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// Copyright 2020 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 COMPONENTS_GC_PUBLIC_PLATFORM_H_
#define COMPONENTS_GC_PUBLIC_PLATFORM_H_
#include <stddef.h>
#include "components/gc/core/gc_export.h"
namespace gc {
// Allocator used to get memory from the embedder.
class GC_EXPORT PageAllocator {
public:
// Memory permissions.
enum Permission { kNoAccess, kRead, kReadWrite, kReadExecute };
virtual ~PageAllocator() = default;
// Page granularity for |AllocatePages()| and |FreePages()|. Addresses and
// lengths must be multiples of |AllocatePageSize()|.
virtual size_t AllocatePageSize() const = 0;
// Page granularity for |SetPermissions()| and |DiscardSystemPages()|.
// Addresses and lengths must be multiples of |CommitPageSize()|.
virtual size_t CommitPageSize() const = 0;
// Allocates memory at the given |address| (hint) with the provided |length|,
// |alignment|, and |permissions|.
virtual void* AllocatePages(void* address,
size_t length,
size_t alignment,
Permission permissions) = 0;
// Frees memory in a range that was allocated by |AllocatedPages()|.
virtual bool FreePages(void* address, size_t length) = 0;
// Sets permissions in a range that was allocated by |AllocatedPages()|.
virtual bool SetPermissions(void* address,
size_t length,
Permission permissions) = 0;
// Potentially frees physical memory in the range [address, address+length).
// Address and size should be aligned with |CommitPageSize()|. Note that this
// call transparently brings back physical memory at an unknown state.
//
// Returns true on success, and false otherwise.
virtual bool DiscardSystemPages(void* address, size_t size) = 0;
};
} // namespace gc
#endif // COMPONENTS_GC_PUBLIC_PLATFORM_H_
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