Switch from epee http server to boost::beast http server. Min boost 1.70

There is roughly a 7.4% increase in performance in the switch to
boost::beast. Additionally, the REST endpoints `/daemon_status`,
`/get_unspent_outs`, and `/submit_raw_tx` do not block in ZMQ calls,
allowing for better response times regardless of `monerod` status.

The REST endpoints `/login and `/get_random_outs` still need updates
to prevent blocking (`/login` is conditional on DB state).

src/CMakeLists.txt

@@ -31,6 +31,7 @@ include_directories(.)
 add_subdirectory(lmdb)
 add_subdirectory(wire)
 add_subdirectory(db)
+add_subdirectory(net)
 add_subdirectory(rpc)
 add_subdirectory(util)
 
@@ -49,12 +50,14 @@ target_link_libraries(monero-lws-daemon-common
     ${MONERO_lmdb}
     monero-lws-common
     monero-lws-db
+    monero-lws-net
     monero-lws-rpc
     monero-lws-rpc-scanner
     monero-lws-wire-json
     monero-lws-util
     ${Boost_CHRONO_LIBRARY}
     ${Boost_PROGRAM_OPTIONS_LIBRARY}
+    ${Boost_SYSTEM_LIBRARY}
     ${Boost_THREAD_LIBRARY}
     ${Boost_THREAD_LIBS_INIT}
     ${EXTRA_LIBRARIES}

src/net/CMakeLists.txt

@@ -0,0 +1,33 @@
+# Copyright (c) 2024, The Monero Project
+#
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without modification, are
+# permitted provided that the following conditions are met:
+#
+# 1. Redistributions of source code must retain the above copyright notice, this list of
+#    conditions and the following disclaimer.
+#
+# 2. Redistributions in binary form must reproduce the above copyright notice, this list
+#    of conditions and the following disclaimer in the documentation and/or other
+#    materials provided with the distribution.
+#
+# 3. Neither the name of the copyright holder nor the names of its contributors may be
+#    used to endorse or promote products derived from this software without specific
+#    prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+# THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+# STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+# THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+set(monero-lws-net_sources zmq_async.cpp)
+set(monero-lws-net_headers zmq_async.h)
+
+add_library(monero-lws-net ${monero-lws-net_sources} ${monero-lws-net_headers})
+target_link_libraries(monero-lws-net monero::libraries)

src/net/zmq_async.cpp

@@ -0,0 +1,105 @@
+// Copyright (c) 2024, The Monero Project
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "zmq_async.h"
+
+#include <stdexcept>
+
+namespace net { namespace zmq
+{
+  const boost::system::error_category& boost_error_category() noexcept
+  {
+      struct category final : boost::system::error_category
+      {
+          virtual const char* name() const noexcept override final
+          {
+              return "error::error_category()";
+          }
+
+          virtual std::string message(int value) const override final
+          {
+              char const* const msg = zmq_strerror(value);
+              if (msg)
+                  return msg;
+              return "zmq_strerror failure";
+          }
+
+          virtual boost::system::error_condition default_error_condition(int value) const noexcept override final
+          {
+              // maps specific errors to generic `std::errc` cases.
+              switch (value)
+              {
+              case EFSM:
+              case ETERM:
+                  break;
+              default:
+                  /* zmq is using cerrno errors. C++ spec indicates that
+                     `std::errc` values must be identical to the cerrno value.
+                     So just map every zmq specific error to the generic errc
+                     equivalent. zmq extensions must be in the switch or they
+                     map to a non-existent errc enum value. */
+                  return boost::system::errc::errc_t(value);
+              }
+              return boost::system::error_condition{value, *this};
+          }
+
+      };
+      static const category instance{};
+      return instance;
+  }
+
+  boost::system::error_code make_error_code(std::error_code code)
+  {
+    if (std::addressof(code.category()) != std::addressof(error_category()))
+      throw std::logic_error{"Expected only ZMQ errors"};
+    return boost::system::error_code{code.value(), boost_error_category()};
+  }
+
+  void free_descriptor::operator()(adescriptor* ptr) noexcept
+  {
+    if (ptr)
+    {
+      ptr->release(); // release ASIO ownership, destroys all queued handlers
+      delete ptr;
+    }
+  }
+
+  expect<async_client> async_client::make(boost::asio::io_service& io, socket zsock)
+  {
+    MONERO_PRECOND(zsock != nullptr);
+
+    int fd = 0;
+    std::size_t length = sizeof(fd);
+    if (zmq_getsockopt(zsock.get(), ZMQ_FD, &fd, &length) != 0)
+      return net::zmq::get_error_code();
+
+    async_client out{std::move(zsock), nullptr, false};
+    out.asock.reset(new adescriptor{io, fd});
+    return out;
+  }
+}} // net // zmq
+

src/net/zmq_async.h

@@ -0,0 +1,165 @@
+// Copyright (c) 2024, The Monero Project
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+//
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+//
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+//
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#pragma once
+
+#include <boost/asio/compose.hpp>
+#include <boost/asio/io_service.hpp>
+#include <boost/asio/posix/stream_descriptor.hpp>
+#include <boost/system/error_code.hpp>
+#include <cstddef>
+#include <memory>
+#include <string>
+#include <zmq.h>
+#include "byte_slice.h"     // monero/contrib/epee/include
+#include "common/expect.h"  // monero/src
+#include "net/zmq.h"
+
+namespace net { namespace zmq
+{
+  //! \return Category for ZMQ errors.
+  const boost::system::error_category& boost_error_category() noexcept;
+
+  //! \return `code` iff the `::net::zmq` error category
+  boost::system::error_code make_error_code(std::error_code code);
+
+  using adescriptor = boost::asio::posix::stream_descriptor;
+
+  struct free_descriptor
+  {
+    void operator()(adescriptor* ptr) noexcept;
+  };
+
+  using asocket = std::unique_ptr<adescriptor, free_descriptor>;
+
+  struct async_client
+  {
+    async_client() = delete;
+    socket zsock;
+    asocket asock;
+    bool close;
+
+    static expect<async_client> make(boost::asio::io_service& io, socket zsock);
+  };
+
+  class read_msg_op
+  {
+    async_client* sock_;
+    std::string* msg_;
+
+  public:
+    read_msg_op(async_client& sock, std::string& msg)
+      : sock_(std::addressof(sock)), msg_(std::addressof(msg))
+    {}
+
+    template<typename F>
+    void operator()(F& self, const boost::system::error_code error = {}, std::size_t = 0)
+    {
+      if (error)
+        return self.complete(error, 0);
+      if (!sock_)
+        return;
+      if (sock_->close)
+        return self.complete(boost::asio::error::operation_aborted, 0);
+
+      assert(sock_->zsock && sock_->asock);
+      expect<std::string> msg = receive(sock_->zsock.get(), ZMQ_DONTWAIT);
+      if (!msg)
+      {
+        if (msg != make_error_code(EAGAIN))
+          return self.complete(make_error_code(msg.error()), 0);
+
+        // try again
+        sock_->asock->async_read_some(boost::asio::null_buffers(), std::move(self));
+        return;
+      }
+
+      *msg_ = std::move(*msg);
+      self.complete(error, msg_->size());
+    }
+  };
+
+  class write_msg_op
+  {
+    async_client* sock_;
+    epee::byte_slice msg_;
+
+  public:
+    write_msg_op(async_client& sock, epee::byte_slice msg)
+      : sock_(std::addressof(sock)), msg_(std::move(msg))
+    {}
+
+    template<typename F>
+    void operator()(F& self, const boost::system::error_code error = {}, std::size_t = 0)
+    {
+     if (error)
+        return self.complete(error, 0);
+      if (!sock_)
+        return;
+      if (sock_->close)
+        return self.complete(boost::asio::error::operation_aborted, 0);
+
+      assert(sock_->zsock && sock_->asock);
+
+      expect<void> status =
+        ::net::zmq::send(msg_.clone(), sock_->zsock.get(), ZMQ_DONTWAIT);
+      if (!status)
+      {
+        if (status != ::net::zmq::make_error_code(EAGAIN))
+          return self.complete(make_error_code(status.error()), 0);
+
+        // try again
+        sock_->asock->async_write_some(boost::asio::null_buffers(), std::move(self));
+        return;
+      }
+
+      self.complete(error, msg_.size());
+    }
+  };
+
+  //! Cannot have an `async_read` and `async_write` at same time (edge trigger)
+  template<typename F>
+  void async_read(async_client& sock, std::string& buffer, F&& f)
+  {
+    // async_compose is required for correct strand invocation, etc
+    boost::asio::async_compose<F, void(boost::system::error_code, std::size_t)>(
+      read_msg_op{sock, buffer}, f, *sock.asock
+    );
+  }
+
+  //! Cannot have an `async_write` and `async_read` at same time (edge trigger)
+  template<typename F>
+  void async_write(async_client& sock, epee::byte_slice msg, F&& f)
+  {
+    // async_compose is required for correct strand invocation, etc
+    boost::asio::async_compose<F, void(boost::system::error_code, std::size_t)>(
+      write_msg_op{sock, std::move(msg)}, f, *sock.asock
+    );
+  }
+
+}} // net // zmq
+