def test_update(self):
        # Put the same document in multiple locations (a mid-migration status)
        # then do an update and ensure that only the correct place has been
        # updated.
        api.set_shard_at_rest('dummy', 1, "dest1/test_sharding")
        doc1 = {'x': 1, 'y': 1}
        self.db1.dummy.insert(doc1)

        api.start_migration('dummy', 1, 'dest2/test_sharding')
        api.set_shard_to_migration_status(
            'dummy', 1, api.ShardStatus.MIGRATING_COPY)
        self.db2.dummy.insert(doc1)

        result = operations.multishard_update('dummy', {}, {'$inc': {'y': 1}})
        self.assertEquals(1, result['n'])

        # Query the correct shard first and see that the counter has been
        # incremented
        result, = operations.multishard_find('dummy', {'x': 1})
        self.assertEquals(2, result['y'])

        # Now spoof the metadata such that the system thinks the data is on
        # shard2. The counter should still be 1 here.
        api.set_shard_at_rest('dummy', 1, "dest2/test_sharding", force=True)
        result, = operations.multishard_find('dummy', {'x': 1})
        self.assertEquals(1, result['y'])

    def test_alive(self):
        api.set_shard_at_rest('dummy', 1, "dest1/test_sharding")
        doc1 = {'x': 1, 'y': 1}
        self.db1.dummy.insert(doc1)

        c = operations.multishard_find('dummy', {})
        self.assertTrue(c.alive)

    def test_sync_uses_correct_connection(self):
        """This tests for a bug found during a rollout. The connection for the
        metadata was assumed to be the same connection as the source data was
        going to be coming from. This is *not* always the case.
        """
        # To test this a migration from new to old will expose the bug
        api.set_shard_at_rest('dummy', 1, "dest2/test_sharding")
        api.start_migration('dummy', 1, "dest1/test_sharding")

        # Mimic the state the shard would be in after a document was copied
        # from one location to another
        doc1 = {'x': 1, 'y': 1}
        doc1['_id'] = self.db1.dummy.insert(doc1)
        self.db2.dummy.insert(doc1)

        # Get the initial oplog position, do an update and then sync from the
        # initial position
        initial_oplog_pos = sharder._get_oplog_pos('dummy', 1)
        self.db2.dummy.update({'x': 1}, {'$inc': {'y': 1}})
        api.set_shard_to_migration_status(
            'dummy', 1, api.ShardStatus.MIGRATING_SYNC)
        sharder._sync_from_oplog('dummy', 1, initial_oplog_pos)

        # The data on the first database should now reflect the update that
        # went through
        doc2, = self.db1.dummy.find({})
        self.assertEquals(2, doc2['y'])

    def test_multishard_count_with_motion(self):
        api.set_shard_at_rest('dummy', 1, "dest1/test_sharding")
        api.set_shard_at_rest('dummy', 2, "dest1/test_sharding")

        doc1 = {'x': 1, 'y': 1}
        doc2 = {'x': 1, 'y': 2}
        doc3 = {'x': 2, 'y': 1}
        doc4 = {'x': 2, 'y': 2}
        self.db1.dummy.insert(doc1)
        self.db1.dummy.insert(doc2)
        self.db1.dummy.insert(doc3)
        self.db1.dummy.insert(doc4)

        results = operations.multishard_find('dummy', {}).count()
        self.assertEquals(4, results)

        # Mimic the shard now being in the second location and there being
        # documents left here
        api.start_migration('dummy', 2, "dest2/test_sharding")
        api.set_shard_to_migration_status(
            'dummy', 2, api.ShardStatus.POST_MIGRATION_PAUSED_AT_DESTINATION)

        self.db2.dummy.insert(doc3)
        self.db2.dummy.insert(doc4)

        results = operations.multishard_find('dummy', {}).count()
        self.assertEquals(4, results)

    def _attempt_migration(self, num_records):
        api.set_shard_at_rest('dummy', 1, "dest1/test_sharding")
        api.set_shard_at_rest('dummy', 2, "dest1/test_sharding")

        account_1 = self._prepare_account_data(
            self.db1, 1, xrange(0, num_records))
        account_2 = self._prepare_account_data(
            self.db1, 2, xrange(0, num_records))

        shard_manager = sharder._begin_migration(
            'dummy', 1, "dest2/test_sharding")
        self._modify_data(account_1, account_2, num_records, num_records)
        while not shard_manager.is_finished():
            time.sleep(0.01)
        self._verify_end_state(
            account_1, account_2, self.unwrapped_dummy_1, self.unwrapped_dummy_2)

        # Check that the data for the other account has remained intact and in
        # the same place
        account_2_actual = list(self.unwrapped_dummy_1.find({'account_id': 2}))
        account_2_actual = list(sorted(
            account_2_actual, key=lambda r: r['some_key']))

        self.assertEquals(account_2, account_2_actual)

        # Now migrate back to the source
        print 'Now migrate backwards...'
        shard_manager = sharder._begin_migration(
            'dummy', 1, "dest1/test_sharding")
        self._modify_data(account_1, account_2, num_records * 2, num_records)
        while not shard_manager.is_finished():
            time.sleep(0.01)
        self._verify_end_state(
            account_1, account_2, self.unwrapped_dummy_2, self.unwrapped_dummy_1)

    def test_query(self):
        api.create_realm("dummy-realm", "some_field", "dummy_collection")
        api.set_shard_at_rest("dummy-realm", 1, "dest1/some_db")
        expected_metadata = {"shard_key": 1, "location": "dest1/some_db", "realm": "dummy-realm"}

        def _trim_results(docs):
            return [{"shard_key": doc["shard_key"], "location": doc["location"], "realm": doc["realm"]} for doc in docs]

        store = metadata.ShardMetadataStore({"name": "dummy-realm"})

        results = _trim_results(store._query_shards_collection())
        self.assertEquals([expected_metadata], results)

        results = _trim_results(store._query_shards_collection(1))
        self.assertEquals([expected_metadata], results)

        results = _trim_results(store._query_shards_collection(2))
        self.assertEquals([], results)

        store = metadata.ShardMetadataStore({"name": "some-other-realm"})
        results = _trim_results(store._query_shards_collection())
        self.assertEquals([], results)

        results = _trim_results(store._query_shards_collection(1))
        self.assertEquals([], results)

    def test_set_shard_at_rest_bad_location(self):
        ensure_realm_exists('some_realm', 'some_field', 'some_collection')

        with self.assertRaises(Exception) as catcher:
            set_shard_at_rest('some_realm', 1, 'bad-cluster/db')
        self.assertEquals(
            catcher.exception.message,
            'Cluster bad-cluster has not been configured')

    def run(self):
        try:
            blue('* Starting migration')
            api.start_migration(
                self.collection_name, self.shard_key, self.new_location)

            # Copy phase
            blue('* Doing copy')
            oplog_pos = _get_oplog_pos(self.collection_name, self.shard_key)
            _do_copy(self.collection_name, self.shard_key, self.insert_throttle)

            # Sync phase
            blue('* Initial oplog sync')
            start_sync_time = time.time()
            api.set_shard_to_migration_status(
                self.collection_name, self.shard_key, metadata.ShardStatus.MIGRATING_SYNC)
            oplog_pos = _sync_from_oplog(
                self.collection_name, self.shard_key, oplog_pos)

            # Ensure that the sync has taken at least as long as our caching time
            # to ensure that all writes will get paused at approximately the same
            # time.
            while time.time() < start_sync_time + api.get_caching_duration():
                time.sleep(0.05)
                oplog_pos = _sync_from_oplog(
                    self.collection_name, self.shard_key, oplog_pos)

            # Now all the caching of metadata should be stopped for this shard.
            # We can flip to being paused at destination and wait ~100ms for any
            # pending updates/inserts to be performed. If these are taking longer
            # than 100ms then you are in a bad place and should rethink sharding.
            blue('* Pausing at destination')
            api.set_shard_to_migration_status(
                self.collection_name, self.shard_key,
                metadata.ShardStatus.POST_MIGRATION_PAUSED_AT_DESTINATION)
            time.sleep(0.1)
            
            blue('* Syncing oplog once more')
            _sync_from_oplog(
                self.collection_name, self.shard_key, oplog_pos)

            # Delete phase
            blue('* Doing deletion')
            api.set_shard_to_migration_status(
                self.collection_name, self.shard_key,
                metadata.ShardStatus.POST_MIGRATION_DELETE)
            _delete_source_data(
                self.collection_name, self.shard_key,
                delete_throttle=self.delete_throttle)

            api.set_shard_at_rest(
                self.collection_name, self.shard_key, self.new_location,
                force=True)

            blue('* Done')
        except:
            self.exception = sys.exc_info()
            raise

    def run(self):
        try:
            # Copy phase
            self.manager.set_phase('copy')
            api.start_migration(
                self.collection_name, self.shard_key, self.new_location)

            oplog_pos = _get_oplog_pos(self.collection_name, self.shard_key)
            _do_copy(self.collection_name, self.shard_key, self.manager)

            # Sync phase
            self.manager.set_phase('sync')
            start_sync_time = time.time()
            api.set_shard_to_migration_status(
                self.collection_name, self.shard_key, metadata.ShardStatus.MIGRATING_SYNC)
            oplog_pos = _sync_from_oplog(
                self.collection_name, self.shard_key, oplog_pos)

            # Ensure that the sync has taken at least as long as our caching time
            # to ensure that all writes will get paused at approximately the same
            # time.
            while time.time() < start_sync_time + api.get_caching_duration():
                time.sleep(0.05)
                oplog_pos = _sync_from_oplog(
                    self.collection_name, self.shard_key, oplog_pos)

            # Now all the caching of metadata should be stopped for this shard.
            # We can flip to being paused at destination and wait ~100ms for any
            # pending updates/inserts to be performed. If these are taking longer
            # than 100ms then you are in a bad place and should rethink sharding.
            api.set_shard_to_migration_status(
                self.collection_name, self.shard_key,
                metadata.ShardStatus.POST_MIGRATION_PAUSED_AT_DESTINATION)
            time.sleep(0.1)
            
            # Sync the oplog one final time to catch any writes that were
            # performed during the pause
            _sync_from_oplog(
                self.collection_name, self.shard_key, oplog_pos)

            # Delete phase
            self.manager.set_phase('delete')
            api.set_shard_to_migration_status(
                self.collection_name, self.shard_key,
                metadata.ShardStatus.POST_MIGRATION_DELETE)
            _delete_source_data(
                self.collection_name, self.shard_key, self.manager)

            api.set_shard_at_rest(
                self.collection_name, self.shard_key, self.new_location,
                force=True)

            self.manager.set_phase('complete')
        except:
            close_thread_connections(threading.current_thread())
            self.exception = sys.exc_info()
            raise

    def test_where_is(self):
        ensure_realm_exists(
            'some_realm', 'some_field', 'some_collection', 'dest1/db')
        set_shard_at_rest('some_realm', 1, 'dest2/db')

        # Specific location
        self.assertEquals('dest2/db', where_is('some_collection', 1))
        # Default location
        self.assertEquals('dest1/db', where_is('some_collection', 2))

    def test_cannot_move_to_same_location(self):
        ensure_realm_exists(
            'some_realm', 'some_field', 'some_collection', 'dest1/db')

        set_shard_at_rest('some_realm', 1, 'dest1/db')

        with self.assertRaises(Exception) as catcher:
            start_migration('some_realm', 1, 'dest1/db')
        self.assertEquals(
            catcher.exception.message, 'Shard is already at dest1/db')

    def test_multishard_find(self):
        api.set_shard_at_rest('dummy', 1, 'dest1/test_sharding')
        api.set_shard_at_rest('dummy', 2, 'dest2/test_sharding')
        doc1 = {'x': 1, 'y': 1}
        doc2 = {'x': 2, 'y': 1}
        self.db1.dummy.insert(doc1)
        self.db2.dummy.insert(doc2)

        c = operations.multishard_find('dummy', {'y': 1})
        results = sorted(list(c), key=lambda d: d['x'])
        self.assertEquals([doc1, doc2], results)

    def test_where_is(self):
        ensure_realm_exists('some_realm', 'some_field', 'some_collection')
        set_shard_at_rest('some_realm', 1, 'dest2/db')

        # Specific location
        self.assertEquals('dest2/db', where_is('some_collection', 1))
        # Lack of a location
        with self.assertRaises(Exception) as catcher:
            self.assertEquals('dest1/db', where_is('some_collection', 2))
        self.assertEquals(
            catcher.exception.message, 'Shard key 2 not placed for some_realm')

    def test_basic_copy(self):
        api.set_shard_at_rest("dummy", 1, "dest1/test_sharding")
        doc1 = {"x": 1, "y": 1}
        doc1["_id"] = self.db1.dummy.insert(doc1)

        api.start_migration("dummy", 1, "dest2/test_sharding")

        sharder._do_copy("dummy", 1)

        # The data should now be on the second database
        doc2, = self.db2.dummy.find({})
        self.assertEquals(doc1, doc2)

    def test_basic_copy(self):
        api.set_shard_at_rest('dummy', 1, "dest1/test_sharding")
        doc1 = {'x': 1, 'y': 1}
        doc1['_id'] = self.db1.dummy.insert(doc1)

        api.start_migration('dummy', 1, "dest2/test_sharding")

        manager = Mock(insert_throttle=None)
        sharder._do_copy('dummy', 1, manager)

        # The data should now be on the second database
        doc2, = self.db2.dummy.find({})
        self.assertEquals(doc1, doc2)

    def test_multi_remove(self):
        # Tests remove across multiple clusters
        api.set_shard_at_rest('dummy', 1, "dest1/test_sharding")
        api.set_shard_at_rest('dummy', 2, "dest2/test_sharding")
        doc1 = {'x': 1, 'y': 1}
        doc2 = {'x': 2, 'y': 1}
        self.db1.dummy.insert(doc1)
        self.db2.dummy.insert(doc2)

        operations.multishard_remove('dummy', {'y': 1})

        self.assertEquals(0, self.db1.dummy.find({}).count())
        self.assertEquals(0, self.db2.dummy.find({}).count())

    def test_multishard_find_with_limit_as_method(self):
        api.set_shard_at_rest('dummy', 1, "dest1/test_sharding")
        api.set_shard_at_rest('dummy', 2, "dest2/test_sharding")
        doc1 = {'x': 1, 'y': 1}
        doc2 = {'x': 1, 'y': 2}
        doc3 = {'x': 2, 'y': 1}
        doc4 = {'x': 2, 'y': 2}
        self.db1.dummy.insert(doc1)
        self.db1.dummy.insert(doc2)
        self.db2.dummy.insert(doc3)
        self.db2.dummy.insert(doc4)

        results = operations.multishard_find('dummy', {}).limit(3)
        self.assertEquals(3, len(list(results)))

    def test_multishard_rewind(self):
        api.set_shard_at_rest('dummy', 1, 'dest1/test_sharding')
        api.set_shard_at_rest('dummy', 2, 'dest2/test_sharding')
        doc1 = {'x': 1, 'y': 1}
        doc2 = {'x': 2, 'y': 1}
        self.db1.dummy.insert(doc1)
        self.db2.dummy.insert(doc2)

        cursor = operations.multishard_find('dummy', {'y': 1}, sort=[('x', 1)])
        found = cursor.next()
        self.assertEquals((1, 1), (found['x'], found['y']))
        cursor.rewind()
        found = cursor.next()
        self.assertEquals((1, 1), (found['x'], found['y']))

    def test_insert(self):
        # Perform an insert with shards set to specific locations.
        api.set_shard_at_rest('dummy', 1, "dest1/test_sharding")
        api.set_shard_at_rest('dummy', 2, "dest2/test_sharding")
        doc1 = {'x': 1, 'y': 1}
        doc2 = {'x': 2, 'y': 1}
        operations.multishard_insert('dummy', doc1)
        operations.multishard_insert('dummy', doc2)

        results = list(self.db1.dummy.find({'y': 1}))
        self.assertEquals([doc1], results)

        results = list(self.db2.dummy.find({'y': 1}))
        self.assertEquals([doc2], results)

    def test_index_inversion(self):
        num_records = 200
        api.set_shard_at_rest('dummy', 1, "dest1/test_sharding")

        account_1 = self._prepare_account_data(
            self.db1, 1, xrange(0, num_records))

        shard_manager = sharder._begin_migration(
            'dummy', 1, "dest2/test_sharding")
        self._modify_data(account_1)
        while not shard_manager.is_finished():
            time.sleep(0.01)
        self._verify_end_state(
            account_1, self.unwrapped_dummy_1, self.unwrapped_dummy_2)