Also, of course, the ingoing or outgoing set of an Atom may be changed by a MindAgent ... why is this not a problem for concurrency?
On Tue, Sep 30, 2008 at 1:51 PM, Linas Vepstas <[EMAIL PROTECTED]>wrote: > 2008/9/30 Ben Goertzel <[EMAIL PROTECTED]>: > > > > Linas, > > > > But the truth values, attention values, etc. associated with an Atom are > not > > immutable ... > > > > so for instance, a MindAgent could add a new Version within a > > CompositeTruthValue > > object associated with an Atom ... > > Hmm. Well, if one thread is looking at a truth value while > another is setting it, then, in today's system, there would be > a crash (because the old value is deleted, and > Atom::getTruthValue() returns a reference). > > This could be solved by having AtomTruthValue() return > a copy, instead of a reference; but then one pays the > penalty of creating a copy, for each and every access. > (this is "copy-on-read"). > > By contrast, in a garbage-collected system, the worst that > would happen is that someone is looking at an "old, stale" > truth value; as opposed to crashing. By the principles > of concurrency, there's "no such thing" as an "old stale > value" in between synchronization primitives. > > --linas > -- Ben Goertzel, PhD CEO, Novamente LLC and Biomind LLC Director of Research, SIAI [EMAIL PROTECTED] "Nothing will ever be attempted if all possible objections must be first overcome " - Dr Samuel Johnson
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