Check if mesh file exists and fall back on restart stream

If neither the file in the mesh stream nor the first file matching
the pattern for the restart file exists, raise an error.

Author: xylar

mpas_analysis/shared/analysis_task.py

@@ -19,6 +19,7 @@
 import time
 import traceback
 import logging
+import os
 import sys
 
 from mpas_analysis.shared.io import NameList, StreamsFile
@@ -506,11 +507,23 @@ def get_mesh_filename(self):
 
         meshStream = self.config.get(self.componentName, 'meshStream')
         try:
-            return self.runStreams.readpath(meshStream)[0]
+            meshFilename = self.runStreams.readpath(meshStream)[0]
         except ValueError:
+            meshFilename = None
+
+        if meshFilename is None or not os.path.exists(meshFilename):
+            # try again with "restart" stream
+            try:
+                meshFilename = self.runStreams.readpath('restart')[0]
+            except ValueError:
+                meshFilename = None
+
+        if meshFilename is None or not os.path.exists(meshFilename):
             raise IOError(
-                f'The MPAS mesh file could not be found: needed to '
-                f'run {self.componentName} analysis')
+                f'The MPAS mesh file could not be found via either '
+                f'"{meshStream}" or "restart" streams')
+
+        return meshFilename
 
 # }}}