Add example for using rate limiter via MultiCurl::setRateLimit()

Author: zachborboa

examples/multi_curl_get_with_rate_limit.php

@@ -0,0 +1,48 @@
+<?php
+require __DIR__ . '/../vendor/autoload.php';
+
+use Curl\MultiCurl;
+
+$start_time = microtime(true);
+
+$multi_curl = new MultiCurl();
+$multi_curl->setRateLimit('2/10s');
+
+$multi_curl->beforeSend(function ($instance) use ($start_time) {
+    echo
+        sprintf('%.6f', round(microtime(true) - $start_time, 6)) . ' - ' .
+        'request ' . $instance->id . ' start' . "\n";
+});
+
+$multi_curl->success(function ($instance) use ($start_time) {
+    echo
+        sprintf('%.6f', round(microtime(true) - $start_time, 6)) . ' - ' .
+        'request ' . $instance->id . ' successful (' . $instance->url . ')' . "\n";
+});
+$multi_curl->error(function ($instance) use ($start_time) {
+    echo
+        sprintf('%.6f', round(microtime(true) - $start_time, 6)) . ' - ' .
+        'request ' . $instance->id . ' unsuccessful (' . $instance->url . ')' . "\n";
+});
+
+$multi_curl->addGet('https://httpbin.org/ip');
+$multi_curl->addGet('https://httpbin.org/status/503');
+
+$multi_curl->addGet('https://httpbin.org/ip');
+$multi_curl->addGet('https://httpbin.org/status/503');
+
+$multi_curl->addGet('https://httpbin.org/ip');
+
+$multi_curl->start();
+
+// $ php multi_curl_get_with_rate_limit.php
+// 0.021839 - request 0 start
+// 0.021894 - request 1 start
+// 0.661308 - request 0 successful (https://httpbin.org/ip)
+// 0.661968 - request 1 unsuccessful (https://httpbin.org/status/503)
+// 10.024627 - request 2 start
+// 10.024694 - request 3 start
+// 10.114304 - request 2 successful (https://httpbin.org/ip)
+// 10.117299 - request 3 unsuccessful (https://httpbin.org/status/503)
+// 20.029945 - request 4 start
+// 20.112836 - request 4 successful (https://httpbin.org/ip)