# Copyright (c) 2010-2012 OpenStack Foundation
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.
# See the License for the specific language governing permissions and
# limitations under the License.

""" Object Server for Swift """

import cPickle as pickle
import os
import multiprocessing
import time
import traceback
import socket
import math
from swift import gettext_ as _
from hashlib import md5

from eventlet import sleep, Timeout

from swift.common.utils import public, get_logger, \
    config_true_value, timing_stats, replication, \
    normalize_delete_at_timestamp, get_log_line, Timestamp
from swift.common.bufferedhttp import http_connect
from swift.common.constraints import check_object_creation, \
    valid_timestamp, check_utf8
from swift.common.exceptions import ConnectionTimeout, DiskFileQuarantined, \
    DiskFileNotExist, DiskFileCollision, DiskFileNoSpace, DiskFileDeleted, \
    DiskFileDeviceUnavailable, DiskFileExpired, ChunkReadTimeout
from swift.obj import ssync_receiver
from swift.common.http import is_success
from swift.common.request_helpers import get_name_and_placement, is_user_meta
from swift.common.swob import HTTPAccepted, HTTPBadRequest, HTTPCreated, \
    HTTPInternalServerError, HTTPNoContent, HTTPNotFound, \
    HTTPPreconditionFailed, HTTPRequestTimeout, HTTPUnprocessableEntity, \
    HTTPClientDisconnect, HTTPMethodNotAllowed, Request, Response, \
    HTTPInsufficientStorage, HTTPForbidden, HTTPException, HeaderKeyDict, \
    HTTPConflict
from swift.obj.diskfile import DATAFILE_SYSTEM_META, DiskFileManager
from swift.common.storage_policy import POLICY_INDEX


class ObjectController(object):
    """Implements the WSGI application for the Swift Object Server."""

    def __init__(self, conf, logger=None):
        """
        Creates a new WSGI application for the Swift Object Server. An
        example configuration is given at
        <source-dir>/etc/object-server.conf-sample or
        /etc/swift/object-server.conf-sample.
        """
        self.logger = logger or get_logger(conf, log_route='object-server')
        self.node_timeout = int(conf.get('node_timeout', 3))
        self.conn_timeout = float(conf.get('conn_timeout', 0.5))
        self.client_timeout = int(conf.get('client_timeout', 60))
        self.disk_chunk_size = int(conf.get('disk_chunk_size', 65536))
        self.network_chunk_size = int(conf.get('network_chunk_size', 65536))
        self.log_requests = config_true_value(conf.get('log_requests', 'true'))
        self.max_upload_time = int(conf.get('max_upload_time', 86400))
        self.slow = int(conf.get('slow', 0))
        self.keep_cache_private = \
            config_true_value(conf.get('keep_cache_private', 'false'))
        replication_server = conf.get('replication_server', None)
        if replication_server is not None:
            replication_server = config_true_value(replication_server)
        self.replication_server = replication_server

        default_allowed_headers = '''
            content-disposition,
            content-encoding,
            x-delete-at,
            x-object-manifest,
            x-static-large-object,
        '''
        extra_allowed_headers = [
            header.strip().lower() for header in conf.get(
                'allowed_headers', default_allowed_headers).split(',')
            if header.strip()
        ]
        self.allowed_headers = set()
        for header in extra_allowed_headers:
            if header not in DATAFILE_SYSTEM_META:
                self.allowed_headers.add(header)
        self.auto_create_account_prefix = \
            conf.get('auto_create_account_prefix') or '.'
        self.expiring_objects_account = self.auto_create_account_prefix + \
            (conf.get('expiring_objects_account_name') or 'expiring_objects')
        self.expiring_objects_container_divisor = \
            int(conf.get('expiring_objects_container_divisor') or 86400)
        # Initialization was successful, so now apply the network chunk size
        # parameter as the default read / write buffer size for the network
        # sockets.
        #
        # NOTE WELL: This is a class setting, so until we get set this on a
        # per-connection basis, this affects reading and writing on ALL
        # sockets, those between the proxy servers and external clients, and
        # those between the proxy servers and the other internal servers.
        #
        # ** Because the primary motivation for this is to optimize how data
        # is written back to the proxy server, we could use the value from the
        # disk_chunk_size parameter. However, it affects all created sockets
        # using this class so we have chosen to tie it to the
        # network_chunk_size parameter value instead.
        socket._fileobject.default_bufsize = self.network_chunk_size

        # Provide further setup sepecific to an object server implemenation.
        self.setup(conf)

    def setup(self, conf):
        """
        Implementation specific setup. This method is called at the very end
        by the constructor to allow a specific implementation to modify
        existing attributes or add its own attributes.

        :param conf: WSGI configuration parameter
        """

        # Common on-disk hierarchy shared across account, container and object
        # servers.
        self._diskfile_mgr = DiskFileManager(conf, self.logger)
        # This is populated by global_conf_callback way below as the semaphore
        # is shared by all workers.
        if 'replication_semaphore' in conf:
            # The value was put in a list so it could get past paste
            self.replication_semaphore = conf['replication_semaphore'][0]
        else:
            self.replication_semaphore = None
        self.replication_failure_threshold = int(
            conf.get('replication_failure_threshold') or 100)
        self.replication_failure_ratio = float(
            conf.get('replication_failure_ratio') or 1.0)

    def get_diskfile(self, device, partition, account, container, obj,
                     policy_idx, **kwargs):
        """
        Utility method for instantiating a DiskFile object supporting a given
        REST API.

        An implementation of the object server that wants to use a different
        DiskFile class would simply over-ride this method to provide that
        behavior.
        """
        return self._diskfile_mgr.get_diskfile(
            device, partition, account, container, obj, policy_idx, **kwargs)

    def async_update(self, op, account, container, obj, host, partition,
                     contdevice, headers_out, objdevice, policy_index):
        """
        Sends or saves an async update.

        :param op: operation performed (ex: 'PUT', or 'DELETE')
        :param account: account name for the object
        :param container: container name for the object
        :param obj: object name
        :param host: host that the container is on
        :param partition: partition that the container is on
        :param contdevice: device name that the container is on
        :param headers_out: dictionary of headers to send in the container
                            request
        :param objdevice: device name that the object is in
        :param policy_index: the associated storage policy index
        """
        headers_out['user-agent'] = 'obj-server %s' % os.getpid()
        full_path = '/%s/%s/%s' % (account, container, obj)
        if all([host, partition, contdevice]):
            try:
                with ConnectionTimeout(self.conn_timeout):
                    ip, port = host.rsplit(':', 1)
                    conn = http_connect(ip, port, contdevice, partition, op,
                                        full_path, headers_out)
                with Timeout(self.node_timeout):
                    response = conn.getresponse()
                    response.read()
                    if is_success(response.status):
                        return
                    else:
                        self.logger.error(_(
                            'ERROR Container update failed '
                            '(saving for async update later): %(status)d '
                            'response from %(ip)s:%(port)s/%(dev)s'),
                            {'status': response.status, 'ip': ip, 'port': port,
                             'dev': contdevice})
            except (Exception, Timeout):
                self.logger.exception(_(
                    'ERROR container update failed with '
                    '%(ip)s:%(port)s/%(dev)s (saving for async update later)'),
                    {'ip': ip, 'port': port, 'dev': contdevice})
        data = {'op': op, 'account': account, 'container': container,
                'obj': obj, 'headers': headers_out}
        timestamp = headers_out['x-timestamp']
        self._diskfile_mgr.pickle_async_update(objdevice, account, container,
                                               obj, data, timestamp,
                                               policy_index)

    def container_update(self, op, account, container, obj, request,
                         headers_out, objdevice, policy_idx):
        """
        Update the container when objects are updated.

        :param op: operation performed (ex: 'PUT', or 'DELETE')
        :param account: account name for the object
        :param container: container name for the object
        :param obj: object name
        :param request: the original request object driving the update
        :param headers_out: dictionary of headers to send in the container
                            request(s)
        :param objdevice: device name that the object is in
        """
        headers_in = request.headers
        conthosts = [h.strip() for h in
                     headers_in.get('X-Container-Host', '').split(',')]
        contdevices = [d.strip() for d in
                       headers_in.get('X-Container-Device', '').split(',')]
        contpartition = headers_in.get('X-Container-Partition', '')

        if len(conthosts) != len(contdevices):
            # This shouldn't happen unless there's a bug in the proxy,
            # but if there is, we want to know about it.
            self.logger.error(_('ERROR Container update failed: different '
                                'numbers of hosts and devices in request: '
                                '"%s" vs "%s"') %
                               (headers_in.get('X-Container-Host', ''),
                                headers_in.get('X-Container-Device', '')))
            return

        if contpartition:
            updates = zip(conthosts, contdevices)
        else:
            updates = []

        headers_out['x-trans-id'] = headers_in.get('x-trans-id', '-')
        headers_out['referer'] = request.as_referer()
        headers_out[POLICY_INDEX] = policy_idx
        for conthost, contdevice in updates:
            self.async_update(op, account, container, obj, conthost,
                              contpartition, contdevice, headers_out,
                              objdevice, policy_idx)

    def delete_at_update(self, op, delete_at, account, container, obj,
                         request, objdevice, policy_index):
        """
        Update the expiring objects container when objects are updated.

        :param op: operation performed (ex: 'PUT', or 'DELETE')
        :param delete_at: scheduled delete in UNIX seconds, int
        :param account: account name for the object
        :param container: container name for the object
        :param obj: object name
        :param request: the original request driving the update
        :param objdevice: device name that the object is in
        :param policy_index: the policy index to be used for tmp dir
        """
        if config_true_value(
                request.headers.get('x-backend-replication', 'f')):
            return
        delete_at = normalize_delete_at_timestamp(delete_at)
        updates = [(None, None)]

        partition = None
        hosts = contdevices = [None]
        headers_in = request.headers
        headers_out = HeaderKeyDict({
            POLICY_INDEX: 0,  # system accounts are always Policy-0
            'x-timestamp': request.timestamp.internal,
            'x-trans-id': headers_in.get('x-trans-id', '-'),
            'referer': request.as_referer()})
        if op != 'DELETE':
            delete_at_container = headers_in.get('X-Delete-At-Container', None)
            if not delete_at_container:
                self.logger.warning(
                    'X-Delete-At-Container header must be specified for '
                    'expiring objects background %s to work properly. Making '
                    'best guess as to the container name for now.' % op)
                # TODO(gholt): In a future release, change the above warning to
                # a raised exception and remove the guess code below.
                delete_at_container = (
                    int(delete_at) / self.expiring_objects_container_divisor *
                    self.expiring_objects_container_divisor)
            partition = headers_in.get('X-Delete-At-Partition', None)
            hosts = headers_in.get('X-Delete-At-Host', '')
            contdevices = headers_in.get('X-Delete-At-Device', '')
            updates = [upd for upd in
                       zip((h.strip() for h in hosts.split(',')),
                           (c.strip() for c in contdevices.split(',')))
                       if all(upd) and partition]
            if not updates:
                updates = [(None, None)]
            headers_out['x-size'] = '0'
            headers_out['x-content-type'] = 'text/plain'
            headers_out['x-etag'] = 'd41d8cd98f00b204e9800998ecf8427e'
        else:
            # DELETEs of old expiration data have no way of knowing what the
            # old X-Delete-At-Container was at the time of the initial setting
            # of the data, so a best guess is made here.
            # Worst case is a DELETE is issued now for something that doesn't
            # exist there and the original data is left where it is, where
            # it will be ignored when the expirer eventually tries to issue the
            # object DELETE later since the X-Delete-At value won't match up.
            delete_at_container = str(
                int(delete_at) / self.expiring_objects_container_divisor *
                self.expiring_objects_container_divisor)
        delete_at_container = normalize_delete_at_timestamp(
            delete_at_container)

        for host, contdevice in updates:
            self.async_update(
                op, self.expiring_objects_account, delete_at_container,
                '%s-%s/%s/%s' % (delete_at, account, container, obj),
                host, partition, contdevice, headers_out, objdevice,
                policy_index)

    @public
    @timing_stats()
    def POST(self, request):
        """Handle HTTP POST requests for the Swift Object Server."""
        device, partition, account, container, obj, policy_idx = \
            get_name_and_placement(request, 5, 5, True)
        req_timestamp = valid_timestamp(request)
        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,
                policy_idx=policy_idx)
        except DiskFileDeviceUnavailable:
            return HTTPInsufficientStorage(drive=device, request=request)
        try:
            orig_metadata = disk_file.read_metadata()
        except (DiskFileNotExist, DiskFileQuarantined):
            return HTTPNotFound(request=request)
        orig_timestamp = Timestamp(orig_metadata.get('X-Timestamp', 0))
        if orig_timestamp >= req_timestamp:
            return HTTPConflict(request=request)
        metadata = {'X-Timestamp': req_timestamp.internal}
        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, policy_idx)
            if orig_delete_at:
                self.delete_at_update('DELETE', orig_delete_at, account,
                                      container, obj, request, device,
                                      policy_idx)
        disk_file.write_metadata(metadata)
        return HTTPAccepted(request=request)

    @public
    @timing_stats()
    def PUT(self, request):
        """Handle HTTP PUT requests for the Swift Object Server."""
        device, partition, account, container, obj, policy_idx = \
            get_name_and_placement(request, 5, 5, True)
        req_timestamp = valid_timestamp(request)
        error_response = check_object_creation(request, obj)
        if error_response:
            return error_response
        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:
            fsize = request.message_length()
        except ValueError as e:
            return HTTPBadRequest(body=str(e), request=request,
                                  content_type='text/plain')
        try:
            disk_file = self.get_diskfile(
                device, partition, account, container, obj,
                policy_idx=policy_idx)
        except DiskFileDeviceUnavailable:
            return HTTPInsufficientStorage(drive=device, request=request)
        try:
            orig_metadata = disk_file.read_metadata()
        except (DiskFileNotExist, DiskFileQuarantined):
            orig_metadata = {}

        # Checks for If-None-Match
        if request.if_none_match is not None and orig_metadata:
            if '*' in request.if_none_match:
                # File exists already so return 412
                return HTTPPreconditionFailed(request=request)
            if orig_metadata.get('ETag') in request.if_none_match:
                # The current ETag matches, so return 412
                return HTTPPreconditionFailed(request=request)

        orig_timestamp = Timestamp(orig_metadata.get('X-Timestamp', 0))
        if orig_timestamp and orig_timestamp >= req_timestamp:
            return HTTPConflict(request=request)
        orig_delete_at = int(orig_metadata.get('X-Delete-At') or 0)
        upload_expiration = time.time() + self.max_upload_time
        etag = md5()
        elapsed_time = 0
        try:
            with disk_file.create(size=fsize) as writer:
                upload_size = 0

                def timeout_reader():
                    with ChunkReadTimeout(self.client_timeout):
                        return request.environ['wsgi.input'].read(
                            self.network_chunk_size)

                try:
                    for chunk in iter(lambda: timeout_reader(), ''):
                        start_time = time.time()
                        if start_time > upload_expiration:
                            self.logger.increment('PUT.timeouts')
                            return HTTPRequestTimeout(request=request)
                        etag.update(chunk)
                        upload_size = writer.write(chunk)
                        elapsed_time += time.time() - start_time
                except ChunkReadTimeout:
                    return HTTPRequestTimeout(request=request)
                if upload_size:
                    self.logger.transfer_rate(
                        'PUT.' + device + '.timing', elapsed_time,
                        upload_size)
                if fsize is not None and fsize != upload_size:
                    return HTTPClientDisconnect(request=request)
                etag = etag.hexdigest()
                if 'etag' in request.headers and \
                        request.headers['etag'].lower() != etag:
                    return HTTPUnprocessableEntity(request=request)
                metadata = {
                    'X-Timestamp': request.timestamp.internal,
                    'Content-Type': request.headers['content-type'],
                    'ETag': etag,
                    'Content-Length': str(upload_size),
                }
                metadata.update(val for val in request.headers.iteritems()
                                if is_user_meta('object', val[0]))
                for header_key in (
                        request.headers.get('X-Backend-Replication-Headers') or
                        self.allowed_headers):
                    if header_key in request.headers:
                        header_caps = header_key.title()
                        metadata[header_caps] = request.headers[header_key]
                writer.put(metadata)
        except DiskFileNoSpace:
            return HTTPInsufficientStorage(drive=device, request=request)
        if orig_delete_at != new_delete_at:
            if new_delete_at:
                self.delete_at_update(
                    'PUT', new_delete_at, account, container, obj, request,
                    device, policy_idx)
            if orig_delete_at:
                self.delete_at_update(
                    'DELETE', orig_delete_at, account, container, obj,
                    request, device, policy_idx)
        self.container_update(
            'PUT', account, container, obj, request,
            HeaderKeyDict({
                'x-size': metadata['Content-Length'],
                'x-content-type': metadata['Content-Type'],
                'x-timestamp': metadata['X-Timestamp'],
                'x-etag': metadata['ETag']}),
            device, policy_idx)
        return HTTPCreated(request=request, etag=etag)

    @public
    @timing_stats()
    def GET(self, request):
        """Handle HTTP GET requests for the Swift Object Server."""
        device, partition, account, container, obj, policy_idx = \
            get_name_and_placement(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,
                policy_idx=policy_idx)
        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 = Timestamp(metadata['X-Timestamp'])
                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(float(file_x_ts))
                response.content_length = obj_size
                try:
                    response.content_encoding = metadata[
                        'Content-Encoding']
                except KeyError:
                    pass
                response.headers['X-Timestamp'] = file_x_ts.normal
                response.headers['X-Backend-Timestamp'] = file_x_ts.internal
                resp = request.get_response(response)
        except (DiskFileNotExist, DiskFileQuarantined) as e:
            headers = {}
            if hasattr(e, 'timestamp'):
                headers['X-Backend-Timestamp'] = e.timestamp.internal
            resp = HTTPNotFound(request=request, headers=headers,
                                conditional_response=True)
        return resp

    @public
    @timing_stats(sample_rate=0.8)
    def HEAD(self, request):
        """Handle HTTP HEAD requests for the Swift Object Server."""
        device, partition, account, container, obj, policy_idx = \
            get_name_and_placement(request, 5, 5, True)
        try:
            disk_file = self.get_diskfile(
                device, partition, account, container, obj,
                policy_idx=policy_idx)
        except DiskFileDeviceUnavailable:
            return HTTPInsufficientStorage(drive=device, request=request)
        try:
            metadata = disk_file.read_metadata()
        except (DiskFileNotExist, DiskFileQuarantined) as e:
            headers = {}
            if hasattr(e, 'timestamp'):
                headers['X-Backend-Timestamp'] = e.timestamp.internal
            return HTTPNotFound(request=request, headers=headers,
                                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 = Timestamp(metadata['X-Timestamp'])
        response.last_modified = math.ceil(float(ts))
        # Needed for container sync feature
        response.headers['X-Timestamp'] = ts.normal
        response.headers['X-Backend-Timestamp'] = ts.internal
        response.content_length = int(metadata['Content-Length'])
        try:
            response.content_encoding = metadata['Content-Encoding']
        except KeyError:
            pass
        return response

    @public
    @timing_stats()
    def DELETE(self, request):
        """Handle HTTP DELETE requests for the Swift Object Server."""
        device, partition, account, container, obj, policy_idx = \
            get_name_and_placement(request, 5, 5, True)
        req_timestamp = valid_timestamp(request)
        try:
            disk_file = self.get_diskfile(
                device, partition, account, container, obj,
                policy_idx=policy_idx)
        except DiskFileDeviceUnavailable:
            return HTTPInsufficientStorage(drive=device, request=request)
        try:
            orig_metadata = disk_file.read_metadata()
        except DiskFileExpired as e:
            orig_timestamp = e.timestamp
            orig_metadata = e.metadata
            response_class = HTTPNotFound
        except DiskFileDeleted as e:
            orig_timestamp = e.timestamp
            orig_metadata = {}
            response_class = HTTPNotFound
        except (DiskFileNotExist, DiskFileQuarantined):
            orig_timestamp = 0
            orig_metadata = {}
            response_class = HTTPNotFound
        else:
            orig_timestamp = Timestamp(orig_metadata.get('X-Timestamp', 0))
            if orig_timestamp < req_timestamp:
                response_class = HTTPNoContent
            else:
                response_class = HTTPConflict
        orig_delete_at = int(orig_metadata.get('X-Delete-At') or 0)
        try:
            req_if_delete_at_val = request.headers['x-if-delete-at']
            req_if_delete_at = int(req_if_delete_at_val)
        except KeyError:
            pass
        except ValueError:
            return HTTPBadRequest(
                request=request,
                body='Bad X-If-Delete-At header value')
        else:
            # request includes x-if-delete-at; we must not place a tombstone
            # if we can not verify the x-if-delete-at time
            if not orig_timestamp:
                # no object found at all
                return HTTPNotFound()
            if orig_delete_at != req_if_delete_at:
                return HTTPPreconditionFailed(
                    request=request,
                    body='X-If-Delete-At and X-Delete-At do not match')
            else:
                # differentiate success from no object at all
                response_class = HTTPNoContent
        if orig_delete_at:
            self.delete_at_update('DELETE', orig_delete_at, account,
                                  container, obj, request, device,
                                  policy_idx)
        if orig_timestamp < req_timestamp:
            disk_file.delete(req_timestamp)
            self.container_update(
                'DELETE', account, container, obj, request,
                HeaderKeyDict({'x-timestamp': req_timestamp.internal}),
                device, policy_idx)
        return response_class(request=request)

    @public
    @replication
    @timing_stats(sample_rate=0.1)
    def REPLICATE(self, request):
        """
        Handle REPLICATE requests for the Swift Object Server.  This is used
        by the object replicator to get hashes for directories.
        """
        device, partition, suffix, policy_idx = \
            get_name_and_placement(request, 2, 3, True)
        try:
            hashes = self._diskfile_mgr.get_hashes(device, partition, suffix,
                                                   policy_idx)
        except DiskFileDeviceUnavailable:
            resp = HTTPInsufficientStorage(drive=device, request=request)
        else:
            resp = Response(body=pickle.dumps(hashes))
        return resp

    @public
    @replication
    @timing_stats(sample_rate=0.1)
    def REPLICATION(self, request):
        return Response(app_iter=ssync_receiver.Receiver(self, request)())

    def __call__(self, env, start_response):
        """WSGI Application entry point for the Swift Object Server."""
        start_time = time.time()
        req = Request(env)
        self.logger.txn_id = req.headers.get('x-trans-id', None)

        if not check_utf8(req.path_info):
            res = HTTPPreconditionFailed(body='Invalid UTF8 or contains NULL')
        else:
            try:
                # disallow methods which have not been marked 'public'
                try:
                    method = getattr(self, req.method)
                    getattr(method, 'publicly_accessible')
                    replication_method = getattr(method, 'replication', False)
                    if (self.replication_server is not None and
                            self.replication_server != replication_method):
                        raise AttributeError('Not allowed method.')
                except AttributeError:
                    res = HTTPMethodNotAllowed()
                else:
                    res = method(req)
            except DiskFileCollision:
                res = HTTPForbidden(request=req)
            except HTTPException as error_response:
                res = error_response
            except (Exception, Timeout):
                self.logger.exception(_(
                    'ERROR __call__ error with %(method)s'
                    ' %(path)s '), {'method': req.method, 'path': req.path})
                res = HTTPInternalServerError(body=traceback.format_exc())
        trans_time = time.time() - start_time
        if self.log_requests:
            log_line = get_log_line(req, res, trans_time, '')
            if req.method in ('REPLICATE', 'REPLICATION') or \
                    'X-Backend-Replication' in req.headers:
                self.logger.debug(log_line)
            else:
                self.logger.info(log_line)
        if req.method in ('PUT', 'DELETE'):
            slow = self.slow - trans_time
            if slow > 0:
                sleep(slow)
        return res(env, start_response)


def global_conf_callback(preloaded_app_conf, global_conf):
    """
    Callback for swift.common.wsgi.run_wsgi during the global_conf
    creation so that we can add our replication_semaphore, used to
    limit the number of concurrent REPLICATION_REQUESTS across all
    workers.

    :param preloaded_app_conf: The preloaded conf for the WSGI app.
                               This conf instance will go away, so
                               just read from it, don't write.
    :param global_conf: The global conf that will eventually be
                        passed to the app_factory function later.
                        This conf is created before the worker
                        subprocesses are forked, so can be useful to
                        set up semaphores, shared memory, etc.
    """
    replication_concurrency = int(
        preloaded_app_conf.get('replication_concurrency') or 4)
    if replication_concurrency:
        # Have to put the value in a list so it can get past paste
        global_conf['replication_semaphore'] = [
            multiprocessing.BoundedSemaphore(replication_concurrency)]


def app_factory(global_conf, **local_conf):
    """paste.deploy app factory for creating WSGI object server apps"""
    conf = global_conf.copy()
    conf.update(local_conf)
    return ObjectController(conf)
