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diff --git a/3rdparty/asio/src/examples/cpp11/allocation/server.cpp b/3rdparty/asio/src/examples/cpp11/allocation/server.cpp
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+//
+// server.cpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <array>
+#include <cstdlib>
+#include <iostream>
+#include <memory>
+#include <type_traits>
+#include <utility>
+#include "asio.hpp"
+
+using asio::ip::tcp;
+
+// Class to manage the memory to be used for handler-based custom allocation.
+// It contains a single block of memory which may be returned for allocation
+// requests. If the memory is in use when an allocation request is made, the
+// allocator delegates allocation to the global heap.
+class handler_memory
+{
+public:
+ handler_memory()
+ : in_use_(false)
+ {
+ }
+
+ handler_memory(const handler_memory&) = delete;
+ handler_memory& operator=(const handler_memory&) = delete;
+
+ void* allocate(std::size_t size)
+ {
+ if (!in_use_ && size < sizeof(storage_))
+ {
+ in_use_ = true;
+ return &storage_;
+ }
+ else
+ {
+ return ::operator new(size);
+ }
+ }
+
+ void deallocate(void* pointer)
+ {
+ if (pointer == &storage_)
+ {
+ in_use_ = false;
+ }
+ else
+ {
+ ::operator delete(pointer);
+ }
+ }
+
+private:
+ // Storage space used for handler-based custom memory allocation.
+ typename std::aligned_storage<1024>::type storage_;
+
+ // Whether the handler-based custom allocation storage has been used.
+ bool in_use_;
+};
+
+// The allocator to be associated with the handler objects. This allocator only
+// needs to satisfy the C++11 minimal allocator requirements.
+template <typename T>
+class handler_allocator
+{
+public:
+ using value_type = T;
+
+ explicit handler_allocator(handler_memory& mem)
+ : memory_(mem)
+ {
+ }
+
+ template <typename U>
+ handler_allocator(const handler_allocator<U>& other) noexcept
+ : memory_(other.memory_)
+ {
+ }
+
+ bool operator==(const handler_allocator& other) const noexcept
+ {
+ return &memory_ == &other.memory_;
+ }
+
+ bool operator!=(const handler_allocator& other) const noexcept
+ {
+ return &memory_ != &other.memory_;
+ }
+
+ T* allocate(std::size_t n) const
+ {
+ return static_cast<T*>(memory_.allocate(sizeof(T) * n));
+ }
+
+ void deallocate(T* p, std::size_t /*n*/) const
+ {
+ return memory_.deallocate(p);
+ }
+
+private:
+ template <typename> friend class handler_allocator;
+
+ // The underlying memory.
+ handler_memory& memory_;
+};
+
+// Wrapper class template for handler objects to allow handler memory
+// allocation to be customised. The allocator_type type and get_allocator()
+// member function are used by the asynchronous operations to obtain the
+// allocator. Calls to operator() are forwarded to the encapsulated handler.
+template <typename Handler>
+class custom_alloc_handler
+{
+public:
+ using allocator_type = handler_allocator<Handler>;
+
+ custom_alloc_handler(handler_memory& m, Handler h)
+ : memory_(m),
+ handler_(h)
+ {
+ }
+
+ allocator_type get_allocator() const noexcept
+ {
+ return allocator_type(memory_);
+ }
+
+ template <typename ...Args>
+ void operator()(Args&&... args)
+ {
+ handler_(std::forward<Args>(args)...);
+ }
+
+private:
+ handler_memory& memory_;
+ Handler handler_;
+};
+
+// Helper function to wrap a handler object to add custom allocation.
+template <typename Handler>
+inline custom_alloc_handler<Handler> make_custom_alloc_handler(
+ handler_memory& m, Handler h)
+{
+ return custom_alloc_handler<Handler>(m, h);
+}
+
+class session
+ : public std::enable_shared_from_this<session>
+{
+public:
+ session(tcp::socket socket)
+ : socket_(std::move(socket))
+ {
+ }
+
+ void start()
+ {
+ do_read();
+ }
+
+private:
+ void do_read()
+ {
+ auto self(shared_from_this());
+ socket_.async_read_some(asio::buffer(data_),
+ make_custom_alloc_handler(handler_memory_,
+ [this, self](std::error_code ec, std::size_t length)
+ {
+ if (!ec)
+ {
+ do_write(length);
+ }
+ }));
+ }
+
+ void do_write(std::size_t length)
+ {
+ auto self(shared_from_this());
+ asio::async_write(socket_, asio::buffer(data_, length),
+ make_custom_alloc_handler(handler_memory_,
+ [this, self](std::error_code ec, std::size_t /*length*/)
+ {
+ if (!ec)
+ {
+ do_read();
+ }
+ }));
+ }
+
+ // The socket used to communicate with the client.
+ tcp::socket socket_;
+
+ // Buffer used to store data received from the client.
+ std::array<char, 1024> data_;
+
+ // The memory to use for handler-based custom memory allocation.
+ handler_memory handler_memory_;
+};
+
+class server
+{
+public:
+ server(asio::io_context& io_context, short port)
+ : acceptor_(io_context, tcp::endpoint(tcp::v4(), port))
+ {
+ do_accept();
+ }
+
+private:
+ void do_accept()
+ {
+ acceptor_.async_accept(
+ [this](std::error_code ec, tcp::socket socket)
+ {
+ if (!ec)
+ {
+ std::make_shared<session>(std::move(socket))->start();
+ }
+
+ do_accept();
+ });
+ }
+
+ tcp::acceptor acceptor_;
+};
+
+int main(int argc, char* argv[])
+{
+ try
+ {
+ if (argc != 2)
+ {
+ std::cerr << "Usage: server <port>\n";
+ return 1;
+ }
+
+ asio::io_context io_context;
+ server s(io_context, std::atoi(argv[1]));
+ io_context.run();
+ }
+ catch (std::exception& e)
+ {
+ std::cerr << "Exception: " << e.what() << "\n";
+ }
+
+ return 0;
+}