Add a warning if join is called and JobManager is suspended

Currently there is a situation that is really hard to notice but quite
dangerous results. When the JobManager is suspended and one calls join()
on a Job this is a no-op and it returns silently without even try to
wait for the job as it could lead to deadlocks. Code using join in such
situation will likely fail in an random way depending on if the job has
already finished fast enough.

This now adds a warning whenever this situation occurs to having a
chance to be noticed and mitigated.

Author: laeubi

runtime/bundles/org.eclipse.core.jobs/src/org/eclipse/core/internal/jobs/JobManager.java

@@ -1005,6 +1005,13 @@ protected boolean join(InternalJob job, long timeout, IProgressMonitor monitor)
 			}
 			//don't join a waiting or sleeping job when suspended (deadlock risk)
 			if (suspended && state != Job.RUNNING) {
+				String pluginId = JobOSGiUtils.getDefault().getBundleId(job);
+				if (pluginId == null) {
+					pluginId = JobManager.PI_JOBS;
+				}
+				RuntimeLog.log(new Status(IStatus.WARNING, pluginId, 0,
+						NLS.bind(JobMessages.JobManager_suspended_problem, job.getName()),
+						new IllegalStateException()));
 				return true;
 			}
 			//it's an error for a job to join itself

runtime/bundles/org.eclipse.core.jobs/src/org/eclipse/core/internal/jobs/JobMessages.java

@@ -22,6 +22,8 @@
 public class JobMessages extends NLS {
 	private static final String BUNDLE_NAME = "org.eclipse.core.internal.jobs.messages"; //$NON-NLS-1$
 
+	public static String JobManager_suspended_problem;
+
 	// Job Manager and Locks
 	public static String jobs_blocked0;
 	public static String jobs_blocked1;

runtime/bundles/org.eclipse.core.jobs/src/org/eclipse/core/internal/jobs/messages.properties

@@ -14,6 +14,7 @@
 ### Runtime jobs plugin messages
 
 ### Job Manager and Locks
+JobManager_suspended_problem=Join was called on job \"{0}\" while JobManager is suspended, this will not work as expected\!
 jobs_blocked0=The user operation is waiting for background work to complete.
 jobs_blocked1=The user operation is waiting for \"{0}\" to complete.
 jobs_unblocked=The user operation is not waiting anymore.