Method processFork

Tests/Libraries/Process/ProcessTest.cpp:373–438

}

void SC::ProcessTest::processFork()
{
    //! [ProcessFork]
    // Cross-platform lightweight clone of current process, sharing memory
    // but keeping any modification after clone "private" (Copy-On-Write).
    // Achieved using "fork" on Posix and "RtlCloneUserProcess" on Windows.
    StringView sharedTag = "INITIAL";
    StringView parentTag = "PARENT";
    StringView saveFile  = "ForkSaveFile.txt";

    // The string will be duplicated using Copy-On-Write (COW)
    String shared = sharedTag;

    // CLONE current process, starting child fork in Suspended state
    // Forked process will be terminated by ProcessFork destructor
    ProcessFork fork;
    SC_TEST_EXPECT(fork.fork(ProcessFork::Suspended));

    // After fork program must check if it's on fork or parent side
    switch (fork.getSide())
    {
    case ProcessFork::ForkChild: {
        report.console.printLine("FORKED process");
        report.console.print("FORKED Shared={0}\n", shared.view());

        // Write the "shared" memory snapshot to the file system
        FileSystem fs;
        SC_TEST_EXPECT(fs.init(report.applicationRootDirectory.view()));
        SC_TEST_EXPECT(fs.writeString(saveFile, shared.view()));

        // Send (as a signal) modified string contents back to Parent
        SC_TEST_EXPECT(fork.getWritePipe().write({shared.view().toCharSpan()}));
    }
    break;
    case ProcessFork::ForkParent: {
        report.console.printLine("PARENT process");
        // Check initial state to be "INITIAL" and modify shared = "PARENT"
        report.console.print("PARENT Shared={0}\n", shared.view());
        SC_TEST_EXPECT(shared == sharedTag and "PARENT");
        shared = parentTag;

        // Resume suspended fork verifying that on its side shared == "INITIAL"
        SC_TEST_EXPECT(fork.resumeChildFork());
        char       string[255] = {0};
        Span<char> received;
        SC_TEST_EXPECT(fork.getReadPipe().read(string, received));
        StringView stringFromFork(received, true, StringEncoding::Ascii);
        report.console.print("PARENT received={0}\n", stringFromFork);
        SC_TEST_EXPECT(stringFromFork == sharedTag);

        // Check creation of "save file" by fork and verify its content too
        FileSystem fs;
        SC_TEST_EXPECT(fs.init(report.applicationRootDirectory.view()));
        String savedData = StringEncoding::Ascii;
        SC_TEST_EXPECT(fs.read(saveFile, savedData));
        SC_TEST_EXPECT(savedData == sharedTag);
        SC_TEST_EXPECT(fs.removeFile(saveFile));