Added "before" method (#34)

Author: peppeocchi

README.md

@@ -278,6 +278,19 @@ $scheduler->php('script.php')->onlyOne(null, function ($lastExecutionTime) {
 });
 ```
 
+### Before job execution
+
+In some cases you might want to run some code, if the job is due to run, before it's being executed.
+For example you might want to add a log entry, ping a url or anything else.
+To do so, you can call the `before` like the example below.
+
+```php
+// $logger here is your own implementation
+$scheduler->php('script.php')->before(function () use ($logger) {
+    $logger->info("script.php started at " . time());
+});
+```
+
 ### After job execution
 
 Sometime you might wish to do something after a job runs. The `then` methods provides you the flexibility to do anything you want after the job execution. The output of the job will be injected to this function.
@@ -297,6 +310,21 @@ $scheduler->php('script.php')->then(function ($output) use ($logger) {
 }, true);
 ```
 
+#### Using "before" and "then" together
+
+```php
+// $logger here is your own implementation
+$scheduler->php('script.php')
+    ->before(function () use ($logger) {
+        $logger->info("script.php started at " . time());
+    })
+    ->then(function ($output) use ($logger) {
+        $logger->info("script.php completed at " . time(), [
+            'output' => $output,
+        ]);
+    });
+```
+
 ### Multiple scheduler runs
 In some cases you might need to run the scheduler multiple times in the same script.
 Although this is not a common case, the following methods will allow you to re-use the same instance of the scheduler.

src/GO/Job.php

@@ -109,6 +109,13 @@ class Job
      */
     private $emailConfig = [];
 
+    /**
+     * A function to execute before the job is executed.
+     *
+     * @var callable
+     */
+    private $before;
+
     /**
      * A function to execute after the job is executed.
      *
@@ -365,6 +372,10 @@ public function run()
         // Write lock file if necessary
         $this->createLockFile();
 
+        if (is_callable($this->before)) {
+            call_user_func($this->before);
+        }
+
         if (is_callable($compiled)) {
             $this->output = $this->exec($compiled);
         } else {
@@ -519,6 +530,20 @@ private function emailOutput()
         return true;
     }
 
+    /**
+     * Set function to be called before job execution
+     * Job object is injected as a parameter to callable function.
+     *
+     * @param callable $fn
+     * @return self
+     */
+    public function before(callable $fn)
+    {
+        $this->before = $fn;
+
+        return $this;
+    }
+
     /**
      * Set a function to be called after job execution.
      * By default this will force the job to run in foreground

tests/GO/JobTest.php

@@ -353,6 +353,24 @@ public function testShouldReturnOutputOfJobExecution()
         $this->assertEquals(['hi'], $job3->getOutput());
     }
 
+    public function testShouldRunCallbackBeforeJobExecution()
+    {
+        $job = new Job(function () {
+            return 'Job for testing before function';
+        });
+
+        $callbackWasExecuted = false;
+        $outputWasSet = false;
+
+        $job->before(function () use ($job, &$callbackWasExecuted, &$outputWasSet) {
+            $callbackWasExecuted = true;
+            $outputWasSet = ! is_null($job->getOutput());
+        })->run();
+
+        $this->assertTrue($callbackWasExecuted);
+        $this->assertFalse($outputWasSet);
+    }
+
     public function testShouldRunCallbackAfterJobExecution()
     {
         $job = new Job(function () {