Add support for Object Expiration feature

Preventing access to expired objects
------------------------------------
Re-enabled accepting X-Delete-At and X-Delete-After headers. During a GET on
an expired object, DiskFileExpired is raised by DiskFile class. This will
result in object-server returning HTTPNotFound (404) to the client.

Tracking objects to be deleted
------------------------------
Objects to be deleted are tracked using "tracker objects". These are PUT into
a special account(a volume, for now). These zero size "tracker objects" have
names that contain:
    * Expiration timestamp
    * Path of the actual object to be deleted

Deleting actual objects from GlusterFS volume
---------------------------------------------
The object-expirer daemon runs a pass once every X seconds. For every pass it
makes, it queries the special account for "tracker objects". Based on
(timestamp, path) present in name of "tracker objects", object-expirer then
deletes the actual object and the corresponding tracker object.

To run object-expirer forever:
    swift-init object-expirer start
To run just once:
    swift-object-expirer -o -v /etc/swift/object-expirer.conf

Caveat/Limitation: Object-expirer needs a separate account(volume) that
is not used by other services like gswauth. By default, this volume is
named "gsexpiring" and is configurable.

More info about object expiration:
http://docs.openstack.org/developer/swift/overview_expiring_objects.html

Change-Id: I876995bf4f16ef4bfdff901561e0558ecf1dc38f
Signed-off-by: Prashanth Pai <ppai@redhat.com>
Reviewed-on: http://review.gluster.org/6891
Tested-by: Chetan Risbud <crisbud@redhat.com>
Reviewed-by: pushpesh sharma <psharma@redhat.com>
Tested-by: pushpesh sharma <psharma@redhat.com>
Reviewed-by: Chetan Risbud <crisbud@redhat.com>

3 files changed, 113 insertions, 13 deletions

diff --git a/gluster/swift/common/constraints.py b/gluster/swift/common/constraints.py
index 7681c49..80616f2 100644
--- a/gluster/swift/common/constraints.py
+++ b/gluster/swift/common/constraints.py
@@ -23,7 +23,7 @@ import swift.common.ring as _ring
 from gluster.swift.common import Glusterfs, ring
 
 MAX_OBJECT_NAME_COMPONENT_LENGTH = 255
-UNSUPPORTED_HEADERS = ['x-delete-at', 'x-delete-after']
+UNSUPPORTED_HEADERS = []
 
 
 def set_object_name_component_length(len=None):
diff --git a/gluster/swift/obj/diskfile.py b/gluster/swift/obj/diskfile.py
index 852f69f..b3e91bc 100644
--- a/gluster/swift/obj/diskfile.py
+++ b/gluster/swift/obj/diskfile.py
@@ -23,6 +23,7 @@ try:
 except ImportError:
     import random
 import logging
+import time
 from collections import defaultdict
 from socket import gethostname
 from hashlib import md5
@@ -33,7 +34,8 @@ from gluster.swift.common.exceptions import AlreadyExistsAsFile, \
     AlreadyExistsAsDir
 from swift.common.utils import TRUE_VALUES, ThreadPool, config_true_value
 from swift.common.exceptions import DiskFileNotExist, DiskFileError, \
-    DiskFileNoSpace, DiskFileDeviceUnavailable, DiskFileNotOpen
+    DiskFileNoSpace, DiskFileDeviceUnavailable, DiskFileNotOpen, \
+    DiskFileExpired
 from swift.common.swob import multi_range_iterator
 
 from gluster.swift.common.exceptions import GlusterFileSystemOSError
@@ -701,6 +703,7 @@ class DiskFile(object):
             the object representation does not exist.
 
         :raises DiskFileNotExist: if the object does not exist
+        :raises DiskFileExpired: if the object has expired
         :returns: itself for use as a context manager
         """
         # Writes are always performed to a temporary file
@@ -731,11 +734,28 @@ class DiskFile(object):
             obj_size = 0
             self._fd = -1
         else:
+            if self._is_object_expired(self._metadata):
+                raise DiskFileExpired(metadata=self._metadata)
             self._fd = fd
 
         self._obj_size = obj_size
         return self
 
+    def _is_object_expired(self, metadata):
+        try:
+            x_delete_at = int(metadata['X-Delete-At'])
+        except KeyError:
+            pass
+        except ValueError:
+            # x-delete-at key is present but not an integer.
+            # TODO: Openstack Swift "quarrantines" the object.
+            # We just let it pass
+            pass
+        else:
+            if x_delete_at <= time.time():
+                return True
+        return False
+
     def _filter_metadata(self):
         if X_TYPE in self._metadata:
             self._metadata.pop(X_TYPE)
diff --git a/gluster/swift/obj/server.py b/gluster/swift/obj/server.py
index 3cdd3c0..8bc080a 100644
--- a/gluster/swift/obj/server.py
+++ b/gluster/swift/obj/server.py
@@ -28,6 +28,14 @@ from swift.obj import server
 
 from gluster.swift.obj.diskfile import OnDiskManager
 
+import os
+from swift.common.exceptions import ConnectionTimeout
+from swift.common.bufferedhttp import http_connect
+from eventlet import Timeout
+from swift.common.http import is_success
+from gluster.swift.common.ring import Ring
+from swift import gettext_ as _
+
 
 class ObjectController(server.ObjectController):
     """
@@ -44,16 +52,10 @@ class ObjectController(server.ObjectController):
 
         :param conf: WSGI configuration parameter
         """
-        # FIXME: Gluster currently does not support x-delete-at, as there is
-        # no mechanism in GlusterFS itself to expire an object, or an external
-        # process that will cull expired objects.
-        try:
-            self.allowed_headers.remove('x-delete-at')
-        except KeyError:
-            pass
         # Common on-disk hierarchy shared across account, container and object
         # servers.
         self._ondisk_mgr = OnDiskManager(conf, self.logger)
+        self.swift_dir = conf.get('swift_dir', '/etc/swift')
 
     def get_diskfile(self, device, partition, account, container, obj,
                      **kwargs):
@@ -77,12 +79,90 @@ class ObjectController(server.ObjectController):
         """
         return
 
-    def delete_at_update(self, *args, **kwargs):
-        """
-        Update the expiring objects container when objects are updated.
+    def get_object_ring(self):
+        if hasattr(self, 'object_ring'):
+            if not self.object_ring:
+                self.object_ring = Ring(self.swift_dir, ring_name='object')
+        else:
+            self.object_ring = Ring(self.swift_dir, ring_name='object')
+        return self.object_ring
 
-        FIXME: Gluster currently does not support delete_at headers.
+    def async_update(self, op, account, container, obj, host, partition,
+                     contdevice, headers_out, objdevice):
         """
+        In Openstack Swift, this method is called by:
+            * container_update (a no-op in gluster-swift)
+            * delete_at_update (to PUT objects into .expiring_objects account)
+
+        The Swift's version of async_update only sends the request to
+        container-server to PUT the object. The container-server calls
+        container_update method which makes an entry for the object in it's
+        database. No actual object is created on disk.
+
+        But in gluster-swift container_update is a no-op, so we'll
+        have to PUT an actual object. We override async_update to create a
+        container first and then the corresponding "tracker object" which
+        tracks expired objects scheduled for deletion.
+        """
+
+        headers_out['user-agent'] = 'obj-server %s' % os.getpid()
+        if all([host, partition, contdevice]):
+            # PUT the container. Send request directly to container-server
+            container_path = '/%s/%s' % (account, container)
+            try:
+                with ConnectionTimeout(self.conn_timeout):
+                    ip, port = host.rsplit(':', 1)
+                    conn = http_connect(ip, port, contdevice, partition, op,
+                                        container_path, headers_out)
+                with Timeout(self.node_timeout):
+                    response = conn.getresponse()
+                    response.read()
+                    if not is_success(response.status):
+                        self.logger.error(_(
+                            'async_update : '
+                            'ERROR Container update failed :%(status)d '
+                            'response from %(ip)s:%(port)s/%(dev)s'),
+                            {'status': response.status, 'ip': ip, 'port': port,
+                             'dev': contdevice})
+                        return
+            except (Exception, Timeout):
+                self.logger.exception(_(
+                    'async_update : '
+                    'ERROR Container update failed :%(ip)s:%(port)s/%(dev)s'),
+                    {'ip': ip, 'port': port, 'dev': contdevice})
+
+            # PUT the tracker object. Send request directly to object-server
+            object_path = '/%s/%s/%s' % (account, container, obj)
+            headers_out['Content-Length'] = 0
+            headers_out['Content-Type'] = 'text/plain'
+            try:
+                with ConnectionTimeout(self.conn_timeout):
+                    # FIXME: Assuming that get_nodes returns single node
+                    part, nodes = self.get_object_ring().get_nodes(account,
+                                                                   container,
+                                                                   obj)
+                    ip = nodes[0]['ip']
+                    port = nodes[0]['port']
+                    objdevice = nodes[0]['device']
+                    conn = http_connect(ip, port, objdevice, partition, op,
+                                        object_path, headers_out)
+                with Timeout(self.node_timeout):
+                    response = conn.getresponse()
+                    response.read()
+                    if is_success(response.status):
+                        return
+                    else:
+                        self.logger.error(_(
+                            'async_update : '
+                            'ERROR Object PUT failed : %(status)d '
+                            'response from %(ip)s:%(port)s/%(dev)s'),
+                            {'status': response.status, 'ip': ip, 'port': port,
+                             'dev': objdevice})
+            except (Exception, Timeout):
+                self.logger.exception(_(
+                    'async_update : '
+                    'ERROR Object PUT failed :%(ip)s:%(port)s/%(dev)s'),
+                    {'ip': ip, 'port': port, 'dev': objdevice})
         return
 
     @public