John, Um, alright then...
But i think your preaching to the converted, simplifying things is what i always try to do. And not just when theres a problem.... If you followed the thread fully you would realise that there was never a problem with my design, though that didnt stop many people from chirping in and offering suggestions. The problem i had was with sqlite not being compatible with the simple design that i wanted. I did try several alternate designs, but only as a way of working around the problem i had with sqlite. It took a long time but eventually i managed to get someone to explain why sqlite had that particular problem, and i was able to modify the sqlite source to resolve the issue. Unfortunately no one has yet commented on my solution, or the problem which it addresses. Basically sqlite has thread safety checking routines which work a little like mutexe's. Every time you enter a bit of code which is potentially thread unsafe it sets a magic number, then resets it when it comes out. This is an attempt to detect when two threads are accessing the same bit of code at the same time. Clearly its not 100% reliable, and is subject to all kinds of thread races, but it does provide some measure of protection. Unfortunately though, the way it has been coded, an unbalanced safety check is performed in the sqlite3_step() function. This is equivalent to entering a mutex but never leaving, which causes deadlock in a multithreaded program. Only in this situation sqlite throws a misuse error any time two or more threads use sqlite3_step() at the same time, even if those threads are synchronised and perfectly safe. The easy solution is to disable the safety checks, the propper solution is to balance out the checks in sqlite3_step() so that users who actually wish to use sqlite in a multithreaded program are free to synchronise access to the api without error and there is still a reasonable level of safety checking for users who do not synchronise properly. Emerson On 1/5/07, John Stanton <[EMAIL PROTECTED]> wrote:
Work on turning "reasonable" into "adequate" or "good" and it will help you get an intuitive feel for the design of programs such as yours. Then your programs will be simple, fast and robust, as Einstein counselled - "Make it as simple a possible, but no simpler". I also suggest that you take Niklaus Wirth's advice and when you run into a difficulty backtrack your work and scrap everything until you reach a point where there are no problems and start again from that point taking a different approach having learned a lesson from your previous attempt. By the way, I doubt whether you are using a modern operating system, it is most likely to be old technology like Windows or Linux. Neither supports much in the way of parallelism.
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