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sqlite: close the database when no more threads need access

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It's required to have more than one connection to the database for the
maxconnections configuration option to work with threads. However,
connection.close() is closing all the connections. Only close the connection
when no more thread need it.

Backported-from: 856b74407bd7f634cae5a8c2d9b84e13d14c12d2
Github-fix: https://github.com/OfflineIMAP/offlineimap/issues/350
Signed-off-by: Nicolas Sebrecht <nicolas.s-dev@laposte.net>
This commit is contained in:
Nicolas Sebrecht 2016-07-22 00:08:45 +02:00
parent 8cca78b265
commit 677afb8d8f
1 changed files with 45 additions and 36 deletions
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17
offlineimap/folder/LocalStatusSQLite.py
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@ -42,6 +42,9 @@ class LocalStatusSQLiteFolder(BaseFolder):
# Current version of our db format. # Current version of our db format.
cur_version = 2 cur_version = 2
# Keep track on how many threads need access to the database.
threads_open_count = 0
threads_open_lock = Lock()
def __init__(self, name, repository): def __init__(self, name, repository):
self.sep = '.' # Needs to be set before super.__init__() self.sep = '.' # Needs to be set before super.__init__()
@ -64,9 +67,12 @@ class LocalStatusSQLiteFolder(BaseFolder):
self.connection = None self.connection = None
def openfiles(self): def openfiles(self):
# Protect the creation/upgrade of database accross threads.
with LocalStatusSQLiteFolder.threads_open_lock:
# Try to establish connection, no need for threadsafety in __init__. # Try to establish connection, no need for threadsafety in __init__.
try: try:
self.connection = sqlite.connect(self.filename, check_same_thread=False) self.connection = sqlite.connect(self.filename, check_same_thread=False)
LocalStatusSQLiteFolder.threads_open_count += 1
except NameError: except NameError:
# sqlite import had failed. # sqlite import had failed.
raise UserWarning("SQLite backend chosen, but cannot connect " raise UserWarning("SQLite backend chosen, but cannot connect "
@ -155,8 +161,8 @@ class LocalStatusSQLiteFolder(BaseFolder):
def __upgrade_db(self, from_ver): def __upgrade_db(self, from_ver):
"""Upgrade the sqlite format from version 'from_ver' to current""" """Upgrade the sqlite format from version 'from_ver' to current"""
if hasattr(self, 'connection'): if self.connection is not None:
self.connection.close() #close old connections first self.connection.close() # Close old connections first.
self.connection = sqlite.connect(self.filename, self.connection = sqlite.connect(self.filename,
check_same_thread = False) check_same_thread = False)
@ -181,8 +187,8 @@ class LocalStatusSQLiteFolder(BaseFolder):
self.connection must point to the opened and valid SQlite self.connection must point to the opened and valid SQlite
database connection.""" database connection."""
self.ui._msg('Creating new Local Status db for %s:%s' \ self.ui._msg('Creating new Local Status db for %s:%s'%
% (self.repository, self)) (self.repository, self))
self.connection.executescript(""" self.connection.executescript("""
CREATE TABLE metadata (key VARCHAR(50) PRIMARY KEY, value VARCHAR(128)); CREATE TABLE metadata (key VARCHAR(50) PRIMARY KEY, value VARCHAR(128));
INSERT INTO metadata VALUES('db_version', '2'); INSERT INTO metadata VALUES('db_version', '2');
@ -225,6 +231,9 @@ class LocalStatusSQLiteFolder(BaseFolder):
self.messagelist[uid]['mtime'] = row[2] self.messagelist[uid]['mtime'] = row[2]
def closefiles(self): def closefiles(self):
with LocalStatusSQLiteFolder.threads_open_lock:
LocalStatusSQLiteFolder.threads_open_count -= 1
if self.threads_open_count < 1:
try: try:
self.connection.close() self.connection.close()
except: except: