cmake: Add `MULTIPROCESS` option

CMakeLists.txt

@@ -155,6 +155,15 @@ if(WITH_QRENCODE)
 endif()
 
 cmake_dependent_option(WITH_DBUS "Enable DBus support." ON "CMAKE_SYSTEM_NAME STREQUAL \"Linux\" AND BUILD_GUI" OFF)
+
+option(WITH_MULTIPROCESS "Build multiprocess bitcoin-node and bitcoin-gui executables in addition to monolithic bitcoind and bitcoin-qt executables. Requires libmultiprocess library. Experimental." OFF)
+if(WITH_MULTIPROCESS)
+  find_package(Libmultiprocess COMPONENTS Lib)
+  find_package(LibmultiprocessNative COMPONENTS Bin
+    NAMES Libmultiprocess
+  )
+endif()
+
 cmake_dependent_option(BUILD_GUI_TESTS "Build test_bitcoin-qt executable." ON "BUILD_GUI;BUILD_TESTS" OFF)
 if(BUILD_GUI)
   set(qt_components Core Gui Widgets LinguistTools)
@@ -495,7 +504,14 @@ message("Configure summary")
 message("=================")
 message("Executables:")
 message("  bitcoind ............................ ${BUILD_DAEMON}")
+message("  bitcoin-node (multiprocess) ......... ${WITH_MULTIPROCESS}")
 message("  bitcoin-qt (GUI) .................... ${BUILD_GUI}")
+if(BUILD_GUI AND WITH_MULTIPROCESS)
+  set(bitcoin_gui_status ON)
+else()
+  set(bitcoin_gui_status OFF)
+endif()
+message("  bitcoin-gui (GUI, multiprocess) ..... ${bitcoin_gui_status}")
 message("  bitcoin-cli ......................... ${BUILD_CLI}")
 message("  bitcoin-tx .......................... ${BUILD_TX}")
 message("  bitcoin-util ........................ ${BUILD_UTIL}")

src/CMakeLists.txt

@@ -31,6 +31,9 @@ add_dependencies(bitcoin_clientversion generate_build_info)
 add_subdirectory(crypto)
 add_subdirectory(univalue)
 add_subdirectory(util)
+if(WITH_MULTIPROCESS)
+  add_subdirectory(ipc)
+endif()
 
 #=============================
 # secp256k1 subtree
@@ -297,6 +300,18 @@ if(BUILD_DAEMON)
     $<TARGET_NAME_IF_EXISTS:bitcoin_wallet>
   )
 endif()
+if(WITH_MULTIPROCESS)
+  add_executable(bitcoin-node
+    bitcoind.cpp
+    init/bitcoin-node.cpp
+  )
+  target_link_libraries(bitcoin-node
+    core_interface
+    bitcoin_node
+    bitcoin_ipc
+    $<TARGET_NAME_IF_EXISTS:bitcoin_wallet>
+  )
+endif()
 
 
 add_library(bitcoin_cli STATIC EXCLUDE_FROM_ALL

src/ipc/CMakeLists.txt

@@ -0,0 +1,18 @@
+# Copyright (c) 2023-present The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or https://opensource.org/license/mit/.
+
+add_library(bitcoin_ipc STATIC EXCLUDE_FROM_ALL
+  capnp/protocol.cpp
+  interfaces.cpp
+  process.cpp
+)
+
+target_capnp_sources(bitcoin_ipc ${PROJECT_SOURCE_DIR}
+  capnp/echo.capnp capnp/init.capnp
+)
+
+target_link_libraries(bitcoin_ipc
+  PRIVATE
+    core_interface
+)

src/qt/CMakeLists.txt

@@ -243,6 +243,23 @@ if(WIN32)
   set_target_properties(bitcoin-qt PROPERTIES WIN32_EXECUTABLE TRUE)
 endif()
 
+if(WITH_MULTIPROCESS)
+  add_executable(bitcoin-gui
+    main.cpp
+    ../init/bitcoin-gui.cpp
+  )
+  target_link_libraries(bitcoin-gui
+    core_interface
+    bitcoinqt
+    bitcoin_node
+    bitcoin_ipc
+  )
+  import_plugins(bitcoin-gui)
+  if(WIN32)
+    set_target_properties(bitcoin-gui PROPERTIES WIN32_EXECUTABLE TRUE)
+  endif()
+endif()
+
 if(BUILD_GUI_TESTS)
   add_subdirectory(test)
 endif()

src/test/CMakeLists.txt

@@ -158,6 +158,28 @@ if(ENABLE_WALLET)
   add_subdirectory(${PROJECT_SOURCE_DIR}/src/wallet/test wallet)
 endif()
 
+if(WITH_MULTIPROCESS)
+  add_library(bitcoin_ipc_test STATIC EXCLUDE_FROM_ALL
+    ipc_test.cpp
+  )
+
+  target_capnp_sources(bitcoin_ipc_test ${PROJECT_SOURCE_DIR}
+    ipc_test.capnp
+  )
+
+  target_link_libraries(bitcoin_ipc_test
+    PRIVATE
+      core_interface
+      univalue
+  )
+
+  target_sources(test_bitcoin
+    PRIVATE
+      ipc_tests.cpp
+  )
+  target_link_libraries(test_bitcoin bitcoin_ipc_test)
+endif()
+
 function(add_boost_test source_file)
   if(NOT EXISTS ${source_file})
     return()