Give processor_t more control over the lifecycle of a job

Jobs are now destroyed by the processor, but they are allowed to
reschedule themselves.  That is, parts of the reschedule functionality
already provided by callback_job_t is moved to the processor.  Not yet
fully supported is JOB_REQUEUE_DIRECT and canceling jobs.

Note: job_t.destroy() is now called not only for queued jobs but also
after execution or cancellation of jobs.  job_t.status can be used to
decide what to do in said method.

src/libstrongswan/processing/jobs/callback_job.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2009 Tobias Brunner
+ * Copyright (C) 2009-2012 Tobias Brunner
  * Copyright (C) 2007-2011 Martin Willi
  * Copyright (C) 2011 revosec AG
  * Hochschule fuer Technik Rapperswil
@@ -56,7 +56,7 @@ struct private_callback_job_t {
 	thread_t *thread;
 
 	/**
-	 * mutex to access jobs interna
+	 * mutex to access private job data
 	 */
 	mutex_t *mutex;
 
@@ -71,9 +71,9 @@ struct private_callback_job_t {
 	private_callback_job_t *parent;
 
 	/**
-	 * TRUE if the job got cancelled
+	 * TRUE if the job got canceled
 	 */
-	bool cancelled;
+	bool canceled;
 
 	/**
 	 * condvar to synchronize the cancellation/destruction of the job
@@ -103,10 +103,10 @@ static void unregister(private_callback_job_t *this)
 	if (this->parent)
 	{
 		this->parent->mutex->lock(this->parent->mutex);
-		if (this->parent->cancelled && !this->cancelled)
+		if (this->parent->canceled && !this->canceled)
 		{
-			/* if the parent has been cancelled but we have not yet, we do not
-			 * unregister until we got cancelled by the parent. */
+			/* if the parent has been canceled but we have not yet, we do not
+			 * unregister until we got canceled by the parent. */
 			this->parent->mutex->unlock(this->parent->mutex);
 			this->destroyable->wait(this->destroyable, this->mutex);
 			this->parent->mutex->lock(this->parent->mutex);
@@ -144,7 +144,7 @@ METHOD(callback_job_t, cancel, void,
 	semaphore_t *terminated = NULL;
 
 	this->mutex->lock(this->mutex);
-	this->cancelled = TRUE;
+	this->canceled = TRUE;
 	/* terminate children */
 	while (this->children->get_first(this->children, (void**)&child) == SUCCESS)
 	{
@@ -177,12 +177,10 @@ METHOD(callback_job_t, cancel, void,
 	}
 }
 
-METHOD(job_t, execute, void,
+METHOD(job_t, execute, job_requeue_t,
 	private_callback_job_t *this)
 {
-	bool cleanup = FALSE, requeue = FALSE;
-
-	thread_cleanup_push((thread_cleanup_t)destroy, this);
+	bool requeue = FALSE;
 
 	this->mutex->lock(this->mutex);
 	this->thread = thread_current();
@@ -191,10 +189,9 @@ METHOD(job_t, execute, void,
 	while (TRUE)
 	{
 		this->mutex->lock(this->mutex);
-		if (this->cancelled)
+		if (this->canceled)
 		{
 			this->mutex->unlock(this->mutex);
-			cleanup = TRUE;
 			break;
 		}
 		this->mutex->unlock(this->mutex);
@@ -210,7 +207,6 @@ METHOD(job_t, execute, void,
 			case JOB_REQUEUE_NONE:
 			default:
 			{
-				cleanup = TRUE;
 				break;
 			}
 		}
@@ -219,14 +215,10 @@ METHOD(job_t, execute, void,
 	this->mutex->lock(this->mutex);
 	this->thread = NULL;
 	this->mutex->unlock(this->mutex);
-	/* manually create a cancellation point to avoid that a cancelled thread
-	 * goes back into the thread pool */
+	/* manually create a cancellation point to avoid that a canceled thread
+	 * goes back into the thread pool at all */
 	thread_cancellation_point();
-	if (requeue)
-	{
-		lib->processor->queue_job(lib->processor, &this->public.job);
-	}
-	thread_cleanup_pop(cleanup);
+	return requeue ? JOB_REQUEUE_FAIR : JOB_REQUEUE_NONE;
 }
 
 METHOD(job_t, get_priority, job_priority_t,

src/libstrongswan/processing/jobs/callback_job.h

@@ -27,33 +27,6 @@ typedef struct callback_job_t callback_job_t;
 #include <library.h>
 #include <processing/jobs/job.h>
 
-
-typedef enum job_requeue_t job_requeue_t;
-
-/**
- * Job requeueing policy.
- *
- * The job requeueing policy defines how a job is handled when the callback
- * function returns.
- */
-enum job_requeue_t {
-
-	/**
-	 * Do not requeue job, destroy it
-	 */
-	JOB_REQUEUE_NONE,
-
-	/**
-	 * Reque the job fairly, meaning it has to requeue as any other job
-	 */
-	JOB_REQUEUE_FAIR,
-
-	/**
-	 * Reexecute the job directly, without the need of requeueing it
-	 */
-	JOB_REQUEUE_DIRECT,
-};
-
 /**
  * The callback function to use for the callback job.
  *

src/libstrongswan/processing/jobs/job.h

@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2012 Tobias Brunner
  * Copyright (C) 2005-2006 Martin Willi
  * Copyright (C) 2005 Jan Hutter
  * Hochschule fuer Technik Rapperswil
@@ -24,6 +25,8 @@
 
 typedef struct job_t job_t;
 typedef enum job_priority_t job_priority_t;
+typedef enum job_requeue_t job_requeue_t;
+typedef enum job_status_t job_status_t;
 
 #include <library.h>
 
@@ -47,19 +50,57 @@ enum job_priority_t {
  */
 extern enum_name_t *job_priority_names;
 
+/**
+ * Job requeueing policy.
+ *
+ * The job requeueing policy defines how a job is handled after it has been
+ * executed.
+ */
+enum job_requeue_t {
+	/** Do not requeue job, destroy it */
+	JOB_REQUEUE_NONE = 0,
+	/** Requeue the job fairly, i.e. it is inserted at the end of the queue */
+	JOB_REQUEUE_FAIR,
+	/** Reexecute the job directly, without the need of requeueing it */
+	JOB_REQUEUE_DIRECT,
+	/** For jobs that rescheduled themselves via scheduler_t */
+	JOB_REQUEUE_SCHEDULED,
+};
+
+/**
+ * Job status
+ */
+enum job_status_t {
+	/** The job is queued and has not yet been executed */
+	JOB_STATUS_QUEUED = 0,
+	/** During execution */
+	JOB_STATUS_EXECUTING,
+	/** If the job got canceled */
+	JOB_STATUS_CANCELED,
+	/** The job was executed successfully */
+	JOB_STATUS_DONE,
+};
+
 /**
  * Job interface as it is stored in the job queue.
  */
 struct job_t {
 
+	/**
+	 * Status of this job, is modified exclusively by the processor/scheduler
+	 */
+	job_status_t status;
+
 	/**
 	 * Execute a job.
 	 *
 	 * The processing facility executes a job using this method. Jobs are
-	 * one-shot, they destroy themself after execution, so don't use a job
-	 * once it has been executed.
+	 * one-shot, they are destroyed after execution (depending on the return
+	 * value here), so don't use a job once it has been queued.
+	 *
+	 * @return			policy how to requeue the job
 	 */
-	void (*execute) (job_t *this);
+	job_requeue_t (*execute) (job_t *this);
 
 	/**
 	 * Get the priority of a job.
@@ -71,8 +112,10 @@ struct job_t {
 	/**
 	 * Destroy a job.
 	 *
-	 * Is only called whenever a job was not executed (e.g. due daemon shutdown).
-	 * After execution, jobs destroy themself.
+	 * Is called after a job is executed or got canceled.  It is also called
+	 * for queued jobs that were never executed.
+	 *
+	 * Use the status of a job to decide what to do during destruction.
 	 */
 	void (*destroy) (job_t *this);
 };