10.2.4 Buffered Asynchronous Channels
The bindings documented in this section are provided by the racket/async-channel library, not racket/base or racket.
See also Thread Mailboxes.
(async-channel? v) → boolean? |
v : any/c |
Returns #t if v is an asynchronous channel,
#f otherwise.
(make-async-channel [limit]) → async-channel? |
limit : (or/c exact-positive-integer? #f) = #f |
Returns an asynchronous channel with a buffer limit of limit
items. A get operation blocks when the channel is empty, and a put
operation blocks when the channel has limit items already.
If limit is #f, the channel buffer has no limit (so
a put never blocks).
The asynchronous channel value can be used directly with sync. The channel blocks until async-channel-get would return a value, and the unblock result is the received value.
(async-channel-get ach) → any/c |
ach : async-channel? |
Blocks until at least one value is available in ach, and then
returns the first of the values that were put into
async-channel.
(async-channel-try-get ach) → any/c |
ach : async-channel? |
If at least one value is immediately available in ach,
returns the first of the values that were put into ach. If
async-channel is empty, the result is #f.
(async-channel-put ach v) → void? |
ach : async-channel? |
v : any/c |
Puts v into ach, blocking if ach’s buffer
is full until space is available.
(async-channel-put-evt async-channel v) → evt? |
async-channel : channel? |
v : any/c |
Returns a synchronizable event that is blocked while
(async-channel-put ach v) would block. The unblock result is
the event itself. See also sync.
Examples: | ||||||||||||||||||
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> (server to-server from-server) | ||||||||||||||||||
#<thread> | ||||||||||||||||||
> (async-channel? to-server) | ||||||||||||||||||
#t | ||||||||||||||||||
> (printf "Adding 1 to 4\n") | ||||||||||||||||||
Adding 1 to 4 | ||||||||||||||||||
> (async-channel-put to-server 'add) | ||||||||||||||||||
> (async-channel-put to-server 4) | ||||||||||||||||||
> (printf "Result is ~a\n" (async-channel-get from-server)) | ||||||||||||||||||
Result is 5 | ||||||||||||||||||
> (printf "Ask server to do a long computation\n") | ||||||||||||||||||
Ask server to do a long computation | ||||||||||||||||||
> (async-channel-put to-server 'long) | ||||||||||||||||||
> (printf "I can do other stuff\n") | ||||||||||||||||||
I can do other stuff | ||||||||||||||||||
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Ok, computation from server is 3 | ||||||||||||||||||
> (async-channel-put to-server 'quit) |