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// Copyright 2017 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_OBJECTS_STRING_TABLE_H_ #define V8_OBJECTS_STRING_TABLE_H_ #include "src/common/assert-scope.h" #include "src/objects/string.h" #include "src/roots/roots.h" // Has to be the last include (doesn't have include guards): #include "src/objects/object-macros.h" namespace v8 { namespace internal { // A generic key for lookups into the string table, which allows heteromorphic // lookup and on-demand creation of new strings. class StringTableKey { public: virtual ~StringTableKey() = default; inline StringTableKey(uint32_t raw_hash_field, int length); uint32_t raw_hash_field() const { DCHECK_NE(0, raw_hash_field_); return raw_hash_field_; } inline uint32_t hash() const; int length() const { return length_; } protected: inline void set_raw_hash_field(uint32_t raw_hash_field); private: uint32_t raw_hash_field_ = 0; int length_; }; class SeqOneByteString; // StringTable, for internalizing strings. The Lookup methods are designed to be // thread-safe, in combination with GC safepoints. // // The string table layout is defined by its Data implementation class, see // StringTable::Data for details. class V8_EXPORT_PRIVATE StringTable { public: static constexpr Tagged<Smi> empty_element() { return Smi::FromInt(0); } static constexpr Tagged<Smi> deleted_element() { return Smi::FromInt(1); } explicit StringTable(Isolate* isolate); ~StringTable(); int Capacity() const; int NumberOfElements() const; // Find string in the string table. If it is not there yet, it is // added. The return value is the string found. Handle<String> LookupString(Isolate* isolate, Handle<String> key); // Find string in the string table, using the given key. If the string is not // there yet, it is created (by the key) and added. The return value is the // string found. template <typename StringTableKey, typename IsolateT> Handle<String> LookupKey(IsolateT* isolate, StringTableKey* key); // {raw_string} must be a tagged String pointer. // Returns a tagged pointer: either a Smi if the string is an array index, an // internalized string, or a Smi sentinel. static Address TryStringToIndexOrLookupExisting(Isolate* isolate, Address raw_string); // Insert a range of strings. Only for use during isolate deserialization. void InsertForIsolateDeserialization( Isolate* isolate, const std::vector<Handle<String>>& strings); void Print(PtrComprCageBase cage_base) const; size_t GetCurrentMemoryUsage() const; // The following methods must be called either while holding the write lock, // or while in a Heap safepoint. void IterateElements(RootVisitor* visitor); void DropOldData(); void NotifyElementsRemoved(int count); void VerifyIfOwnedBy(Isolate* isolate); private: class Data; Data* EnsureCapacity(PtrComprCageBase cage_base, int additional_elements); std::atomic<Data*> data_; // Write mutex is mutable so that readers of concurrently mutated values (e.g. // NumberOfElements) are allowed to lock it while staying const. mutable base::Mutex write_mutex_; Isolate* isolate_; }; } // namespace internal } // namespace v8 #include "src/objects/object-macros-undef.h" #endif // V8_OBJECTS_STRING_TABLE_H_