processor: add an execute_job() method to directly execute an important job

If all worker threads are busy and waiting for an event, we must ensure that
a job delivering that event gets executed. This new method has this property
for CRITICAL jobs, using a worker if we have one, but executing the job directly
if not.

src/libstrongswan/processing/processor.c

@@ -401,6 +401,31 @@ METHOD(processor_t, queue_job, void,
 	this->mutex->unlock(this->mutex);
 }
 
+METHOD(processor_t, execute_job, void,
+	private_processor_t *this, job_t *job)
+{
+	job_priority_t prio;
+	bool queued = FALSE;
+
+	this->mutex->lock(this->mutex);
+	if (get_idle_threads_nolock(this))
+	{
+		prio = sane_prio(job->get_priority(job));
+		job->status = JOB_STATUS_QUEUED;
+		/* insert job in front to execute it immediately */
+		this->jobs[prio]->insert_first(this->jobs[prio], job);
+		queued = TRUE;
+	}
+	this->job_added->signal(this->job_added);
+	this->mutex->unlock(this->mutex);
+
+	if (!queued)
+	{
+		job->execute(job);
+		job->destroy(job);
+	}
+}
+
 METHOD(processor_t, set_threads, void,
 	private_processor_t *this, u_int count)
 {
@@ -512,6 +537,7 @@ processor_t *processor_create()
 			.get_working_threads = _get_working_threads,
 			.get_job_load = _get_job_load,
 			.queue_job = _queue_job,
+			.execute_job = _execute_job,
 			.set_threads = _set_threads,
 			.get_threads = _get_threads,
 			.cancel = _cancel,

src/libstrongswan/processing/processor.h

@@ -74,6 +74,16 @@ struct processor_t {
 	 */
 	void (*queue_job) (processor_t *this, job_t *job);
 
+	/**
+	 * Directly execute a job with an idle worker thread.
+	 *
+	 * If no idle thread is available, the job gets executed by the calling
+	 * thread.
+	 *
+	 * @param job			job, gets destroyed
+	 */
+	void (*execute_job)(processor_t *this, job_t *job);
+
 	/**
 	 * Set the number of threads to use in the processor.
 	 *