[VSTGUI 3.6] Reaper calls effGetChunk on mouse action (???)

When the user stops moving the knob, Reaper gets the plugin chunk to store an undo point. There is some code in Reaper to throttle effGetChunk calls to the plugin, so that it doesn't get flooded.

You should ask him to come here rather than discussing by remote control... As I say, there is code to throttle the calls to effGetChunk. The system usually works fine, even for plugins with massive state (big samplers, etc). This can't be disabled in Reaper per-plugin, though the user preference "avoid restoring VST state on undo/redo if possible" may disable it globally. As a best-practice sort of thing, plugins should be designed to handle effGetChunk in a cheap and threadsafe way. The plugin should not choke if (following his analogy) the user does decide to press "save" repeatedly.

Schwa, thanks a lot for clearing up my issue a bit. > there is code to throttle the calls to effGetChunk Do you mean that this is something that I can control from the plugin's side? I still wonder about the actual calling sequence. I don't have my code before me right now, but I stopped debugging just where I lost the trace of where the mouse up message went. I was thinking it just gets passed onto to the listener, but apparently the AudioEffect class gets notified as well (?). Can you shed some light on this? (VSTSDK 2.4 here) Nonetheless, you're right with the non-blocking practice. I'm currently assembling all kinds of xml-based data upon a getChunk/setChunk request, and use CriticalSections around all. But I know there's room for improvement... so if there's something I could tell Reaper in the meantime, let me know :) Sascha

Hi sascha, welcome! Reaper internally throttles calls, so if the user goes mad clicking knobs, the plugin won't get flooded with effGetChunk requests. The signal Reaper uses to set an undo point is an audioMasterEndEdit notification from the plugin. On receiving that message, if enough time (1.5 seconds or so) has passed since since the last chunk request, Reaper will call effGetChunk. I don't think there is a VST mechanism for the host to find out whether the plugin has mouse capture or not, apart from the implied notification in audioMasterBeginEdit/audioMasterEndEdit. Was there a particular problem you were looking at?