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/*
* Copyright (C) 2017 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef INCLUDE_PERFETTO_BASE_PAGED_MEMORY_H_
#define INCLUDE_PERFETTO_BASE_PAGED_MEMORY_H_
#include <memory>
#include "perfetto/base/build_config.h"
#include "perfetto/base/container_annotations.h"
// We need to track the committed size on windows and when ASAN is enabled.
#if PERFETTO_BUILDFLAG(PERFETTO_OS_WIN) || defined(ADDRESS_SANITIZER)
#define TRACK_COMMITTED_SIZE() 1
#else
#define TRACK_COMMITTED_SIZE() 0
#endif
namespace perfetto {
namespace base {
class PagedMemory {
public:
// Initializes an invalid PagedMemory pointing to nullptr.
PagedMemory();
~PagedMemory();
PagedMemory(PagedMemory&& other) noexcept;
PagedMemory& operator=(PagedMemory&& other);
enum AllocationFlags {
// By default, Allocate() crashes if the underlying mmap fails (e.g., if out
// of virtual address space). When this flag is provided, an invalid
// PagedMemory pointing to nullptr is returned in this case instead.
kMayFail = 1 << 0,
// By default, Allocate() commits the allocated memory immediately. When
// this flag is provided, the memory virtual address space may only be
// reserved and the user should call EnsureCommitted() before writing to
// memory addresses.
kDontCommit = 1 << 1,
};
// Allocates |size| bytes using mmap(MAP_ANONYMOUS). The returned memory is
// guaranteed to be page-aligned and guaranteed to be zeroed. |size| must be a
// multiple of 4KB (a page size). For |flags|, see the AllocationFlags enum
// above.
static PagedMemory Allocate(size_t size, int flags = 0);
// Hint to the OS that the memory range is not needed and can be discarded.
// The memory remains accessible and its contents may be retained, or they
// may be zeroed. This function may be a NOP on some platforms. Returns true
// if implemented.
bool AdviseDontNeed(void* p, size_t size);
// Ensures that at least the first |committed_size| bytes of the allocated
// memory region are committed. The implementation may commit memory in larger
// chunks above |committed_size|. Crashes if the memory couldn't be committed.
#if TRACK_COMMITTED_SIZE()
void EnsureCommitted(size_t committed_size);
#else // TRACK_COMMITTED_SIZE()
void EnsureCommitted(size_t /*committed_size*/) {}
#endif // TRACK_COMMITTED_SIZE()
inline void* Get() const noexcept { return p_; }
inline bool IsValid() const noexcept { return !!p_; }
inline size_t size() const noexcept { return size_; }
private:
PagedMemory(char* p, size_t size);
PagedMemory(const PagedMemory&) = delete;
// Defaulted for implementation of move constructor + assignment.
PagedMemory& operator=(const PagedMemory&) = default;
char* p_ = nullptr;
size_t size_ = 0;
#if TRACK_COMMITTED_SIZE()
size_t committed_size_ = 0u;
#endif // TRACK_COMMITTED_SIZE()
};
} // namespace base
} // namespace perfetto
#endif // INCLUDE_PERFETTO_BASE_PAGED_MEMORY_H_
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