Swift源码分析----swift-proxy与swift-account(2)

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接续上一篇博客：

PUT

/swift/proxy/controllers/account.py----class AccountController(Controller)----def PUT

def PUT(self, req):"""HTTP PUT request handler."""    if not self.app.allow_account_management:        return HTTPMethodNotAllowed(            request=req,            headers={'Allow': ', '.join(self.allowed_methods)})    error_response = check_metadata(req, 'account')    if error_response:        return error_response    if len(self.account_name) > MAX_ACCOUNT_NAME_LENGTH:        resp = HTTPBadRequest(request=req)        resp.body = 'Account name length of %d longer than %d' % \                        (len(self.account_name), MAX_ACCOUNT_NAME_LENGTH)        return resp                    # 获取指定account的分区号和所有副本节点；    account_partition, accounts = \            self.app.account_ring.get_nodes(self.account_name)    # 根据原始请求和额外的头信息，为后端的请求生成头信息字典；    headers = self.generate_request_headers(req, transfer=True)    clear_info_cache(self.app, req.environ, self.account_name)    resp = self.make_requests(            req, self.app.account_ring, account_partition, 'PUT',            req.swift_entity_path, [headers] * len(accounts))            self.add_acls_from_sys_metadata(resp)    return resp

这里代码比较好理解，这里来看以下方法make_requests的实现，这个方法是比较重要的：

def make_requests(self, req, ring, part, method, path, headers, query_string=''):    """    发送一个HTTP请求到多个节点，并汇聚所有返回的响应信息；    根据投票机制，根据现实所有响应信息，返回通过投票机制的响应信息（因为是获取多个节点的响应信息）；            调用示例：    resp = self.make_requests(        req, self.app.account_ring, account_partition, 'PUT',        req.path_info, [headers] * len(accounts))    """    # get_part_nodes：获取一个分区所有副本相关的节点信息；    start_nodes = ring.get_part_nodes(part)    nodes = GreenthreadSafeIterator(self.app.iter_nodes(ring, part))    pile = GreenAsyncPile(len(start_nodes))            for head in headers:         # _make_request：发送请求迭代器，实现一次发送请求到一个远程节点；        pile.spawn(self._make_request, nodes, part, method, path,                   head, query_string, self.app.logger.thread_locals)    response = []    statuses = []    for resp in pile:        if not resp:            continue        response.append(resp)        statuses.append(resp[0])        if self.have_quorum(statuses, len(start_nodes)):            break    # give any pending requests *some* chance to finish    pile.waitall(self.app.post_quorum_timeout)    while len(response) < len(start_nodes):        response.append((HTTP_SERVICE_UNAVAILABLE, '', '', ''))    statuses, reasons, resp_headers, bodies = zip(*response)            # 根据投票机制，根据现实所有响应信息，实现返回通过投票机制的响应信息（因为是获取多个节点的响应信息）；    return self.best_response(req, statuses, reasons, bodies,                              '%s %s' % (self.server_type, req.method),                              headers=resp_headers)

具体的解释代码注释中已经标注了，也是比较好理解的，再来看一下这里方法best_response的具体实现：

def best_response(self, req, statuses, reasons, bodies, server_type, etag=None, headers=None):     """     从一些服务器给定响应的列表，根据投票机制，根据现实所有响应信息，实现返回通过投票机制的响应信息；     """    # Response：WSGI相应对象类；    resp = Response(request=req)    if len(statuses):        for hundred in (HTTP_OK, HTTP_MULTIPLE_CHOICES, HTTP_BAD_REQUEST):            hstatuses = [s for s in statuses if hundred <= s < hundred + 100]            if len(hstatuses) >= quorum_size(len(statuses)):                status = max(hstatuses)                status_index = statuses.index(status)                resp.status = '%s %s' % (status, reasons[status_index])                resp.body = bodies[status_index]                if headers:                    update_headers(resp, headers[status_index])                if etag:                    resp.headers['etag'] = etag.strip('"')                return resp    self.app.logger.error(_('%(type)s returning 503 for %(statuses)s'),                          {'type': server_type, 'statuses': statuses})    resp.status = '503 Internal Server Error'    return resp

/swift/account/server.py----class AccountController(object)----def PUT

def PUT(self, req):"""处理HTTP协议PUT请求；       PUT请求会handle两种类型的HTTP请求：当url中有<container>时，会新建/更新container的metadata信息；当url中没有<container>时，会更新account的metadata信息；"""    # 分割和验证给定的请求路径，获取drive, part, account, container；    drive, part, account, container = split_and_validate_path(req, 3, 4)            # mount_check是是否进行mount检查；    # 如果进行mount检查，并且检查结果没有挂载，则引发http 507错误，提示磁盘没有足够存储空间；    if self.mount_check and not check_mount(self.root, drive):        return HTTPInsufficientStorage(drive=drive, request=req)            # 当url中有<container>时，会新建/更新container的信息；    if container:   # put account container        pending_timeout = None        if 'x-trans-id' in req.headers:            pending_timeout = 3                    # _get_account_broker是一个内部方法，功能是返回一个AccountBroker的实例，用于代理对sqlite数据库的操作；        broker = self._get_account_broker(drive, part, account, pending_timeout=pending_timeout)                    # 如果相关的数据库不存在，则进行数据库的初始化操作；        if account.startswith(self.auto_create_account_prefix) and not os.path.exists(broker.db_file):                            # normalize_timestamp：把timestamp（时间戳）转换为标准格式；            # initialize：数据库初始化；            try:                broker.initialize(normalize_timestamp(req.headers.get('x-timestamp') or time.time()))            except DatabaseAlreadyExists:                pass        if req.headers.get('x-account-override-deleted', 'no').lower() != 'yes' and broker.is_deleted():            return HTTPNotFound(request=req)                    # 应用给定的属性建立container（在数据库中）；        broker.put_container(container, req.headers['x-put-timestamp'],                                 req.headers['x-delete-timestamp'],                                 req.headers['x-object-count'],                                 req.headers['x-bytes-used'])        if req.headers['x-delete-timestamp'] > req.headers['x-put-timestamp']:            return HTTPNoContent(request=req)        else:            return HTTPCreated(request=req)            # 当url中没有<container>时，会更新account的metadata信息    else:   # put account        # _get_account_broker是一个内部方法，功能是返回一个AccountBroker的实例，用于代理对sqlite数据库的操作；        broker = self._get_account_broker(drive, part, account)        # normalize_timestamp：把timestamp（时间戳）转换为标准格式；        timestamp = normalize_timestamp(req.headers['x-timestamp'])                    # 如果对应的数据库对象不存在，则进行数据库的初始化操作；        if not os.path.exists(broker.db_file):            try:                broker.initialize(timestamp)                created = True            except DatabaseAlreadyExists:                created = False                    # is_status_deleted：如果状态标志为DELETED，则返回true；        elif broker.is_status_deleted():            return self._deleted_response(broker, req, HTTPForbidden, body='Recently deleted')        else:            # 检测帐号的数据库是否被删除；            created = broker.is_deleted()            # 如果put_timestamp小于当前的时间戳timestamp，则更新put_timestamp；            broker.update_put_timestamp(timestamp)            if broker.is_deleted():                return HTTPConflict(request=req)                    metadata = {}        # 根据requesthead中的以'x-account-meta-'开始的key的值更新到metadata；        metadata.update((key, (value, timestamp))                        for key, value in req.headers.iteritems()                        if is_sys_or_user_meta('account', key))                    # 更新数据库的metadata字段(AccountBroker#update_metadata)；        # 更新数据库的元数据字典；        if metadata:            broker.update_metadata(metadata)                    # 如果created==True，返回201Created，否则返回202Accepted        if created:            return HTTPCreated(request=req)        else:            return HTTPAccepted(request=req)

PUT请求会handle两种类型的HTTP请求：
当url中有<container>时，会新建/更新container的metadata信息；
当url中没有<container>时，会更新account的metadata信息；

POST

/swift/proxy/controllers/account.py----class AccountController(Controller)----def POST

def POST(self, req):"""HTTP POST request handler."""    if len(self.account_name) > MAX_ACCOUNT_NAME_LENGTH:        resp = HTTPBadRequest(request=req)        resp.body = 'Account name length of %d longer than %d' % (len(self.account_name), MAX_ACCOUNT_NAME_LENGTH)        return resp    error_response = check_metadata(req, 'account')    if error_response:        return error_response            # 获取指定account的分区号和所有副本节点；    account_partition, accounts = self.app.account_ring.get_nodes(self.account_name)            # 根据原始请求和额外的头信息，为后端的请求生成头信息字典；    headers = self.generate_request_headers(req, transfer=True)            clear_info_cache(self.app, req.environ, self.account_name)            resp = self.make_requests(            req, self.app.account_ring, account_partition, 'POST',            req.swift_entity_path, [headers] * len(accounts))            # 如果没有找到指定account，则先建立这个account；    # 再实现对其的POST操作；    if resp.status_int == HTTP_NOT_FOUND and self.app.account_autocreate:        self.autocreate_account(req.environ, self.account_name)        resp = self.make_requests(            req, self.app.account_ring, account_partition, 'POST',            req.swift_entity_path, [headers] * len(accounts))            self.add_acls_from_sys_metadata(resp)    return resp

/swift/account/server.py----class AccountController(object)----def POST

def POST(self, req):    """    处理HTTP协议的POST请求；    实现更新account的元数据信息，从head中取出特定要求的metadata更新至指定account的数据库(AccountBroker#update_metadata)；    """    drive, part, account = split_and_validate_path(req, 3)    if 'x-timestamp' not in req.headers or not check_float(req.headers['x-timestamp']):        return HTTPBadRequest(body='Missing or bad timestamp',                              request=req,                              content_type='text/plain')    if self.mount_check and not check_mount(self.root, drive):        return HTTPInsufficientStorage(drive=drive, request=req)            # _get_account_broker是一个内部方法，功能是返回一个AccountBroker的实例，用于代理对sqlite数据库的操作；    broker = self._get_account_broker(drive, part, account)            if broker.is_deleted():        return self._deleted_response(broker, req, HTTPNotFound)            # 把timestamp（时间戳）转换为标准格式；    timestamp = normalize_timestamp(req.headers['x-timestamp'])            metadata = {}    metadata.update((key, (value, timestamp))                    for key, value in req.headers.iteritems()                    if is_sys_or_user_meta('account', key))            # 然后从head中取出特定要求的metadata更新至数据库；    if metadata:        broker.update_metadata(metadata)            return HTTPNoContent(request=req)

DELETE

/swift/proxy/controllers/account.py----class AccountController(Controller)----def DELETE

def DELETE(self, req):"""HTTP DELETE request handler."""    if req.query_string:        return HTTPBadRequest(request=req)    if not self.app.allow_account_management:        return HTTPMethodNotAllowed(            request=req,            headers={'Allow': ', '.join(self.allowed_methods)})            # 获取指定account的分区号和所有副本节点；    account_partition, accounts = self.app.account_ring.get_nodes(self.account_name)                # 根据原始请求和额外的头信息，为后端的请求生成头信息字典；    headers = self.generate_request_headers(req)            clear_info_cache(self.app, req.environ, self.account_name)            resp = self.make_requests(        req, self.app.account_ring, account_partition, 'DELETE',        req.swift_entity_path, [headers] * len(accounts))

/swift/account/server.py----class AccountController(object)----def DELETE

def DELETE(self, req):    """    处理HTTP协议DELETE请求；    DELETE请求会删除当前account，但是这里的删除是逻辑删除，只是标记account为删除状态，并不会真正删除account和相关资源；    """    # 分割和验证给定的请求路径，获取drive, part, account；    drive, part, account = split_and_validate_path(req, 3)            # mount_check是是否进行mount检查；    # 如果进行mount检查，并且检查结果没有挂载，则引发http 507错误，提示磁盘没有足够存储空间；    # root是devices所在根目录；    # self.root = conf.get('devices', '/srv/node')    if self.mount_check and not check_mount(self.root, drive):        return HTTPInsufficientStorage(drive=drive, request=req)            # 检查head是否包含特定信息'x-timestamp'；    if 'x-timestamp' not in req.headers or \            not check_float(req.headers['x-timestamp']):        return HTTPBadRequest(body='Missing timestamp', request=req, content_type='text/plain')            # _get_account_broker是一个内部方法，功能是返回一个AccountBroker的实例，用于代理对sqlite数据库的操作；    broker = self._get_account_broker(drive, part, account)            # 如果对应的数据库中的对象已经删除，则引发http错误提示；    if broker.is_deleted():        return self._deleted_response(broker, req, HTTPNotFound)            # 对数据库中的对象进行删除状态的标记工作，并不会执行文件的删除工作；    broker.delete_db(req.headers['x-timestamp'])    return self._deleted_response(broker, req, HTTPNoContent)