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David Given kirjoitti 26.6.2008 kello 0:51:


[...]

   K= lanes.keeper()
   f(K)    -- launches sublane, gives access to the keeper table
Is this actually true shared data between the two lanes? That is, either lane can read or write to it and the other one will see it? If so, cool 
--- but how did you make it work?
Yes, it's true shared data. And it's shared by 1..N lanes, anyone the creating lane has passed the pointer to it.
There is a pool of storage states, which carry the kept data (maybe I'll use them for FIFOs as well but that's an implementation issue). The lanes see the table as userdata, which essentially means only one level of indexing is usable: 

	K.a= 50		--ok
	K.b= { 50, 42, anything=9 }		-- ok, written atomically
K.b.anything= 5 -- NOT ok, will read K.b and set the local copy's .anything to 5 (and then forget it)
Keeper tables maybe cannot be waited upon, which makes the Linda you mentioned seem very lucrative. I was actually close to that idea myself, but didn't know what re-writing to an existing slot should do. Now I know. :) 

-asko





...
One thing nobody's mentioned is a third IPC mechanism which doesn't get a lot of press these days, called Linda. I think this is best described 
as a pipe which is a table:

t = tuple() --- access Linda tuplespace (traditionally, Linda only has
               one)

Thread 1:
 t.foo = 1 -- writes value to tuplespace
 t.foo = 2 -- blocks until the slot is vacant, then writes

Thread 2:
 print(t.foo) -- blocks until the slot is full, and consumes it,
                 returning the value
 print(t.foo) -- blocks again

There's also a primitive for polling a value without consuming it.

I think this provides a rather richer IPC system than a simple message
pipe, allowing you to use the same tuplespace for implementing a variety 
of different protocols simultaneously; also, the table-like semantics
looks to me like it would fit Lua very nicely.