Job: explain functionality of the job helper in the readme

Author: glaubinix

README.md

@@ -558,10 +558,21 @@ $job = $client->jobs()->show($jobId);
 Returns the job.
 
 ##### Wait for a job to finish
+This will periodically poll the job status until the job either finished or the maximum wait time was reached
 ```php
-$numberOfMinutesToWait = 3;
+$numberOfSecondsToWait = 30;
 $jobHelper = new \PrivatePackagist\ApiClient\JobHelper($client);
-$job = $jobHelper->waitForJob($jobId, $numberOfMinutesToWait);
+try {
+    $job = $jobHelper->waitForJob($jobId, $numberOfSecondsToWait);
+} catch (\PrivatePackagist\ApiClient\Exception\JobTimeoutException $e) {
+    // Job didn't finish within the specified time
+} catch (\PrivatePackagist\ApiClient\Exception\JobErrorException $e) {
+    // Job finished with an error. See the message for more information
+    echo $e->getMessage();
+}
+
+
+
 ```
 Returns the job.
 

src/Exception/JobTimeoutException.php

@@ -0,0 +1,8 @@
+<?php
+
+namespace PrivatePackagist\ApiClient\Exception;
+
+class JobTimeoutException extends RuntimeException
+{
+
+}

src/JobHelper.php

@@ -3,6 +3,7 @@
 namespace PrivatePackagist\ApiClient;
 
 use PrivatePackagist\ApiClient\Exception\JobErrorException;
+use PrivatePackagist\ApiClient\Exception\JobTimeoutException;
 
 class JobHelper
 {
@@ -14,9 +15,15 @@ public function __construct(Client $packagistClient)
         $this->packagistClient = $packagistClient;
     }
 
-    public function waitForJob($jobId, $maxWaitMinutes = 3)
+    /**
+     * @param string $jobId
+     * @param int $maxWaitSeconds
+     * @param int $waitInterval
+     * @return array
+     */
+    public function waitForJob($jobId, $maxWaitSeconds = 30, $waitInterval = 5)
     {
-        $maxWaitTime = new \DateTimeImmutable(sprintf('+%s minutes', $maxWaitMinutes));
+        $maxWaitTime = new \DateTimeImmutable(sprintf('+%s seconds', $maxWaitSeconds));
         while ($maxWaitTime> new \DateTimeImmutable()) {
             $job = $this->packagistClient->jobs()->show($jobId);
 
@@ -28,9 +35,9 @@ public function waitForJob($jobId, $maxWaitMinutes = 3)
                 throw new JobErrorException($job);
             }
 
-            sleep(1);
+            sleep($waitInterval);
         }
 
-        throw new \Exception(sprintf('Job has not finish after %s minutes', $maxWaitMinutes));
+        throw new JobTimeoutException(sprintf('Job has not finish after %s seconds', $maxWaitSeconds));
     }
 }