space_.SetGrowthControlState(state);
}


bool Heap::GrowthControlState() {
  return old_space_.GrowthControlState();
}


void Heap::WriteProtect(bool read_only) {
  read_only_ = read_only;
  new_space_.WriteProtect(read_only);
  old_space_.WriteProtect(read_only);
}


intptr_t Heap::TopOffset(Heap::Space space) {
  if (space == kNew) {
    return OFFSET_OF(Heap, new_space_) + Scavenger::top_offset();
  } else {
    ASSERT(space == kOld);
    return OFFSET_OF(Heap, old_space_) + PageSpace::top_offset();
  }
}


intptr_t Heap::EndOffset(Heap::Space space) {
  if (space == kNew) {
    return OFFSET_OF(Heap, new_space_) + Scavenger::end_offset();
  } else {
    ASSERT(space == kOld);
    return OFFSET_OF(Heap, old_space_) + PageSpace::end_offset();
  }
}


void Heap::Init(Isolate* isolate,
                intptr_t max_new_gen_words,
                intptr_t max_old_gen_words,
                intptr_t max_external_words) {
  ASSERT(isolate->heap() == NULL);
  Heap* heap = new Heap(isolate, max_new_gen_words, max_old_gen_words,
                        max_external_words);
  isolate->set_heap(heap);
}


void Heap::AddRegionsToObjectSet(ObjectSet* set) const {
  new_space_.AddRegionsToObjectSet(set);
  old_space_.AddRegionsToObjectSet(set);
}


ObjectSet* Heap::CreateAllocatedObjectSet(
    Zone* zone,
    MarkExpectation mark_expectation) const {
  ObjectSet* allocated_set = new (zone) ObjectSet(zone);

  this->AddRegionsToObjectSet(allocated_set);
  {
    VerifyObjectVisitor object_visitor(isolate(), allocated_set,
                                       mark_expectation);
    this->VisitObjectsNoImagePages(&object_visitor);
  }
  {
    VerifyObjectVisitor object_visitor(isolate(), allocated_set,
                                       kRequireMarked);
    this->VisitObjectsImagePages(&object_visitor);
  }

  Isolate* vm_isolate = Dart::vm_isolate();
  vm_isolate->heap()->AddRegionsToObjectSet(allocated_set);
  {
    // VM isolate heap is premarked.
    VerifyObjectVisitor vm_object_visitor(isolate(), allocated_set,
                                          kRequireMarked);
    vm_isolate->heap()->VisitObjects(&vm_object_visitor);
  }

  return allocated_set;
}


bool Heap::Verify(MarkExpectation mark_expectation) const {
  HeapIterationScope heap_iteration_scope;
  return VerifyGC(mark_expectation);
}


bool Heap::VerifyGC(MarkExpectation mark_expectation) const {
  StackZone stack_zone(Thread::Current());
  ObjectSet* allocated_set =
      CreateAllocatedObjectSet(stack_zone.GetZone(), mark_expectation);
  VerifyPointersVisitor visitor(isolate(), allocated_set);
  VisitObjectPointers(&visitor);

  // Only returning a value so that Heap::Validate can be called from an ASSERT.
  return true;
}


void Heap::PrintSizes() const {
  OS::PrintErr(
      "New space (%" Pd64 "k of %" Pd64
      "k) "
      "Old space (%" Pd64 "k of %" Pd64 "k)\n",
      (UsedInWords(kNew) / KBInWords), (CapacityInWords(kNew) / KBInWords),
      (UsedInWords(kOld) / KBInWords), (CapacityInWords(kOld) / KBInWords));
}


int64_t Heap::UsedInWords(Space space) const {
  return space == kNew ? new_space_.UsedInWords() : old_space_.UsedInWords();
}


int64_t Heap::CapacityInWords(Space space) const {
  return space == kNew ? new_space_.CapacityInWords()
                       : old_space_.CapacityInWords();
}


int64_t Heap::ExternalInWords(Space space) const {
  return space == kNew ? new_space_.ExternalInWords()
                       : old_space_.ExternalInWords();
}


int64_t Heap::GCTimeInMicros(Space space) const {
  if (space == kNew) {
    return new_space_.gc_time_micros();
  }
  return old_space_.gc_time_micros();
}


intptr_t Heap::Collections(Space space) const {
  if (space == kNew) {
    return new_space_.collections();
  }
  return old_space_.collections();
}


const char* Heap::GCReasonToString(GCReason gc_reason) {
  switch (gc_reason) {
    case kNewSpace:
      return "new space";
    case kPromotion:
      return "promotion";
    case kOldSpace:
      return "old space";
    case kFull:
      return "full";
    case kGCAtAlloc:
      return "debugging";
    case kGCTestCase:
      return "test case";
    default:
      UNREACHABLE();
      return "";
  }
}


int64_t Heap::PeerCount() const {
  return new_weak_tables_[kPeers]->count() + old_weak_tables_[kPeers]->count();
}


int64_t Heap::HashCount() const {
  return new_weak_tables_[kHashes]->count() +
         old_weak_tables_[kHashes]->count();
}


int64_t Heap::ObjectIdCount() const {
  return new_weak_tables_[kObjectIds]->count() +
         old_weak_tables_[kObjectIds]->count();
}


void Heap::ResetObjectIdTable() {
  new_weak_tables_[kObjectIds]->Reset();
  old_weak_tables_[kObjectIds]->Reset();
}


intptr_t Heap::GetWeakEntry(RawObject* raw_obj, WeakSelector sel) const {
  if (raw_obj->IsNewObject()) {
    return new_weak_tables_[sel]->GetValue(raw_obj);
  }
  ASSERT(raw_obj->IsOldObject());
  return old_weak_tables_[sel]->GetValue(raw_obj);
}


void Heap::SetWeakEntry(RawObject* raw_obj, WeakSelector sel, intptr_t val) {
  if (raw_obj->IsNewObject()) {
    new_weak_tables_[sel]->SetValue(raw_obj, val);
  } else {
    ASSERT(raw_obj->IsOldObject());
    old_weak_tables_[sel]->SetValue(raw_obj, val);
  }
}


#ifndef PRODUCT
void Heap::PrintToJSONObject(Space space, JSONObject* object) const {
  if (space == kNew) {
    new_space_.PrintToJSONObject(object);
  } else {
    old_space_.PrintToJSONObject(object);
  }
}
#endif  // PRODUCT


void Heap::RecordBeforeGC(Space space, GCReason reason) {
  ASSERT((space == kNew && gc_new_space_in_progress_) ||
         (space == kOld && gc_old_space_in_progress_));
  stats_.num_++;
  stats_.space_ = space;
  stats_.reason_ = reason;
  stats_.before_.micros_ = OS::GetCurrentMonotonicMicros();
  stats_.before_.new_ = new_space_.GetCurrentUsage();
  stats_.before_.old_ = old_space_.GetCurrentUsage();
  for (int i = 0; i < GCStats::kTimeEntries; i++)
    stats_.times_[i] = 0;
  for (int i = 0; i < GCStats::kDataEntries; i++)
    stats_.data_[i] = 0;
}


void Heap::RecordAfterGC(Space space) {
  stats_.after_.micros_ = OS::GetCurrentMonotonicMicros();
  int64_t delta = stats_.after_.micros_ - stats_.before_.micros_;
  if (stats_.space_ == kNew) {
    new_space_.AddGCTime(delta);
    new_space_.IncrementCollections();
  } else {
    old_space_.AddGCTime(delta);
    old_space_.IncrementCollections();
  }
  stats_.after_.new_ = new_space_.GetCurrentUsage();
  stats_.after_.old_ = old_space_.GetCurrentUsage();
  ASSERT((space == kNew && gc_new_space_in_progress_) ||
         (space == kOld && gc_old_space_in_progress_));
#ifndef PRODUCT
  if (FLAG_support_service && Service::gc_stream.enabled() &&
      !ServiceIsolate::IsServiceIsolateDescendant(Isolate::Current())) {
    ServiceEvent event(Isolate::Current(), ServiceEvent::kGC);
    event.set_gc_stats(&stats_);
    Service::HandleEvent(&event);
  }
#endif  // !PRODUCT
}


void Heap::PrintStats() {
  if (!FLAG_verbose_gc) return;

  if ((FLAG_verbose_gc_hdr != 0) &&
      (((stats_.num_ - 1) % FLAG_verbose_gc_hdr) == 0)) {
    OS::PrintErr(
        "[              |                      |     |       |      "
        "| new gen     | new gen     | new gen "
        "| old gen       | old gen       | old gen     "
        "| sweep | safe- | roots/| stbuf/| tospc/| weaks/|               ]\n"
        "[ GC isolate   | space (reason)       | GC# | start | time "
        "| used (kB)   | capacity kB | external"
        "| used (kB)     | capacity (kB) | external kB "
        "| thread| point |marking| reset | sweep |swplrge| data          ]\n"
        "[              |                      |     |  (s)  | (ms) "
        "|before| after|before| after| b4 |aftr"
        "| before| after | before| after |before| after"
        "| (ms)  | (ms)  | (ms)  | (ms)  | (ms)  | (ms)  |               ]\n");
  }

  // clang-format off
  const char* space_str = stats_.space_ == kNew ? "Scavenge" : "Mark-Sweep";
  OS::PrintErr(
    "[ GC %9" Pd64 " : %10s(%9s), "  // GC(isolate), space(reason)
    "%4" Pd ", "  // count
    "%6.2f, "  // start time
    "%5.1f, "  // total time
    "%5" Pd ", %5" Pd ", "  // new gen: in use before/after
    "%5" Pd ", %5" Pd ", "  // new gen: capacity before/after
    "%3" Pd ", %3" Pd ", "  // new gen: external before/after
    "%6" Pd ", %6" Pd ", "  // old gen: in use before/after
    "%6" Pd ", %6" Pd ", "  // old gen: capacity before/after
    "%5" Pd ", %5" Pd ", "  // old gen: external before/after
    "%6.2f, %6.2f, %6.2f, %6.2f, %6.2f, %6.2f, "  // times
    "%" Pd ", %" Pd ", %" Pd ", %" Pd ", "  // data
    "]\n",  // End with a comma to make it easier to import in spreadsheets.
    isolate()->main_port(), space_str, GCReasonToString(stats_.reason_),
    stats_.num_,
    MicrosecondsToSeconds(isolate()->UptimeMicros()),
    MicrosecondsToMilliseconds(stats_.after_.micros_ -
                                    stats_.before_.micros_),
    RoundWordsToKB(stats_.before_.new_.used_in_words),
    RoundWordsToKB(stats_.after_.new_.used_in_words),
    RoundWordsToKB(stats_.before_.new_.capacity_in_words),
    RoundWordsToKB(stats_.after_.new_.capacity_in_words),
    RoundWordsToKB(stats_.before_.new_.external_in_words),
    RoundWordsToKB(stats_.after_.new_.external_in_words),
    RoundWordsToKB(stats_.before_.old_.used_in_words),
    RoundWordsToKB(stats_.after_.old_.used_in_words),
    RoundWordsToKB(stats_.before_.old_.capacity_in_words),
    RoundWordsToKB(stats_.after_.old_.capacity_in_words),
    RoundWordsToKB(stats_.before_.old_.external_in_words),
    RoundWordsToKB(stats_.after_.old_.external_in_words),
    MicrosecondsToMilliseconds(stats_.times_[0]),
    MicrosecondsToMilliseconds(stats_.times_[1]),
    MicrosecondsToMilliseconds(stats_.times_[2]),
    MicrosecondsToMilliseconds(stats_.times_[3]),
    MicrosecondsToMilliseconds(stats_.times_[4]),
    MicrosecondsToMilliseconds(stats_.times_[5]),
    stats_.data_[0],
    stats_.data_[1],
    stats_.data_[2],
    stats_.data_[3]);
  // clang-format on
}


void Heap::PrintStatsToTimeline(TimelineEventScope* event) {
#if !defined(PRODUCT)
  if ((event == NULL) || !event->enabled()) {
    return;
  }
  event->SetNumArguments(12);
  event->FormatArgument(0, "Before.New.Used (kB)", "%" Pd "",
                        RoundWordsToKB(stats_.before_.new_.used_in_words));
  event->FormatArgument(1, "After.New.Used (kB)", "%" Pd "",
                        RoundWordsToKB(stats_.after_.new_.used_in_words));
  event->FormatArgument(2, "Before.Old.Used (kB)", "%" Pd "",
                        RoundWordsToKB(stats_.before_.old_.used_in_words));
  event->FormatArgument(3, "After.Old.Used (kB)", "%" Pd "",
                        RoundWordsToKB(stats_.after_.old_.used_in_words));

  event->FormatArgument(4, "Before.New.Capacity (kB)", "%" Pd "",
                        RoundWordsToKB(stats_.before_.new_.capacity_in_words));
  event->FormatArgument(5, "After.New.Capacity (kB)", "%" Pd "",
                        RoundWordsToKB(stats_.after_.new_.capacity_in_words));
  event->FormatArgument(6, "Before.Old.Capacity (kB)", "%" Pd "",
                        RoundWordsToKB(stats_.before_.old_.capacity_in_words));
  event->FormatArgument(7, "After.Old.Capacity (kB)", "%" Pd "",
                        RoundWordsToKB(stats_.after_.old_.capacity_in_words));

  event->FormatArgument(8, "Before.New.External (kB)", "%" Pd "",
                        RoundWordsToKB(stats_.before_.new_.external_in_words));
  event->FormatArgument(9, "After.New.External (kB)", "%" Pd "",
                        RoundWordsToKB(stats_.after_.new_.external_in_words));
  event->FormatArgument(10, "Before.Old.External (kB)", "%" Pd "",
                        RoundWordsToKB(stats_.before_.old_.external_in_words));
  event->FormatArgument(11, "After.Old.External (kB)", "%" Pd "",
                        RoundWordsToKB(stats_.after_.old_.external_in_words));
#endif  // !defined(PRODUCT)
}


NoHeapGrowthControlScope::NoHeapGrowthControlScope()
    : StackResource(Thread::Current()) {
  Heap* heap = reinterpret_cast<Isolate*>(isolate())->heap();
  current_growth_controller_state_ = heap->GrowthControlState();
  heap->DisableGrowthControl();
}


NoHeapGrowthControlScope::~NoHeapGrowthControlScope() {
  Heap* heap = reinterpret_cast<Isolate*>(isolate())->heap();
  heap->SetGrowthControlState(current_growth_controller_state_);
}


WritableVMIsolateScope::WritableVMIsolateScope(Thread* thread)
    : StackResource(thread) {
  Dart::vm_isolate()->heap()->WriteProtect(false);
}


WritableVMIsolateScope::~WritableVMIsolateScope() {
  ASSERT(Dart::vm_isolate()->heap()->UsedInWords(Heap::kNew) == 0);
  Dart::vm_isolate()->heap()->WriteProtect(true);
}

}  // namespace dart