Line data    Source code

       1             : // Copyright 2017 the V8 project authors. All rights reserved.
       2             : // Use of this source code is governed by a BSD-style license that can be
       3             : // found in the LICENSE file.
       4             : 
       5             : #ifndef V8_SNAPSHOT_SERIALIZER_ALLOCATOR_H_
       6             : #define V8_SNAPSHOT_SERIALIZER_ALLOCATOR_H_
       7             : 
       8             : #include "src/snapshot/serializer-common.h"
       9             : 
      10             : namespace v8 {
      11             : namespace internal {
      12             : 
      13             : class Serializer;
      14             : 
      15        2274 : class SerializerAllocator final {
      16             :  public:
      17             :   explicit SerializerAllocator(Serializer* serializer);
      18             : 
      19             :   SerializerReference Allocate(AllocationSpace space, uint32_t size);
      20             :   SerializerReference AllocateMap();
      21             :   SerializerReference AllocateLargeObject(uint32_t size);
      22             :   SerializerReference AllocateOffHeapBackingStore();
      23             : 
      24             :   void UseCustomChunkSize(uint32_t chunk_size);
      25             : 
      26             : #ifdef DEBUG
      27             :   bool BackReferenceIsAlreadyAllocated(
      28             :       SerializerReference back_reference) const;
      29             : #endif
      30             : 
      31             :   std::vector<SerializedData::Reservation> EncodeReservations() const;
      32             : 
      33             :   void OutputStatistics();
      34             : 
      35             :  private:
      36             :   // We try to not exceed this size for every chunk. We will not succeed for
      37             :   // larger objects though.
      38             :   uint32_t TargetChunkSize(int space);
      39             : 
      40             :   static constexpr int kNumberOfPreallocatedSpaces =
      41             :       SerializerDeserializer::kNumberOfPreallocatedSpaces;
      42             :   static constexpr int kNumberOfSpaces =
      43             :       SerializerDeserializer::kNumberOfSpaces;
      44             : 
      45             :   // Objects from the same space are put into chunks for bulk-allocation
      46             :   // when deserializing. We have to make sure that each chunk fits into a
      47             :   // page. So we track the chunk size in pending_chunk_ of a space, but
      48             :   // when it exceeds a page, we complete the current chunk and start a new one.
      49             :   uint32_t pending_chunk_[kNumberOfPreallocatedSpaces];
      50             :   std::vector<uint32_t> completed_chunks_[kNumberOfPreallocatedSpaces];
      51             : 
      52             :   // Number of maps that we need to allocate.
      53             :   uint32_t num_maps_ = 0;
      54             : 
      55             :   // We map serialized large objects to indexes for back-referencing.
      56             :   uint32_t large_objects_total_size_ = 0;
      57             :   uint32_t seen_large_objects_index_ = 0;
      58             : 
      59             :   // Used to keep track of the off-heap backing stores used by TypedArrays/
      60             :   // ArrayBuffers. Note that the index begins at 1 and not 0, because when a
      61             :   // TypedArray has an on-heap backing store, the backing_store pointer in the
      62             :   // corresponding ArrayBuffer will be null, which makes it indistinguishable
      63             :   // from index 0.
      64             :   uint32_t seen_backing_stores_index_ = 1;
      65             : 
      66             :   uint32_t custom_chunk_size_ = 0;
      67             : 
      68             :   // The current serializer.
      69             :   Serializer* const serializer_;
      70             : 
      71             :   DISALLOW_COPY_AND_ASSIGN(SerializerAllocator);
      72             : };
      73             : 
      74             : }  // namespace internal
      75             : }  // namespace v8
      76             : 
      77             : #endif  // V8_SNAPSHOT_SERIALIZER_ALLOCATOR_H_