Swift源码分析----swift-proxy与swift-object(1)

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概述：

这篇博客主要关注swift-proxy与swift-object服务中PUT，POST，DELETE，GET，HEAD等方法的对应调用实现；

源码解析部分(代码中较重要的部分已经进行了相关的注释)：

GETorHEAD

/swift/proxy/controllers/obj.py----class ContainerController(Controller)----def GETorHEAD

def GETorHEAD(self, req):    """    处理HTTP协议GET或者HEAD请求；    """    # 获取指定object所属的container的信息；    container_info = self.container_info(self.account_name, self.container_name, req)            req.acl = container_info['read_acl']    if 'swift.authorize' in req.environ:        aresp = req.environ['swift.authorize'](req)        if aresp:            return aresp    # 获取指定object所对应的分区号；    partition = self.app.object_ring.get_part(self.account_name, self.container_name, self.object_name)            resp = self.GETorHEAD_base(            req, _('Object'), self.app.object_ring, partition,            req.swift_entity_path)    if ';' in resp.headers.get('content-type', ''):        # strip off swift_bytes from content-type        content_type, check_extra_meta = resp.headers['content-type'].rsplit(';', 1)        if check_extra_meta.lstrip().startswith('swift_bytes='):            resp.content_type = content_type    return resp

/swift/obj/server.py----class ContainerController(object)----def HEAD

def HEAD(self, request):    """    检索返回一个object的metadata，同GET请求的处理方法几乎一致，唯一不同的是不在body中返回file；    """    device, partition, account, container, obj = split_and_validate_path(request, 5, 5, True)    try:        disk_file = self.get_diskfile(device, partition, account, container, obj)    except DiskFileDeviceUnavailable:        return HTTPInsufficientStorage(drive=device, request=request)    try:        metadata = disk_file.read_metadata()    except (DiskFileNotExist, DiskFileQuarantined):        return HTTPNotFound(request=request, conditional_response=True)    response = Response(request=request, conditional_response=True)    response.headers['Content-Type'] = metadata.get('Content-Type', 'application/octet-stream')    for key, value in metadata.iteritems():        if is_user_meta('object', key) or key.lower() in self.allowed_headers:            response.headers[key] = value    response.etag = metadata['ETag']    ts = metadata['X-Timestamp']    response.last_modified = math.ceil(float(ts))    # Needed for container sync feature    response.headers['X-Timestamp'] = ts    response.content_length = int(metadata['Content-Length'])    try:        response.content_encoding = metadata['Content-Encoding']    except KeyError:        pass    return response

/swift/obj/server.py----class ContainerController(object)----def GET

def GET(self, request):    """    检索一个object对象，在response.heads中返回metadata，在response.body中返回objectdata，流程如下：    1.根据url中的信息新建DiskFile对象file，检查request.heads中的必要K-V，检查mount情况；    2.如果file#is_deleted或者file.metadata中'X-Delete-At'小于当前时间(表示已标记为准备删除)      或者通过file#get_data_file_size查看文件是否异常，如果已经删除或存在异常，返回404HTTPNotFound；    3.检查request.heads里的'If-match'和'If-none-match'，前者检查file.metadata中的'ETag'是否与其一致确定所检索的文件，后者确定如果没有匹配的是否返回file的etag信息；    4.确定了需要操作的file，利用file的iterator，将其绑定response的构造函数参数app_iter，      并且将file.metadata写入response.heads中，并返回response；    """    device, partition, account, container, obj = split_and_validate_path(request, 5, 5, True)            keep_cache = self.keep_cache_private or (        'X-Auth-Token' not in request.headers and        'X-Storage-Token' not in request.headers)            try:        disk_file = self.get_diskfile(device, partition, account, container, obj)    except DiskFileDeviceUnavailable:        return HTTPInsufficientStorage(drive=device, request=request)            try:        with disk_file.open():            metadata = disk_file.get_metadata()            obj_size = int(metadata['Content-Length'])            file_x_ts = metadata['X-Timestamp']            file_x_ts_flt = float(file_x_ts)            file_x_ts_utc = datetime.fromtimestamp(file_x_ts_flt, UTC)            if_unmodified_since = request.if_unmodified_since                            if if_unmodified_since and file_x_ts_utc > if_unmodified_since:                return HTTPPreconditionFailed(request=request)            if_modified_since = request.if_modified_since            if if_modified_since and file_x_ts_utc <= if_modified_since:                return HTTPNotModified(request=request)            keep_cache = (self.keep_cache_private or                          ('X-Auth-Token' not in request.headers and                           'X-Storage-Token' not in request.headers))            response = Response(                app_iter=disk_file.reader(keep_cache=keep_cache),                request=request, conditional_response=True)            response.headers['Content-Type'] = metadata.get('Content-Type', 'application/octet-stream')            for key, value in metadata.iteritems():                if is_user_meta('object', key) or key.lower() in self.allowed_headers:                    response.headers[key] = value            response.etag = metadata['ETag']            response.last_modified = math.ceil(file_x_ts_flt)            response.content_length = obj_size            try:                response.content_encoding = metadata['Content-Encoding']            except KeyError:                pass            response.headers['X-Timestamp'] = file_x_ts            resp = request.get_response(response)                    except (DiskFileNotExist, DiskFileQuarantined):        resp = HTTPNotFound(request=request, conditional_response=True)    return resp

POST

/swift/proxy/controllers/obj.py----class ContainerController(Controller)----def POST

def POST(self, req):    """    处理HTTP协议POST请求；    """    # 计算预计删除对象时间？？？    if 'x-delete-after' in req.headers:        try:            x_delete_after = int(req.headers['x-delete-after'])        except ValueError:            return HTTPBadRequest(request=req,                                  content_type='text/plain',                                  body='Non-integer X-Delete-After')        req.headers['x-delete-at'] = normalize_delete_at_timestamp(time.time() + x_delete_after)            # 在object的实现方法中，系统默认以PUT方法来实现POST方法；    if self.app.object_post_as_copy:        req.method = 'PUT'        req.path_info = '/v1/%s/%s/%s' % (self.account_name, self.container_name, self.object_name)        req.headers['Content-Length'] = 0        req.headers['X-Copy-From'] = quote('/%s/%s' % (self.container_name, self.object_name))        req.headers['X-Fresh-Metadata'] = 'true'        req.environ['swift_versioned_copy'] = True        if req.environ.get('QUERY_STRING'):            req.environ['QUERY_STRING'] += '&multipart-manifest=get'        else:            req.environ['QUERY_STRING'] = 'multipart-manifest=get'        resp = self.PUT(req)        if resp.status_int != HTTP_CREATED:            return resp        return HTTPAccepted(request=req)            else:        error_response = check_metadata(req, 'object')        if error_response:            return error_response        container_info = self.container_info(            self.account_name, self.container_name, req)        container_partition = container_info['partition']        containers = container_info['nodes']        req.acl = container_info['write_acl']        if 'swift.authorize' in req.environ:            aresp = req.environ['swift.authorize'](req)            if aresp:                return aresp        if not containers:            return HTTPNotFound(request=req)        if 'x-delete-at' in req.headers:            try:                x_delete_at = normalize_delete_at_timestamp(int(req.headers['x-delete-at']))                if int(x_delete_at) < time.time():                    return HTTPBadRequest(                        body='X-Delete-At in past', request=req,                        content_type='text/plain')            except ValueError:                return HTTPBadRequest(request=req,                                      content_type='text/plain',                                      body='Non-integer X-Delete-At')            req.environ.setdefault('swift.log_info', []).append('x-delete-at:%s' % x_delete_at)            delete_at_container = normalize_delete_at_timestamp(                int(x_delete_at) /self.app.expiring_objects_container_divisor *self.app.expiring_objects_container_divisor)            delete_at_part, delete_at_nodes = \                    self.app.container_ring.get_nodes(self.app.expiring_objects_account, delete_at_container)        else:            delete_at_container = delete_at_part = delete_at_nodes = None        partition, nodes = self.app.object_ring.get_nodes(self.account_name, self.container_name, self.object_name)        req.headers['X-Timestamp'] = normalize_timestamp(time.time())        headers = self._backend_requests(            req, len(nodes), container_partition, containers,            delete_at_container, delete_at_part, delete_at_nodes)        resp = self.make_requests(req, self.app.object_ring, partition, 'POST', req.swift_entity_path, headers)                    return resp

/swift/obj/server.py----class ContainerController(object)----def POST

def POST(self, request):    """         更新object的元数据信息，流程如下：    1.从requesturl中提取device,partition, account, container, obj；      检查requestheads中的'x-timestamp'是否存在，检查mount情况；    2.根据请求信息新建DiskFile对象file，检查是否存在；      (包括检查metadata中的'X-Delete-At',调用file#is_deleted()和检查file.data_size)    3.如果检查都通过，则根据request.heads中的元素更新metadata；    4.从request.heads中提取'X-Delete-At'并与file.metadata中的相同字段比较；      根据较新的值调用file#delete_at_update()，通知更新container的信息；    5.调用file#put()方法将metadata写入到.meta文件和data_file的扩展属性中；            实现更新object的元数据信息；    并通知object的更新到container；    """    # 根据request.path获取device、partition、account、container、obj等参数；    device, partition, account, container, obj = split_and_validate_path(request, 5, 5, True)    if 'x-timestamp' not in request.headers or not check_float(request.headers['x-timestamp']):        return HTTPBadRequest(body='Missing timestamp', request=request, content_type='text/plain')    new_delete_at = int(request.headers.get('X-Delete-At') or 0)    if new_delete_at and new_delete_at < time.time():        return HTTPBadRequest(body='X-Delete-At in past', request=request, content_type='text/plain')            try:        disk_file = self.get_diskfile(device, partition, account, container, obj)    except DiskFileDeviceUnavailable:        return HTTPInsufficientStorage(drive=device, request=request)    try:        orig_metadata = disk_file.read_metadata()    except (DiskFileNotExist, DiskFileQuarantined):        return HTTPNotFound(request=request)    orig_timestamp = orig_metadata.get('X-Timestamp', '0')    if orig_timestamp >= request.headers['x-timestamp']:        return HTTPConflict(request=request)            metadata = {'X-Timestamp': request.headers['x-timestamp']}    metadata.update(val for val in request.headers.iteritems() if is_user_meta('object', val[0]))    for header_key in self.allowed_headers:       if header_key in request.headers:            header_caps = header_key.title()            metadata[header_caps] = request.headers[header_key]            orig_delete_at = int(orig_metadata.get('X-Delete-At') or 0)            if orig_delete_at != new_delete_at:        if new_delete_at:            self.delete_at_update('PUT', new_delete_at, account, container, obj, request, device)        if orig_delete_at:            self.delete_at_update('DELETE', orig_delete_at, account, container, obj, request, device)    disk_file.write_metadata(metadata)    return HTTPAccepted(request=request)

下一篇博客将继续swift-proxy与swift-object的分析工作。