ec3po: Remove sys.exit() call from the end of StartLoop() functions.

This removes explicit process exit() from both console and interpeter ec3po
StartLoop() functions.  Use of exit() is incompatible with running these
functions in threads instead of subprocesses.  This should be a no-op,
since letting execution finish in Python should be equivalent to
sys.exit().

Since exit() in the finally: block effectively suppressed exceptions, the
same behavior is now achieved in interpreter.StartLoop() by use of an
except: block, same as console.StartLoop() already had.

BRANCH=none
BUG=b:79684405
TEST=All servod processes still exit promptly and without printing
tracebacks, upon either ctrl+c from console where servod launched, or from
SIGTERM to parent servod process.  I confirmed that the new code was in use
by adding an extra logging line on each of ec3po console and interpreter
loop start (not present in uploaded patch).  Testing performed with a
servo_micro attached to an octopus_ite.

Change-Id: Ie92610de88fea78f6c50f5e49b9d0940f209cd92
Signed-off-by: Matthew Blecker <matthewb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1278085
Reviewed-by: Aseda Aboagye <aaboagye@chromium.org>

2 files changed, 19 insertions, 11 deletions

diff --git a/util/ec3po/console.py b/util/ec3po/console.py
index 608e1b7cba..3657ceb20e 100755
--- a/util/ec3po/console.py
+++ b/util/ec3po/console.py
@@ -825,13 +825,13 @@ def StartLoop(console, command_active):
     command_active: multiprocessing.Value indicating if servod owns
         the console, or user owns the console. This prevents input collisions.
   """
-  console.logger.debug('Console is being served on %s.', console.user_pty)
-  console.logger.debug('Console master is on %s.', console.master_pty)
-  console.logger.debug('Command interface is being served on %s.',
-      console.interface_pty)
-  console.logger.debug(console)
-
   try:
+    console.logger.debug('Console is being served on %s.', console.user_pty)
+    console.logger.debug('Console master is on %s.', console.master_pty)
+    console.logger.debug('Command interface is being served on %s.',
+        console.interface_pty)
+    console.logger.debug(console)
+
     # This checks for HUP to indicate if the user has connected to the pty.
     ep = select.epoll()
     ep.register(console.master_pty, select.EPOLLHUP)
@@ -907,10 +907,14 @@ def StartLoop(console, command_active):
       while not console.oobm_queue.empty():
         console.logger.debug('OOBM queue ready for reading.')
         console.ProcessOOBMQueue()
+
   except KeyboardInterrupt:
     pass
+
+  # TODO(crbug.com/894870): Stop suppressing all exceptions.
   except:
     traceback.print_exc()
+
   finally:
     # Unregister poll.
     ep.unregister(console.master_pty)
@@ -921,8 +925,6 @@ def StartLoop(console, command_active):
     os.close(console.master_pty)
     os.close(console.interface_pty)
     console.logger.debug('Exit ec3po console loop for %s', console.user_pty)
-    # Exit.
-    sys.exit(0)
 
 
 def main(argv):
diff --git a/util/ec3po/interpreter.py b/util/ec3po/interpreter.py
index 9a0880f49c..9af5a67dd9 100644
--- a/util/ec3po/interpreter.py
+++ b/util/ec3po/interpreter.py
@@ -20,7 +20,6 @@ import logging
 import os
 import Queue
 import select
-import sys
 
 
 COMMAND_RETRIES = 3  # Number of attempts to retry a command.
@@ -408,11 +407,18 @@ def StartLoop(interp):
         if obj is interp.ec_uart_pty:
           interp.SendCmdToEC()
 
+  except KeyboardInterrupt:
+    pass
+
+  # TODO(crbug.com/894870): Stop suppressing all exceptions.
+  except:
+    traceback.print_exc()
+
   finally:
     # Close pipes.
     interp.cmd_pipe.close()
     interp.dbg_pipe.close()
     # Close file descriptor.
     interp.ec_uart_pty.close()
-    # Exit.
-    sys.exit(0)
+    interp.logger.debug('Exit ec3po interpreter loop for %s',
+                        interp.ec_uart_pty_name)