Hi, Sergey! On Dec 04, Sergey Vojtovich wrote: > > > > > "SHOW VARIABLES" looks correct. So I have only two ideas: > > > - Fix INSTALL PLUGIN so it releases LOCK_plugin before registering > > > variables. Sounds like the best solution, but there are a few > > > more things to fix, e.g. UNINTALL PLUGIN. > > > > Is it possible? On a quick look I wasn't able to answer that :( > It should be quite easy: for INSTALL PLUGIN we just move test_plugin_options() > to plugin_initialize() while plugin state is PLUGIN_IS_UNINITIALIZED. Same for > UNINSTALL PLUGIN.
Okay. Looks like it'll work. > > Here's yet another idea: don't protect plugin->ref_cnt and > > plugin->state with LOCK_plugin. Then intern_plugin_lock and > > intern_plugin_unlock could be completely lock-free. One would need > > to increment ref_cnt before or at the same time as checking the > > state. It *seems* that the rest of the code could support that with > > very few changes. But it'd need more analysys. > > Well, lock-free ref_count is not a problem. Lock-free state is > challenging, but looks doable. What about reap_plugins() which is > called by plugin_unlock()? reap_plugins() would need a lock, of course. No lock for intern_plugin_unlock() means that it might mark reap_needed=true, but before the plugin is reaped, another thread might lock it again and reap_plugins() will do nothing. Not a big deal. Still, there're race conditions around intern_plugin_lock() - when a plugin gets uninstalled and a new plugin is installed and intern_plugin_lock() doesn't notice it. I *think* we can solve all that, looks doable, indeed. But I'd rather prefer a simple solution now, if you can move test_plugin_options() as you want to. We can do lockless plugin reference counting later, when LOCK_plugin will be a performance bottleneck. Regards, Sergei _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : [email protected] Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
