ui/gfx/generic_shared_memory_id.h

// Copyright 2015 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 UI_GFX_GENERIC_SHARED_MEMORY_ID_H_
#define UI_GFX_GENERIC_SHARED_MEMORY_ID_H_

#include <stddef.h>
#include <stdint.h>

#include <functional>

#include "base/hash/hash.h"
#include "base/trace_event/memory_allocator_dump.h"
#include "ui/gfx/gfx_export.h"

namespace gfx {

// Defines an ID type which is used across all types of shared memory
// allocations in content/. This ID type is in ui/gfx, as components outside
// content/ may need to hold an ID (but should not generate one).
class GFX_EXPORT GenericSharedMemoryId {
 public:
  int id;

  // Invalid ID is -1 to match semantics of base::AtomicSequenceNumber.
  GenericSharedMemoryId() : id(-1) {}
  explicit GenericSharedMemoryId(int id) : id(id) {}
  GenericSharedMemoryId(const GenericSharedMemoryId& other) = default;
  GenericSharedMemoryId& operator=(const GenericSharedMemoryId& other) =
      default;

  bool is_valid() const { return id >= 0; }

  bool operator==(const GenericSharedMemoryId& other) const {
    return id == other.id;
  }

  bool operator<(const GenericSharedMemoryId& other) const {
    return id < other.id;
  }
};

// Generates GUID which can be used to trace shared memory using its
// GenericSharedMemoryId.
GFX_EXPORT base::trace_event::MemoryAllocatorDumpGuid
GetGenericSharedGpuMemoryGUIDForTracing(
    uint64_t tracing_process_id,
    GenericSharedMemoryId generic_shared_memory_id);

}  // namespace gfx

namespace std {

template <>
struct hash<gfx::GenericSharedMemoryId> {
  size_t operator()(gfx::GenericSharedMemoryId key) const {
    return std::hash<int>()(key.id);
  }
};

template <typename Second>
struct hash<std::pair<gfx::GenericSharedMemoryId, Second>> {
  size_t operator()(
      const std::pair<gfx::GenericSharedMemoryId, Second>& pair) const {
    return base::HashInts(pair.first.id, pair.second);
  }
};

}  // namespace std

#endif  // UI_GFX_GENERIC_SHARED_MEMORY_ID_H_