Add nonunix platform support

.github/workflows/bitcoin-core-ci.yml

@@ -18,6 +18,8 @@ concurrency:
 
 env:
   BITCOIN_REPO: bitcoin/bitcoin
+  # Temporary: use PR #35084 until it merges; revert to refs/heads/master after
+  BITCOIN_CORE_REF: refs/pull/35084/merge
   LLVM_VERSION: 22
   LIBCXX_DIR: /tmp/libcxx-build/
 
@@ -78,6 +80,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           repository: ${{ env.BITCOIN_REPO }}
+          ref: ${{ env.BITCOIN_CORE_REF }}
           fetch-depth: 1
 
       - name: Checkout libmultiprocess
@@ -194,6 +197,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           repository: ${{ env.BITCOIN_REPO }}
+          ref: ${{ env.BITCOIN_CORE_REF }}
           fetch-depth: 1
 
       - name: Checkout libmultiprocess

CMakeLists.txt

@@ -13,7 +13,7 @@ endif()
 include("cmake/compat_find.cmake")
 
 find_package(Threads REQUIRED)
-find_package(CapnProto 0.7 QUIET NO_MODULE)
+find_package(CapnProto 0.9 QUIET NO_MODULE)
  if(NOT CapnProto_FOUND)
    message(FATAL_ERROR
      "Cap'n Proto is required but was not found.\n"

ci/configs/olddeps.bash

@@ -1,5 +1,5 @@
 CI_DESC="CI job using old Cap'n Proto and cmake versions"
 CI_DIR=build-olddeps
 export CXXFLAGS="-Werror -Wall -Wextra -Wpedantic -Wno-unused-parameter -Wno-error=array-bounds"
-NIX_ARGS=(--argstr capnprotoVersion "0.7.1" --argstr cmakeVersion "3.12.4")
+NIX_ARGS=(--argstr capnprotoVersion "0.9.2" --argstr cmakeVersion "3.12.4")
 BUILD_ARGS=(-k)

doc/design.md

@@ -120,7 +120,7 @@ sequenceDiagram
     participant PMT as ProxyMethodTraits
     participant Impl as Actual C++ Method
 
-    serverInvoke->>SF1: SF1::invoke 
+    serverInvoke->>SF1: SF1::invoke
     SF1->>SF2: SF2::invoke
     SF2->>SR: SR::invoke
     SR->>SC: SC::invoke
@@ -167,7 +167,7 @@ Thread mapping enables each client thread to have a dedicated server thread proc
 Thread mapping is initialized by defining an interface method with a `ThreadMap` parameter and/or response. The example below adds `ThreadMap` to the `construct` method because libmultiprocess calls the `construct` method automatically.
 
 ```capnp
-interface InitInterface $Proxy.wrap("Init") { 
+interface InitInterface $Proxy.wrap("Init") {
     construct @0 (threadMap: Proxy.ThreadMap) -> (threadMap :Proxy.ThreadMap);
 }
 ```

doc/versions.md

@@ -7,9 +7,12 @@ Library versions are tracked with simple
 Versioning policy is described in the [version.h](../include/mp/version.h)
 include.
 
-## v13
+## v14
 - Current unstable version.
 
+## [v13.0](https://github.com/bitcoin-core/libmultiprocess/commits/v13.0)
+- Adds support for nonunix platforms, making API changes that are not backwards compatible.
+
 ## [v12.0](https://github.com/bitcoin-core/libmultiprocess/commits/v12.0)
 - Adds an optional `max_connections` parameter to `ListenConnections` ([#269](https://github.com/bitcoin-core/libmultiprocess/pull/269)).
 - Used in Bitcoin Core 32.x and newer releases with [#35684](https://github.com/bitcoin/bitcoin/pull/35684).

example/calculator.cpp

@@ -6,8 +6,7 @@
 #include <init.capnp.h>
 #include <init.capnp.proxy.h> // NOLINT(misc-include-cleaner) // IWYU pragma: keep
 
-#include <charconv>
-#include <cstring>
+#include <cstring> // IWYU pragma: keep
 #include <fstream>
 #include <functional>
 #include <iostream>
@@ -16,9 +15,9 @@
 #include <kj/memory.h>
 #include <memory>
 #include <mp/proxy-io.h>
+#include <mp/util.h>
 #include <stdexcept>
 #include <string>
-#include <system_error>
 #include <utility>
 
 class CalculatorImpl : public Calculator
@@ -51,14 +50,10 @@ int main(int argc, char** argv)
         std::cout << "Usage: mpcalculator <fd>\n";
         return 1;
     }
-    int fd;
-    if (std::from_chars(argv[1], argv[1] + strlen(argv[1]), fd).ec != std::errc{}) {
-        std::cerr << argv[1] << " is not a number or is larger than an int\n";
-        return 1;
-    }
+    mp::SocketId socket{mp::StartSpawned(argv[1])};
     mp::EventLoop loop("mpcalculator", LogPrint);
     std::unique_ptr<Init> init = std::make_unique<InitImpl>();
-    mp::ServeStream<InitInterface>(loop, fd, *init);
+    mp::ServeStream<InitInterface>(loop, mp::MakeStream(loop.m_io_context, socket), *init);
     loop.loop();
     return 0;
 }

example/example.cpp

@@ -19,20 +19,20 @@
 #include <string>
 #include <thread>
 #include <tuple>
+#include <utility>
 #include <vector>
 
 namespace fs = std::filesystem;
 
 static auto Spawn(mp::EventLoop& loop, const std::string& process_argv0, const std::string& new_exe_name)
 {
-    int pid;
-    const int fd = mp::SpawnProcess(pid, [&](int fd) -> std::vector<std::string> {
+    const auto [pid, socket] = mp::SpawnProcess([&](mp::SpawnConnectInfo info) -> std::vector<std::string> {
         fs::path path = process_argv0;
         path.remove_filename();
         path.append(new_exe_name);
-        return {path.string(), std::to_string(fd)};
+        return {path.string(), std::move(info)};
     });
-    return std::make_tuple(mp::ConnectStream<InitInterface>(loop, fd), pid);
+    return std::make_tuple(mp::ConnectStream<InitInterface>(loop, mp::MakeStream(loop.m_io_context, socket)), pid);
 }
 
 static void LogPrint(mp::LogMessage log_data)

example/printer.cpp

@@ -7,18 +7,17 @@
 #include <init.capnp.h>
 #include <init.capnp.proxy.h> // NOLINT(misc-include-cleaner) // IWYU pragma: keep
 
-#include <charconv>
-#include <cstring>
+#include <cstring> // IWYU pragma: keep
 #include <fstream>
 #include <iostream>
 #include <kj/async.h>
 #include <kj/common.h>
 #include <kj/memory.h>
 #include <memory>
 #include <mp/proxy-io.h>
+#include <mp/util.h>
 #include <stdexcept>
 #include <string>
-#include <system_error>
 
 class PrinterImpl : public Printer
 {
@@ -44,14 +43,10 @@ int main(int argc, char** argv)
         std::cout << "Usage: mpprinter <fd>\n";
         return 1;
     }
-    int fd;
-    if (std::from_chars(argv[1], argv[1] + strlen(argv[1]), fd).ec != std::errc{}) {
-        std::cerr << argv[1] << " is not a number or is larger than an int\n";
-        return 1;
-    }
+    mp::SocketId socket{mp::StartSpawned(argv[1])};
     mp::EventLoop loop("mpprinter", LogPrint);
     std::unique_ptr<Init> init = std::make_unique<InitImpl>();
-    mp::ServeStream<InitInterface>(loop, fd, *init);
+    mp::ServeStream<InitInterface>(loop, mp::MakeStream(loop.m_io_context, socket), *init);
     loop.loop();
     return 0;
 }

include/mp/proxy-io.h

@@ -18,6 +18,7 @@
 #include <cstdlib>
 #include <functional>
 #include <kj/function.h>
+#include <kj/io.h>
 #include <map>
 #include <memory>
 #include <optional>
@@ -213,6 +214,12 @@ class Logger
 
 std::string LongThreadName(const char* exe_name);
 
+//! Wrap a socket file descriptor as an async stream, taking ownership of the fd.
+inline Stream MakeStream(kj::AsyncIoContext& io_context, SocketId socket)
+{
+    return io_context.lowLevelProvider->wrapSocketFd(socket, kj::LowLevelAsyncIoProvider::TAKE_OWNERSHIP);
+}
+
 //! Event loop implementation.
 //!
 //! Cap'n Proto threading model is very simple: all I/O operations are
@@ -311,11 +318,12 @@ class EventLoop
     //! Callback functions to run on async thread.
     std::optional<CleanupList> m_async_fns MP_GUARDED_BY(m_mutex);
 
-    //! Pipe read handle used to wake up the event loop thread.
-    int m_wait_fd = -1;
+    //! Socket pair used to post and wait for wakeups to the event loop thread.
+    kj::Own<kj::AsyncIoStream> m_wait_stream;
+    kj::Own<kj::AsyncIoStream> m_post_stream;
 
-    //! Pipe write handle used to wake up the event loop thread.
-    int m_post_fd = -1;
+    //! Synchronous writer used to write to m_post_stream.
+    kj::Own<kj::OutputStream> m_post_writer;
 
     //! Number of EventLoopRef instances referencing this event loop. This is a
     //! sum of the number of client and server objects (Connection, ProxyClient,
@@ -451,7 +459,7 @@ class Connection
     //! Capability::Client handles owned by ProxyClient objects), then schedules
     //! asynchronous cleanup functions to run in a worker thread (to run
     //! destructors of m_impl instances owned by ProxyServer objects).
-    ~Connection();
+    ~Connection() noexcept(false);
 
     //! Register synchronous cleanup function to run on event loop thread (with
     //! access to capnp thread local variables) when disconnect() is called.
@@ -824,17 +832,15 @@ kj::Promise<T> ProxyServer<Thread>::post(Fn&& fn)
     return ret;
 }
 
-//! Given stream file descriptor, make a new ProxyClient object to send requests
-//! over the stream. Also create a new Connection object embedded in the
-//! client that is freed when the client is closed.
+//! Given a stream, make a new ProxyClient object to send requests over it.
+//! Also create a new Connection object embedded in the client that is freed
+//! when the client is closed.
 template <typename InitInterface>
-std::unique_ptr<ProxyClient<InitInterface>> ConnectStream(EventLoop& loop, int fd)
+std::unique_ptr<ProxyClient<InitInterface>> ConnectStream(EventLoop& loop, Stream stream)
 {
     typename InitInterface::Client init_client(nullptr);
     std::unique_ptr<Connection> connection;
     loop.sync([&] {
-        auto stream =
-            loop.m_io_context.lowLevelProvider->wrapSocketFd(fd, kj::LowLevelAsyncIoProvider::TAKE_OWNERSHIP);
         connection = std::make_unique<Connection>(loop, kj::mv(stream));
         init_client = connection->m_rpc_system->bootstrap(ServerVatId().vat_id).castAs<InitInterface>();
         Connection* connection_ptr = connection.get();
@@ -905,22 +911,18 @@ void _Listen(const std::shared_ptr<Listener>& listener, EventLoop& loop, InitImp
         }));
 }
 
-//! Given stream file descriptor and an init object, handle requests on the
-//! stream by calling methods on the Init object.
+//! Given a stream and an init object, handle requests on the stream by calling
+//! methods on the Init object.
 template <typename InitInterface, typename InitImpl>
-void ServeStream(EventLoop& loop, int fd, InitImpl& init)
+void ServeStream(EventLoop& loop, Stream stream, InitImpl& init)
 {
-    _Serve<InitInterface>(
-        loop,
-        loop.m_io_context.lowLevelProvider->wrapSocketFd(fd, kj::LowLevelAsyncIoProvider::TAKE_OWNERSHIP),
-        init,
-        [] {});
+    _Serve<InitInterface>(loop, kj::mv(stream), init, [] {});
 }
 
-//! Given listening socket file descriptor and an init object, handle incoming
+//! Given listening socket identifier and an init object, handle incoming
 //! connections and requests by calling methods on the Init object.
 template <typename InitInterface, typename InitImpl>
-void ListenConnections(EventLoop& loop, int fd, InitImpl& init, std::optional<size_t> max_connections = std::nullopt)
+void ListenConnections(EventLoop& loop, SocketId fd, InitImpl& init, std::optional<size_t> max_connections = std::nullopt)
 {
     loop.sync([&]() {
         auto listener{std::make_shared<Listener>(

include/mp/proxy.h

@@ -315,21 +315,21 @@ template <typename Field, int flags>
 struct Accessor : public Field
 {
     //! Field is present from the Cap'n Proto Params struct (client -> server).
-    static const bool in = flags & FIELD_IN;
+    static constexpr bool in = (flags & FIELD_IN) != 0;
     //! Field is present from the Cap'n Proto Results struct (server -> client).
-    static const bool out = flags & FIELD_OUT;
+    static constexpr bool out = (flags & FIELD_OUT) != 0;
     //! Field has a companion has{Name} boolean field in the Cap'n Proto struct.
     //! This is used to represent optional primitive values (e.g. C++
     //! std::optional<int>) because Cap'n Proto doesn't allow primitive fields to
     //! be unset.
-    static const bool optional = flags & FIELD_OPTIONAL;
+    static constexpr bool optional = (flags & FIELD_OPTIONAL) != 0;
     //! Results field has a companion want{Name} boolean field in the Params
     //! struct. Used for optional output parameters (e.g. C++ int*) and set to
     //! true if the caller passed a non-null pointer and wants the result.
-    static const bool requested = flags & FIELD_REQUESTED;
+    static constexpr bool requested = (flags & FIELD_REQUESTED) != 0;
     //! Field is a Cap'n Proto pointer type (struct, list, text, data,
     //! interface) as opposed to a primitive type (bool, int, float, enum).
-    static const bool boxed = flags & FIELD_BOXED;
+    static constexpr bool boxed = (flags & FIELD_BOXED) != 0;
 };
 
 //! Wrapper around std::function for passing std::function objects between client and servers.

include/mp/type-context.h

@@ -12,11 +12,11 @@
 
 namespace mp {
 template <typename Output>
+    requires FieldTypeIs<Output, Context::Builder>
 void CustomBuildField(TypeList<>,
     Priority<1>,
     ClientInvokeContext& invoke_context,
-    Output&& output,
-    typename std::enable_if<std::is_same<decltype(output.get()), Context::Builder>::value>::type* enable = nullptr)
+    Output&& output)
 {
     auto& connection = invoke_context.connection;
     auto& thread_context = invoke_context.thread_context;

include/mp/type-interface.h

@@ -21,12 +21,12 @@ kj::Own<typename Interface::Server> CustomMakeProxyServer(InvokeContext& context
 }
 
 template <typename Impl, typename Value, typename Output>
+    requires InterfaceField<Output>
 void CustomBuildField(TypeList<std::unique_ptr<Impl>>,
     Priority<1>,
     InvokeContext& invoke_context,
     Value&& value,
-    Output&& output,
-    typename Decay<decltype(output.get())>::Calls* enable = nullptr)
+    Output&& output)
 {
     if (value) {
         using Interface = typename decltype(output.get())::Calls;
@@ -35,12 +35,12 @@ void CustomBuildField(TypeList<std::unique_ptr<Impl>>,
 }
 
 template <typename Impl, typename Value, typename Output>
+    requires InterfaceField<Output>
 void CustomBuildField(TypeList<std::shared_ptr<Impl>>,
     Priority<2>,
     InvokeContext& invoke_context,
     Value&& value,
-    Output&& output,
-    typename Decay<decltype(output.get())>::Calls* enable = nullptr)
+    Output&& output)
 {
     if (value) {
         using Interface = typename decltype(output.get())::Calls;
@@ -49,12 +49,12 @@ void CustomBuildField(TypeList<std::shared_ptr<Impl>>,
 }
 
 template <typename Impl, typename Output>
+    requires InterfaceField<Output>
 void CustomBuildField(TypeList<Impl&>,
     Priority<1>,
     InvokeContext& invoke_context,
     Impl& value,
-    Output&& output,
-    typename decltype(output.get())::Calls* enable = nullptr)
+    Output&& output)
 {
     // Disable deleter so proxy server object doesn't attempt to delete the
     // wrapped implementation when the proxy client is destroyed or
@@ -77,12 +77,12 @@ std::unique_ptr<Impl> CustomMakeProxyClient(InvokeContext& context, typename Int
 }
 
 template <typename LocalType, typename Input, typename ReadDest>
+    requires InterfaceField<Input>
 decltype(auto) CustomReadField(TypeList<std::unique_ptr<LocalType>>,
     Priority<1>,
     InvokeContext& invoke_context,
     Input&& input,
-    ReadDest&& read_dest,
-    typename Decay<decltype(input.get())>::Calls* enable = nullptr)
+    ReadDest&& read_dest)
 {
     using Interface = typename Decay<decltype(input.get())>::Calls;
     if (CustomHasField(TypeList<LocalType>(), invoke_context, input)) {
@@ -93,12 +93,12 @@ decltype(auto) CustomReadField(TypeList<std::unique_ptr<LocalType>>,
 }
 
 template <typename LocalType, typename Input, typename ReadDest>
+    requires InterfaceField<Input>
 decltype(auto) CustomReadField(TypeList<std::shared_ptr<LocalType>>,
     Priority<1>,
     InvokeContext& invoke_context,
     Input&& input,
-    ReadDest&& read_dest,
-    typename Decay<decltype(input.get())>::Calls* enable = nullptr)
+    ReadDest&& read_dest)
 {
     using Interface = typename Decay<decltype(input.get())>::Calls;
     if (CustomHasField(TypeList<LocalType>(), invoke_context, input)) {