DB: Encode the device to the DB id

Currently the DB ids, used to identify a database broker, is a uuid
(uuid4). This is a great unique identifier, however we don't tend to
track DB ids.
When we replicate to other primaries or nodes. We track which brokers we
replicate with or replicate with us via the incoming_sync and
outgoing_sync tables. These contain the DB id of the broker in question
and a timestamp.
These tables entries do get reclaimed over time, so gives us a nice
snapshot of whose been replicating with us.

Unfortuantly however, as we don't track these UUIDs to a broker or node
when we want to go look at these tables in search for replication problems
we tend to be at a loss.

This patch helps to identify the source by adding the device to the DB
id:

   <uuid4>-<device>

The patch uses the device as written in the path of the broker. Now when
we look into the sync tables we can look up in the ring and know exactly
which node it came from (or talking to). Although this only helps if you
use unique device names across the cluster.

An ID is generated when an account or container is first initialised.
But also after an rsync or rsyn_then_merge on the RPC (new location) side.
So as things replicate we'll get updated device's in the ID, which will also
show up in syncs in the future as the new node starts to replicate.

When applied to an existing cluster, there will be a mix of <uuid4> and
<uuid4 + device> IDs. But these ids are just text, and they will slowly
change as things get replicated/rebalanced around.

Change-Id: I58063c3830fb7b01c26fe1fa5aaec6353ff555c6

swift/account/backend.py

@@ -16,7 +16,6 @@
 Pluggable Back-end for Account Server
 """
 
-from uuid import uuid4
 
 import sqlite3
 
@@ -154,7 +153,7 @@ class AccountBroker(DatabaseBroker):
         conn.execute('''
             UPDATE account_stat SET account = ?, created_at = ?, id = ?,
                    put_timestamp = ?, status_changed_at = ?
-            ''', (self.account, Timestamp.now().internal, str(uuid4()),
+            ''', (self.account, Timestamp.now().internal, self._new_db_id(),
                   put_timestamp, put_timestamp))
 
     def create_policy_stat_table(self, conn):

swift/common/db.py

@@ -592,6 +592,10 @@ class DatabaseBroker(object):
                 _('Broker error trying to rollback locked connection'))
             conn.close()
 
+    def _new_db_id(self):
+        device_name = os.path.basename(self.get_device_path())
+        return "%s-%s" % (str(uuid4()), device_name)
+
     def newid(self, remote_id):
         """
         Re-id the database.  This should be called after an rsync.
@@ -601,7 +605,7 @@ class DatabaseBroker(object):
         with self.get() as conn:
             row = conn.execute('''
                 UPDATE %s_stat SET id=?
-            ''' % self.db_type, (str(uuid4()),))
+            ''' % self.db_type, (self._new_db_id(),))
             row = conn.execute('''
                 SELECT ROWID FROM %s ORDER BY ROWID DESC LIMIT 1
             ''' % self.db_contains_type).fetchone()

swift/container/backend.py

@@ -579,7 +579,7 @@ class ContainerBroker(DatabaseBroker):
                 put_timestamp, status_changed_at, storage_policy_index)
             VALUES (?, ?, ?, ?, ?, ?, ?);
         """, (self.account, self.container, Timestamp.now().internal,
-              str(uuid4()), put_timestamp, put_timestamp,
+              self._new_db_id(), put_timestamp, put_timestamp,
               storage_policy_index))
 
     def create_policy_stat_table(self, conn, storage_policy_index=0):

test/unit/account/test_backend.py

@@ -30,6 +30,7 @@ from contextlib import contextmanager
 import random
 import mock
 import base64
+import shutil
 
 import six
 
@@ -1071,6 +1072,40 @@ class TestAccountBroker(unittest.TestCase):
                 "SELECT COUNT(*) FROM policy_stat").fetchall()[0][0]
         self.assertEqual(nrows, 2)
 
+    @with_tempdir
+    def test_newid(self, tempdir):
+        # test DatabaseBroker.newid
+        db_path = os.path.join(
+            tempdir, "d1234", 'accounts', 'part', 'suffix', 'hsh')
+        os.makedirs(db_path)
+        broker = AccountBroker(os.path.join(db_path, 'my.db'),
+                               account='a')
+        broker.initialize(Timestamp('1').internal, 0)
+        id = broker.get_info()['id']
+        broker.newid('someid')
+        self.assertNotEqual(id, broker.get_info()['id'])
+        # ends in the device name (from the path) unless it's an old
+        # container with just a uuid4 (tested in legecy broker
+        # tests e.g *BeforeMetaData)
+        if len(id) > 36:
+            self.assertTrue(id.endswith('d1234'))
+        # But the newid'ed version will now have the decide
+        self.assertTrue(broker.get_info()['id'].endswith('d1234'))
+
+        # if we move the broker (happens after an rsync)
+        new_db_path = os.path.join(
+            tempdir, "d5678", 'contianers', 'part', 'suffix', 'hsh')
+        os.makedirs(new_db_path)
+        shutil.copy(os.path.join(db_path, 'my.db'),
+                    os.path.join(new_db_path, 'my.db'))
+
+        new_broker = AccountBroker(os.path.join(new_db_path, 'my.db'),
+                                   account='a')
+        new_broker.newid(id)
+        # ends in the device name (from the path)
+        self.assertFalse(new_broker.get_info()['id'].endswith('d1234'))
+        self.assertTrue(new_broker.get_info()['id'].endswith('d5678'))
+
 
 def prespi_AccountBroker_initialize(self, conn, put_timestamp, **kwargs):
     """

test/unit/container/test_backend.py

@@ -18,6 +18,7 @@ import base64
 import errno
 import os
 import inspect
+import shutil
 import unittest
 from time import sleep, time
 from uuid import uuid4
@@ -3328,13 +3329,39 @@ class TestContainerBroker(unittest.TestCase):
         hashc = '%032x' % (int(hasha, 16) ^ int(hashb, 16))
         self.assertEqual(broker.get_info()['hash'], hashc)
 
-    def test_newid(self):
+    @with_tempdir
+    def test_newid(self, tempdir):
         # test DatabaseBroker.newid
-        broker = ContainerBroker(':memory:', account='a', container='c')
+        db_path = os.path.join(
+            tempdir, "d1234", 'contianers', 'part', 'suffix', 'hsh')
+        os.makedirs(db_path)
+        broker = ContainerBroker(os.path.join(db_path, 'my.db'),
+                                 account='a', container='c')
         broker.initialize(Timestamp('1').internal, 0)
         id = broker.get_info()['id']
         broker.newid('someid')
         self.assertNotEqual(id, broker.get_info()['id'])
+        # ends in the device name (from the path) unless it's an old
+        # container with just a uuid4 (tested in legecy broker
+        # tests e.g *BeforeMetaData)
+        if len(id) > 36:
+            self.assertTrue(id.endswith('d1234'))
+        # But the newid'ed version will now have the decide
+        self.assertTrue(broker.get_info()['id'].endswith('d1234'))
+
+        # if we move the broker (happens after an rsync)
+        new_db_path = os.path.join(
+            tempdir, "d5678", 'containers', 'part', 'suffix', 'hsh')
+        os.makedirs(new_db_path)
+        shutil.copy(os.path.join(db_path, 'my.db'),
+                    os.path.join(new_db_path, 'my.db'))
+
+        new_broker = ContainerBroker(os.path.join(new_db_path, 'my.db'),
+                                     account='a', container='c')
+        new_broker.newid(id)
+        # ends in the device name (from the path)
+        self.assertFalse(new_broker.get_info()['id'].endswith('d1234'))
+        self.assertTrue(new_broker.get_info()['id'].endswith('d5678'))
 
     def test_get_items_since(self):
         # test DatabaseBroker.get_items_since