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Subject: Re: NSOperation, Sqlite, library routine called out of sequence - msg#02187List: cocoa-devThe DatabaseManager is synchronized. If any class is to communicate with the db, it does that through the DatabaseManager. The latter just provides proxy methods. I think, that should result in classes getting the instance of the DatabaseManager only when it is no longer (or not yet) used by other classes. But that does nothing to prevent multiple threads from performing additional concurrent actions on the database. It's not enough to just control access to the shared singleton, if the actions performed by the singleton aren't also thread-safe. All the queries, updates, etc. need thread-safety, too. -- GG _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@xxxxxxxxxxxxxxx) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/maillists%40codeha.us This email sent to maillists@xxxxxxxxx Thread at a glance:
Previous Message by Date: click to view message previewRe: NSOperation, Sqlite, library routine called out of sequenceThe DatabaseManager is synchronized. If any class is to communicate with the db, it does that through the DatabaseManager. The latter just provides proxy methods. I think, that should result in classes getting the instance of the DatabaseManager only when it is no longer (or not yet) used by other classes. + (DatabaseManager*)sharedManager { @synchronized(self) { if (sharedDatabaseManager == nil) { [[self alloc] init]; // assignment not done here } } return sharedDatabaseManager; } + (id)allocWithZone:(NSZone *)zone { @synchronized(self) { if (sharedDatabaseManager == nil) { sharedDatabaseManager = [super allocWithZone:zone]; [sharedDatabaseManager initDb]; return sharedDatabaseManager; } } return nil; } On Apr 29, 2009, at 10:52 PM, Greg Guerin wrote: ÐÐÐÐÑÐÐ ÐÐÐÑÑÐÐ wrote: In short, i get an error calling the same synchronized singleton DatabaseManager from different threads. Are you sure your database accesses are synchronized (i.e. thread- safe)? I see nothing in the posted code that uses @synchronized or any other locking mechanism. -- GG _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@xxxxxxxxxxxxxxx) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/ok5.admin%40gmail.com This email sent to ok5.admin@xxxxxxxxx _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@xxxxxxxxxxxxxxx) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/maillists%40codeha.us This email sent to maillists@xxxxxxxxx Next Message by Date: click to view message previewRe: NSOperation, Sqlite, library routine called out of sequenceHm... That really works! Thanks a lot. Putting the bodies of those methods in @synchronized(self) blocks helped Thanks a lot again. On Apr 29, 2009, at 11:33 PM, Greg Guerin wrote: ÐÐÐÐÑÐÐ ÐÐÐÑÑÐÐ wrote: The DatabaseManager is synchronized. If any class is to communicate with the db, it does that through the DatabaseManager. The latter just provides proxy methods. I think, that should result in classes getting the instance of the DatabaseManager only when it is no longer (or not yet) used by other classes. But that does nothing to prevent multiple threads from performing additional concurrent actions on the database. It's not enough to just control access to the shared singleton, if the actions performed by the singleton aren't also thread-safe. All the queries, updates, etc. need thread-safety, too. -- GG _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@xxxxxxxxxxxxxxx) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/ok5.admin%40gmail.com This email sent to ok5.admin@xxxxxxxxx _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@xxxxxxxxxxxxxxx) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/maillists%40codeha.us This email sent to maillists@xxxxxxxxx Previous Message by Thread: click to view message previewRe: NSOperation, Sqlite, library routine called out of sequenceThe DatabaseManager is synchronized. If any class is to communicate with the db, it does that through the DatabaseManager. The latter just provides proxy methods. I think, that should result in classes getting the instance of the DatabaseManager only when it is no longer (or not yet) used by other classes. + (DatabaseManager*)sharedManager { @synchronized(self) { if (sharedDatabaseManager == nil) { [[self alloc] init]; // assignment not done here } } return sharedDatabaseManager; } + (id)allocWithZone:(NSZone *)zone { @synchronized(self) { if (sharedDatabaseManager == nil) { sharedDatabaseManager = [super allocWithZone:zone]; [sharedDatabaseManager initDb]; return sharedDatabaseManager; } } return nil; } On Apr 29, 2009, at 10:52 PM, Greg Guerin wrote: ÐÐÐÐÑÐÐ ÐÐÐÑÑÐÐ wrote: In short, i get an error calling the same synchronized singleton DatabaseManager from different threads. Are you sure your database accesses are synchronized (i.e. thread- safe)? I see nothing in the posted code that uses @synchronized or any other locking mechanism. -- GG _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@xxxxxxxxxxxxxxx) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/ok5.admin%40gmail.com This email sent to ok5.admin@xxxxxxxxx _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@xxxxxxxxxxxxxxx) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/maillists%40codeha.us This email sent to maillists@xxxxxxxxx Next Message by Thread: click to view message previewRe: NSOperation, Sqlite, library routine called out of sequenceHm... That really works! Thanks a lot. Putting the bodies of those methods in @synchronized(self) blocks helped Thanks a lot again. On Apr 29, 2009, at 11:33 PM, Greg Guerin wrote: ÐÐÐÐÑÐÐ ÐÐÐÑÑÐÐ wrote: The DatabaseManager is synchronized. If any class is to communicate with the db, it does that through the DatabaseManager. The latter just provides proxy methods. I think, that should result in classes getting the instance of the DatabaseManager only when it is no longer (or not yet) used by other classes. But that does nothing to prevent multiple threads from performing additional concurrent actions on the database. It's not enough to just control access to the shared singleton, if the actions performed by the singleton aren't also thread-safe. All the queries, updates, etc. need thread-safety, too. -- GG _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@xxxxxxxxxxxxxxx) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/ok5.admin%40gmail.com This email sent to ok5.admin@xxxxxxxxx _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@xxxxxxxxxxxxxxx) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/maillists%40codeha.us This email sent to maillists@xxxxxxxxx Loading Comments...
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