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From: Andreas Huber (ahd6974-spamboostorgtrap_at_[hidden])
Date: 2008-08-02 15:46:05
>> You can't, see above. Two asynchronous state machine must only exchange
>> data in
>> a, well, asynchronous manner. That is, have the requesting state machine
>> an event to the other FSM, which in turn posts the requested data in an
>> back to the requesting FSM. Of course you'll have to be careful to always
>> *copy* the data and never let both state machines access the same data
>> e.g. pointers.
> Lets assume, this "shared data" is defined externally to the FSMs, and
> then a ptr to the data is passed to them all (in the constructors or
> by means of an event). If this data is accessed in a thread-safe
> manner, then such a design doesn't seem to be dangerous, does it?
It depends on how long the lock is taken by each FSM. If we're just talking
lock, read/write, unlock then no I don't think you'd have any problems with
just two FSMs. The longer the lock is taken the more could shared data
access become a bottleneck and adversely affect performance.
Of course, for Tims problem (access of state-local data), this is not a good
solution as it would inevitably make the data non-local.
-- Andreas Huber When replying by private email, please remove the words spam and trap from the address shown in the header.
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