// Copyright (c) 2012 The Chromium 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 BASE_MEMORY_REF_COUNTED_MEMORY_H_ #define BASE_MEMORY_REF_COUNTED_MEMORY_H_ #include #include #include #include #include "base/base_export.h" #include "base/containers/span.h" #include "base/memory/ref_counted.h" #include "base/memory/shared_memory_mapping.h" namespace base { class ReadOnlySharedMemoryRegion; // A generic interface to memory. This object is reference counted because most // of its subclasses own the data they carry, and this interface needs to // support heterogeneous containers of these different types of memory. class BASE_EXPORT RefCountedMemory : public RefCountedThreadSafe { public: // Retrieves a pointer to the beginning of the data we point to. If the data // is empty, this will return NULL. virtual const unsigned char* front() const = 0; // Size of the memory pointed to. virtual size_t size() const = 0; // Returns true if |other| is byte for byte equal. bool Equals(const scoped_refptr& other) const; // Handy method to simplify calling front() with a reinterpret_cast. template const T* front_as() const { return reinterpret_cast(front()); } // Alias for front() to make it possible for RefCountedMemory to implicitly // convert to span. const unsigned char* data() const { return front(); } protected: friend class RefCountedThreadSafe; RefCountedMemory(); virtual ~RefCountedMemory(); }; // An implementation of RefCountedMemory, where the ref counting does not // matter. class BASE_EXPORT RefCountedStaticMemory : public RefCountedMemory { public: RefCountedStaticMemory() : data_(nullptr), length_(0) {} RefCountedStaticMemory(const void* data, size_t length) : data_(static_cast(length ? data : nullptr)), length_(length) {} RefCountedStaticMemory(const RefCountedStaticMemory&) = delete; RefCountedStaticMemory& operator=(const RefCountedStaticMemory&) = delete; // RefCountedMemory: const unsigned char* front() const override; size_t size() const override; private: ~RefCountedStaticMemory() override; const unsigned char* data_; size_t length_; }; // An implementation of RefCountedMemory, where the data is stored in a STL // vector. class BASE_EXPORT RefCountedBytes : public RefCountedMemory { public: RefCountedBytes(); // Constructs a RefCountedBytes object by copying from |initializer|. explicit RefCountedBytes(const std::vector& initializer); explicit RefCountedBytes(base::span initializer); // Constructs a RefCountedBytes object by copying |size| bytes from |p|. RefCountedBytes(const unsigned char* p, size_t size); // Constructs a RefCountedBytes object by zero-initializing a new vector of // |size| bytes. explicit RefCountedBytes(size_t size); RefCountedBytes(const RefCountedBytes&) = delete; RefCountedBytes& operator=(const RefCountedBytes&) = delete; // Constructs a RefCountedBytes object by performing a swap. (To non // destructively build a RefCountedBytes, use the constructor that takes a // vector.) static scoped_refptr TakeVector( std::vector* to_destroy); // RefCountedMemory: const unsigned char* front() const override; size_t size() const override; const std::vector& data() const { return data_; } std::vector& data() { return data_; } // Non-const versions of front() and front_as() that are simply shorthand for // data().data(). unsigned char* front() { return data_.data(); } template T* front_as() { return reinterpret_cast(front()); } private: ~RefCountedBytes() override; std::vector data_; }; // An implementation of RefCountedMemory, where the bytes are stored in a STL // string. Use this if your data naturally arrives in that format. class BASE_EXPORT RefCountedString : public RefCountedMemory { public: RefCountedString(); RefCountedString(const RefCountedString&) = delete; RefCountedString& operator=(const RefCountedString&) = delete; // Constructs a RefCountedString object by performing a swap. (To non // destructively build a RefCountedString, use the default constructor and // copy into object->data()). static scoped_refptr TakeString(std::string* to_destroy); static scoped_refptr TakeString(std::string&& str); // RefCountedMemory: const unsigned char* front() const override; size_t size() const override; const std::string& data() const { return data_; } std::string& data() { return data_; } private: ~RefCountedString() override; std::string data_; }; // An implementation of RefCountedMemory, where the bytes are stored in a // std::u16string. class BASE_EXPORT RefCountedString16 : public base::RefCountedMemory { public: RefCountedString16(); RefCountedString16(const RefCountedString16&) = delete; RefCountedString16& operator=(const RefCountedString16&) = delete; // Constructs a RefCountedString16 object by performing a swap. static scoped_refptr TakeString( std::u16string* to_destroy); static scoped_refptr TakeString(std::u16string&& str); // RefCountedMemory: const unsigned char* front() const override; size_t size() const override; protected: ~RefCountedString16() override; private: std::u16string data_; }; // An implementation of RefCountedMemory, where the bytes are stored in // ReadOnlySharedMemoryMapping. class BASE_EXPORT RefCountedSharedMemoryMapping : public RefCountedMemory { public: // Constructs a RefCountedMemory object by taking ownership of an already // mapped ReadOnlySharedMemoryMapping object. explicit RefCountedSharedMemoryMapping(ReadOnlySharedMemoryMapping mapping); RefCountedSharedMemoryMapping(const RefCountedSharedMemoryMapping&) = delete; RefCountedSharedMemoryMapping& operator=( const RefCountedSharedMemoryMapping&) = delete; // Convenience method to map all of |region| and take ownership of the // mapping. Returns an empty scoped_refptr if the map operation fails. static scoped_refptr CreateFromWholeRegion( const ReadOnlySharedMemoryRegion& region); // RefCountedMemory: const unsigned char* front() const override; size_t size() const override; private: ~RefCountedSharedMemoryMapping() override; const ReadOnlySharedMemoryMapping mapping_; const size_t size_; }; } // namespace base #endif // BASE_MEMORY_REF_COUNTED_MEMORY_H_