utils, examples: Add ExperimentManager CM

Adds an ExperimentManager context manager for scripts:

 - No more ugly stack traces after execution if something goes wrong

 - No more ugly and easy to forget try-finally blocks

1 files changed, 6 insertions, 4 deletions

diff --git a/examples/two-layers.py b/examples/two-layers.py
index 6d22673..6e4671f 100755
--- a/examples/two-layers.py
+++ b/examples/two-layers.py
@@ -16,7 +16,7 @@ import rumba.prototypes.rlite as rl
 import rumba.prototypes.irati as irati
 
 import rumba.log as log
-
+from rumba.utils import ExperimentManager
 
 log.set_logging_level('DEBUG')
 
@@ -54,8 +54,10 @@ exp = rl.Experiment(tb, nodes = [a, b, c, d])
 
 print(exp)
 
-try:
+with ExperimentManager(exp):
     exp.swap_in()
     exp.bootstrap_prototype()
-finally:
-    exp.swap_out()
+    sb = StoryBoard(exp, duration=15, servers=[])
+    sb.run_command(7.5, a, 'echo "7.5 secs in. We are at $(hostname)"')
+    sb.run_command(12, b, 'echo "12 secs in. We are at $(hostname)"')
+    sb.start()