ec3po console and interpreter: Handle EOFError from the pipes.

EOF is expected sometimes upon shutdown, when one thread (console or
interpreter) manages to close its write side of a pipe before the other
thread receives the shutdown pipe unblocked notification.  EOF is now
considered another indication to shutdown.

BRANCH=none
BUG=b:79684405
TEST=With this change plus CL:1279145 to switch to threading, I am no
longer able to reproduce the formerly occasional EOFError tracebacks upon
shutdown, with either ctrl+c or SIGTERM.  Basic servod functionality
continues to work, including dut-control ec_uart_pty, servo_console_pty
(both tested with minicom), dut_i2c_mux, enable_ite_dfu, get_ite_chipid.
Testing performed with a servo_micro connected to an octopus_ite.  I tested
both without and with CL:1279145 i.e. both with subprocesses and with
threads (though I only ever encountered EOFError with the latter).

Change-Id: Iaa1ddc5f05a32ef806fa5f84d0ed0ad4739189ce
Signed-off-by: Matthew Blecker <matthewb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1284509
Reviewed-by: Nick Sanders <nsanders@chromium.org>
Reviewed-by: Ruben Rodriguez Buchillon <coconutruben@chromium.org>

1 files changed, 13 insertions, 3 deletions

diff --git a/util/ec3po/interpreter.py b/util/ec3po/interpreter.py
index fd811716de..86272f6646 100644
--- a/util/ec3po/interpreter.py
+++ b/util/ec3po/interpreter.py
@@ -347,7 +347,11 @@ class Interpreter(object):
     self.dbg_pipe.send(data)
 
   def HandleUserData(self):
-    """Handle any incoming commands from the user."""
+    """Handle any incoming commands from the user.
+
+    Raises:
+      EOFError: Allowed to propagate through from self.cmd_pipe.recv().
+    """
     self.logger.log(1, 'Command data available.  Begin processing.')
     data = self.cmd_pipe.recv()
     # Process the command.
@@ -418,11 +422,17 @@ def StartLoop(interp, shutdown_pipe=None):
 
         # Handle any commands from the user.
         elif obj is interp.cmd_pipe:
-          interp.HandleUserData()
+          try:
+            interp.HandleUserData()
+          except EOFError:
+            interp.logger.debug(
+                'ec3po interpreter received EOF from cmd_pipe in '
+                'HandleUserData()')
+            continue_looping = False
 
         elif obj is shutdown_pipe:
           interp.logger.debug(
-              'ec3po console received shutdown pipe unblocked notification')
+              'ec3po interpreter received shutdown pipe unblocked notification')
           continue_looping = False
 
       for obj in writeable: