>> On Mon, Jul 03 2017 21:18, Timothy Baldridge wrote:
> This means, if you want to execute take correctly you must ensure that only
> one thread executes the take instance at one time, since channels already
> operate via a channel-level lock, it makes sense to run the transducer
> inside the channels' lock.
I looked at the code and got somewhat surprised that transducer can be
potentially called within all 3 methods - take!, put! and close!. Not sure if
this could be done differently, but given this implementation it indeed makes
sense to block all 3 methods.
I think the docs regarding the blocking behavior and the timing of transducer's
execution could be improved. I always naively assumed that transducers are
executed on the same thread within put!, but in fact xform is called only when
the value is added to the buffer and can happen both on current thread and on
the thread pool.
This is what I dug so far regarding put!:
1) (half-full buf and pending takes)
-> transform and add to buf on the same thread
2) (nil buf or full buf) and pending takes
-> dispatch to pending take on the thread pool
3) (half full buf and no pending takes)
-> transform and add to buf on the same thread
4) (nil of full buf)
-> append to puts list
I find 2 troublesome. It means that this line:
https://github.com/clojure/core.async/blob/master/src/main/clojure/clojure/core/async/impl/channels.clj#L135
can be reached in the corner case when buffer is full and there are pending
takes. If so then the current val is dispatched to the leading pending take
bypassing buf completely. I think that line is intended to be reached only for
unbuffered chans. Am I mistaken here?
Vitalie
--
You received this message because you are subscribed to the Google
Groups "Clojure" group.
To post to this group, send email to clojure@googlegroups.com
Note that posts from new members are moderated - please be patient with your
first post.
To unsubscribe from this group, send email to
clojure+unsubscr...@googlegroups.com
For more options, visit this group at
http://groups.google.com/group/clojure?hl=en
---
You received this message because you are subscribed to the Google Groups
"Clojure" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to clojure+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
