ladybird/Userland/Libraries/LibIPC/Encoder.h
Timothy Flynn 34160743dc LibIPC: Avoid redundant copy of every tranferred IPC message
For every IPC message sent, we currently prepend the message size to the
IPC message buffer. This incurs the cost of copying the entire message
to its newly allocated position. Instead, reserve the bytes for the size
at the front of the buffer upon creation. Prevent dangerous access to
the buffer with specific public methods.
2024-01-03 10:17:00 +01:00

171 lines
3.6 KiB
C++

/*
* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2023, Tim Flynn <trflynn89@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Concepts.h>
#include <AK/HashMap.h>
#include <AK/StdLibExtras.h>
#include <AK/Variant.h>
#include <LibCore/SharedCircularQueue.h>
#include <LibIPC/Concepts.h>
#include <LibIPC/Forward.h>
#include <LibIPC/Message.h>
namespace IPC {
template<typename T>
ErrorOr<void> encode(Encoder&, T const&)
{
static_assert(DependentFalse<T>, "Base IPC::encode() was instantiated");
VERIFY_NOT_REACHED();
}
class Encoder {
public:
explicit Encoder(MessageBuffer& buffer)
: m_buffer(buffer)
{
}
template<typename T>
ErrorOr<void> encode(T const& value);
ErrorOr<void> extend_capacity(size_t capacity)
{
TRY(m_buffer.extend_data_capacity(capacity));
return {};
}
ErrorOr<void> append(u8 const* values, size_t count)
{
TRY(m_buffer.append_data(values, count));
return {};
}
ErrorOr<void> append_file_descriptor(int fd)
{
TRY(m_buffer.append_file_descriptor(fd));
return {};
}
ErrorOr<void> encode_size(size_t size);
private:
MessageBuffer& m_buffer;
};
template<Arithmetic T>
ErrorOr<void> encode(Encoder& encoder, T const& value)
{
TRY(encoder.append(reinterpret_cast<u8 const*>(&value), sizeof(value)));
return {};
}
template<Enum T>
ErrorOr<void> encode(Encoder& encoder, T const& value)
{
return encoder.encode(to_underlying(value));
}
template<>
ErrorOr<void> encode(Encoder&, float const&);
template<>
ErrorOr<void> encode(Encoder&, double const&);
template<>
ErrorOr<void> encode(Encoder&, String const&);
template<>
ErrorOr<void> encode(Encoder&, StringView const&);
template<>
ErrorOr<void> encode(Encoder&, ByteString const&);
template<>
ErrorOr<void> encode(Encoder&, ByteBuffer const&);
template<>
ErrorOr<void> encode(Encoder&, JsonValue const&);
template<>
ErrorOr<void> encode(Encoder&, Duration const&);
template<>
ErrorOr<void> encode(Encoder&, UnixDateTime const&);
template<>
ErrorOr<void> encode(Encoder&, URL const&);
template<>
ErrorOr<void> encode(Encoder&, File const&);
template<>
ErrorOr<void> encode(Encoder&, Empty const&);
template<Concepts::Vector T>
ErrorOr<void> encode(Encoder& encoder, T const& vector)
{
// NOTE: Do not change this encoding without also updating LibC/netdb.cpp.
TRY(encoder.encode_size(vector.size()));
for (auto const& value : vector)
TRY(encoder.encode(value));
return {};
}
template<Concepts::HashMap T>
ErrorOr<void> encode(Encoder& encoder, T const& hashmap)
{
TRY(encoder.encode_size(hashmap.size()));
for (auto it : hashmap) {
TRY(encoder.encode(it.key));
TRY(encoder.encode(it.value));
}
return {};
}
template<Concepts::SharedSingleProducerCircularQueue T>
ErrorOr<void> encode(Encoder& encoder, T const& queue)
{
return encoder.encode(IPC::File { queue.fd() });
}
template<Concepts::Optional T>
ErrorOr<void> encode(Encoder& encoder, T const& optional)
{
TRY(encoder.encode(optional.has_value()));
if (optional.has_value())
TRY(encoder.encode(optional.value()));
return {};
}
template<Concepts::Variant T>
ErrorOr<void> encode(Encoder& encoder, T const& variant)
{
TRY(encoder.encode(variant.index()));
return variant.visit([&](auto const& value) {
return encoder.encode(value);
});
}
// This must be last so that it knows about the above specializations.
template<typename T>
ErrorOr<void> Encoder::encode(T const& value)
{
return IPC::encode(*this, value);
}
}