Source Code for Module buildbot.db.schema.manager

 1  from twisted.python import reflect 
 2   
 3  # note that schema modules are not loaded unless an upgrade is taking place 
 4   
 5  CURRENT_VERSION = 5 
 6   
 7 -class DBSchemaManager(object): 
 8      """ 
 9      This class is responsible for managing the database schema and upgrading it 
10      as necessary.  This includes both the *actual* database and the old pickle 
11      database, as migrations move data between the two. 
12   
13      Note that this class is *entirely synchronous*!  Performing any other operations 
14      while changing the schema is just asking for trouble. 
15      """ 
16 -    def __init__(self, spec, basedir): 
17          self.spec = spec 
18          self.basedir = basedir 
19          self.dbapi = self.spec.get_dbapi() 
20   
21 -    def get_db_version(self, conn=None): 
22          """ 
23          Get the current schema version for this database 
24          """ 
25          close_conn = False 
26          if not conn: 
27              conn = self.spec.get_sync_connection() 
28              close_conn = True 
29          c = conn.cursor() 
30          try: 
31              try: 
32                  c.execute("SELECT version FROM version") 
33                  rows = c.fetchall() 
34                  assert len(rows) == 1, "%i rows in version table! (should only be 1)" % len(rows) 
35                  return rows[0][0] 
36              except (self.dbapi.OperationalError, self.dbapi.ProgrammingError): 
37                  # no version table = version 0 
38                  return 0 
39          finally: 
40              if close_conn: 
41                  conn.close() 
42   
43 -    def get_current_version(self): 
44          """ 
45          Get the current db version for this release of buildbot 
46          """ 
47          return CURRENT_VERSION 
48   
49 -    def is_current(self): 
50          """ 
51          Is this database current? 
52          """ 
53          return self.get_db_version() == self.get_current_version() 
54   
55 -    def upgrade(self, quiet=False): 
56          """ 
57          Upgrade this database to the current version 
58          """ 
59          conn = self.spec.get_sync_connection() 
60          try: 
61              while self.get_db_version() < self.get_current_version(): 
62                  next_version = self.get_db_version() + 1 
63                  next_version_module = reflect.namedModule("buildbot.db.schema.v%d" % next_version) 
64                  upg = next_version_module.Upgrader(self.dbapi, conn, self.basedir, quiet) 
65                  upg.upgrade() 
66                  conn.commit() 
67                  assert self.get_db_version() == next_version 
68          finally: 
69              conn.close() 
70