Very minor cleanup in gedf_test.py

1 files changed, 12 insertions, 8 deletions

diff --git a/unit_trace/gedf_test.py b/unit_trace/gedf_test.py
index cf66142..993e99a 100644
--- a/unit_trace/gedf_test.py
+++ b/unit_trace/gedf_test.py
@@ -18,11 +18,10 @@ import sys
 
 def gedf_test(stream):
 
-    # Two lists to model the system: tasks occupying a CPU and tasks eligible
-    # to do so. Also, m = the number of CPUs.
-    eligible = []
-    on_cpu = []
-    m = None
+    # System model
+    eligible = []   # Tasks eligible
+    on_cpu = []     # Tasks running
+    m = None        # CPUs
 
     # Time of the last record we saw. Only run the G-EDF test when the time
     # is updated.
@@ -59,13 +58,12 @@ def gedf_test(stream):
         # Move a Job from the eligible queue to on_cpu
         elif record.type_name == 'switch_to':
             pos = _find_job(record,eligible)
-            try:
-                job = eligible[pos]
-            except TypeError:
+            if pos is None:
                 msg = "Event %d tried to switch to a job that was not eligible\n"
                 msg = msg % (record.id)
                 sys.stderr.write(msg)
                 exit()
+            job = eligible[pos]
             del eligible[pos]
             on_cpu.append(job)
 
@@ -84,6 +82,12 @@ def gedf_test(stream):
         # been marked as complete, remove it from the model.
         elif record.type_name == 'switch_away':
             pos = _find_job(record,on_cpu)
+            if pos is None:
+                msg = ("Event %d tried to switch to switch away a job" +
+                    " that was not running\n")
+                msg = msg % (record.id)
+                sys.stderr.write(msg)
+                exit()
             job = on_cpu[pos]
             del on_cpu[pos]
             if job.is_complete == False: