minor symfony#10097 [Process] clarify idle timeout (Tobion)

This PR was merged into the 2.4 branch.

Discussion
----------

[Process] clarify idle timeout

| Q             | A
| ------------- | ---
| Bug fix?      | sort of
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | n/a

Makes idle timeout in line with symfony#9466

Commits
-------

9f07b4d [Process] clarify idle timeout

Author: fabpot

src/Symfony/Component/Process/Process.php

@@ -730,7 +730,7 @@ public function setCommandLine($commandline)
     }
 
     /**
-     * Gets the process timeout.
+     * Gets the process timeout (max. runtime).
      *
      * @return float|null The timeout in seconds or null if it's disabled
      */
@@ -740,17 +740,17 @@ public function getTimeout()
     }
 
     /**
-     * Gets the process idle timeout.
+     * Gets the process idle timeout (max. time since last output).
      *
-     * @return float|null
+     * @return float|null The timeout in seconds or null if it's disabled
      */
     public function getIdleTimeout()
     {
         return $this->idleTimeout;
     }
 
     /**
-     * Sets the process timeout.
+     * Sets the process timeout (max. runtime).
      *
      * To disable the timeout, set this value to null.
      *
@@ -768,9 +768,11 @@ public function setTimeout($timeout)
     }
 
     /**
-     * Sets the process idle timeout.
+     * Sets the process idle timeout (max. time since last output).
      *
-     * @param integer|float|null $timeout
+     * To disable the timeout, set this value to null.
+     *
+     * @param integer|float|null $timeout The timeout in seconds
      *
      * @return self The current Process instance.
      *
@@ -991,7 +993,7 @@ public function checkTimeout()
             throw new ProcessTimedOutException($this, ProcessTimedOutException::TYPE_GENERAL);
         }
 
-        if (0 < $this->idleTimeout && $this->idleTimeout < microtime(true) - $this->lastOutputTime) {
+        if (null !== $this->idleTimeout && $this->idleTimeout < microtime(true) - $this->lastOutputTime) {
             $this->stop(0);
 
             throw new ProcessTimedOutException($this, ProcessTimedOutException::TYPE_IDLE);