Program Listing for File codecs.hpp
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/*
* SPDX-FileCopyrightText: Copyright (c) 2023-2024 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
* SPDX-License-Identifier: Apache-2.0
*
* 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 HOLOSCAN_CORE_CODECS_HPP
#define HOLOSCAN_CORE_CODECS_HPP
#include <complex>
#include <cstdint>
#include <functional>
#include <memory>
#include <string>
#include <type_traits>
#include <typeindex>
#include <typeinfo>
#include <unordered_map>
#include <utility>
#include <vector>
#include "./common.hpp"
#include "./endpoint.hpp"
#include "./errors.hpp"
#include "./expected.hpp"
#include "./type_traits.hpp"
#include "gxf/core/expected.hpp"
#include "gxf/serialization/serialization_buffer.hpp"
// Note: Currently the GXF UCX extension transmits using little-endian byte order. All hardware
// supported by Holoscan SDK is also little endian. To support big endian platforms, we
// would need to update the codecs in this file to properly handle endianness.
namespace holoscan {
// codec template struct so users can define their own codec class
// i.e. following the design of yaml-cpp's YAML::convert
template <typename T>
struct codec;
// Codec type 1: trivial binary types (float, etc.)
//
// Types that can be serialized by writing binary data where the number
// of bytes to be written is based on sizeof(typeT).
template <typename typeT>
static inline expected<size_t, RuntimeError> serialize_trivial_type(const typeT& value,
Endpoint* endpoint) {
return endpoint->write_trivial_type(&value);
}
template <typename typeT>
static inline expected<typeT, RuntimeError> deserialize_trivial_type(Endpoint* endpoint) {
typeT encoded;
auto maybe_value = endpoint->read_trivial_type(&encoded);
if (!maybe_value) { return forward_error(maybe_value); }
return encoded;
}
// TODO: currently not handling integer types separately
template <typename typeT>
struct codec {
static expected<size_t, RuntimeError> serialize(const typeT& value, Endpoint* endpoint) {
return serialize_trivial_type<typeT>(value, endpoint);
}
static expected<typeT, RuntimeError> deserialize(Endpoint* endpoint) {
return deserialize_trivial_type<typeT>(endpoint);
}
};
// Codec type 3: basic container types
//
// For vectorT types storing multiple items contiguously in memory
// (e.g. std::vector, std::array, std::string).
//
// It requires that vectorT have methods size(), data(), and operator[]
#pragma pack(push, 1)
struct ContiguousDataHeader {
size_t size;
uint8_t bytes_per_element;
};
#pragma pack(pop)
template <typename vectorT>
static inline expected<size_t, RuntimeError> serialize_binary_blob(const vectorT& data,
Endpoint* endpoint) {
ContiguousDataHeader header;
header.size = data.size();
header.bytes_per_element = header.size > 0 ? sizeof(data[0]) : 1;
auto size = endpoint->write_trivial_type<ContiguousDataHeader>(&header);
if (!size) { return forward_error(size); }
auto size2 = endpoint->write(data.data(), header.size * header.bytes_per_element);
if (!size2) { return forward_error(size2); }
return size.value() + size2.value();
}
template <typename vectorT>
static inline expected<vectorT, RuntimeError> deserialize_binary_blob(Endpoint* endpoint) {
ContiguousDataHeader header;
auto header_size = endpoint->read_trivial_type<ContiguousDataHeader>(&header);
if (!header_size) { return forward_error(header_size); }
vectorT data;
data.resize(header.size);
auto result = endpoint->read(data.data(), header.size * header.bytes_per_element);
if (!result) { return forward_error(result); }
return data;
}
// codec for vector of trivially serializable typeT
template <typename typeT>
struct codec<std::vector<typeT>> {
static expected<size_t, RuntimeError> serialize(const std::vector<typeT>& value,
Endpoint* endpoint) {
return serialize_binary_blob<std::vector<typeT>>(value, endpoint);
}
static expected<std::vector<typeT>, RuntimeError> deserialize(Endpoint* endpoint) {
return deserialize_binary_blob<std::vector<typeT>>(endpoint);
}
};
// deserialize_array is exactly like deserialize_binary_blob, but without a call to resize()
template <typename arrayT>
static inline expected<arrayT, RuntimeError> deserialize_array(Endpoint* endpoint) {
ContiguousDataHeader header;
auto header_size = endpoint->read_trivial_type<ContiguousDataHeader>(&header);
if (!header_size) { return forward_error(header_size); }
arrayT data;
auto result = endpoint->read(data.data(), header.size * header.bytes_per_element);
if (!result) { return forward_error(result); }
return data;
}
// codec for array of trivially serializable typeT and size N
template <typename typeT, size_t N>
struct codec<std::array<typeT, N>> {
static expected<size_t, RuntimeError> serialize(const std::array<typeT, N>& value,
Endpoint* endpoint) {
return serialize_binary_blob<std::array<typeT, N>>(value, endpoint);
}
static expected<std::array<typeT, N>, RuntimeError> deserialize(Endpoint* endpoint) {
return deserialize_array<std::array<typeT, N>>(endpoint);
}
};
// codec for std::string
template <>
struct codec<std::string> {
static expected<size_t, RuntimeError> serialize(const std::string& value, Endpoint* endpoint) {
return serialize_binary_blob<std::string>(value, endpoint);
}
static expected<std::string, RuntimeError> deserialize(Endpoint* endpoint) {
return deserialize_binary_blob<std::string>(endpoint);
}
};
// will hold Python cloudpickle strings in this container to differentiate from std::string
struct CloudPickleSerializedObject {
std::string serialized;
};
// codec for CloudPickleSerializedObject
template <>
struct codec<CloudPickleSerializedObject> {
static expected<size_t, RuntimeError> serialize(const CloudPickleSerializedObject& value,
Endpoint* endpoint) {
return serialize_binary_blob<std::string>(value.serialized, endpoint);
}
static expected<CloudPickleSerializedObject, RuntimeError> deserialize(Endpoint* endpoint) {
auto maybe_string = deserialize_binary_blob<std::string>(endpoint);
if (!maybe_string) { return forward_error(maybe_string); }
CloudPickleSerializedObject cloudpickle_obj{std::move(maybe_string.value())};
return cloudpickle_obj;
}
};
// Codec type 4: serialization of std::vector<bool> only
//
// Performs bit-packing/unpacking to/from uint8_t type for more efficient serialization.
// codec of std::vector<bool>
template <>
struct codec<std::vector<bool>> {
static expected<size_t, RuntimeError> serialize(const std::vector<bool>& data,
Endpoint* endpoint) {
size_t total_bytes = 0;
size_t num_bits = data.size();
size_t num_bytes = (num_bits + 7) / 8; // the number of bytes needed to store the bits
auto size = endpoint->write_trivial_type<size_t>(&num_bits);
if (!size) { return forward_error(size); }
total_bytes += size.value();
std::vector<uint8_t> packed_data(num_bytes, 0); // Create a vector to store the packed data
for (size_t i = 0; i < num_bits; ++i) {
if (data[i]) {
packed_data[i / 8] |= (1 << (i % 8)); // Pack the bits into the bytes
}
}
auto result = endpoint->write(packed_data.data(), packed_data.size());
if (!result) { return forward_error(result); }
total_bytes += result.value();
return total_bytes;
}
static expected<std::vector<bool>, RuntimeError> deserialize(Endpoint* endpoint) {
size_t num_bits;
auto size = endpoint->read_trivial_type<size_t>(&num_bits);
if (!size) { return forward_error(size); }
size_t num_bytes =
(num_bits + 7) / 8; // Calculate the number of bytes needed to store the bits
std::vector<uint8_t> packed_data(num_bytes, 0); // Create a vector to store the packed data
auto result = endpoint->read(packed_data.data(), packed_data.size());
if (!result) { return forward_error(result); }
std::vector<bool> data(num_bits, false); // Create a vector to store the unpacked data
for (size_t i = 0; i < num_bits; ++i) {
if (packed_data[i / 8] & (1 << (i % 8))) { // Unpack the bits from the bytes
data[i] = true;
}
}
return data;
}
};
// Codec type 5: serialization of nested container types
// e.g. std::vector<std::vector<float>>, std::vector<std::string>
//
template <typename typeT>
static inline expected<size_t, RuntimeError> serialize_vector_of_vectors(const typeT& vectors,
Endpoint* endpoint) {
size_t total_size = 0;
// header is just the total number of vectors
size_t num_vectors = vectors.size();
auto size = endpoint->write_trivial_type<size_t>(&num_vectors);
if (!size) { return forward_error(size); }
total_size += size.value();
using vectorT = typename typeT::value_type;
// now transmit each individual vector
for (const auto& vector : vectors) {
size = codec<vectorT>::serialize(vector, endpoint);
if (!size) { return forward_error(size); }
total_size += size.value();
}
return total_size;
}
template <typename typeT>
static inline expected<typeT, RuntimeError> deserialize_vector_of_vectors(Endpoint* endpoint) {
size_t num_vectors;
auto size = endpoint->read_trivial_type<size_t>(&num_vectors);
if (!size) { return forward_error(size); }
using vectorT = typename typeT::value_type;
std::vector<vectorT> data;
data.reserve(num_vectors);
for (size_t i = 0; i < num_vectors; i++) {
auto vec = codec<vectorT>::deserialize(endpoint);
if (!vec) { return forward_error(vec); }
data.push_back(vec.value());
}
return data;
}
template <typename typeT>
struct codec<std::vector<std::vector<typeT>>> {
static expected<size_t, RuntimeError> serialize(const std::vector<std::vector<typeT>>& value,
Endpoint* endpoint) {
return serialize_vector_of_vectors<std::vector<std::vector<typeT>>>(value, endpoint);
}
static expected<std::vector<std::vector<typeT>>, RuntimeError> deserialize(Endpoint* endpoint) {
return deserialize_vector_of_vectors<std::vector<std::vector<typeT>>>(endpoint);
}
};
template <>
struct codec<std::vector<std::string>> {
static expected<size_t, RuntimeError> serialize(const std::vector<std::string>& value,
Endpoint* endpoint) {
return serialize_vector_of_vectors<std::vector<std::string>>(value, endpoint);
}
static expected<std::vector<std::string>, RuntimeError> deserialize(Endpoint* endpoint) {
return deserialize_vector_of_vectors<std::vector<std::string>>(endpoint);
}
};
// codec for shared_ptr types
// Serializes the contents of the shared_ptr. On deserialize, a new shared_ptr to the deserialized
// value is returned.
template <typename typeT>
struct codec<std::shared_ptr<typeT>> {
static expected<size_t, RuntimeError> serialize(std::shared_ptr<typeT> value,
Endpoint* endpoint) {
return codec<typeT>::serialize(*value, endpoint);
}
static expected<std::shared_ptr<typeT>, RuntimeError> deserialize(Endpoint* endpoint) {
auto value = codec<typeT>::deserialize(endpoint);
if (!value) { return forward_error(value); }
return std::make_shared<typeT>(value.value());
}
};
} // namespace holoscan
#endif/* HOLOSCAN_CORE_CODECS_HPP */