ttygroup/boartty
Code Issues Proposed changes

Ensure single-threaded db access

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SQLite doesn't really like concurrent access so mediate it with
a lock.

Change-Id: Ibb7aed2a5f028a2a01b61b37fa24f634e4898fbe
This commit is contained in:
James E. Blair 2014-05-17 20:21:43 -04:00
parent a5bb8ec113
commit 7ea4ad8b36
1 changed files with 12 additions and 3 deletions
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15
gertty/db.py
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@ -12,7 +12,9 @@
# License for the specific language governing permissions and limitations # License for the specific language governing permissions and limitations
# under the License. # under the License.
import time
import logging import logging
import threading
import alembic import alembic
import alembic.config import alembic.config
@ -344,9 +346,10 @@ class Database(object):
self.migrate() self.migrate()
self.session_factory = sessionmaker(bind=self.engine) self.session_factory = sessionmaker(bind=self.engine)
self.session = scoped_session(self.session_factory) self.session = scoped_session(self.session_factory)
self.lock = threading.Lock()
def getSession(self): def getSession(self):
return DatabaseSession(self.session) return DatabaseSession(self)
def migrate(self): def migrate(self):
conn = self.engine.connect() conn = self.engine.connect()
@ -366,10 +369,13 @@ class Database(object):
alembic.command.upgrade(config, 'head') alembic.command.upgrade(config, 'head')
class DatabaseSession(object): class DatabaseSession(object):
def __init__(self, session): def __init__(self, database):
self.session = session self.database = database
self.session = database.session
def __enter__(self): def __enter__(self):
self.database.lock.acquire()
self.start = time.time()
return self return self
def __exit__(self, etype, value, tb): def __exit__(self, etype, value, tb):
@ -379,6 +385,9 @@ class DatabaseSession(object):
self.session().commit() self.session().commit()
self.session().close() self.session().close()
self.session = None self.session = None
end = time.time()
self.database.log.debug("Database lock held %s seconds" % (end-self.start,))
self.database.lock.release()
def abort(self): def abort(self):
self.session().rollback() self.session().rollback()