Squashed 'src/ipc/libmultiprocess/' content from commit 35944ffd23fa

git-subtree-dir: src/ipc/libmultiprocess
git-subtree-split: 35944ffd23fa26652b82210351d50e896ce16c8f

example/printer.cpp

@@ -0,0 +1,51 @@
+// Copyright (c) 2021 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <charconv>
+#include <fstream>
+#include <init.capnp.h>
+#include <init.capnp.proxy.h> // NOLINT(misc-include-cleaner)
+#include <init.h>
+#include <iostream>
+#include <memory>
+#include <mp/proxy-io.h>
+#include <printer.h>
+#include <stdexcept>
+#include <string>
+
+class PrinterImpl : public Printer
+{
+public:
+    void print(const std::string& message) override { std::cout << "mpprinter: " << message << std::endl; }
+};
+
+class InitImpl : public Init
+{
+public:
+    std::unique_ptr<Printer> makePrinter() override { return std::make_unique<PrinterImpl>(); }
+};
+
+static void LogPrint(bool raise, const std::string& message)
+{
+    if (raise) throw std::runtime_error(message);
+    std::ofstream("debug.log", std::ios_base::app) << message << std::endl;
+}
+
+int main(int argc, char** argv)
+{
+    if (argc != 2) {
+        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::EventLoop loop("mpprinter", LogPrint);
+    std::unique_ptr<Init> init = std::make_unique<InitImpl>();
+    mp::ServeStream<InitInterface>(loop, fd, *init);
+    loop.loop();
+    return 0;
+}