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// Copyright 2016 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.
#ifndef V8_HEAP_ARRAY_BUFFER_TRACKER_INL_H_
#define V8_HEAP_ARRAY_BUFFER_TRACKER_INL_H_
#include "src/heap/array-buffer-tracker.h"
#include "src/heap/heap-inl.h"
#include "src/heap/spaces-inl.h"
#include "src/numbers/conversions-inl.h"
#include "src/objects/js-array-buffer-inl.h"
#include "src/objects/objects.h"
#define TRACE_BS(...) \
do { \
if (FLAG_trace_backing_store) PrintF(__VA_ARGS__); \
} while (false)
namespace v8 {
namespace internal {
void ArrayBufferTracker::RegisterNew(
Heap* heap, JSArrayBuffer buffer,
std::shared_ptr<BackingStore> backing_store) {
if (!backing_store) return;
// If {buffer_start} is {nullptr}, we don't have to track and free it.
if (!backing_store->buffer_start()) return;
// ArrayBuffer tracking works only for small objects.
DCHECK(!heap->IsLargeObject(buffer));
DCHECK_EQ(backing_store->buffer_start(), buffer.backing_store());
const size_t length = backing_store->PerIsolateAccountingLength();
Page* page = Page::FromHeapObject(buffer);
{
base::MutexGuard guard(page->mutex());
LocalArrayBufferTracker* tracker = page->local_tracker();
if (tracker == nullptr) {
page->AllocateLocalTracker();
tracker = page->local_tracker();
}
DCHECK_NOT_NULL(tracker);
TRACE_BS("ABT:reg bs=%p mem=%p (length=%zu) cnt=%ld\n",
backing_store.get(), backing_store->buffer_start(),
backing_store->byte_length(), backing_store.use_count());
tracker->Add(buffer, std::move(backing_store));
}
// TODO(wez): Remove backing-store from external memory accounting.
// We may go over the limit of externally allocated memory here. We call the
// api function to trigger a GC in this case.
reinterpret_cast<v8::Isolate*>(heap->isolate())
->AdjustAmountOfExternalAllocatedMemory(length);
}
std::shared_ptr<BackingStore> ArrayBufferTracker::Unregister(
Heap* heap, JSArrayBuffer buffer) {
std::shared_ptr<BackingStore> backing_store;
Page* page = Page::FromHeapObject(buffer);
{
base::MutexGuard guard(page->mutex());
LocalArrayBufferTracker* tracker = page->local_tracker();
DCHECK_NOT_NULL(tracker);
backing_store = tracker->Remove(buffer);
}
// TODO(wez): Remove backing-store from external memory accounting.
const size_t length = backing_store->PerIsolateAccountingLength();
heap->update_external_memory(-static_cast<intptr_t>(length));
return backing_store;
}
std::shared_ptr<BackingStore> ArrayBufferTracker::Lookup(Heap* heap,
JSArrayBuffer buffer) {
if (buffer.backing_store() == nullptr) return {};
Page* page = Page::FromHeapObject(buffer);
base::MutexGuard guard(page->mutex());
LocalArrayBufferTracker* tracker = page->local_tracker();
DCHECK_NOT_NULL(tracker);
return tracker->Lookup(buffer);
}
template <typename Callback>
void LocalArrayBufferTracker::Free(Callback should_free) {
size_t freed_memory = 0;
for (TrackingData::iterator it = array_buffers_.begin();
it != array_buffers_.end();) {
// Unchecked cast because the map might already be dead at this point.
JSArrayBuffer buffer = JSArrayBuffer::unchecked_cast(it->first);
const size_t length = it->second->PerIsolateAccountingLength();
if (should_free(buffer)) {
// Destroy the shared pointer, (perhaps) freeing the backing store.
TRACE_BS("ABT:die bs=%p mem=%p (length=%zu) cnt=%ld\n",
it->second.get(), it->second->buffer_start(),
it->second->byte_length(), it->second.use_count());
it = array_buffers_.erase(it);
freed_memory += length;
} else {
++it;
}
}
if (freed_memory > 0) {
page_->DecrementExternalBackingStoreBytes(
ExternalBackingStoreType::kArrayBuffer, freed_memory);
// TODO(wez): Remove backing-store from external memory accounting.
page_->heap()->update_external_memory_concurrently_freed(freed_memory);
}
}
template <typename MarkingState>
void ArrayBufferTracker::FreeDead(Page* page, MarkingState* marking_state) {
// Callers need to ensure having the page lock.
LocalArrayBufferTracker* tracker = page->local_tracker();
if (tracker == nullptr) return;
tracker->Free([marking_state](JSArrayBuffer buffer) {
return marking_state->IsWhite(buffer);
});
if (tracker->IsEmpty()) {
page->ReleaseLocalTracker();
}
}
void LocalArrayBufferTracker::Add(JSArrayBuffer buffer,
std::shared_ptr<BackingStore> backing_store) {
auto length = backing_store->PerIsolateAccountingLength();
page_->IncrementExternalBackingStoreBytes(
ExternalBackingStoreType::kArrayBuffer, length);
AddInternal(buffer, std::move(backing_store));
}
void LocalArrayBufferTracker::AddInternal(
JSArrayBuffer buffer, std::shared_ptr<BackingStore> backing_store) {
auto ret = array_buffers_.insert({buffer, std::move(backing_store)});
USE(ret);
// Check that we indeed inserted a new value and did not overwrite an existing
// one (which would be a bug).
DCHECK(ret.second);
}
std::shared_ptr<BackingStore> LocalArrayBufferTracker::Remove(
JSArrayBuffer buffer) {
TrackingData::iterator it = array_buffers_.find(buffer);
// Check that we indeed find a key to remove.
DCHECK(it != array_buffers_.end());
// Steal the underlying shared pointer before erasing the entry.
std::shared_ptr<BackingStore> backing_store = std::move(it->second);
TRACE_BS("ABT:rm bs=%p mem=%p (length=%zu) cnt=%ld\n", backing_store.get(),
backing_store->buffer_start(), backing_store->byte_length(),
backing_store.use_count());
// Erase the entry.
array_buffers_.erase(it);
// Update accounting.
auto length = backing_store->PerIsolateAccountingLength();
page_->DecrementExternalBackingStoreBytes(
ExternalBackingStoreType::kArrayBuffer, length);
return backing_store;
}
std::shared_ptr<BackingStore> LocalArrayBufferTracker::Lookup(
JSArrayBuffer buffer) {
TrackingData::iterator it = array_buffers_.find(buffer);
if (it != array_buffers_.end()) {
return it->second;
}
return {};
}
#undef TRACE_BS
} // namespace internal
} // namespace v8
#endif // V8_HEAP_ARRAY_BUFFER_TRACKER_INL_H_
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