utils/log: add indentcontext

Add indentcontext context manager to save having to add try/finally
clauses around indenting code just to ensure dedenting.

wa/framework/configuration/core.py

@@ -945,12 +945,9 @@ class JobGenerator(object):
 
     def add_section(self, section, workloads):
         new_node = self.root_node.add_section(section)
-        log.indent()
-        try:
+        with log.indentcontext():
             for workload in workloads:
                 new_node.add_workload(workload)
-        finally:
-            log.dedent()
 
     def add_workload(self, workload):
         self.root_node.add_workload(workload)

wa/framework/configuration/tree.py

@@ -38,12 +38,9 @@ class JobSpecSource(object):
 
     def _log_self(self):
         logger.debug('Creating {} node'.format(self.kind))
-        log.indent()
-        try:
+        with log.indentcontext():
             for key, value in self.config.iteritems():
                 logger.debug('"{}" to "{}"'.format(key, value))
-        finally:
-            log.dedent()
 
 
 class WorkloadEntry(JobSpecSource):

wa/framework/plugin.py

@@ -626,8 +626,7 @@ class PluginLoader(object):
 
     def _discover_in_module(self, module):  # NOQA pylint: disable=too-many-branches
         self.logger.debug('Checking module %s', module.__name__)
-        log.indent()
-        try:
+        with log.indentcontext():
             for obj in vars(module).itervalues():
                 if inspect.isclass(obj):
                     if not issubclass(obj, Plugin):
@@ -647,9 +646,6 @@ class PluginLoader(object):
                             self.logger.warning(e)
                         else:
                             raise e
-        finally:
-            log.dedent()
-            pass
 
     def _add_found_plugin(self, obj):
         """

wa/framework/resource.py

@@ -239,12 +239,9 @@ class ResourceResolver(object):
             self.logger.debug('Loading getter {}'.format(gettercls.name))
             getter = self.loader.get_plugin(name=gettercls.name,
                                             kind="resource_getter")
-            log.indent()
-            try:
+            with log.indentcontext():
                 getter.initialize()
                 getter.register(self)
-            finally:
-                log.dedent()
             self.getters.append(getter)
 
     def register(self, source, priority=SourcePriority.local):

wa/utils/log.py

@@ -21,6 +21,7 @@ import os
 import string
 import subprocess
 import threading
+from contextlib import contextmanager
 
 import colorama
 
@@ -148,6 +149,15 @@ def dedent():
     _indent_level -= 1
 
 
+@contextmanager
+def indentcontext():
+    indent()
+    try:
+        yield
+    finally:
+        dedent()
+
+
 def set_indent_level(level):
     global _indent_level
     old_level = _indent_level