New module to import and process benchmark output

This is the beginning of a module to import and process benchmark
outputs.  The module currently supports importing of a bench.out and
validating it against a schema file.  In future this could grow a set
of routines that benchmark consumers may find useful to build their
own analysis tools.  I have altered validate_bench to use this module
too.

	* benchtests/scripts/import_bench.py: New file.
	* benchtests/scripts/validate_benchout.py: Import import_bench
	instead of jsonschema.
	(validate_bench): Remove function.
	(main): Use import_bench.

benchtests/scripts/validate_benchout.py

@@ -27,37 +27,26 @@ import sys
 import os
 
 try:
-    import jsonschema
+    import import_bench as bench
 except ImportError:
-    print('Could not find jsonschema module.  Output not validated.')
+    print('Import Error: Output will not be validated.')
     # Return success because we don't want the bench target to fail just
     # because the jsonschema module was not found.
     sys.exit(os.EX_OK)
 
 
-def validate_bench(benchfile, schemafile):
-    """Validate benchmark file
-
-    Validate a benchmark output file against a JSON schema.
+def print_and_exit(message, exitcode):
+    """Prints message to stderr and returns the exit code.
 
     Args:
-        benchfile: The file name of the bench.out file.
-        schemafile: The file name of the JSON schema file to validate
-        bench.out against.
+        message: The message to print
+        exitcode: The exit code to return
 
-    Exceptions:
-        jsonschema.ValidationError: When bench.out is not valid
-        jsonschema.SchemaError: When the JSON schema is not valid
-        IOError: If any of the files are not found.
+    Returns:
+        The passed exit code
     """
-    with open(benchfile, 'r') as bfile:
-        with open(schemafile, 'r') as sfile:
-            bench = json.load(bfile)
-            schema = json.load(sfile)
-            jsonschema.validate(bench, schema)
-
-    # If we reach here, we're all good.
-    print("Benchmark output in %s is valid." % benchfile)
+    print(message, file=sys.stderr)
+    return exitcode
 
 
 def main(args):
@@ -73,11 +62,23 @@ def main(args):
         Exceptions thrown by validate_bench
     """
     if len(args) != 2:
-        print("Usage: %s <bench.out file> <bench.out schema>" % sys.argv[0],
-                file=sys.stderr)
-        return os.EX_USAGE
+        return print_and_exit("Usage: %s <bench.out file> <bench.out schema>"
+                % sys.argv[0], os.EX_USAGE)
 
-    validate_bench(args[0], args[1])
+    try:
+        bench.parse_bench(args[0], args[1])
+    except IOError as e:
+        return print_and_exit("IOError(%d): %s" % (e.errno, e.strerror),
+                os.EX_OSFILE)
+
+    except bench.validator.ValidationError as e:
+        return print_and_exit("Invalid benchmark output: %s" % e.message,
+            os.EX_DATAERR)
+
+    except bench.validator.SchemaError as e:
+        return print_and_exit("Invalid schema: %s" % e.message, os.EX_DATAERR)
+
+    print("Benchmark output in %s is valid." % args[0])
     return os.EX_OK