Feature Requests item #3322973, was opened at 2011-06-20 11:59 Message generated for change (Tracker Item Submitted) made by zmoelnig You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=478073&aid=3322973...
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: puredata-dev Group: None Status: Open Priority: 5 Private: No Submitted By: IOhannes m zmlnig (zmoelnig) Assigned to: Miller Puckette (millerpuckette) Summary: make clocks thread safe
Initial Comment: when writing threaded externals, i often find myself wanting Pd to call a callback from the main thread, depending on the "other" thread's state.
e.g. when doing asynchronous data acquisition, i want to notify Pd when new data has arrived, so it can be delivered in the main thread.
the obvious way is to use t_clock, and registers a new clock_delay() event from within the helper-thread; Pd will then callback in the next tick. unfortunately the clock_set(),... methods are not thread safe, possibly leading to corruption of the clock_setlist when accessing them simultaneously.
one workaround is to use the global sys_lock(), but i find this to terribly slow down the entire Pd process, esp. when i have to call sys_lock() multiple times before ticks. that's most likely because sys_lock() locks about everything. an alternative i used in the past, is to have a special (mutex-protected) flag, indicating whether i already have a clock running that is waiting to be called back from the main thread.
however, i find this quite complicated
therefore, i propose to make the clock_delay/clock_set/clock_unset methods threadsafe, by internally maintaining a separate mutex that solely protects the clock_setlist.
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You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=478073&aid=3322973...