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vigo dot von dot harrach at gmx dot de ¶
13 years ago
curl_multi_select($mh, $timeout) simply blocks for $timeout seconds while curl_multi_exec() returns CURLM_CALL_MULTI_PERFORM. Otherwise, it works as intended, and blocks until at least one connection has completed or $timeout seconds, whatever happens first.



For that reason, curl_multi_exec() should always be wrapped:



<?php

  function full_curl_multi_exec($mh, &$still_running) {

    do {

      $rv = curl_multi_exec($mh, $still_running);

    } while ($rv == CURLM_CALL_MULTI_PERFORM);

    return $rv;

  }

?>



With that, the core of "multi" processing becomes (ignoring error handling for brevity):



<?php

  full_curl_multi_exec($mh, $still_running); // start requests

  do { // "wait for completion"-loop

    curl_multi_select($mh); // non-busy (!) wait for state change

    full_curl_multi_exec($mh, $still_running); // get new state

    while ($info = curl_multi_info_read($mh)) {

      // process completed request (e.g. curl_multi_getcontent($info['handle']))

    }

  } while ($still_running);

?>



Note that after starting requests, retrieval is done in the background - one of the better shots at parallel processing in PHP.
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