parallel geocoding using PHP

geocode-parallel.php

#!/usr/bin/php
<?php

// 1. install https://github.com/stil/curl-easy
//
// composer require stil/curl-easy
//
// 2. fill a text file 'queries.txt' with queries, e.g. 
// Berlin
// Madrid
// Palermo
// Casablanca
// 24.77701,121.02189
// 31.79261,35.21785
// 9.54828,44.07715
// 59.92903,30.32989 
//
// 3. add the APIKEY to the .php file 
// 4. run this script

require 'vendor/autoload.php';

$APIKEY = 'YOURAPIKEY';



function generate_opencage_request_url(String $key, String $query)
{
  $base = 'https://api.opencagedata.com/geocode/v1/json';
  $params = array(
    'key' => $key,
    'query' => $query,
    'limit' => 1,
    'no_annotations' => 1
  );
  return $base.'?'.http_build_query($params);
}



// Read file into $queries
$queries = [];
$fh = fopen('queries.txt', 'r');
while (($line = fgets($fh)) !== false) {
  array_push($queries, rtrim($line));
}
fclose($fh);
// var_dump($queries);



// Create cURL\Request for each query
$requests = [];
foreach ($queries as $query) {
  $request_url = generate_opencage_request_url($APIKEY, $query);
  // print $request_url."\n";

  $request = new \cURL\Request($request_url);
  array_push($requests, $request);
}


// Create queue
$queue = new \cURL\RequestsQueue;
$queue->getDefaultOptions()
      ->set(CURLOPT_TIMEOUT, 5)
      ->set(CURLOPT_RETURNTRANSFER, true);

$queue->addListener('complete', function (\cURL\Event $event) use (&$requests) {
  $response = $event->response;
  $json = $response->getContent();
  $data = json_decode($json, true);

  // var_dump($data['status']);
  if ($data['status']['code'] == 200) {
    if (!empty($data['results'])) {
      $result = $data['results'][0];
      print $result['formatted']."\n";
    }
  }

  if ($next = array_pop($requests)) {
      $event->queue->attach($next);
  }
});

// three requests in parallel
$queue->attach(array_pop($requests));
$queue->attach(array_pop($requests));
$queue->attach(array_pop($requests));
$queue->send();