Merge #18677: Multiprocess build support

e2bab2aa162ae38b2bf8195b577c982402fbee9d multiprocess: add multiprocess travis configuration (Russell Yanofsky)
603fd6a2e708c04ef6c9880f89d0a4cbaa6fc7c5 depends: add MULTIPROCESS depends option (Russell Yanofsky)
5d1377b52bfcd4edf8553aaf332bfeb92fc554cc build: multiprocess autotools changes (Russell Yanofsky)

Pull request description:

  This PR is part of the [process separation project](https://github.com/bitcoin/bitcoin/projects/10).

  ---

  This PR consists of build changes only. It adds an `--enable-multiprocess` autoconf option (off by default and marked experimental), that builds new `bitcoin-node` and `bitcoin-gui` binaries. These currently function the same as existing `bitcoind` and `bitcoin-qt` binaries, but are extended in #10102 with IPC features to execute node, wallet, and gui functions in separate processes.

  In addition to adding the `--enable-multiprocess` config flag, it also adds a depends package and autoconf rules to build with the [libmultiprocess](https://github.com/chaincodelabs/libmultiprocess) library, and it adds new travis configuration to exercise the build code and run functional tests with the new binaries.

  The changes in this PR were originally part of #10102 but were moved into #16367 to be able to develop and review the multiprocess build changes independently of the code changes. #16367 was briefly merged and then reverted in #18588. Only change since #16367 has been dropping the `native_boost.mk` depends package which was pointed out to be no longer necessary in https://github.com/bitcoin/bitcoin/pull/16367#issuecomment-596484337 and https://github.com/bitcoin/bitcoin/pull/18588#pullrequestreview-391765649

ACKs for top commit:
  practicalswift:
    ACK e2bab2aa162ae38b2bf8195b577c982402fbee9d
  Sjors:
    tACK e2bab2aa162ae38b2bf8195b577c982402fbee9d on macOS 10.15.4
  hebasto:
    ACK e2bab2aa162ae38b2bf8195b577c982402fbee9d, tested on Linux Mint 19.3 (x86_64):

Tree-SHA512: b5a76eab5abf63d9d8b6d628cbdff4cc1888eef15cafa0a5d56369e2f9d02595fed623f4b74b2cf2830c42c05a774f0943e700f9c768a82d9d348cad199e135c

23 files changed, 289 insertions, 44 deletions

diff --git a/.gitignore b/.gitignore
index 1c487f43a7..5b9ec1f355 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,6 +5,8 @@
 src/bitcoin
 src/bitcoind
 src/bitcoin-cli
+src/bitcoin-gui
+src/bitcoin-node
 src/bitcoin-tx
 src/bitcoin-wallet
 src/test/fuzz
diff --git a/.travis.yml b/.travis.yml
index 4acfe4db76..1598813ed2 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -129,6 +129,12 @@ jobs:
         FILE_ENV="./ci/test/00_setup_env_native_fuzz.sh"
 
     - stage: test
+      name: 'x86_64 Linux [GOAL: install]  [bionic]  [multiprocess]'
+      if: type != pull_request OR commit_message =~ /depends:|multiprocess:/ # Skip on non-depends, non-multiprocess PRs
+      env: >-
+        FILE_ENV="./ci/test/00_setup_env_native_multiprocess.sh"
+
+    - stage: test
       name: 'x86_64 Linux  [GOAL: install]  [bionic]  [no wallet]'
       env: >-
         FILE_ENV="./ci/test/00_setup_env_native_nowallet.sh"
diff --git a/ci/test/00_setup_env.sh b/ci/test/00_setup_env.sh
index 2c08fdbcd8..deb4643731 100755
--- a/ci/test/00_setup_env.sh
+++ b/ci/test/00_setup_env.sh
@@ -34,6 +34,7 @@ export USE_BUSY_BOX=${USE_BUSY_BOX:-false}
 export RUN_UNIT_TESTS=${RUN_UNIT_TESTS:-true}
 export RUN_FUNCTIONAL_TESTS=${RUN_FUNCTIONAL_TESTS:-true}
 export TEST_PREVIOUS_RELEASES=${TEST_PREVIOUS_RELEASES:-false}
+export TEST_RUNNER_ENV=${TEST_RUNNER_ENV:-}
 export RUN_FUZZ_TESTS=${RUN_FUZZ_TESTS:-false}
 export CONTAINER_NAME=${CONTAINER_NAME:-ci_unnamed}
 export DOCKER_NAME_TAG=${DOCKER_NAME_TAG:-ubuntu:18.04}
diff --git a/ci/test/00_setup_env_native_multiprocess.sh b/ci/test/00_setup_env_native_multiprocess.sh
new file mode 100644
index 0000000000..0fc989085c
--- /dev/null
+++ b/ci/test/00_setup_env_native_multiprocess.sh
@@ -0,0 +1,14 @@
+#!/usr/bin/env bash
+#
+# Copyright (c) 2020 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+export LC_ALL=C.UTF-8
+
+export CONTAINER_NAME=ci_native_multiprocess
+export PACKAGES="cmake python3"
+export DEP_OPTS="MULTIPROCESS=1"
+export GOAL="install"
+export BITCOIN_CONFIG=""
+export TEST_RUNNER_ENV="BITCOIND=bitcoin-node"
diff --git a/ci/test/06_script_b.sh b/ci/test/06_script_b.sh
index ed720bcd00..51d84ee39d 100755
--- a/ci/test/06_script_b.sh
+++ b/ci/test/06_script_b.sh
@@ -37,7 +37,7 @@ fi
 
 if [ "$RUN_FUNCTIONAL_TESTS" = "true" ]; then
   BEGIN_FOLD functional-tests
-  DOCKER_EXEC LD_LIBRARY_PATH=$DEPENDS_DIR/$HOST/lib test/functional/test_runner.py --ci $MAKEJOBS --tmpdirprefix "${BASE_SCRATCH_DIR}/test_runner/" --ansi --combinedlogslen=4000 ${TEST_RUNNER_EXTRA} --quiet --failfast
+  DOCKER_EXEC LD_LIBRARY_PATH=$DEPENDS_DIR/$HOST/lib ${TEST_RUNNER_ENV} test/functional/test_runner.py --ci $MAKEJOBS --tmpdirprefix "${BASE_SCRATCH_DIR}/test_runner/" --ansi --combinedlogslen=4000 ${TEST_RUNNER_EXTRA} --quiet --failfast
   END_FOLD
 fi
 
diff --git a/configure.ac b/configure.ac
index 58f464a73a..7f0c5dbd7a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -242,6 +242,24 @@ if test x$enable_bip70 != xno; then
   AC_MSG_ERROR([BIP70 is no longer supported!])
 fi
 
+AC_ARG_WITH([libmultiprocess],
+  [AS_HELP_STRING([--with-libmultiprocess=yes|no|auto],
+  [Build with libmultiprocess library. (default: auto, i.e. detect with pkg-config)])],
+  [with_libmultiprocess=$withval],
+  [with_libmultiprocess=auto])
+
+AC_ARG_WITH([mpgen],
+  [AS_HELP_STRING([--with-mpgen=yes|no|auto|PREFIX],
+  [Build with libmultiprocess codegen tool. Useful to specify different libmultiprocess host system library and build system codegen tool prefixes when cross-compiling (default is host system libmultiprocess prefix)])],
+  [with_mpgen=$withval],
+  [with_mpgen=auto])
+
+AC_ARG_ENABLE([multiprocess],
+  [AS_HELP_STRING([--enable-multiprocess],
+  [build multiprocess bitcoin-node, bitcoin-wallet, and bitcoin-gui executables in addition to monolithic bitcoind and bitcoin-qt executables. Requires libmultiprocess library. Experimental (default is no)])],
+  [enable_multiprocess=$enableval],
+  [enable_multiprocess=no])
+
 AC_ARG_ENABLE(man,
     [AS_HELP_STRING([--disable-man],
                     [do not install man pages (default is to install)])],,
@@ -1389,6 +1407,50 @@ AM_CONDITIONAL([EMBEDDED_UNIVALUE],[test x$need_bundled_univalue = xyes])
 AC_SUBST(UNIVALUE_CFLAGS)
 AC_SUBST(UNIVALUE_LIBS)
 
+dnl libmultiprocess library check
+
+libmultiprocess_found=no
+if test "x$with_libmultiprocess" = xyes || test "x$with_libmultiprocess" = xauto; then
+  if test "x$use_pkgconfig" = xyes; then
+    m4_ifdef([PKG_CHECK_MODULES], [PKG_CHECK_MODULES([LIBMULTIPROCESS], [libmultiprocess], [
+       libmultiprocess_found=yes;
+       libmultiprocess_prefix=`$PKG_CONFIG --variable=prefix libmultiprocess`;
+    ], [true])])
+  fi
+elif test "x$with_libmultiprocess" != xno; then
+  AC_MSG_ERROR([--with-libmultiprocess=$with_libmultiprocess value is not yes, auto, or no])
+fi
+AC_SUBST(LIBMULTIPROCESS_CFLAGS)
+AC_SUBST(LIBMULTIPROCESS_LIBS)
+
+dnl Enable multiprocess check
+
+if test "x$enable_multiprocess" = xyes; then
+  if test "x$libmultiprocess_found" != xyes; then
+    AC_MSG_ERROR([--enable-multiprocess=yes option specified but libmultiprocess library was not found. May need to install libmultiprocess library, or specify install path with PKG_CONFIG_PATH environment variable. Running 'pkg-config --debug libmultiprocess' may be helpful for debugging.])
+  fi
+  build_multiprocess=yes
+elif test "x$enable_multiprocess" = xauto; then
+  build_multiprocess=$libmultiprocess_found
+else
+  build_multiprocess=no
+fi
+
+AM_CONDITIONAL([BUILD_MULTIPROCESS],[test "x$build_multiprocess" = xyes])
+AM_CONDITIONAL([BUILD_BITCOIN_NODE], [test "x$build_multiprocess" = xyes])
+AM_CONDITIONAL([BUILD_BITCOIN_GUI], [test "x$build_multiprocess" = xyes])
+
+dnl codegen tools check
+
+if test x$build_multiprocess != xno; then
+  if test "x$with_mpgen" = xyes || test "x$with_mpgen" = xauto; then
+    MPGEN_PREFIX="$libmultiprocess_prefix"
+  elif test "x$with_mpgen" != xno; then
+    MPGEN_PREFIX="$with_mpgen";
+  fi
+  AC_SUBST(MPGEN_PREFIX)
+fi
+
 AC_MSG_CHECKING([whether to build bitcoind])
 AM_CONDITIONAL([BUILD_BITCOIND], [test x$build_bitcoind = xyes])
 AC_MSG_RESULT($build_bitcoind)
@@ -1667,6 +1729,7 @@ esac
 
 echo
 echo "Options used to compile and link:"
+echo "  multiprocess  = $build_multiprocess"
 echo "  with wallet   = $enable_wallet"
 echo "  with gui / qt = $bitcoin_enable_qt"
 if test x$bitcoin_enable_qt != xno; then
diff --git a/depends/Makefile b/depends/Makefile
index 5f5247f881..5ad82bb56a 100644
--- a/depends/Makefile
+++ b/depends/Makefile
@@ -13,6 +13,7 @@ NO_QR ?=
 NO_WALLET ?=
 NO_ZMQ ?=
 NO_UPNP ?=
+MULTIPROCESS ?=
 FALLBACK_DOWNLOAD_PATH ?= https://bitcoincore.org/depends-sources
 
 BUILD = $(shell ./config.guess)
@@ -107,6 +108,7 @@ qt_packages_$(NO_QT) = $(qt_packages) $(qt_$(host_os)_packages) $(qt_$(host_arch
 wallet_packages_$(NO_WALLET) = $(wallet_packages)
 upnp_packages_$(NO_UPNP) = $(upnp_packages)
 zmq_packages_$(NO_ZMQ) = $(zmq_packages)
+multiprocess_packages_$(MULTIPROCESS) = $(multiprocess_packages)
 
 packages += $($(host_arch)_$(host_os)_packages) $($(host_os)_packages) $(qt_packages_) $(wallet_packages_) $(upnp_packages_)
 native_packages += $($(host_arch)_$(host_os)_native_packages) $($(host_os)_native_packages)
@@ -115,6 +117,11 @@ ifneq ($(zmq_packages_),)
 packages += $(zmq_packages)
 endif
 
+ifeq ($(multiprocess_packages_),)
+packages += $(multiprocess_packages)
+native_packages += $(multiprocess_native_packages)
+endif
+
 all_packages = $(packages) $(native_packages)
 
 meta_depends = Makefile funcs.mk builders/default.mk hosts/default.mk hosts/$(host_os).mk builders/$(build_os).mk
@@ -155,6 +162,7 @@ $(host_prefix)/share/config.site : config.site.in $(host_prefix)/.stamp_$(final_
             -e 's|@no_zmq@|$(NO_ZMQ)|' \
             -e 's|@no_wallet@|$(NO_WALLET)|' \
             -e 's|@no_upnp@|$(NO_UPNP)|' \
+            -e 's|@multiprocess@|$(MULTIPROCESS)|' \
             -e 's|@debug@|$(DEBUG)|' \
             $< > $@
 	$(AT)touch $@
diff --git a/depends/README.md b/depends/README.md
index 79865ff011..c12ea8bcb3 100644
--- a/depends/README.md
+++ b/depends/README.md
@@ -91,6 +91,7 @@ The following can be set when running make: make FOO=bar
     NO_ZMQ: Don't download/build/cache packages needed for enabling zeromq
     NO_WALLET: Don't download/build/cache libs needed to enable the wallet
     NO_UPNP: Don't download/build/cache packages needed for enabling upnp
+    MULTIPROCESS: build libmultiprocess (experimental, requires cmake)
     DEBUG: disable some optimizations and enable more runtime checking
     HOST_ID_SALT: Optional salt to use when generating host package ids
     BUILD_ID_SALT: Optional salt to use when generating build package ids
diff --git a/depends/config.site.in b/depends/config.site.in
index fb9bf713cc..103aa0d2ff 100644
--- a/depends/config.site.in
+++ b/depends/config.site.in
@@ -16,6 +16,9 @@ fi
 if test -z $with_qt_bindir && test -z "@no_qt@"; then
   with_qt_bindir=$depends_prefix/native/bin
 fi
+if test -z $with_mpgen && test -n "@multiprocess@"; then
+  with_mpgen=$depends_prefix/native
+fi
 
 if test -z $with_qrencode && test -n "@no_qr@"; then
   with_qrencode=no
@@ -25,6 +28,10 @@ if test -z $enable_wallet && test -n "@no_wallet@"; then
   enable_wallet=no
 fi
 
+if test -z $enable_multiprocess && test -n "@multiprocess@"; then
+  enable_multiprocess=yes
+fi
+
 if test -z $with_miniupnpc && test -n "@no_upnp@"; then
   with_miniupnpc=no
 fi
diff --git a/depends/funcs.mk b/depends/funcs.mk
index a4434b5167..135ebba9f8 100644
--- a/depends/funcs.mk
+++ b/depends/funcs.mk
@@ -130,11 +130,11 @@ $(1)_config_env+=$($(1)_config_env_$(host_arch)_$(host_os)) $($(1)_config_env_$(
 
 $(1)_config_env+=PKG_CONFIG_LIBDIR=$($($(1)_type)_prefix)/lib/pkgconfig
 $(1)_config_env+=PKG_CONFIG_PATH=$($($(1)_type)_prefix)/share/pkgconfig
+$(1)_config_env+=CMAKE_MODULE_PATH=$($($(1)_type)_prefix)/lib/cmake
 $(1)_config_env+=PATH=$(build_prefix)/bin:$(PATH)
 $(1)_build_env+=PATH=$(build_prefix)/bin:$(PATH)
 $(1)_stage_env+=PATH=$(build_prefix)/bin:$(PATH)
 $(1)_autoconf=./configure --host=$($($(1)_type)_host) --prefix=$($($(1)_type)_prefix) $$($(1)_config_opts) CC="$$($(1)_cc)" CXX="$$($(1)_cxx)"
-
 ifneq ($($(1)_nm),)
 $(1)_autoconf += NM="$$($(1)_nm)"
 endif
@@ -156,6 +156,15 @@ endif
 ifneq ($($(1)_ldflags),)
 $(1)_autoconf += LDFLAGS="$$($(1)_ldflags)"
 endif
+
+$(1)_cmake=cmake -DCMAKE_INSTALL_PREFIX=$($($(1)_type)_prefix)
+ifneq ($($(1)_type),build)
+ifneq ($(host),$(build))
+$(1)_cmake += -DCMAKE_SYSTEM_NAME=$($(host_os)_cmake_system) -DCMAKE_SYSROOT=$(host_prefix)
+$(1)_cmake += -DCMAKE_C_COMPILER_TARGET=$(host) -DCMAKE_C_COMPILER=$(firstword $($($(1)_type)_CC)) -DCMAKE_C_FLAGS="$(wordlist 2,1000,$($($(1)_type)_CC))"
+$(1)_cmake += -DCMAKE_CXX_COMPILER_TARGET=$(host) -DCMAKE_CXX_COMPILER=$(firstword $($($(1)_type)_CXX)) -DCMAKE_CXX_FLAGS="$(wordlist 2,1000,$($($(1)_type)_CXX))"
+endif
+endif
 endef
 
 define int_add_cmds
diff --git a/depends/hosts/android.mk b/depends/hosts/android.mk
index 969ec2a1cb..eabd84bbbe 100644
--- a/depends/hosts/android.mk
+++ b/depends/hosts/android.mk
@@ -9,3 +9,4 @@ android_CXX=$(ANDROID_TOOLCHAIN_BIN)/$(HOST)$(ANDROID_API_LEVEL)-clang++
 android_CC=$(ANDROID_TOOLCHAIN_BIN)/$(HOST)$(ANDROID_API_LEVEL)-clang
 android_RANLIB=$(ANDROID_TOOLCHAIN_BIN)/$(HOST)-ranlib
 endif
+android_cmake_system=Android
diff --git a/depends/hosts/darwin.mk b/depends/hosts/darwin.mk
index 1bc4fb8189..82e086a326 100644
--- a/depends/hosts/darwin.mk
+++ b/depends/hosts/darwin.mk
@@ -14,3 +14,4 @@ darwin_debug_CFLAGS=-O1
 darwin_debug_CXXFLAGS=$(darwin_debug_CFLAGS)
 
 darwin_native_toolchain=native_cctools
+darwin_cmake_system=Darwin
diff --git a/depends/hosts/linux.mk b/depends/hosts/linux.mk
index b13a0f1ad7..8ab448ce5f 100644
--- a/depends/hosts/linux.mk
+++ b/depends/hosts/linux.mk
@@ -29,3 +29,4 @@ i686_linux_CXX=$(default_host_CXX) -m32
 x86_64_linux_CC=$(default_host_CC) -m64
 x86_64_linux_CXX=$(default_host_CXX) -m64
 endif
+linux_cmake_system=Linux
diff --git a/depends/hosts/mingw32.mk b/depends/hosts/mingw32.mk
index dbfb62fdcf..be5fec570c 100644
--- a/depends/hosts/mingw32.mk
+++ b/depends/hosts/mingw32.mk
@@ -8,3 +8,5 @@ mingw32_debug_CFLAGS=-O1
 mingw32_debug_CXXFLAGS=$(mingw32_debug_CFLAGS)
 
 mingw32_debug_CPPFLAGS=-D_GLIBCXX_DEBUG -D_GLIBCXX_DEBUG_PEDANTIC
+
+mingw_cmake_system=Windows
diff --git a/depends/packages/boost.mk b/depends/packages/boost.mk
index cbe4fe4d97..970c81041e 100644
--- a/depends/packages/boost.mk
+++ b/depends/packages/boost.mk
@@ -1,7 +1,7 @@
 package=boost
 $(package)_version=1_70_0
 $(package)_download_path=https://dl.bintray.com/boostorg/release/1.70.0/source/
-$(package)_file_name=$(package)_$($(package)_version).tar.bz2
+$(package)_file_name=boost_$($(package)_version).tar.bz2
 $(package)_sha256_hash=430ae8354789de4fd19ee52f3b1f739e1fba576f0aded0897c3c2bc00fb38778
 
 define $(package)_set_vars
diff --git a/depends/packages/capnp.mk b/depends/packages/capnp.mk
new file mode 100644
index 0000000000..abeb26545f
--- /dev/null
+++ b/depends/packages/capnp.mk
@@ -0,0 +1,18 @@
+package=capnp
+$(package)_version=$(native_$(package)_version)
+$(package)_download_path=$(native_$(package)_download_path)
+$(package)_file_name=$(native_$(package)_file_name)
+$(package)_sha256_hash=$(native_$(package)_sha256_hash)
+$(package)_dependencies=native_$(package)
+
+define $(package)_config_cmds
+  $($(package)_autoconf) --with-external-capnp
+endef
+
+define $(package)_build_cmds
+  $(MAKE)
+endef
+
+define $(package)_stage_cmds
+  $(MAKE) DESTDIR=$($(package)_staging_dir) install
+endef
diff --git a/depends/packages/libmultiprocess.mk b/depends/packages/libmultiprocess.mk
new file mode 100644
index 0000000000..3e5cf5f160
--- /dev/null
+++ b/depends/packages/libmultiprocess.mk
@@ -0,0 +1,18 @@
+package=libmultiprocess
+$(package)_version=$(native_$(package)_version)
+$(package)_download_path=$(native_$(package)_download_path)
+$(package)_file_name=$(native_$(package)_file_name)
+$(package)_sha256_hash=$(native_$(package)_sha256_hash)
+$(package)_dependencies=native_$(package) boost capnp
+
+define $(package)_config_cmds
+  $($(package)_cmake)
+endef
+
+define $(package)_build_cmds
+  $(MAKE)
+endef
+
+define $(package)_stage_cmds
+  $(MAKE) DESTDIR=$($(package)_staging_dir) install
+endef
diff --git a/depends/packages/native_capnp.mk b/depends/packages/native_capnp.mk
new file mode 100644
index 0000000000..ed5a6deee2
--- /dev/null
+++ b/depends/packages/native_capnp.mk
@@ -0,0 +1,18 @@
+package=native_capnp
+$(package)_version=0.7.0
+$(package)_download_path=https://capnproto.org/
+$(package)_download_file=capnproto-c++-$($(package)_version).tar.gz
+$(package)_file_name=capnproto-cxx-$($(package)_version).tar.gz
+$(package)_sha256_hash=c9a4c0bd88123064d483ab46ecee777f14d933359e23bff6fb4f4dbd28b4cd41
+
+define $(package)_config_cmds
+  $($(package)_autoconf)
+endef
+
+define $(package)_build_cmds
+  $(MAKE)
+endef
+
+define $(package)_stage_cmds
+  $(MAKE) DESTDIR=$($(package)_staging_dir) install
+endef
diff --git a/depends/packages/native_libmultiprocess.mk b/depends/packages/native_libmultiprocess.mk
new file mode 100644
index 0000000000..c50fdc3f6b
--- /dev/null
+++ b/depends/packages/native_libmultiprocess.mk
@@ -0,0 +1,18 @@
+package=native_libmultiprocess
+$(package)_version=5741d750a04e644a03336090d8979c6d033e32c0
+$(package)_download_path=https://github.com/chaincodelabs/libmultiprocess/archive
+$(package)_file_name=$($(package)_version).tar.gz
+$(package)_sha256_hash=ac848db49a6ed53e423c62d54bd87f1f08cbb0326254a8667e10bbfe5bf032a4
+$(package)_dependencies=native_capnp
+
+define $(package)_config_cmds
+  $($(package)_cmake)
+endef
+
+define $(package)_build_cmds
+  $(MAKE)
+endef
+
+define $(package)_stage_cmds
+  $(MAKE) DESTDIR=$($(package)_staging_dir) install
+endef
diff --git a/depends/packages/packages.mk b/depends/packages/packages.mk
index 42dbaa77a6..8fe2c771c9 100644
--- a/depends/packages/packages.mk
+++ b/depends/packages/packages.mk
@@ -16,6 +16,9 @@ zmq_packages=zeromq
 
 upnp_packages=miniupnpc
 
+multiprocess_packages = libmultiprocess capnp
+multiprocess_native_packages = native_libmultiprocess native_capnp
+
 darwin_native_packages = native_biplist native_ds_store native_mac_alias
 
 ifneq ($(build_os),darwin)
diff --git a/doc/multiprocess.md b/doc/multiprocess.md
new file mode 100644
index 0000000000..471d8561f7
--- /dev/null
+++ b/doc/multiprocess.md
@@ -0,0 +1,35 @@
+# Multiprocess Bitcoin
+
+On unix systems, the `--enable-multiprocess` build option can be passed to `./configure` to build new `bitcoin-node`, `bitcoin-wallet`, and `bitcoin-gui` executables alongside existing `bitcoind` and `bitcoin-qt` executables.
+
+`bitcoin-node` is a drop-in replacement for `bitcoind`, and `bitcoin-gui` is a drop-in replacement for `bitcoin-qt`, and there are no differences in use or external behavior between the new and old executables. But internally (after [#10102](https://github.com/bitcoin/bitcoin/pull/10102)), `bitcoin-gui` will spawn a `bitcoin-node` process to run P2P and RPC code, communicating with it across a socket pair, and `bitcoin-node` will spawn `bitcoin-wallet` to run wallet code, also communicating over a socket pair. This will let node, wallet, and GUI code run in separate address spaces for better isolation, and allow future improvements like being able to start and stop components independently on different machines and environments.
+
+## Next steps
+
+Specific next steps after [#10102](https://github.com/bitcoin/bitcoin/pull/10102) will be:
+
+- [ ] Adding `-ipcbind` and `-ipcconnect` options to `bitcoin-node`, `bitcoin-wallet`, and `bitcoin-gui` executables so they can listen and connect to TCP ports and unix socket paths. This will allow separate processes to be started and stopped any time and connect to each other.
+- [ ] Adding `-server` and `-rpcbind` options to the `bitcoin-wallet` executable so wallet processes can handle RPC requests directly without going through the node.
+- [ ] Supporting windows, not just unix systems. The existing socket code is already cross-platform, so the only windows-specific code that needs to be written is code spawning a process and passing a socket descriptor. This can be implemented with `CreateProcess` and `WSADuplicateSocket`. Example: https://memset.wordpress.com/2010/10/13/win32-api-passing-socket-with-ipc-method/.
+- [ ] Adding sandbox features, restricting subprocess access to resources and data. See [https://eklitzke.org/multiprocess-bitcoin](https://eklitzke.org/multiprocess-bitcoin).
+
+## Debugging
+
+After [#10102](https://github.com/bitcoin/bitcoin/pull/10102), the `-debug=ipc` command line option can be used to see requests and responses between processes.
+
+## Installation
+
+The multiprocess feature requires [Cap'n Proto](https://capnproto.org/) and [libmultiprocess](https://github.com/chaincodelabs/libmultiprocess) as dependencies. A simple way to get starting using it without installing these dependencies manually is to use the [depends system](../depends) with the `MULTIPROCESS=1` [dependency option](../depends#dependency-options) passed to make:
+
+```
+cd <BITCOIN_SOURCE_DIRECTORY>
+make -C depends NO_QT=1 MULTIPROCESS=1
+./configure --prefix=$PWD/depends/x86_64-pc-linux-gnu
+make
+src/bitcoin-node -regtest -printtoconsole -debug=ipc
+BITCOIND=bitcoin-node test/functional/test_runner.py
+```
+
+The configure script will pick up settings and library locations from the depends directory, so there is no need to pass `--enable-multiprocess` as a separate flag when using the depends system (it's controlled by the `MULTIPROCESS=1` option).
+
+Alternately, you can install [Cap'n Proto](https://capnproto.org/) and [libmultiprocess](https://github.com/chaincodelabs/libmultiprocess) packages on your system, and just run `./configure --enable-multiprocess` without using the depends system. The configure script will be able to locate the installed packages via [pkg-config](https://www.freedesktop.org/wiki/Software/pkg-config/). See [Installation](https://github.com/chaincodelabs/libmultiprocess#installation) section of the libmultiprocess readme for install steps. See [build-unix.md](build-unix.md) and [build-osx.md](build-osx.md) for information about installing dependencies in general.
diff --git a/src/Makefile.am b/src/Makefile.am
index 13812de0e7..c5cd1c1ea7 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -85,6 +85,10 @@ if BUILD_BITCOIND
   bin_PROGRAMS += bitcoind
 endif
 
+if BUILD_BITCOIN_NODE
+  bin_PROGRAMS += bitcoin-node
+endif
+
 if BUILD_BITCOIN_CLI
   bin_PROGRAMS += bitcoin-cli
 endif
@@ -546,22 +550,21 @@ libbitcoin_cli_a_SOURCES = \
 nodist_libbitcoin_util_a_SOURCES = $(srcdir)/obj/build.h
 #
 
-# bitcoind binary #
-bitcoind_SOURCES = bitcoind.cpp
-bitcoind_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
-bitcoind_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
-bitcoind_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
+# bitcoind & bitcoin-node binaries #
+bitcoin_daemon_sources = bitcoind.cpp
+bitcoin_bin_cppflags = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
+bitcoin_bin_cxxflags = $(AM_CXXFLAGS) $(PIE_FLAGS)
+bitcoin_bin_ldflags = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
 
 if TARGET_WINDOWS
-bitcoind_SOURCES += bitcoind-res.rc
+bitcoin_daemon_sources += bitcoind-res.rc
 endif
 
-bitcoind_LDADD = \
-  $(LIBBITCOIN_SERVER) \
+bitcoin_bin_ldadd = \
   $(LIBBITCOIN_WALLET) \
   $(LIBBITCOIN_COMMON) \
-  $(LIBUNIVALUE) \
   $(LIBBITCOIN_UTIL) \
+  $(LIBUNIVALUE) \
   $(LIBBITCOIN_ZMQ) \
   $(LIBBITCOIN_CONSENSUS) \
   $(LIBBITCOIN_CRYPTO) \
@@ -570,7 +573,19 @@ bitcoind_LDADD = \
   $(LIBMEMENV) \
   $(LIBSECP256K1)
 
-bitcoind_LDADD += $(BOOST_LIBS) $(BDB_LIBS) $(MINIUPNPC_LIBS) $(EVENT_PTHREADS_LIBS) $(EVENT_LIBS) $(ZMQ_LIBS)
+bitcoin_bin_ldadd += $(BOOST_LIBS) $(BDB_LIBS) $(MINIUPNPC_LIBS) $(EVENT_PTHREADS_LIBS) $(EVENT_LIBS) $(ZMQ_LIBS)
+
+bitcoind_SOURCES = $(bitcoin_daemon_sources)
+bitcoind_CPPFLAGS = $(bitcoin_bin_cppflags)
+bitcoind_CXXFLAGS = $(bitcoin_bin_cxxflags)
+bitcoind_LDFLAGS = $(bitcoin_bin_ldflags)
+bitcoind_LDADD = $(LIBBITCOIN_SERVER) $(bitcoin_bin_ldadd)
+
+bitcoin_node_SOURCES = $(bitcoin_daemon_sources)
+bitcoin_node_CPPFLAGS = $(bitcoin_bin_cppflags)
+bitcoin_node_CXXFLAGS = $(bitcoin_bin_cxxflags)
+bitcoin_node_LDFLAGS = $(bitcoin_bin_ldflags)
+bitcoin_node_LDADD = $(LIBBITCOIN_SERVER) $(bitcoin_bin_ldadd)
 
 # bitcoin-cli binary #
 bitcoin_cli_SOURCES = bitcoin-cli.cpp
@@ -614,29 +629,14 @@ bitcoin_tx_LDADD += $(BOOST_LIBS)
 
 # bitcoin-wallet binary #
 bitcoin_wallet_SOURCES = bitcoin-wallet.cpp
-bitcoin_wallet_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
-bitcoin_wallet_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
-bitcoin_wallet_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
+bitcoin_wallet_CPPFLAGS = $(bitcoin_bin_cppflags)
+bitcoin_wallet_CXXFLAGS = $(bitcoin_bin_cxxflags)
+bitcoin_wallet_LDFLAGS = $(bitcoin_bin_ldflags)
+bitcoin_wallet_LDADD = $(LIBBITCOIN_WALLET_TOOL) $(bitcoin_bin_ldadd)
 
 if TARGET_WINDOWS
 bitcoin_wallet_SOURCES += bitcoin-wallet-res.rc
 endif
-
-bitcoin_wallet_LDADD = \
-  $(LIBBITCOIN_WALLET_TOOL) \
-  $(LIBBITCOIN_WALLET) \
-  $(LIBBITCOIN_COMMON) \
-  $(LIBBITCOIN_CONSENSUS) \
-  $(LIBBITCOIN_UTIL) \
-  $(LIBBITCOIN_CRYPTO) \
-  $(LIBBITCOIN_ZMQ) \
-  $(LIBLEVELDB) \
-  $(LIBLEVELDB_SSE42) \
-  $(LIBMEMENV) \
-  $(LIBSECP256K1) \
-  $(LIBUNIVALUE)
-
-bitcoin_wallet_LDADD += $(BOOST_LIBS) $(BDB_LIBS) $(EVENT_PTHREADS_LIBS) $(EVENT_LIBS) $(MINIUPNPC_LIBS) $(ZMQ_LIBS)
 #
 
 # bitcoinconsensus library #
diff --git a/src/Makefile.qt.include b/src/Makefile.qt.include
index cf09eee2cb..13bfea7646 100644
--- a/src/Makefile.qt.include
+++ b/src/Makefile.qt.include
@@ -3,6 +3,11 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 bin_PROGRAMS += qt/bitcoin-qt
+
+if BUILD_BITCOIN_GUI
+  bin_PROGRAMS += bitcoin-gui
+endif
+
 EXTRA_LIBRARIES += qt/libbitcoinqt.a
 
 # bitcoin qt core #
@@ -294,29 +299,43 @@ QT_FORMS_H=$(join $(dir $(QT_FORMS_UI)),$(addprefix ui_, $(notdir $(QT_FORMS_UI:
 # Most files will depend on the forms and moc files as includes. Generate them
 # before anything else.
 $(QT_MOC): $(QT_FORMS_H)
-$(qt_libbitcoinqt_a_OBJECTS) $(qt_bitcoin_qt_OBJECTS) : | $(QT_MOC)
+$(qt_libbitcoinqt_a_OBJECTS) $(qt_bitcoin_qt_OBJECTS) $(bitcoin_gui_OBJECTS) : | $(QT_MOC)
 
-# bitcoin-qt binary #
-qt_bitcoin_qt_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(BITCOIN_QT_INCLUDES) \
+# bitcoin-qt and bitcoin-gui binaries #
+bitcoin_qt_cppflags = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(BITCOIN_QT_INCLUDES) \
   $(QT_INCLUDES) $(QR_CFLAGS)
-qt_bitcoin_qt_CXXFLAGS = $(AM_CXXFLAGS) $(QT_PIE_FLAGS)
+bitcoin_qt_cxxflags = $(AM_CXXFLAGS) $(QT_PIE_FLAGS)
 
-qt_bitcoin_qt_SOURCES = qt/main.cpp
+bitcoin_qt_sources = qt/main.cpp
 if TARGET_WINDOWS
-  qt_bitcoin_qt_SOURCES += $(BITCOIN_RC)
+  bitcoin_qt_sources += $(BITCOIN_RC)
 endif
-qt_bitcoin_qt_LDADD = qt/libbitcoinqt.a $(LIBBITCOIN_SERVER)
+bitcoin_qt_ldadd = qt/libbitcoinqt.a $(LIBBITCOIN_SERVER)
 if ENABLE_WALLET
-qt_bitcoin_qt_LDADD += $(LIBBITCOIN_UTIL) $(LIBBITCOIN_WALLET)
+bitcoin_qt_ldadd += $(LIBBITCOIN_UTIL) $(LIBBITCOIN_WALLET)
 endif
 if ENABLE_ZMQ
-qt_bitcoin_qt_LDADD += $(LIBBITCOIN_ZMQ) $(ZMQ_LIBS)
+bitcoin_qt_ldadd += $(LIBBITCOIN_ZMQ) $(ZMQ_LIBS)
 endif
-qt_bitcoin_qt_LDADD += $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBITCOIN_UTIL) $(LIBBITCOIN_CONSENSUS) $(LIBBITCOIN_CRYPTO) $(LIBUNIVALUE) $(LIBLEVELDB) $(LIBLEVELDB_SSE42) $(LIBMEMENV) \
+bitcoin_qt_ldadd += $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBITCOIN_UTIL) $(LIBBITCOIN_CONSENSUS) $(LIBBITCOIN_CRYPTO) $(LIBUNIVALUE) $(LIBLEVELDB) $(LIBLEVELDB_SSE42) $(LIBMEMENV) \
   $(BOOST_LIBS) $(QT_LIBS) $(QT_DBUS_LIBS) $(QR_LIBS) $(BDB_LIBS) $(MINIUPNPC_LIBS) $(LIBSECP256K1) \
   $(EVENT_PTHREADS_LIBS) $(EVENT_LIBS)
-qt_bitcoin_qt_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(QT_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
-qt_bitcoin_qt_LIBTOOLFLAGS = $(AM_LIBTOOLFLAGS) --tag CXX
+bitcoin_qt_ldflags = $(RELDFLAGS) $(AM_LDFLAGS) $(QT_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
+bitcoin_qt_libtoolflags = $(AM_LIBTOOLFLAGS) --tag CXX
+
+qt_bitcoin_qt_CPPFLAGS = $(bitcoin_qt_cppflags)
+qt_bitcoin_qt_CXXFLAGS = $(bitcoin_qt_cxxflags)
+qt_bitcoin_qt_SOURCES = $(bitcoin_qt_sources)
+qt_bitcoin_qt_LDADD = $(bitcoin_qt_ldadd)
+qt_bitcoin_qt_LDFLAGS = $(bitcoin_qt_ldflags)
+qt_bitcoin_qt_LIBTOOLFLAGS = $(bitcoin_qt_libtoolflags)
+
+bitcoin_gui_CPPFLAGS = $(bitcoin_qt_cppflags)
+bitcoin_gui_CXXFLAGS = $(bitcoin_qt_cxxflags)
+bitcoin_gui_SOURCES = $(bitcoin_qt_sources)
+bitcoin_gui_LDADD = $(bitcoin_qt_ldadd)
+bitcoin_gui_LDFLAGS = $(bitcoin_qt_ldflags)
+bitcoin_gui_LIBTOOLFLAGS = $(bitcoin_qt_libtoolflags)
 
 #locale/foo.ts -> locale/foo.qm
 QT_QM=$(QT_TS:.ts=.qm)