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  77 >3.4. How to request background computation</A
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  80 >&#13;You will also notice the presence of a request_background_data() called in the
  81 constructor. This function, in eventhooks.c, does verify for the presence of the
  82 state information that could be precomputed by the main window background
  83 computation. If it has not been precomputed, we ask for a computation and show
  84 partial data. We also register a hook that will be called (notified) by the main
  85 window when the requested data will become ready, so the viewer can update
  86 itself with the new data. If no partial information would have made sense in a
  87 particular viewer, one could choose to shown a "waiting for computation" message
  88 while waiting for the notification. See lttvwindow/lttvwindowtraces.h for the API
  89 of the background requests.
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