Hello all While I was trying to use TICSWndControl as base class to share handles for message and consume less OS resources I ran into a very strange problem, that took me some nights of sleep, after a lot of researching I have found a problem in WndControl shared handles implementation, and I made an example program that shows the problem
I will try to explain the situation The main problem is in the management of registered message queue, when you create a new object it will register its message to the message assignment queue by using AllocateMsgHandlers, so I create I component and it will assign the message 1025 to FMsgRelease, if I create another one, it will assign message 1026 to FMsgRelease of the other control If I Post message 1025 to the first component, just after posting I free it, it will release 1025 from the message queue, making it available for use, and then I create a new component (It will assign 1025 for the new control). When the message is received, it will be received by the third component, but I sent the message to the first one! In my demo program I simulate the following situation: I have two types of classes (TMyControl and TMyControl2) On TMyControl I register a test message TMyControl2 is simple descendent of TICSWndControl, the only thing is that it will call AllocateHWnd on constructor, so it will allocate the release message The path to error: - Create one instance of TMyControl (Messages 1025 and 1026 will be reserved for it (1025 = Release, 1026 = Test) - Create another instance of TMyControl (Messages 1027 and 1028 will be reserved for it) - Post message 1026 to first instance (1026 is a test message) - Free first instance of TMyControl (That was supposed to receive the message, but messages 1025 and 1026 will be released and free to be used for another control) - Create an instance of TMyControl2 (Message 1025 will be assigned to it as FMsgRelease) - Create an instance of TMyControl2 (Message 1026 will be assigned to it as FMsgRelease) Ok, when the handle received message 1026 (That was a message supposed to be received by an instance of TMyControl) it will be actually received by the second instance of TMyControl2, which will release the control since 1026 is now mapped to FMsgRelease message!! Do you have any suggestion of fix? I thought that when releasing a message handler we must in some way clean the message queue if there is any message in windows queue that was directed to that component, but how to do it? The link for test application is: www.intertruco.com.br/download/ICSWndError.rar Thank you very much Eric -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
