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// 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 <stddef.h>
#include <memory>
#include <string>
#include <vector>
#include "base/base_export.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/memory/shared_memory.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<RefCountedMemory> {
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<RefCountedMemory>& other) const;
// Handy method to simplify calling front() with a reinterpret_cast.
template<typename T> const T* front_as() const {
return reinterpret_cast<const T*>(front());
}
protected:
friend class RefCountedThreadSafe<RefCountedMemory>;
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<const unsigned char*>(length ? data : nullptr)),
length_(length) {}
// RefCountedMemory:
const unsigned char* front() const override;
size_t size() const override;
private:
~RefCountedStaticMemory() override;
const unsigned char* data_;
size_t length_;
DISALLOW_COPY_AND_ASSIGN(RefCountedStaticMemory);
};
// 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<unsigned char>& 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);
// Constructs a RefCountedBytes object by performing a swap. (To non
// destructively build a RefCountedBytes, use the constructor that takes a
// vector.)
static scoped_refptr<RefCountedBytes> TakeVector(
std::vector<unsigned char>* to_destroy);
// RefCountedMemory:
const unsigned char* front() const override;
size_t size() const override;
const std::vector<unsigned char>& data() const { return data_; }
std::vector<unsigned char>& 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 <typename T>
T* front_as() {
return reinterpret_cast<T*>(front());
}
private:
~RefCountedBytes() override;
std::vector<unsigned char> data_;
DISALLOW_COPY_AND_ASSIGN(RefCountedBytes);
};
// 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();
// 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<RefCountedString> TakeString(std::string* to_destroy);
// 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_;
DISALLOW_COPY_AND_ASSIGN(RefCountedString);
};
// An implementation of RefCountedMemory, where the bytes are stored in
// SharedMemory.
class BASE_EXPORT RefCountedSharedMemory : public RefCountedMemory {
public:
// Constructs a RefCountedMemory object by taking ownership of an already
// mapped SharedMemory object.
RefCountedSharedMemory(std::unique_ptr<SharedMemory> shm, size_t size);
// RefCountedMemory:
const unsigned char* front() const override;
size_t size() const override;
private:
~RefCountedSharedMemory() override;
const std::unique_ptr<SharedMemory> shm_;
const size_t size_;
DISALLOW_COPY_AND_ASSIGN(RefCountedSharedMemory);
};
// 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);
// 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<RefCountedSharedMemoryMapping> 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_;
DISALLOW_COPY_AND_ASSIGN(RefCountedSharedMemoryMapping);
};
} // namespace base
#endif // BASE_MEMORY_REF_COUNTED_MEMORY_H_