asynclistener.py

# Encapsulates subprocess.Popen, forwarding stdout to a supplied
# ProcessListener (on a separate thread)
class AsyncProcess(object):
    def __init__(self, arg_list, env, listener,
            # "path" is an option in build systems
            path="",
            # "shell" is an options in build systems
            shell=False):

        self.listener = listener
        self.killed = False

        self.start_time = time.time()

        # Hide the console window on Windows
        startupinfo = None
        if os.name == "nt":
            startupinfo = subprocess.STARTUPINFO()
            startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW

        # Set temporary PATH to locate executable in arg_list
        if path:
            old_path = os.environ["PATH"]
            # The user decides in the build system whether he wants to append $PATH
            # or tuck it at the front: "$PATH;C:\\new\\path", "C:\\new\\path;$PATH"
            os.environ["PATH"] = os.path.expandvars(path).encode(sys.getfilesystemencoding())

        proc_env = os.environ.copy()
        proc_env.update(env)
        for k, v in proc_env.iteritems():
            proc_env[k] = os.path.expandvars(v).encode(sys.getfilesystemencoding())

        self.proc = subprocess.Popen(arg_list, stdout=subprocess.PIPE,
            stderr=subprocess.PIPE, startupinfo=startupinfo, env=proc_env, shell=shell)

        if path:
            os.environ["PATH"] = old_path

        if self.proc.stdout:
            thread.start_new_thread(self.read_stdout, ())

        if self.proc.stderr:
            thread.start_new_thread(self.read_stderr, ())

    def kill(self):
        if not self.killed:
            self.killed = True
            self.proc.terminate()
            self.listener = None

    def poll(self):
        return self.proc.poll() == None

    def exit_code(self):
        return self.proc.poll()

    def read_stdout(self):
        while True:
            data = os.read(self.proc.stdout.fileno(), 2**15)

            if data != "":
                if self.listener:
                    self.listener.on_data(self, data)
            else:
                self.proc.stdout.close()
                if self.listener:
                    self.listener.on_finished(self)
                break

    def read_stderr(self):
        while True:
            data = os.read(self.proc.stderr.fileno(), 2**15)

            if data != "":
                if self.listener:
                    self.listener.on_data(self, data)
            else:
                self.proc.stderr.close()
                break