// Copyright 2020 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/heap/cppgc/heap-base.h"

#include <memory>

#include "include/cppgc/heap-consistency.h"
#include "include/cppgc/platform.h"
#include "src/base/logging.h"
#include "src/base/platform/platform.h"
#include "src/base/sanitizer/lsan-page-allocator.h"
#include "src/heap/base/stack.h"
#include "src/heap/cppgc/globals.h"
#include "src/heap/cppgc/heap-config.h"
#include "src/heap/cppgc/heap-object-header.h"
#include "src/heap/cppgc/heap-page.h"
#include "src/heap/cppgc/heap-statistics-collector.h"
#include "src/heap/cppgc/heap-visitor.h"
#include "src/heap/cppgc/marking-verifier.h"
#include "src/heap/cppgc/object-view.h"
#include "src/heap/cppgc/page-memory.h"
#include "src/heap/cppgc/platform.h"
#include "src/heap/cppgc/prefinalizer-handler.h"
#include "src/heap/cppgc/stats-collector.h"
#include "src/heap/cppgc/unmarker.h"
#include "src/heap/cppgc/write-barrier.h"

namespace cppgc {
namespace internal {

namespace {

class ObjectSizeCounter : private HeapVisitor<ObjectSizeCounter> {
  friend class HeapVisitor<ObjectSizeCounter>;

 public:
  size_t GetSize(RawHeap& heap) {
    Traverse(heap);
    return accumulated_size_;
  }

 private:
  static size_t ObjectSize(const HeapObjectHeader& header) {
    return ObjectView<>(header).Size();
  }

  bool VisitHeapObjectHeader(HeapObjectHeader& header) {
    if (header.IsFree()) return true;
    accumulated_size_ += ObjectSize(header);
    return true;
  }

  size_t accumulated_size_ = 0;
};

#if defined(CPPGC_YOUNG_GENERATION)
class AgeTableResetter final : protected HeapVisitor<AgeTableResetter> {
  friend class HeapVisitor<AgeTableResetter>;

 public:
  AgeTableResetter() : age_table_(CagedHeapLocalData::Get().age_table) {}

  void Run(RawHeap& raw_heap) { Traverse(raw_heap); }

 protected:
  bool VisitPage(BasePage& page) {
    if (!page.contains_young_objects()) {
#if defined(DEBUG)
      DCHECK_EQ(AgeTable::Age::kOld,
                age_table_.GetAgeForRange(
                    CagedHeap::OffsetFromAddress(page.PayloadStart()),
                    CagedHeap::OffsetFromAddress(page.PayloadEnd())));
#endif  // defined(DEBUG)
      return true;
    }

    // Mark the entire page as old in the age-table.
    // TODO(chromium:1029379): Consider decommitting pages once in a while.
    age_table_.SetAgeForRange(CagedHeap::OffsetFromAddress(page.PayloadStart()),
                              CagedHeap::OffsetFromAddress(page.PayloadEnd()),
                              AgeTable::Age::kOld,
                              AgeTable::AdjacentCardsPolicy::kIgnore);
    // Promote page.
    page.set_as_containing_young_objects(false);
    return true;
  }

  bool VisitNormalPage(NormalPage& page) { return VisitPage(page); }
  bool VisitLargePage(LargePage& page) { return VisitPage(page); }

 private:
  AgeTable& age_table_;
};
#endif  // defined(CPPGC_YOUNG_GENERATION)

}  // namespace

HeapBase::HeapBase(
    std::shared_ptr<cppgc::Platform> platform,
    const std::vector<std::unique_ptr<CustomSpaceBase>>& custom_spaces,
    StackSupport stack_support, MarkingType marking_support,
    SweepingType sweeping_support, GarbageCollector& garbage_collector)
    : raw_heap_(this, custom_spaces),
      platform_(std::move(platform)),
      oom_handler_(std::make_unique<FatalOutOfMemoryHandler>(this)),
#if defined(LEAK_SANITIZER)
      lsan_page_allocator_(std::make_unique<v8::base::LsanPageAllocator>(
          platform_->GetPageAllocator())),
#endif  // LEAK_SANITIZER
      page_backend_(InitializePageBackend(*page_allocator())),
      stats_collector_(std::make_unique<StatsCollector>(platform_.get())),
      stack_(std::make_unique<heap::base::Stack>(
          v8::base::Stack::GetStackStart())),
      prefinalizer_handler_(std::make_unique<PreFinalizerHandler>(*this)),
      compactor_(raw_heap_),
      object_allocator_(raw_heap_, *page_backend_, *stats_collector_,
                        *prefinalizer_handler_, *oom_handler_,
                        garbage_collector),
      sweeper_(*this),
      strong_persistent_region_(*oom_handler_),
      weak_persistent_region_(*oom_handler_),
      strong_cross_thread_persistent_region_(*oom_handler_),
      weak_cross_thread_persistent_region_(*oom_handler_),
#if defined(CPPGC_YOUNG_GENERATION)
      remembered_set_(*this),
#endif  // defined(CPPGC_YOUNG_GENERATION)
      stack_support_(stack_support),
      marking_support_(marking_support),
      sweeping_support_(sweeping_support) {
  stats_collector_->RegisterObserver(
      &allocation_observer_for_PROCESS_HEAP_STATISTICS_);
}

HeapBase::~HeapBase() = default;

PageAllocator* HeapBase::page_allocator() const {
#if defined(LEAK_SANITIZER)
  return lsan_page_allocator_.get();
#else   // !LEAK_SANITIZER
  return platform_->GetPageAllocator();
#endif  // !LEAK_SANITIZER
}

size_t HeapBase::ObjectPayloadSize() const {
  return ObjectSizeCounter().GetSize(const_cast<RawHeap&>(raw_heap()));
}

// static
std::unique_ptr<PageBackend> HeapBase::InitializePageBackend(
    PageAllocator& allocator) {
#if defined(CPPGC_CAGED_HEAP)
  auto& caged_heap = CagedHeap::Instance();
  return std::make_unique<PageBackend>(caged_heap.page_allocator(),
                                       caged_heap.page_allocator());
#else   // !CPPGC_CAGED_HEAP
  return std::make_unique<PageBackend>(allocator, allocator);
#endif  // !CPPGC_CAGED_HEAP
}

size_t HeapBase::ExecutePreFinalizers() {
#ifdef CPPGC_ALLOW_ALLOCATIONS_IN_PREFINALIZERS
  // Allocations in pre finalizers should not trigger another GC.
  cppgc::subtle::NoGarbageCollectionScope no_gc_scope(*this);
#else
  // Pre finalizers are forbidden from allocating objects.
  cppgc::subtle::DisallowGarbageCollectionScope no_gc_scope(*this);
#endif  // CPPGC_ALLOW_ALLOCATIONS_IN_PREFINALIZERS
  prefinalizer_handler_->InvokePreFinalizers();
  return prefinalizer_handler_->ExtractBytesAllocatedInPrefinalizers();
}

#if defined(CPPGC_YOUNG_GENERATION)
void HeapBase::EnableGenerationalGC() {
  DCHECK(in_atomic_pause());
  if (HeapHandle::is_young_generation_enabled_) return;
  // Notify the global flag that the write barrier must always be enabled.
  YoungGenerationEnabler::Enable();
  // Enable young generation for the current heap.
  HeapHandle::is_young_generation_enabled_ = true;
  // Assume everything that has so far been allocated is young.
  object_allocator_.MarkAllPagesAsYoung();
}

void HeapBase::ResetRememberedSet() {
  DCHECK(in_atomic_pause());
  class AllLABsAreEmpty final : protected HeapVisitor<AllLABsAreEmpty> {
    friend class HeapVisitor<AllLABsAreEmpty>;

   public:
    explicit AllLABsAreEmpty(RawHeap& raw_heap) { Traverse(raw_heap); }

    bool value() const { return !some_lab_is_set_; }

   protected:
    bool VisitNormalPageSpace(NormalPageSpace& space) {
      some_lab_is_set_ |=
          static_cast<bool>(space.linear_allocation_buffer().size());
      return true;
    }

   private:
    bool some_lab_is_set_ = false;
  };
  DCHECK(AllLABsAreEmpty(raw_heap()).value());

  if (!generational_gc_supported()) {
    DCHECK(remembered_set_.IsEmpty());
    return;
  }

  AgeTableResetter age_table_resetter;
  age_table_resetter.Run(raw_heap());

  remembered_set_.Reset();
}

#endif  // defined(CPPGC_YOUNG_GENERATION)

void HeapBase::Terminate() {
  CHECK(!IsMarking());
  CHECK(!in_disallow_gc_scope());
  // Cannot use IsGCAllowed() as `Terminate()` will be invoked after detaching
  // which implies GC is prohibited at this point.
  CHECK(!sweeper().IsSweepingOnMutatorThread());

  sweeper().FinishIfRunning();

#if defined(CPPGC_YOUNG_GENERATION)
  if (generational_gc_supported()) {
    DCHECK(is_young_generation_enabled());
    HeapHandle::is_young_generation_enabled_ = false;
    YoungGenerationEnabler::Disable();
  }
#endif  // defined(CPPGC_YOUNG_GENERATION)

  constexpr size_t kMaxTerminationGCs = 20;
  size_t gc_count = 0;
  bool more_termination_gcs_needed = false;
  do {
    // Clear root sets.
    strong_persistent_region_.ClearAllUsedNodes();
    weak_persistent_region_.ClearAllUsedNodes();
    {
      PersistentRegionLock guard;
      strong_cross_thread_persistent_region_.ClearAllUsedNodes();
      weak_cross_thread_persistent_region_.ClearAllUsedNodes();
    }

#if defined(CPPGC_YOUNG_GENERATION)
    if (generational_gc_supported()) {
      // Unmark the heap so that the sweeper destructs all objects.
      // TODO(chromium:1029379): Merge two heap iterations (unmarking +
      // sweeping) into forced finalization.
      SequentialUnmarker unmarker(raw_heap());
    }
#endif  // defined(CPPGC_YOUNG_GENERATION)

    in_atomic_pause_ = true;
    stats_collector()->NotifyMarkingStarted(CollectionType::kMajor,
                                            GCConfig::MarkingType::kAtomic,
                                            GCConfig::IsForcedGC::kForced);
    object_allocator().ResetLinearAllocationBuffers();
    stats_collector()->NotifyMarkingCompleted(0);
    ExecutePreFinalizers();
    // TODO(chromium:1029379): Prefinalizers may black-allocate objects (under a
    // compile-time option). Run sweeping with forced finalization here.
    sweeper().Start({SweepingConfig::SweepingType::kAtomic,
                     SweepingConfig::CompactableSpaceHandling::kSweep});
    in_atomic_pause_ = false;
    sweeper().FinishIfRunning();
    more_termination_gcs_needed =
        strong_persistent_region_.NodesInUse() ||
        weak_persistent_region_.NodesInUse() || [this]() {
          PersistentRegionLock guard;
          return strong_cross_thread_persistent_region_.NodesInUse() ||
                 weak_cross_thread_persistent_region_.NodesInUse();
        }();
    gc_count++;
  } while (more_termination_gcs_needed && (gc_count < kMaxTerminationGCs));

  CHECK_EQ(0u, strong_persistent_region_.NodesInUse());
  CHECK_EQ(0u, weak_persistent_region_.NodesInUse());
  {
    PersistentRegionLock guard;
    CHECK_EQ(0u, strong_cross_thread_persistent_region_.NodesInUse());
    CHECK_EQ(0u, weak_cross_thread_persistent_region_.NodesInUse());
  }
  CHECK_LE(gc_count, kMaxTerminationGCs);

  object_allocator().ResetLinearAllocationBuffers();
  disallow_gc_scope_++;
}

HeapStatistics HeapBase::CollectStatistics(
    HeapStatistics::DetailLevel detail_level) {
  if (detail_level == HeapStatistics::DetailLevel::kBrief) {
    return {stats_collector_->allocated_memory_size(),
            stats_collector_->resident_memory_size(),
            stats_collector_->allocated_object_size(),
            HeapStatistics::DetailLevel::kBrief,
            {},
            {}};
  }

  sweeper_.FinishIfRunning();
  object_allocator_.ResetLinearAllocationBuffers();
  return HeapStatisticsCollector().CollectDetailedStatistics(this);
}

void HeapBase::CallMoveListeners(Address from, Address to,
                                 size_t size_including_header) {
  for (const auto& listener : move_listeners_) {
    listener->OnMove(from, to, size_including_header);
  }
}

void HeapBase::RegisterMoveListener(MoveListener* listener) {
  // Registering the same listener multiple times would work, but probably
  // indicates a mistake in the component requesting the registration.
  DCHECK_EQ(std::find(move_listeners_.begin(), move_listeners_.end(), listener),
            move_listeners_.end());
  move_listeners_.push_back(listener);
}

void HeapBase::UnregisterMoveListener(MoveListener* listener) {
  auto it =
      std::remove(move_listeners_.begin(), move_listeners_.end(), listener);
  move_listeners_.erase(it, move_listeners_.end());
}

bool HeapBase::IsGCAllowed() const {
  // GC is prohibited in a GC forbidden scope, or when currently sweeping an
  // object.
  return !sweeper().IsSweepingOnMutatorThread() && !in_no_gc_scope();
}

ClassNameAsHeapObjectNameScope::ClassNameAsHeapObjectNameScope(HeapBase& heap)
    : heap_(heap),
      saved_heap_object_name_value_(heap_.name_of_unnamed_object()) {
  heap_.set_name_of_unnamed_object(
      HeapObjectNameForUnnamedObject::kUseClassNameIfSupported);
}

ClassNameAsHeapObjectNameScope::~ClassNameAsHeapObjectNameScope() {
  heap_.set_name_of_unnamed_object(saved_heap_object_name_value_);
}

}  // namespace internal
}  // namespace cppgc
