Asynchronous sleep

[sminnee]

I was building some async code that triggers a delayed retry in the case of an error, similar to:

$promise = $client->getAsync(...);

$promise->then(
  function ($result) { ... },
  function ($error) {
    sleep(5); 
    $client->getAsync(...);
  }
);

Of course, sleep(5) is blocking. Is there an asynchronous equivalent for sleep, such as a promise that will resolve within a wait() call after the given amount of time? If not, can one be added to the library?

[alexeyshockov]

There is no concurrent version of sleep() in Guzzle Promises out of the box. You can take a look at a library (I'm the developer) which integrates Guzzle with React PHP. With React you can use timers to create "sleep promises" (see sleep_fn).

But if you need just delayed retries, try to use the default retry middleware. Also a usage example.

[mtdowling]

Guzzle (the client) also supports the delay request option which can be used to delay the sending of a request: http://docs.guzzlephp.org/en/stable/request-options.html#delay.

[sminnee]

Thanks for the advice. I'll check out the React bridge.

The default retry middleware, uses the Guzzle delay option, which uses a `usleep() call. My understanding is that this would block other requests from being processed in the meantime.

My use-case is a domain scanner, so efficient parallel processing is quite important for its overall performance.

[mtdowling]

Only the blocking handlers use usleep. The CurlMultiHandler does not.

[abiusx]

You can use GuzzleHttp to send a request to a non-existing server with a certain delay. This can work as an async sleep.

[elcreator]

Only the blocking handlers use usleep. The CurlMultiHandler does not.

CurlMultiHandler uses usleep too: https://github.com/guzzle/guzzle/blob/7.8/src/Handler/CurlMultiHandler.php#L187