yocto-sumo源码解析（六）: setup_bitbake

1. 创造日志handler： 在status_only模式，不需要日志以及UI

    # Ensure logging messages get sent to the UI as events
    handler = bb.event.LogHandler()
    if not configParams.status_only:
        # In status only mode there are no logs and no UI
        logger.addHandler(handler)

2. 取得ui模块并设置特征集：

    if configParams.server_only:
        featureset = []
        ui_module = None
    else:
        ui_module = import_extension_module(bb.ui, configParams.ui, 'main')
        # Collect the feature set for the UI
        featureset = getattr(ui_module, "featureSet", [])

    if extrafeatures:
        for feature in extrafeatures:
            if not feature in featureset:
                featureset.append(feature)

3. 远程模式下返回远程server连接：

    server_connection = None

    if configParams.remote_server:
        # Connect to a remote XMLRPC server
        server_connection = bb.server.xmlrpcclient.connectXMLRPC(configParams.remote_server, featureset,
                                                                 configParams.observe_only, configParams.xmlrpctoken)

4. 本地模式下返回本地server连接：

    else:
        retries = 8
        while retries:
            try:
                topdir, lock = lockBitbake()
                sockname = topdir + "/bitbake.sock"
                if lock:
                    if configParams.status_only or configParams.kill_server:
                        logger.info("bitbake server is not running.")
                        lock.close()
                        return None, None
                    # we start a server with a given configuration
                    logger.info("Starting bitbake server...")
                    # Clear the event queue since we already displayed messages
                    bb.event.ui_queue = []
                    server = bb.server.process.BitBakeServer(lock, sockname, configuration, featureset)

                else:
                    logger.info("Reconnecting to bitbake server...")
                    if not os.path.exists(sockname):
                        print("Previous bitbake instance shutting down?, waiting to retry...")
                        i = 0
                        lock = None
                        # Wait for 5s or until we can get the lock
                        while not lock and i < 50:
                            time.sleep(0.1)
                            _, lock = lockBitbake()
                            i += 1
                        if lock:
                            bb.utils.unlockfile(lock)
                        raise bb.server.process.ProcessTimeout("Bitbake still shutting down as socket exists but no lock?")
                if not configParams.server_only:
                    try:
                        server_connection = bb.server.process.connectProcessServer(sockname, featureset)
                    except EOFError:
                        # The server may have been shutting down but not closed the socket yet. If that happened,
                        # ignore it.
                        pass

                if server_connection or configParams.server_only:
                    break
            except BBMainFatal:
                raise
            except (Exception, bb.server.process.ProcessTimeout) as e:
                if not retries:
                    raise
                retries -= 1
                if isinstance(e, (bb.server.process.ProcessTimeout, BrokenPipeError)):
                    logger.info("Retrying server connection...")
                else:
                    logger.info("Retrying server connection... (%s)" % traceback.format_exc())
            if not retries:
                bb.fatal("Unable to connect to bitbake server, or start one")
            if retries < 5:
               time.sleep(5)

5. 清理日志handler，返回服务器连接以及ui模块：

    if configParams.kill_server:
        server_connection.connection.terminateServer()
        server_connection.terminate()
        bb.event.ui_queue = []
        logger.info("Terminated bitbake server.")
        return None, None

    # Restore the environment in case the UI needs it
    for k in cleanedvars:
        os.environ[k] = cleanedvars[k]

    logger.removeHandler(handler)

    return server_connection, ui_module