openstack nova 源码分析3-nova目录下的service.py、driver.py

问题导读





1.nova下的service.py的源码主要完成什么任务？
2.driver.py位于哪个目录下？





nova下的service.py的源码，有些地方不好或者是错了，希望大家帮我指出！

import inspect  
import os  
 
import eventlet  
import greenlet  
 
from nova import context  
from nova import db  
from nova import exception  
from nova import flags  
from nova import log as logging  
from nova import rpc  
from nova import utils  
from nova import version  
from nova import wsgi  
 
 
LOG = logging.getLogger('nova.service')  
 
FLAGS = flags.FLAGS#flags.py中有一句 FLAGS = FlagValues()，那么直接查看FlagValues()这个类，会发现这个类是继承于gflags.FlagValues.  
 
flags.DEFINE_integer('report_interval', 10,  
                     'seconds between nodes reporting state to datastore',  
                     lower_bound=1)#参数名称，默认值和简短说明  
flags.DEFINE_integer('periodic_interval', 60,  
                     'seconds between running periodic tasks',  
                     lower_bound=1)  
flags.DEFINE_string('ec2_listen', "0.0.0.0",  
                    'IP address for EC2 API to listen')  
flags.DEFINE_integer('ec2_listen_port', 8773, 'port for ec2 api to listen')  
flags.DEFINE_string('osapi_listen', "0.0.0.0",  
                    'IP address for OpenStack API to listen')  
flags.DEFINE_integer('osapi_listen_port', 8774, 'port for os api to listen')  
flags.DEFINE_string('api_paste_config', "api-paste.ini",  
                    'File name for the paste.deploy config for nova-api')  
 
#Launcher 类 包含run_server ,launch_server,stop,wait 4个函数，其实功能非常简单，首先初始化Launcher将self_services弄成一个空列表  
#run_server就是开始和等待一个server的完成，launcher_server就是将该server加入到该类初始化的列表中，  
#stop 就是for循环遍历self_services列表中的服务然后一个一个的kill掉  
#wait 函数就是 Waits until all services have been stopped  
class Launcher(object):  
    """Launch one or more services and wait for them to complete.""" 
 
    def __init__(self):  
        """Initialize the service launcher.  
 
        :returns: None  
 
        """ 
        self._services = []  
 
    @staticmethod 
    def run_server(server):  
        """Start and wait for a server to finish.  
 
        :param service: Server to run and wait for.  
        :returns: None  
 
        """ 
        server.start()  
        server.wait()  
 
    def launch_server(self, server):#在360行被调用  
        """Load and start the given server.  
 
        :param server: The server you would like to start.  
        :returns: None  
 
        """ 
        gt = eventlet.spawn(self.run_server, server)  
        self._services.append(gt)  
 
    def stop(self):  
        """Stop all services which are currently running.  
 
        :returns: None  
 
        """ 
        for service in self._services:  
            service.kill()  
 
    def wait(self):  
        """Waits until all services have been stopped, and then returns.  
 
        :returns: None  
 
        """ 
        for service in self._services:  
            try:  
                service.wait()  
            except greenlet.GreenletExit:  
                pass 
 
 
class Service(object):  
    """Service object for binaries running on hosts.  
 
    A service takes a manager and enables rpc by listening to queues based  
    on topic. It also periodically runs tasks on the manager and reports  
    it state to the database services table.""" 
 
    def __init__(self, host, binary, topic, manager, report_interval=None,  
                 periodic_interval=None, *args, **kwargs):  
        self.host = host  
        self.binary = binary  
        self.topic = topic  
        #动态的生成manager类，并动态生成实例  
        self.manager_class_name = manager#在create函数中指定  
        manager_class = utils.import_class(self.manager_class_name)#动态的import该类  
        self.manager = manager_class(host=self.host, *args, **kwargs)#动态的生成实例  
        #  设置参数：应该是服务间隔时间之类的。  
        self.report_interval = report_interval  
        self.periodic_interval = periodic_interval  
        #设置多出来的一些参数。  
        super(Service, self).__init__(*args, **kwargs)  
        self.saved_args, self.saved_kwargs = args, kwargs  
        #设置一个列表 不知道是不是后面有需要用的地方 果然在185行 发现了  
        self.timers = []  
 
    def start(self):  
        #设置版本  
        vcs_string = version.version_string_with_vcs()  
        logging.audit(_('Starting %(topic)s node (version %(vcs_string)s)'),  
                      {'topic': self.topic, 'vcs_string': vcs_string})  
        #初始化host  
        self.manager.init_host()  
          
        self.model_disconnected = False 
        ctxt = context.get_admin_context()  
        try:  
            service_ref = db.service_get_by_args(ctxt,  
                                                 self.host,  
                                                 self.binary)  
            self.service_id = service_ref['id']  
        except exception.NotFound:  
            self._create_service_ref(ctxt)#该函数位于187行  
 
        if 'nova-compute' == self.binary:  
            self.manager.update_available_resource(ctxt)  
 
        self.conn = rpc.create_connection(new=True)  
        logging.debug("Creating Consumer connection for Service %s" %  
                      self.topic)  
 
        # Share this same connection for these Consumers  
        self.conn.create_consumer(self.topic, self, fanout=False)  
 
        node_topic = '%s.%s' % (self.topic, self.host)#节点的topic 包括了topic 和 host  
        self.conn.create_consumer(node_topic, self, fanout=False)  
 
        self.conn.create_consumer(self.topic, self, fanout=True)  
 
        # Consume from all consumers in a thread  
        self.conn.consume_in_thread()  
 
        if self.report_interval:  
            pulse = utils.LoopingCall(self.report_state)#在265中可以找到report_state 他的作用是在存储中更新服务的状态  
            pulse.start(interval=self.report_interval, now=False)  
            self.timers.append(pulse)  
 
        if self.periodic_interval:  
            periodic = utils.LoopingCall(self.periodic_tasks)#在260行发现 Periodic_tasks任务在一个周期性间隔跑  
            periodic.start(interval=self.periodic_interval, now=False)  
            self.timers.append(periodic)  
 
    def _create_service_ref(self, context):  
        zone = FLAGS.node_availability_zone  
        service_ref = db.service_create(context,  
                                        {'host': self.host,  
                                         'binary': self.binary,  
                                         'topic': self.topic,  
                                         'report_count': 0,  
                                         'availability_zone': zone})  
        self.service_id = service_ref['id']#猜测应该是获取当前服务的id  
 
    def __getattr__(self, key):  
        manager = self.__dict__.get('manager', None)  
        return getattr(manager, key)  
 
    @classmethod 
    def create(cls, host=None, binary=None, topic=None, manager=None,  
               report_interval=None, periodic_interval=None):  
        """Instantiates class and passes back application object.  
 
        :param host: defaults to FLAGS.host  
        :param binary: defaults to basename of executable  
        :param topic: defaults to bin_name - 'nova-' part  
        :param manager: defaults to FLAGS.<topic>_manager  
        :param report_interval: defaults to FLAGS.report_interval  
        :param periodic_interval: defaults to FLAGS.periodic_interval  
 
        """ 
        if not host:  
            host = FLAGS.host  
        if not binary:  
            binary = os.path.basename(inspect.stack()[-1][1])  
        if not topic:  
            topic = binary.rpartition('nova-')[2]  
        if not manager:  
            manager = FLAGS.get('%s_manager' % topic, None)  
        if not report_interval:  
            report_interval = FLAGS.report_interval  
        if not periodic_interval:  
            periodic_interval = FLAGS.periodic_interval  
        service_obj = cls(host, binary, topic, manager,  
                          report_interval, periodic_interval)#此处 调用的是该类的init的默认函数       
 
        return service_obj  
 
    def kill(self):  
        """Destroy the service object in the datastore.""" 
        self.stop()  
        try:  
            db.service_destroy(context.get_admin_context(), self.service_id)  
        except exception.NotFound:  
            logging.warn(_('Service killed that has no database entry'))  
 
    def stop(self):  
        # Try to shut the connection down, but if we get any sort of  
        # errors, go ahead and ignore them.. as we're shutting down anyway  
        try:  
            self.conn.close()  
        except Exception:  
            pass 
        for x in self.timers:   #遍历曾经添加到self.timers中的每一个“间隔”（不是很清楚） 然后将其stop  
            try:  
                x.stop()  
            except Exception:  
                pass 
        self.timers = [] #重新将self.timers置空  
 
    def wait(self):  
        for x in self.timers:  
            try:  
                x.wait()  
            except Exception:  
                pass 
 
    def periodic_tasks(self):  
        """Tasks to be run at a periodic interval.""" 
        #任务在一个周期性间隔跑  
        self.manager.periodic_tasks(context.get_admin_context())  
 
    def report_state(self):  
        """Update the state of this service in the datastore.""" 
        #在数据存储更新服务的状态。  
        ctxt = context.get_admin_context()  
        try:  
            try:  
                service_ref = db.service_get(ctxt, self.service_id)  
            except exception.NotFound:  
                logging.debug(_('The service database object disappeared, ' 
                                'Recreating it.'))  
                self._create_service_ref(ctxt)  
                service_ref = db.service_get(ctxt, self.service_id)  
 
            db.service_update(ctxt,  
                             self.service_id,  
                             {'report_count': service_ref['report_count'] + 1})  
 
            # TODO(termie): make this pattern be more elegant.  
            if getattr(self, 'model_disconnected', False):  
                self.model_disconnected = False 
                logging.error(_('Recovered model server connection!'))  
 
        # TODO(vish): this should probably only catch connection errors  
        except Exception:  # pylint: disable=W0702  
            if not getattr(self, 'model_disconnected', False):  
                self.model_disconnected = True 
                logging.exception(_('model server went away'))  
 
 
class WSGIService(object):  
    """Provides ability to launch API from a 'paste' configuration.""" 
    #提供能够从一个‘paste’配置启动api的服务  
 
    def __init__(self, name, loader=None):  
        """Initialize, but do not start the WSGI server.  
 
        :param name: The name of the WSGI server given to the loader.  
        :param loader: Loads the WSGI application using the given name.  
        :returns: None  
 
        """ 
        #初始化 但是并没有开是wsgi的服务。  
        self.name = name  
        self.loader = loader or wsgi.Loader()  
        self.app = self.loader.load_app(name)#将wsgi服务的名字给到self.loader,然后用那名字将其 装载到wsgi application  
        self.host = getattr(FLAGS, '%s_listen' % name, "0.0.0.0") #返回主机host getattr Found at: __builtin__  
        #getattr(object, name[, default]) -> value得知返回的是value  
 
 
        self.port = getattr(FLAGS, '%s_listen_port' % name, 0)#端口 port  
        self.server = wsgi.Server(name,  
                                  self.app,  
                                  host=self.host,  
                                  port=self.port)  
 
    def start(self):  
        """Start serving this service using loaded configuration.  
 
        Also, retrieve updated port number in case '0' was passed in, which  
        indicates a random port should be used.  
 
        :returns: None  
 
        """ 
        self.server.start()  
        self.port = self.server.port  
 
    def stop(self):  
        """Stop serving this API.  
 
        :returns: None  
 
        """ 
        self.server.stop()  
 
    def wait(self):  
        """Wait for the service to stop serving this API.  
 
        :returns: None  
 
        """ 
        self.server.wait()  
 
 
# NOTE(vish): the global launcher is to maintain the existing  
#             functionality of calling service.serve +  
#             service.wait  
_launcher = None 
 
 
def serve(*servers):  
    global _launcher  
    if not _launcher:  
        _launcher = Launcher() #s实例化Launcher  
    for server in servers:  
        _launcher.launch_server(server)  
 
 
def wait():  
    # After we've loaded up all our dynamic bits, check  
    # whether we should print help  
      
 
    #flags.py中 有一句  
    #FLAGS = FlagValues()，那么直接查看FlagValues()这个类，这个类是继承于gflags.FlagValues.  
 
 
    flags.DEFINE_flag(flags.HelpFlag())  
    flags.DEFINE_flag(flags.HelpshortFlag())  
    flags.DEFINE_flag(flags.HelpXMLFlag())  
    FLAGS.ParseNewFlags()  
    logging.debug(_('Full set of FLAGS:'))  
    for flag in FLAGS:  
        flag_get = FLAGS.get(flag, None)  
        logging.debug('%(flag)s : %(flag_get)s' % locals())  
    try:  
        _launcher.wait()  
    except KeyboardInterrupt:  
        _launcher.stop()  
复制代码

这个文件位于\nova\virt，是一个底层的driver.py,源代码如下（我 觉得比较重要的computerDriver类列出来 了，并将下面的每个函数分离 加以注释《见下面图片》！我看见后面好多函数都是继承的ComputerDriver比如nova\virt\libvirt下面的connection.py里面的class LibvirtConnection(driver.ComputeDriver):）：

"""  
Driver base-classes:  
 
    (Beginning of) the contract that compute drivers must follow, and shared  
    types that support that contract  
""" 
 
from nova.compute import power_state  
 
 
class InstanceInfo(object):  
    def __init__(self, name, state):  
        self.name = name  
        assert state in power_state.valid_states(), "Bad state: %s" % state  
        self.state = state  
 
 
def block_device_info_get_root(block_device_info):  
    block_device_info = block_device_info or {}  
    return block_device_info.get('root_device_name')  
 
 
def block_device_info_get_swap(block_device_info):  
    block_device_info = block_device_info or {}  
    return block_device_info.get('swap') or {'device_name': None,  
                                             'swap_size': 0}  
 
 
def swap_is_usable(swap):  
    return swap and swap['device_name'] and swap['swap_size'] > 0 
 
 
def block_device_info_get_ephemerals(block_device_info):  
    block_device_info = block_device_info or {}  
    ephemerals = block_device_info.get('ephemerals') or []  
    return ephemerals  
 
 
def block_device_info_get_mapping(block_device_info):  
    block_device_info = block_device_info or {}  
    block_device_mapping = block_device_info.get('block_device_mapping') or []  
    return block_device_mapping  
 
 
class ComputeDriver(object):  
    """Base class for compute drivers.  
 
    The interface to this class talks in terms of 'instances' (Amazon EC2 and  
    internal Nova terminology), by which we mean 'running virtual machine'  
    (XenAPI terminology) or domain (Xen or libvirt terminology).  
 
    An instance has an ID, which is the identifier chosen by Nova to represent  
    the instance further up the stack.  This is unfortunately also called a  
    'name' elsewhere.  As far as this layer is concerned, 'instance ID' and  
    'instance name' are synonyms.  
 
    Note that the instance ID or name is not human-readable or  
    customer-controlled -- it's an internal ID chosen by Nova.  At the  
    nova.virt layer, instances do not have human-readable names at all -- such  
    things are only known higher up the stack.  
 
    Most virtualization platforms will also have their own identity schemes,  
    to uniquely identify a VM or domain.  These IDs must stay internal to the  
    platform-specific layer, and never escape the connection interface.  The  
    platform-specific layer is responsible for keeping track of which instance  
    ID maps to which platform-specific ID, and vice versa.  
 
    In contrast, the list_disks and list_interfaces calls may return  
    platform-specific IDs.  These identify a specific virtual disk or specific  
    virtual network interface, and these IDs are opaque to the rest of Nova.  
 
    Some methods here take an instance of nova.compute.service.Instance.  This  
    is the datastructure used by nova.compute to store details regarding an  
    instance, and pass them into this layer.  This layer is responsible for  
    translating that generic datastructure into terms that are specific to the  
    virtualization platform.  
 
    """ 
    #此处为了让大家看的明白 将 ComputerDriver的类图 列出来  
 
    def init_host(self, host):  
        """Initialize anything that is necessary for the driver to function,  
        including catching up with currently running VM's on the given host.""" 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def get_info(self, instance_name):  
        """Get the current status of an instance, by name (not ID!)  
 
        Returns a dict containing:  
 
        :state:           the running state, one of the power_state codes  
        :max_mem:         (int) the maximum memory in KBytes allowed  
        :mem:             (int) the memory in KBytes used by the domain  
        :num_cpu:         (int) the number of virtual CPUs for the domain  
        :cpu_time:        (int) the CPU time used in nanoseconds  
        """ 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def list_instances(self):  
        """  
        Return the names of all the instances known to the virtualization  
        layer, as a list.  
        """ 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def list_instances_detail(self):  
        """Return a list of InstanceInfo for all registered VMs""" 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def spawn(self, context, instance,  
              network_info=None, block_device_info=None):  
        """  
        Create a new instance/VM/domain on the virtualization platform.  
 
        Once this successfully completes, the instance should be  
        running (power_state.RUNNING).  
 
        If this fails, any partial instance should be completely  
        cleaned up, and the virtualization platform should be in the state  
        that it was before this call began.  
 
        :param context: security context  
        :param instance: Instance object as returned by DB layer.  
                         This function should use the data there to guide  
                         the creation of the new instance.  
        :param network_info:  
           :py:meth:`~nova.network.manager.NetworkManager.get_instance_nw_info`  
        :param block_device_info:  
        """ 
        raise NotImplementedError()  
 
    def destroy(self, instance, network_info, cleanup=True):  
        """Destroy (shutdown and delete) the specified instance.  
 
        If the instance is not found (for example if networking failed), this  
        function should still succeed.  It's probably a good idea to log a  
        warning in that case.  
 
        :param instance: Instance object as returned by DB layer.  
        :param network_info:  
           :py:meth:`~nova.network.manager.NetworkManager.get_instance_nw_info`  
        :param cleanup:  
 
        """ 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def reboot(self, instance, network_info):  
        """Reboot the specified instance.  
 
        :param instance: Instance object as returned by DB layer.  
        :param network_info:  
           :py:meth:`~nova.network.manager.NetworkManager.get_instance_nw_info`  
        """ 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def snapshot_instance(self, context, instance_id, image_id):  
        raise NotImplementedError()  
 
    def get_console_pool_info(self, console_type):  
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def get_console_output(self, instance):  
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def get_ajax_console(self, instance):  
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def get_diagnostics(self, instance):  
        """Return data about VM diagnostics""" 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def get_host_ip_addr(self):  
        """  
        Retrieves the IP address of the dom0  
        """ 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def attach_volume(self, context, instance_id, volume_id, mountpoint):  
        """Attach the disk at device_path to the instance at mountpoint""" 
        raise NotImplementedError()  
 
    def detach_volume(self, context, instance_id, volume_id):  
        """Detach the disk attached to the instance at mountpoint""" 
        raise NotImplementedError()  
 
    def compare_cpu(self, cpu_info):  
        """Compares given cpu info against host 确保vm能运行  
 
        Before attempting to migrate a VM to this host,  
        compare_cpu is called to ensure that the VM will  
        actually run here.  
 
        :param cpu_info: (str) JSON structure describing the source CPU.  
        :returns: None if migration is acceptable  
        :raises: :py:class:`~nova.exception.InvalidCPUInfo` if migration  
                 is not acceptable.  
        """ 
        raise NotImplementedError()  
 
    def migrate_disk_and_power_off(self, instance, dest):  
        """  
        Transfers the disk of a running instance in multiple phases, turning  
        off the instance before the end.  
        """ 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def snapshot(self, context, instance, image_id):  
        """  
        Snapshots the specified instance.  
 
        :param context: security context  
        :param instance: Instance object as returned by DB layer.  
        :param image_id: Reference to a pre-created image that will  
                         hold the snapshot.  
        """ 
        raise NotImplementedError()  
 
    def finish_migration(self, context, instance, disk_info, network_info,  
                         resize_instance):  
        #打开一个迁移的实例，完成一个调整  
        """Completes a resize, turning on the migrated instance  
 
        :param network_info:  
           :py:meth:`~nova.network.manager.NetworkManager.get_instance_nw_info`  
        """ 
        raise NotImplementedError()  
 
    def revert_migration(self, instance):  
        #返回一个调整，推动回到实例？  
        """Reverts a resize, powering back on the instance""" 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def pause(self, instance, callback):  
        """Pause the specified instance.""" 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def unpause(self, instance, callback):  
        """Unpause paused VM instance""" 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def suspend(self, instance, callback):  
        # 挂起指定的实例  
        """suspend the specified instance""" 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def resume(self, instance, callback):  
        """resume the specified instance""" 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def rescue(self, context, instance, callback, network_info):  
        #恢复指定的实例  
        """Rescue the specified instance""" 
        raise NotImplementedError()  
 
    def unrescue(self, instance, callback, network_info):  
        """Unrescue the specified instance""" 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def update_available_resource(self, ctxt, host):  
        #在computeNode表中更新电脑资源管理的信息  
        """Updates compute manager resource info on ComputeNode table.  
 
        This method is called when nova-compute launches, and  
        whenever admin executes "nova-manage service update_resource".  
 
        :param ctxt: security context  
        :param host: hostname that compute manager is currently running  
 
        """ 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def live_migration(self, ctxt, instance_ref, dest,  
                       post_method, recover_method):  
        #分发处理高负荷，当有高负荷操作时候，大量生成 live_mirgration  
        """Spawning live_migration operation for distributing high-load.  
 
        :param ctxt: security context  
        :param instance_ref:  
            nova.db.sqlalchemy.models.Instance object  
            instance object that is migrated.  
        :param dest: destination host  
        :param post_method:  
            post operation method.  
            expected nova.compute.manager.post_live_migration.  
        :param recover_method:  
            recovery method when any exception occurs.  
            expected nova.compute.manager.recover_live_migration.  
 
        """ 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def refresh_security_group_rules(self, security_group_id):  
        #改变安全组之后调用  
        """This method is called after a change to security groups.  
 
        All security groups and their associated rules live in the datastore,  
        and calling this method should apply the updated rules to instances  
        running the specified security group.  
 
        An error should be raised if the operation cannot complete.  
 
        """ 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def refresh_security_group_members(self, security_group_id):  
        #当一个安全组被添加到一个实例，这个方法被调用  
        """This method is called when a security group is added to an instance.  
 
        This message is sent to the virtualization drivers on hosts that are  
        running an instance that belongs to a security group that has a rule  
        that references the security group identified by `security_group_id`.  
        It is the responsiblity of this method to make sure any rules  
        that authorize traffic flow with members of the security group are  
        updated and any new members can communicate, and any removed members  
        cannot.  
 
        Scenario:  
            * we are running on host 'H0' and we have an instance 'i-0'.  
            * instance 'i-0' is a member of security group 'speaks-b'  
            * group 'speaks-b' has an ingress rule that authorizes group 'b'  
            * another host 'H1' runs an instance 'i-1'  
            * instance 'i-1' is a member of security group 'b'  
 
            When 'i-1' launches or terminates we will recieve the message  
            to update members of group 'b', at which time we will make  
            any changes needed to the rules for instance 'i-0' to allow  
            or deny traffic coming from 'i-1', depending on if it is being  
            added or removed from the group.  
 
        In this scenario, 'i-1' could just as easily have been running on our  
        host 'H0' and this method would still have been called.  The point was  
        that this method isn't called on the host where instances of that  
        group are running (as is the case with  
        :method:`refresh_security_group_rules`) but is called where references  
        are made to authorizing those instances.  
 
        An error should be raised if the operation cannot complete.  
 
        """ 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def refresh_provider_fw_rules(self, security_group_id):  
        #这触发一个基于数据库改变的防火墙的更新  
        """This triggers a firewall update based on database changes.  
 
        When this is called, rules have either been added or removed from the  
        datastore.  You can retrieve rules with  
        :method:`nova.db.api.provider_fw_rule_get_all`.  
 
        Provider rules take precedence over security group rules.  If an IP  
        would be allowed by a security group ingress rule, but blocked by  
        a provider rule, then packets from the IP are dropped.  This includes  
        intra-project traffic in the case of the allow_project_net_traffic  
        flag for the libvirt-derived classes.  
 
        """ 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def reset_network(self, instance):  
        """reset networking for specified instance""" 
        # TODO(Vek): Need to pass context in for access to auth_token  
        pass 
 
    def ensure_filtering_rules_for_instance(self, instance_ref, network_info):  
        #设置过滤规则,并等待它完成  
        """Setting up filtering rules and waiting for its completion.  
 
        To migrate an instance, filtering rules to hypervisors  
        and firewalls are inevitable on destination host.  
        ( Waiting only for filtering rules to hypervisor,  
        since filtering rules to firewall rules can be set faster).  
 
        Concretely, the below method must be called.  
        - setup_basic_filtering (for nova-basic, etc.)  
        - prepare_instance_filter(for nova-instance-instance-xxx, etc.)  
 
        to_xml may have to be called since it defines PROJNET, PROJMASK.  
        but libvirt migrates those value through migrateToURI(),  
        so , no need to be called.  
 
        Don't use thread for this method since migration should  
        not be started when setting-up filtering rules operations  
        are not completed.  
 
        :params instance_ref: nova.db.sqlalchemy.models.Instance object  
 
        """ 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def unfilter_instance(self, instance, network_info):  
        """Stop filtering instance""" 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def set_admin_password(self, context, instance_id, new_pass=None):  
        """  
        Set the root password on the specified instance.  
 
        The first parameter is an instance of nova.compute.service.Instance,  
        and so the instance is being specified as instance.name. The second  
        parameter is the value of the new password.  
        """ 
        raise NotImplementedError()  
 
    def inject_file(self, instance, b64_path, b64_contents):  
        """在指定的实例上写文件  
        Writes a file on the specified instance.  
 
        The first parameter is an instance of nova.compute.service.Instance,  
        and so the instance is being specified as instance.name. The second  
        parameter is the base64-encoded path to which the file is to be  
        written on the instance; the third is the contents of the file, also  
        base64-encoded.  
        """ 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def agent_update(self, instance, url, md5hash):  
        #在指定的实例中更新代理  
        """  
        Update agent on the specified instance.  
 
        The first parameter is an instance of nova.compute.service.Instance,  
        and so the instance is being specified as instance.name. The second  
        parameter is the URL of the agent to be fetched and updated on the  
        instance; the third is the md5 hash of the file for verification  
        purposes.  
        """ 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def inject_network_info(self, instance, nw_info):  
        #为指定的实例注入网络信息  
        """inject network info for specified instance""" 
        # TODO(Vek): Need to pass context in for access to auth_token  
        pass 
 
    def poll_rescued_instances(self, timeout):  
        #轮询已经恢复的实例  
        """Poll for rescued instances""" 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def host_power_action(self, host, action):  
        """Reboots, shuts down or powers up the host.""" 
        raise NotImplementedError()  
 
    def set_host_enabled(self, host, enabled):  
        #设置指定的主机有能力接受新的实例  
        """Sets the specified host's ability to accept new instances.""" 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def plug_vifs(self, instance, network_info):  
        """Plugs in VIFs to networks.""" 
        # TODO(Vek): Need to pass context in for access to auth_token  
        raise NotImplementedError()  
 
    def update_host_status(self):  
        """Refresh host stats""" 
        raise NotImplementedError()  
 
    def get_host_stats(self, refresh=False):  
        """Return currently known host stats""" 
        raise NotImplementedError()  
 
    def list_disks(self, instance_name):  
        """  
        Return the IDs of all the virtual disks attached to the specified  
        instance, as a list.  These IDs are opaque to the caller (they are  
        only useful for giving back to this layer as a parameter to  
        disk_stats).  These IDs only need to be unique for a given instance.  
 
        Note that this function takes an instance ID.  
        """ 
        raise NotImplementedError()  
 
    def list_interfaces(self, instance_name):  
        """  
        Return the IDs of all the virtual network interfaces attached to the  
        specified instance, as a list.  These IDs are opaque to the caller  
        (they are only useful for giving back to this layer as a parameter to  
        interface_stats).  These IDs only need to be unique for a given  
        instance.  
 
        Note that this function takes an instance ID.  
        """ 
        raise NotImplementedError()  
 
    def resize(self, instance, flavor):  
        """  
        Resizes/Migrates the specified instance.  
 
        The flavor parameter determines whether or not the instance RAM and  
        disk space are modified, and if so, to what size.  
        """ 
        raise NotImplementedError()  
 
    def block_stats(self, instance_name, disk_id):  
        """  
        Return performance counters associated with the given disk_id on the  
        given instance_name.  These are returned as [rd_req, rd_bytes, wr_req,  
        wr_bytes, errs], where rd indicates read, wr indicates write, req is  
        the total number of I/O requests made, bytes is the total number of  
        bytes transferred, and errs is the number of requests held up due to a  
        full pipeline.  
 
        All counters are long integers.  
 
        This method is optional.  On some platforms (e.g. XenAPI) performance  
        statistics can be retrieved directly in aggregate form, without Nova  
        having to do the aggregation.  On those platforms, this method is  
        unused.  
 
        Note that this function takes an instance ID.  
        """ 
        raise NotImplementedError()  
 
    def interface_stats(self, instance_name, iface_id):  
        """  
        Return performance counters associated with the given iface_id on the  
        given instance_id.  These are returned as [rx_bytes, rx_packets,  
        rx_errs, rx_drop, tx_bytes, tx_packets, tx_errs, tx_drop], where rx  
        indicates receive, tx indicates transmit, bytes and packets indicate  
        the total num
 
ber of bytes or packets transferred, and errs and dropped  
        is the total number of packets failed / dropped.  
 
        All counters are long integers.  
 
        This method is optional.  On some platforms (e.g. XenAPI) performance  
        statistics can be retrieved directly in aggregate form, without Nova  
        having to do the aggregation.  On those platforms, this method is  
        unused.  
 
        Note that this function takes an instance ID.  
        """ 
        raise NotImplementedError()  
复制代码

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