1 // Copyright 2006-2008 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_SNAPSHOT_H_ 6 #define V8_SNAPSHOT_SNAPSHOT_H_ 7 8 #include "src/snapshot/serialize.h" 9 10 namespace v8 { 11 namespace internal { 12 13 // Forward declarations. 14 class Isolate; 15 class PartialSerializer; 16 class StartupSerializer; 17 18 class Snapshot : public AllStatic { 19 public: 20 class Metadata { 21 public: data_(data)22 explicit Metadata(uint32_t data = 0) : data_(data) {} embeds_script()23 bool embeds_script() { return EmbedsScriptBits::decode(data_); } set_embeds_script(bool v)24 void set_embeds_script(bool v) { 25 data_ = EmbedsScriptBits::update(data_, v); 26 } 27 RawValue()28 uint32_t& RawValue() { return data_; } 29 30 private: 31 class EmbedsScriptBits : public BitField<bool, 0, 1> {}; 32 uint32_t data_; 33 }; 34 35 // Initialize the Isolate from the internal snapshot. Returns false if no 36 // snapshot could be found. 37 static bool Initialize(Isolate* isolate); 38 // Create a new context using the internal partial snapshot. 39 static MaybeHandle<Context> NewContextFromSnapshot( 40 Isolate* isolate, Handle<JSGlobalProxy> global_proxy); 41 42 static bool HaveASnapshotToStartFrom(Isolate* isolate); 43 44 static bool EmbedsScript(Isolate* isolate); 45 46 static uint32_t SizeOfFirstPage(Isolate* isolate, AllocationSpace space); 47 48 49 // To be implemented by the snapshot source. 50 static const v8::StartupData* DefaultSnapshotBlob(); 51 52 static v8::StartupData CreateSnapshotBlob( 53 const StartupSerializer& startup_ser, 54 const PartialSerializer& context_ser, Snapshot::Metadata metadata); 55 56 #ifdef DEBUG 57 static bool SnapshotIsValid(v8::StartupData* snapshot_blob); 58 #endif // DEBUG 59 60 private: 61 static Vector<const byte> ExtractStartupData(const v8::StartupData* data); 62 static Vector<const byte> ExtractContextData(const v8::StartupData* data); 63 static Metadata ExtractMetadata(const v8::StartupData* data); 64 65 // Snapshot blob layout: 66 // [0] metadata 67 // [1 - 6] pre-calculated first page sizes for paged spaces 68 // [7] serialized start up data length 69 // ... serialized start up data 70 // ... serialized context data 71 72 static const int kNumPagedSpaces = LAST_PAGED_SPACE - FIRST_PAGED_SPACE + 1; 73 74 static const int kMetadataOffset = 0; 75 static const int kFirstPageSizesOffset = kMetadataOffset + kInt32Size; 76 static const int kStartupLengthOffset = 77 kFirstPageSizesOffset + kNumPagedSpaces * kInt32Size; 78 static const int kStartupDataOffset = kStartupLengthOffset + kInt32Size; 79 ContextOffset(int startup_length)80 static int ContextOffset(int startup_length) { 81 return kStartupDataOffset + startup_length; 82 } 83 84 DISALLOW_IMPLICIT_CONSTRUCTORS(Snapshot); 85 }; 86 87 #ifdef V8_USE_EXTERNAL_STARTUP_DATA 88 void SetSnapshotFromFile(StartupData* snapshot_blob); 89 #endif 90 91 } // namespace internal 92 } // namespace v8 93 94 #endif // V8_SNAPSHOT_SNAPSHOT_H_ 95