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// Copyright 2013 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef GPU_COMMAND_BUFFER_COMMON_MAILBOX_H_
#define GPU_COMMAND_BUFFER_COMMON_MAILBOX_H_
#include <stdint.h>
#include <string.h>
#include <string>
#include "base/component_export.h"
// From gl2/gl2ext.h.
#ifndef GL_MAILBOX_SIZE_CHROMIUM
#define GL_MAILBOX_SIZE_CHROMIUM 16
#endif
namespace gpu {
// Importance to use in tracing. Higher values get the memory cost attributed,
// and equal values share the cost. We want the client to "win" over the
// service, since the service is acting on its behalf.
enum class TracingImportance : int {
kNotOwner = 0,
kServiceOwner = 1,
kClientOwner = 2,
};
// A mailbox is an unguessable name that references a SharedImage.
// This name can be passed across processes permitting one process to share
// a SharedImage with another. The mailbox name consists of a random
// set of bytes, optionally with a checksum (in debug mode) to verify the
// name is valid.
struct COMPONENT_EXPORT(GPU_MAILBOX) Mailbox {
using Name = int8_t[GL_MAILBOX_SIZE_CHROMIUM];
Mailbox();
static Mailbox FromVolatile(const volatile Mailbox& other) {
// Because the copy constructor is trivial, const_cast is safe.
return const_cast<const Mailbox&>(other);
}
bool IsZero() const;
void SetZero();
void SetName(const int8_t* name);
// Generate a unique unguessable mailbox name.
static Mailbox Generate();
// Verify that the mailbox was created through Mailbox::Generate. This only
// works in Debug (always returns true in Release). This is not a secure
// check, only to catch bugs where clients forgot to call Mailbox::Generate.
bool Verify() const;
// Returns the first four bytes of the mailbox name as an unsigned integer.
uint32_t ToU32() const;
std::string ToDebugString() const;
bool operator==(const Mailbox& other) const;
std::strong_ordering operator<=>(const Mailbox& other) const;
template <typename H>
friend H AbslHashValue(H h, const Mailbox& m) {
// As the name is cryptographically random bytes, the first few bytes should
// be more than sufficient as a hash.
return H::combine(std::move(h), m.ToU32());
}
Name name;
};
} // namespace gpu
template <>
struct std::hash<gpu::Mailbox> {
std::size_t operator()(const gpu::Mailbox& m) const noexcept {
// As the name is cryptographically random bytes, the first few bytes should
// be more than sufficient as a hash.
return m.ToU32();
}
};
#endif // GPU_COMMAND_BUFFER_COMMON_MAILBOX_H_
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