# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
+"""
+Utilities for database operations.
+
+Some note on migration and indexing tools:
+
+We store information about what the state of the database is in the
+'mediagoblin' document of the 'app_metadata' collection. Keys in that
+document relevant to here:
+
+ - 'migration_number': The integer representing the current state of
+ the migrations
+"""
+
+import copy
# Imports that other modules might use
-from pymongo import DESCENDING
+from pymongo import ASCENDING, DESCENDING
+from pymongo.errors import InvalidId
from mongokit import ObjectId
+
+from mediagoblin.db.indexes import ACTIVE_INDEXES, DEPRECATED_INDEXES
+
+
+################
+# Indexing tools
+################
+
+
+def add_new_indexes(database, active_indexes=ACTIVE_INDEXES):
+ """
+ Add any new indexes to the database.
+
+ Args:
+ - database: pymongo or mongokit database instance.
+ - active_indexes: indexes to possibly add in the pattern of:
+ {'collection_name': {
+ 'identifier': {
+ 'index': [index_foo_goes_here],
+ 'unique': True}}
+ where 'index' is the index to add and all other options are
+ arguments for collection.create_index.
+
+ Returns:
+ A list of indexes added in form ('collection', 'index_name')
+ """
+ indexes_added = []
+
+ for collection_name, indexes in active_indexes.iteritems():
+ collection = database[collection_name]
+ collection_indexes = collection.index_information().keys()
+
+ for index_name, index_data in indexes.iteritems():
+ if not index_name in collection_indexes:
+ # Get a copy actually so we don't modify the actual
+ # structure
+ index_data = copy.copy(index_data)
+ index = index_data.pop('index')
+ collection.create_index(
+ index, name=index_name, **index_data)
+
+ indexes_added.append((collection_name, index_name))
+
+ return indexes_added
+
+
+def remove_deprecated_indexes(database, deprecated_indexes=DEPRECATED_INDEXES):
+ """
+ Remove any deprecated indexes from the database.
+
+ Args:
+ - database: pymongo or mongokit database instance.
+ - deprecated_indexes: the indexes to deprecate in the pattern of:
+ {'collection_name': {
+ 'identifier': {
+ 'index': [index_foo_goes_here],
+ 'unique': True}}
+
+ (... although we really only need the 'identifier' here, as the
+ rest of the information isn't used in this case. But it's kept
+ around so we can remember what it was)
+
+ Returns:
+ A list of indexes removed in form ('collection', 'index_name')
+ """
+ indexes_removed = []
+
+ for collection_name, indexes in deprecated_indexes.iteritems():
+ collection = database[collection_name]
+ collection_indexes = collection.index_information().keys()
+
+ for index_name, index_data in indexes.iteritems():
+ if index_name in collection_indexes:
+ collection.drop_index(index_name)
+
+ indexes_removed.append((collection_name, index_name))
+
+ return indexes_removed
+
+
+#################
+# Migration tools
+#################
+
+# The default migration registry...
+#
+# Don't set this yourself! RegisterMigration will automatically fill
+# this with stuff via decorating methods in migrations.py
+
+class MissingCurrentMigration(Exception): pass
+
+
+MIGRATIONS = {}
+
+
+class RegisterMigration(object):
+ """
+ Tool for registering migrations
+
+ Call like:
+
+ @RegisterMigration(33)
+ def update_dwarves(database):
+ [...]
+
+ This will register your migration with the default migration
+ registry. Alternately, to specify a very specific
+ migration_registry, you can pass in that as the second argument.
+
+ Note, the number of your migration should NEVER be 0 or less than
+ 0. 0 is the default "no migrations" state!
+ """
+ def __init__(self, migration_number, migration_registry=MIGRATIONS):
+ assert migration_number > 0, "Migration number must be > 0!"
+ assert not migration_registry.has_key(migration_number), \
+ "Duplicate migration numbers detected! That's not allowed!"
+
+ self.migration_number = migration_number
+ self.migration_registry = migration_registry
+
+ def __call__(self, migration):
+ self.migration_registry[self.migration_number] = migration
+ return migration
+
+
+class MigrationManager(object):
+ """
+ Migration handling tool.
+
+ Takes information about a database, lets you update the database
+ to the latest migrations, etc.
+ """
+ def __init__(self, database, migration_registry=MIGRATIONS):
+ """
+ Args:
+ - database: database we're going to migrate
+ - migration_registry: where we should find all migrations to
+ run
+ """
+ self.database = database
+ self.migration_registry = migration_registry
+ self._sorted_migrations = None
+
+ def _ensure_current_migration_record(self):
+ """
+ If there isn't a database[u'app_metadata'] mediagoblin entry
+ with the 'current_migration', throw an error.
+ """
+ if self.database_current_migration() is None:
+ raise MissingCurrentMigration(
+ "Tried to call function which requires "
+ "'current_migration' set in database")
+
+ @property
+ def sorted_migrations(self):
+ """
+ Sort migrations if necessary and store in self._sorted_migrations
+ """
+ if not self._sorted_migrations:
+ self._sorted_migrations = sorted(
+ self.migration_registry.items(),
+ # sort on the key... the migration number
+ key=lambda migration_tuple: migration_tuple[0])
+
+ return self._sorted_migrations
+
+ def latest_migration(self):
+ """
+ Return a migration number for the latest migration, or 0 if
+ there are no migrations.
+ """
+ if self.sorted_migrations:
+ return self.sorted_migrations[-1][0]
+ else:
+ # If no migrations have been set, we start at 0.
+ return 0
+
+ def set_current_migration(self, migration_number):
+ """
+ Set the migration in the database to migration_number
+ """
+ # Add the mediagoblin migration if necessary
+ self.database[u'app_metadata'].update(
+ {u'_id': u'mediagoblin'},
+ {u'$set': {u'current_migration': migration_number}},
+ upsert=True)
+
+ def install_migration_version_if_missing(self):
+ """
+ Sets the migration to the latest version if no migration
+ version at all is set.
+ """
+ mgoblin_metadata = self.database[u'app_metadata'].find_one(
+ {u'_id': u'mediagoblin'})
+ if not mgoblin_metadata:
+ latest_migration = self.latest_migration()
+ self.set_current_migration(latest_migration)
+
+ def database_current_migration(self):
+ """
+ Return the current migration in the database.
+ """
+ mgoblin_metadata = self.database[u'app_metadata'].find_one(
+ {u'_id': u'mediagoblin'})
+ if not mgoblin_metadata:
+ return None
+ else:
+ return mgoblin_metadata[u'current_migration']
+
+ def database_at_latest_migration(self):
+ """
+ See if the database is at the latest migration.
+ Returns a boolean.
+ """
+ current_migration = self.database_current_migration()
+ return current_migration == self.latest_migration()
+
+ def migrations_to_run(self):
+ """
+ Get a list of migrations to run still, if any.
+
+ Note that calling this will set your migration version to the
+ latest version if it isn't installed to anything yet!
+ """
+ self._ensure_current_migration_record()
+
+ db_current_migration = self.database_current_migration()
+
+ return [
+ (migration_number, migration_func)
+ for migration_number, migration_func in self.sorted_migrations
+ if migration_number > db_current_migration]
+
+ def migrate_new(self, pre_callback=None, post_callback=None):
+ """
+ Run all migrations.
+
+ Includes two optional args:
+ - pre_callback: if called, this is a callback on something to
+ run pre-migration. Takes (migration_number, migration_func)
+ as arguments
+ - pre_callback: if called, this is a callback on something to
+ run post-migration. Takes (migration_number, migration_func)
+ as arguments
+ """
+ # If we aren't set to any version number, presume we're at the
+ # latest (which means we'll do nothing here...)
+ self.install_migration_version_if_missing()
+
+ for migration_number, migration_func in self.migrations_to_run():
+ if pre_callback:
+ pre_callback(migration_number, migration_func)
+ migration_func(self.database)
+ self.set_current_migration(migration_number)
+ if post_callback:
+ post_callback(migration_number, migration_func)
projects / mediagoblin.git / blobdiff