[StGIT PATCH 4/4] Add optional logging of subprocess execution

["Karl Hasselström" <kha@treskal.com>]

Now that the subprocess calling has been refactored and is in a nice
shape, it's quite simple to add some logging facilities. This patch
adds two separate log modes, switched by the STG_SUBPROCESS_LOG
environment variable:

  * Setting it to "debug" prints the executable name and all
    arguments, and the subprocess return value.

  * Setting it to "profile" prints just the executable name, and the
    (wallclock) time elapsed during the call.

  * Not setting it will disable logging, of course.

Signed-off-by: Karl Hasselström <kha@treskal.com>

---

 stgit/run.py |   27 +++++++++++++++++++++++++++
 1 files changed, 27 insertions(+), 0 deletions(-)

diff --git a/stgit/run.py b/stgit/run.py
index 1bc4759..719ecb7 100644
--- a/stgit/run.py
+++ b/stgit/run.py
@@ -22,11 +22,22 @@ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 # to stay Python 2.3 compatible.
 import popen2, os
 
+import datetime
+
+from  stgit.out import *
+
 class RunException(Exception):
     """Thrown when something bad happened when we tried to run the
     subprocess."""
     pass
 
+_all_log_modes = ['debug', 'profile']
+_log_mode = os.environ.get('STG_SUBPROCESS_LOG', '')
+if _log_mode and not _log_mode in _all_log_modes:
+    out.warn(('Unknown log mode "%s" specified in $STG_SUBPROCESS_LOG.'
+              % _log_mode),
+             'Valid values are: %s' % ', '.join(_all_log_modes))
+
 class Run:
     exc = RunException
     def __init__(self, *cmd):
@@ -37,6 +48,18 @@ class Run:
         self.__good_retvals = [0]
         self.__env = None
         self.__indata = None
+    def __log_start(self, cmd):
+        if _log_mode == 'debug':
+            out.start('Running subprocess %s' % cmd)
+        elif _log_mode == 'profile':
+            out.start('Running subprocess %s' % cmd[0])
+            self.__starttime = datetime.datetime.now()
+    def __log_end(self, retcode):
+        if _log_mode == 'debug':
+            out.done('return code: %d' % retcode)
+        elif _log_mode == 'profile':
+            duration = datetime.datetime.now() - self.__starttime
+            out.done('%1.3f s' % (duration.microseconds/1e6 + duration.seconds))
     def __run_io(self, cmd):
         """Run with captured IO. Note: arguments are parsed by the
         shell. We single-quote them, so don't use anything with single
@@ -47,6 +70,7 @@ class Run:
             ecmd = (['env'] + ['%s=%s' % (key, val)
                                for key, val in self.__env.iteritems()]
                     + cmd)
+        self.__log_start(ecmd)
         p = popen2.Popen3(' '.join(["'%s'" % c for c in ecmd]), True)
         if self.__indata != None:
             p.tochild.write(self.__indata)
@@ -54,6 +78,7 @@ class Run:
         outdata = p.fromchild.read()
         errdata = p.childerr.read()
         self.exitcode = p.wait() >> 8
+        self.__log_end(self.exitcode)
         if errdata or self.exitcode not in self.__good_retvals:
             raise self.exc('%s failed with code %d:\n%s'
                            % (cmd[0], self.exitcode, errdata))
@@ -63,7 +88,9 @@ class Run:
         the shell."""
         assert self.__env == None
         assert self.__indata == None
+        self.__log_start(cmd)
         self.exitcode = os.spawnvp(os.P_WAIT, cmd[0], cmd)
+        self.__log_end(self.exitcode)
         if not self.exitcode in self.__good_retvals:
             raise self.exc('%s failed with code %d'
                            % (cmd[0], self.exitcode))