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);
 };

src/libstrongswan/processing/processor.c

@@ -1,7 +1,7 @@
 /*
  * Copyright (C) 2005-2011 Martin Willi
  * Copyright (C) 2011 revosec AG
- * Copyright (C) 2008-2011 Tobias Brunner
+ * Copyright (C) 2008-2012 Tobias Brunner
  * Copyright (C) 2005 Jan Hutter
  * Hochschule fuer Technik Rapperswil
  *
@@ -58,7 +58,7 @@ struct private_processor_t {
 
 	/**
 	 * All threads managed in the pool (including threads that have been
-	 * cancelled, this allows to join them during destruction)
+	 * canceled, this allows to join them later), as worker_thread_t
 	 */
 	linked_list_t *threads;
 
@@ -72,11 +72,6 @@ struct private_processor_t {
 	 */
 	int prio_threads[JOB_PRIO_MAX];
 
-	/**
-	 * Priority of the job executed by a thread
-	 */
-	thread_value_t *priority;
-
 	/**
 	 * access to job lists is locked through this mutex
 	 */
@@ -93,39 +88,72 @@ struct private_processor_t {
 	condvar_t *thread_terminated;
 };
 
-static void process_jobs(private_processor_t *this);
+
+/**
+ * Worker thread
+ */
+typedef struct {
+
+	/**
+	 * Reference to the processor
+	 */
+	private_processor_t *processor;
+
+	/**
+	 * The actual thread
+	 */
+	thread_t *thread;
+
+	/**
+	 * Job currently being executed by this worker thread
+	 */
+	job_t *job;
+
+	/**
+	 * Priority of the current job
+	 */
+	job_priority_t priority;
+
+} worker_thread_t;
+
+static void process_jobs(worker_thread_t *worker);
 
 /**
  * restart a terminated thread
  */
-static void restart(private_processor_t *this)
+static void restart(worker_thread_t *worker)
 {
-	thread_t *thread;
+	private_processor_t *this = worker->processor;
 
 	DBG2(DBG_JOB, "terminated worker thread %.2u", thread_current_id());
 
-	/* respawn thread if required */
 	this->mutex->lock(this->mutex);
-	if (this->desired_threads < this->total_threads ||
-		(thread = thread_create((thread_main_t)process_jobs, this)) == NULL)
-	{
-		this->total_threads--;
-		this->thread_terminated->signal(this->thread_terminated);
-	}
-	else
-	{
-		this->threads->insert_last(this->threads, thread);
-	}
-	this->mutex->unlock(this->mutex);
-}
+	/* cleanup worker thread  */
+	this->working_threads[worker->priority]--;
+	worker->job->status = JOB_STATUS_CANCELED;
+	worker->job->destroy(worker->job);
+	worker->job = NULL;
 
-/**
- * Decrement working thread count of a priority class
- */
-static void decrement_working_threads(private_processor_t *this)
-{
-	this->mutex->lock(this->mutex);
-	this->working_threads[(intptr_t)this->priority->get(this->priority)]--;
+	/* respawn thread if required */
+	if (this->desired_threads >= this->total_threads)
+	{
+		worker_thread_t *new_worker;
+
+		INIT(new_worker,
+			.processor = this,
+		);
+		new_worker->thread = thread_create((thread_main_t)process_jobs,
+										   new_worker);
+		if (new_worker->thread)
+		{
+			this->threads->insert_last(this->threads, new_worker);
+			this->mutex->unlock(this->mutex);
+			return;
+		}
+		free(new_worker);
+	}
+	this->total_threads--;
+	this->thread_terminated->signal(this->thread_terminated);
 	this->mutex->unlock(this->mutex);
 }
 
@@ -147,9 +175,11 @@ static u_int get_idle_threads_nolock(private_processor_t *this)
 /**
  * Process queued jobs, called by the worker threads
  */
-static void process_jobs(private_processor_t *this)
+static void process_jobs(worker_thread_t *worker)
 {
-	/* worker threads are not cancellable by default */
+	private_processor_t *this = worker->processor;
+
+	/* worker threads are not cancelable by default */
 	thread_cancelability(FALSE);
 
 	DBG2(DBG_JOB, "started worker thread %.2u", thread_current_id());
@@ -157,7 +187,6 @@ static void process_jobs(private_processor_t *this)
 	this->mutex->lock(this->mutex);
 	while (this->desired_threads >= this->total_threads)
 	{
-		job_t *job = NULL;
 		int i, reserved = 0, idle;
 
 		idle = get_idle_threads_nolock(this);
@@ -176,27 +205,52 @@ static void process_jobs(private_processor_t *this)
 				reserved += this->prio_threads[i] - this->working_threads[i];
 			}
 			if (this->jobs[i]->remove_first(this->jobs[i],
-											(void**)&job) == SUCCESS)
+											(void**)&worker->job) == SUCCESS)
 			{
+				job_requeue_t requeue;
+
 				this->working_threads[i]++;
+				worker->job->status = JOB_STATUS_EXECUTING;
+				worker->priority = i;
 				this->mutex->unlock(this->mutex);
-				this->priority->set(this->priority, (void*)(intptr_t)i);
-				/* terminated threads are restarted to get a constant pool */
-				thread_cleanup_push((thread_cleanup_t)restart, this);
-				thread_cleanup_push((thread_cleanup_t)decrement_working_threads,
-									this);
-				job->execute(job);
-				thread_cleanup_pop(FALSE);
+				/* canceled threads are restarted to get a constant pool */
+				thread_cleanup_push((thread_cleanup_t)restart, worker);
+				while (TRUE)
+				{
+					requeue = worker->job->execute(worker->job);
+					if (requeue != JOB_REQUEUE_DIRECT)
+					{
+						break;
+					}
+				}
 				thread_cleanup_pop(FALSE);
 				this->mutex->lock(this->mutex);
 				this->working_threads[i]--;
+				switch (requeue)
+				{
+					case JOB_REQUEUE_NONE:
+						worker->job->status = JOB_STATUS_DONE;
+						worker->job->destroy(worker->job);
+						break;
+					case JOB_REQUEUE_FAIR:
+						worker->job->status = JOB_STATUS_QUEUED;
+						this->jobs[i]->insert_last(this->jobs[i], worker->job);
+						this->job_added->signal(this->job_added);
+						break;
+					case JOB_REQUEUE_SCHEDULED:
+						worker->job->status = JOB_STATUS_QUEUED;
+						/* fall-through */
+					default:
+						break;
+				}
 				break;
 			}
 		}
-		if (!job)
+		if (!worker->job)
 		{
 			this->job_added->wait(this->job_added, this->mutex);
 		}
+		worker->job = NULL;
 	}
 	this->total_threads--;
 	this->thread_terminated->signal(this->thread_terminated);
@@ -266,6 +320,8 @@ METHOD(processor_t, queue_job, void,
 	job_priority_t prio;
 
 	prio = sane_prio(job->get_priority(job));
+	job->status = JOB_STATUS_QUEUED;
+
 	this->mutex->lock(this->mutex);
 	this->jobs[prio]->insert_last(this->jobs[prio], job);
 	this->job_added->signal(this->job_added);
@@ -278,19 +334,26 @@ METHOD(processor_t, set_threads, void,
 	this->mutex->lock(this->mutex);
 	if (count > this->total_threads)
 	{	/* increase thread count */
+		worker_thread_t *worker;
 		int i;
-		thread_t *current;
 
 		this->desired_threads = count;
 		DBG1(DBG_JOB, "spawning %d worker threads", count - this->total_threads);
 		for (i = this->total_threads; i < count; i++)
 		{
-			current = thread_create((thread_main_t)process_jobs, this);
-			if (current)
+			INIT(worker,
+				.processor = this,
+			);
+			worker->thread = thread_create((thread_main_t)process_jobs, worker);
+			if (worker->thread)
 			{
-				this->threads->insert_last(this->threads, current);
+				this->threads->insert_last(this->threads, worker);
 				this->total_threads++;
 			}
+			else
+			{
+				free(worker);
+			}
 		}
 	}
 	else if (count < this->total_threads)
@@ -304,7 +367,7 @@ METHOD(processor_t, set_threads, void,
 METHOD(processor_t, destroy, void,
 	private_processor_t *this)
 {
-	thread_t *current;
+	worker_thread_t *worker;
 	int i;
 
 	set_threads(this, 0);
@@ -315,12 +378,12 @@ METHOD(processor_t, destroy, void,
 		this->thread_terminated->wait(this->thread_terminated, this->mutex);
 	}
 	while (this->threads->remove_first(this->threads,
-									   (void**)&current) == SUCCESS)
+									  (void**)&worker) == SUCCESS)
 	{
-		current->join(current);
+		worker->thread->join(worker->thread);
+		free(worker);
 	}
 	this->mutex->unlock(this->mutex);
-	this->priority->destroy(this->priority);
 	this->thread_terminated->destroy(this->thread_terminated);
 	this->job_added->destroy(this->job_added);
 	this->mutex->destroy(this->mutex);
@@ -351,7 +414,6 @@ processor_t *processor_create()
 			.destroy = _destroy,
 		},
 		.threads = linked_list_create(),
-		.priority = thread_value_create(NULL),
 		.mutex = mutex_create(MUTEX_TYPE_DEFAULT),
 		.job_added = condvar_create(CONDVAR_TYPE_DEFAULT),
 		.thread_terminated = condvar_create(CONDVAR_TYPE_DEFAULT),

src/libstrongswan/processing/processor.h

@@ -51,7 +51,7 @@ struct processor_t {
 	/**
 	 * Get the number of threads currently working, per priority class.
 	 *
-	 * @param				prioritiy to check
+	 * @param				priority to check
 	 * @return				number of threads in priority working
 	 */
 	u_int (*get_working_threads)(processor_t *this, job_priority_t prio);

src/libstrongswan/processing/scheduler.c

@@ -250,6 +250,7 @@ METHOD(scheduler_t, schedule_job_tv, void,
 
 	event = malloc_thing(event_t);
 	event->job = job;
+	event->job->status = JOB_STATUS_QUEUED;
 	event->time = tv;
 
 	this->mutex->lock(this->mutex);