Dynamic Dataflow Modeling in Ptolemy II - Ptolemy Project ...

satisfy requiredFiringsPerIteration for the actors with that parameter, (3) repeating a
basic iteration until the submodel is deadlocked. Among these three definitions, (2)
overrides (1), (3) overrides (1) and (2). Also notice that while definition (1) and (2) are
also applicable for top level DDF models, definition (3) is only applicable for embedded
DDF submodels.
We also have the following rules for transferring tokens into and out of DDF submodels.
If the user manually adds tokenConsumptionRate and tokenProductionRate parameters to
the input ports and output ports of the DDF composite actor, the local DDFDirector will
leave them as they are and obey them assuming the user knows the consequence of
his(her) actions. If the rates of some ports are not manually defined, the local
DDFDirector will try to define them in a reasonable way. For the input port, the
tokenConsumptionRate is set to the minimum number of tokens needed to satisfy one of
destination actors connected to this input port. Therefore the rate could be zero if one of
destination actors already has enough tokens on the channel connected to this input port.
However, if no actor in the DDF composite actor gets fired during the previous iteration,
the tokenConsumptionRate is set to the minimum number of tokens needed to satisfy one
of destination actors that are connected to this input port and haven’t been satisfied on the
connecting channels. The motivation behind this seemingly complicated procedure is to
try to break a deadlock using minimum number of tokens. When every destination actor
connected to this input port has been satisfied and the submodel is still deadlocked in the
previous iteration, the tokenConsumptionRate of this input port is set to zero. For the
output port (which has no tokenProductionRate parameter added by the user), the local
DDFDirector will not set the rate for this output port because in general there is no way
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