Fix #8749.

- When a job needs to go dependent on another job, we no longer use recursion
  to manage the execution stack. Instead the job is simply marked as waiting
  and we execute other jobs with no dependencies in the meantime. When a job
  completes, all dependents are moved back onto the unscheduled list and
  executed as needed.

- Adjustments to ResolveValueNodeJob to handle the now asynchronous nature
  of waiting.

src/apps/debugger/Jobs.cpp

@@ -1,4 +1,5 @@
 /*
+ * Copyright 2012, Rene Gollent, rene@gollent.com.
  * Copyright 2009, Ingo Weinhold, ingo_weinhold@gmx.de.
  * Distributed under the terms of the MIT License.
  */
@@ -523,6 +524,9 @@ ResolveValueNodeValueJob::_ResolveNodeValue()
 				fValueNode, fValueNode->Name().String(), parentNode);
 			return error;
 		}
+
+		if (State() == JOB_STATE_WAITING)
+			return B_OK;
 	}
 
 	// resolve the node child location, if necessary
@@ -629,6 +633,8 @@ ResolveValueNodeValueJob::_ResolveParentNodeValue(ValueNode* parentNode)
 			// "Not found" can happen due to a race condition between
 			// unlocking the worker and starting to wait.
 			break;
+		case JOB_DEPENDENCY_ACTIVE:
+			return B_OK;
 		case JOB_DEPENDENCY_FAILED:
 		case JOB_DEPENDENCY_ABORTED:
 		default:

src/apps/debugger/Worker.cpp

@@ -1,4 +1,5 @@
 /*
+ * Copyright 2012, Rene Gollent, rene@gollent.com.
  * Copyright 2009, Ingo Weinhold, ingo_weinhold@gmx.de.
  * Distributed under the terms of the MIT License.
  */
@@ -138,6 +139,15 @@ void
 Job::SetWaitStatus(job_wait_status status)
 {
 	fWaitStatus = status;
+	switch (fWaitStatus) {
+	case JOB_DEPENDENCY_ACTIVE:
+		fState = JOB_STATE_WAITING;
+		break;
+	default:
+		fState = JOB_STATE_ACTIVE;
+		break;
+
+	}
 }
 
 
@@ -346,18 +356,6 @@ Worker::WaitForJob(Job* waitingJob, const JobKey& key)
 	waitingJob->SetDependency(job);
 	job->DependentJobs().Add(waitingJob);
 
-	// TODO: Continuations would be nice. For the time being we have to use
-	// recursion. Disadvantages are that we'll use more stack and that aborting
-	// a job waiting for a dependency won't abort the job before the dependency
-	// is done.
-	locker.Unlock();
-	_ProcessJobs(waitingJob);
-	locker.Lock();
-
-	// ignore the actual wait status when the game is over anyway
-	if (fTerminating || waitingJob->State() == JOB_STATE_ABORTED)
-		return JOB_DEPENDENCY_ABORTED;
-
 	return waitingJob->WaitStatus();
 }
 
@@ -372,7 +370,7 @@ Worker::_WorkerLoopEntry(void* data)
 status_t
 Worker::_WorkerLoop()
 {
-	_ProcessJobs(NULL);
+	_ProcessJobs();
 
 	// clean up aborted jobs
 	AutoLocker<Worker> locker(this);
@@ -384,7 +382,7 @@ Worker::_WorkerLoop()
 
 
 void
-Worker::_ProcessJobs(Job* waitingJob)
+Worker::_ProcessJobs()
 {
 	while (true) {
 		AutoLocker<Worker> locker(this);
@@ -395,8 +393,10 @@ Worker::_ProcessJobs(Job* waitingJob)
 
 			status_t error = acquire_sem(fWorkToDoSem);
 			if (error != B_OK) {
-				if (error == B_INTERRUPTED)
+				if (error == B_INTERRUPTED) {
+					locker.Lock();
 					continue;
+				}
 				break;
 			}
 
@@ -404,13 +404,9 @@ Worker::_ProcessJobs(Job* waitingJob)
 		}
 
 		// clean up aborted jobs
-		while (Job* job = fAbortedJobs.RemoveHead()) {
+		while (Job* job = fAbortedJobs.RemoveHead())
 			_FinishJob(job);
 
-			if (waitingJob != NULL && waitingJob->State() != JOB_STATE_WAITING)
-				break;
-		}
-
 		// process the next job
 		if (Job* job = fUnscheduledJobs.RemoveHead()) {
 			job->SetState(JOB_STATE_ACTIVE);
@@ -422,12 +418,10 @@ Worker::_ProcessJobs(Job* waitingJob)
 			if (job->State() == JOB_STATE_ACTIVE) {
 				job->SetState(
 					error == B_OK ? JOB_STATE_SUCCEEDED : JOB_STATE_FAILED);
-			}
+			} else if (job->State() == JOB_STATE_WAITING)
+				continue;
 
 			_FinishJob(job);
-
-			if (waitingJob != NULL && waitingJob->State() != JOB_STATE_WAITING)
-				break;
 		}
 	}
 }
@@ -492,7 +486,10 @@ Worker::_FinishJob(Job* job)
 		while (Job* dependentJob = job->DependentJobs().RemoveHead()) {
 			dependentJob->SetDependency(NULL);
 			dependentJob->SetWaitStatus(waitStatus);
+			fUnscheduledJobs.Add(dependentJob);
 		}
+
+		release_sem(fWorkToDoSem);
 	}
 
 	if (job->State() != JOB_STATE_ABORTED)

src/apps/debugger/Worker.h

@@ -182,7 +182,7 @@ private:
 	static	status_t			_WorkerLoopEntry(void* data);
 			status_t			_WorkerLoop();
 
-			void				_ProcessJobs(Job* waitingJob);
+			void				_ProcessJobs();
 			void				_AbortJob(Job* job, bool removeFromTable);
 			void				_FinishJob(Job* job);