Use int enumerations for log error constants

Change-Id: Iac6f4d860c220c653bbae17e7b1d69249259bd88

oslo_concurrency/processutils.py

@@ -26,6 +26,7 @@ import shlex
 import signal
 import time
 
+import enum
 from oslo_utils import importutils
 from oslo_utils import strutils
 from oslo_utils import timeutils
@@ -96,8 +97,24 @@ def _subprocess_setup(on_preexec_fn):
         on_preexec_fn()
 
 
-LOG_ALL_ERRORS = 1
+@enum.unique
-LOG_FINAL_ERROR = 2
+class LogErrors(enum.IntEnum):
+    """Enumerations that affect if stdout and stderr are logged on error."""
+
+    #: No logging on errors.
+    DEFAULT = 0
+
+    #: Log an error on **each** occurence of an error.
+    ALL = 1
+
+    #: Log an error on the last attempt that errored **only**.
+    FINAL = 2
+
+
+# Retain these aliases for a number of releases...
+LOG_ALL_ERRORS = LogErrors.ALL
+LOG_FINAL_ERROR = LogErrors.FINAL
+LOG_DEFAULT_ERROR = LogErrors.DEFAULT
 
 
 def execute(*cmd, **kwargs):
@@ -137,17 +154,16 @@ def execute(*cmd, **kwargs):
     :param loglevel:        log level for execute commands.
     :type loglevel:         int.  (Should be logging.DEBUG or logging.INFO)
     :param log_errors:      Should stdout and stderr be logged on error?
-                            Possible values are None=default,
+                            Possible values are
-                            LOG_FINAL_ERROR, or LOG_ALL_ERRORS. None
+                            :py:attr:`~.LogErrors.DEFAULT`,
-                            implies no logging on errors. The values
+                            :py:attr:`~.LogErrors.FINAL`, or
-                            LOG_FINAL_ERROR and LOG_ALL_ERRORS are
+                            :py:attr:`~.LogErrors.ALL`. Note that the
-                            relevant when multiple attempts of command
+                            values :py:attr:`~.LogErrors.FINAL` and
-                            execution are requested using the
+                            :py:attr:`~.LogErrors.ALL`
-                            'attempts' parameter. If LOG_FINAL_ERROR
+                            are **only** relevant when multiple attempts of
-                            is specified then only log an error on the
+                            command execution are requested using the
-                            last attempt, and LOG_ALL_ERRORS requires
+                            ``attempts`` parameter.
-                            logging on each occurence of an error.
+    :type log_errors:       :py:class:`~.LogErrors`
-    :type log_errors:       integer.
     :param binary:          On Python 3, return stdout and stderr as bytes if
                             binary is True, as Unicode otherwise.
     :type binary:           boolean
@@ -188,6 +204,8 @@ def execute(*cmd, **kwargs):
     shell = kwargs.pop('shell', False)
     loglevel = kwargs.pop('loglevel', logging.DEBUG)
     log_errors = kwargs.pop('log_errors', None)
+    if log_errors is None:
+        log_errors = LogErrors.DEFAULT
     binary = kwargs.pop('binary', False)
     on_execute = kwargs.pop('on_execute', None)
     on_completion = kwargs.pop('on_completion', None)
@@ -202,7 +220,9 @@ def execute(*cmd, **kwargs):
     if kwargs:
         raise UnknownArgumentError(_('Got unknown keyword args: %r') % kwargs)
 
-    if log_errors not in [None, LOG_ALL_ERRORS, LOG_FINAL_ERROR]:
+    if isinstance(log_errors, six.integer_types):
+        log_errors = LogErrors(log_errors)
+    if not isinstance(log_errors, LogErrors):
         raise InvalidArgumentError(_('Got invalid arg log_errors: %r') %
                                    log_errors)
 

requirements.txt

@@ -4,6 +4,7 @@
 
 pbr<2.0,>=1.3
 Babel>=1.3
+enum34;python_version=='2.7' or python_version=='2.6'
 iso8601>=0.1.9
 oslo.config>=1.11.0 # Apache-2.0
 oslo.i18n>=1.5.0 # Apache-2.0