io.jesi.backpack.async — io.jesi/backpack 7.4.0

<? clj/s macro

(<? ch)

Same as core.async <! but throws an exception if the channel returns a throwable object. Also will not crash if channel is nil.

chan clj/s

(chan)

(chan buf-or-n)

(chan buf-or-n xform)

(chan buf-or-n xform ex-handler)

Creates a channel with an optional buffer, an optional transducer (like (map f), (filter p) etc or a composition thereof), and an optional exception-handler. If buf-or-n is a number, will create and use a fixed buffer of that size. If a transducer is supplied a buffer must be specified. ex-handler must be a fn of one argument - if an exception occurs during transformation it will be called with the Throwable as an argument, and any non-nil return value will be placed in the channel.

close! clj/s

(close! chan)

Closes a channel. The channel will no longer accept any puts (they will be ignored). Data in the channel remains available for taking, until exhausted, after which takes will return nil. If there are any pending takes, they will be dispatched with nil. Closing a closed channel is a no-op. Returns the channel.

Logically closing happens after all puts have been delivered. Therefore, any blocked or parked puts will remain blocked/parked until a taker releases them.

closed? clj/s

(closed? chan)

returns true if the channel is nil or closed

go clj/s macro

(go & body)

Asynchronously executes the body, returning immediately to the calling thread. Additionally, any visible calls to <!, >! and alt!/alts! channel operations within the body will block (if necessary) by 'parking' the calling thread rather than tying up an OS thread (or the only JS thread when in ClojureScript). Upon completion of the operation, the body will be resumed.

Returns a channel which will receive the result of the body when completed

go-call clj/s macro

(go-call f chan)

Takes a function and a channel. Takes the value of the chanel using <? and applies it to f. Returns a channel which contains the result (or exception).

go-retry clj/s macro

(go-retry {:keys [retries delay should-retry-fn]
           :or {retries 5
                delay 1
                should-retry-fn (quote io.jesi.backpack.exceptions/exception?)}}
          &
          body)

Attempts to evaluate a go block and retries it if should-retry-fn which is invoked with block's evaluation result evaluates to false. should-retry-fn is optional and by default it will simply check if result is an exception. If the evaluation still fails after given retries, the last failed result will be returned in channel. Parameters:

• retries - how many times to retry (default 5 times)
• delay - how long to wait in seconds between retries (default 1s)
• should-retry-fn - function that is invoked with result of block's evaluation and should indicate whether to retry (if it returns true) or not (returns false)

go-try clj/s macro

(go-try & body)

Asynchronously executes the body in a go block. Returns a channel which will receive the result of the body when completed or an exception if one is thrown.

open? clj/s

(open? chan)

returns true if the channel is open. The complement of closed?

put! clj/s

(put! chan val)

Asynchronously puts a val into a channel if it's open. nil values are ignored. Returns the channel.

when-open clj/s macro

(when-open chan & body)