Fix the prefix of messages caputured from stderr

Swift caputures both sys.stdout and sys.stderr messages and
transfers them to syslog. However, whole of the messages
uses the "STDOUT:" prefix, currently.

It will be quite confusable for debugging purpose because we
cannot make sure whether "Swift didn't caputure stderr" or
"Swift captured stderr but didn't show it" when we want to log
some stderr messages.

This patch enables to allow a new prefix "STDERR:" and use it
for sys.stderr.

Change-Id: Idf4649e9860b77c3600a5cd0a3e0bd674b31fb4f

swift/common/utils.py

@@ -1062,19 +1062,21 @@ class NullLogger(object):
 
 class LoggerFileObject(object):
 
-    def __init__(self, logger):
+    def __init__(self, logger, log_type='STDOUT'):
         self.logger = logger
+        self.log_type = log_type
 
     def write(self, value):
         value = value.strip()
         if value:
             if 'Connection reset by peer' in value:
-                self.logger.error(_('STDOUT: Connection reset by peer'))
+                self.logger.error(
+                    _('%s: Connection reset by peer'), self.log_type)
             else:
-                self.logger.error(_('STDOUT: %s'), value)
+                self.logger.error(_('%s: %s'), self.log_type, value)
 
     def writelines(self, values):
-        self.logger.error(_('STDOUT: %s'), '#012'.join(values))
+        self.logger.error(_('%s: %s'), self.log_type, '#012'.join(values))
 
     def close(self):
         pass
@@ -1641,7 +1643,7 @@ def capture_stdio(logger, **kwargs):
     if kwargs.pop('capture_stdout', True):
         sys.stdout = LoggerFileObject(logger)
     if kwargs.pop('capture_stderr', True):
-        sys.stderr = LoggerFileObject(logger)
+        sys.stderr = LoggerFileObject(logger, 'STDERR')
 
 
 def parse_options(parser=None, once=False, test_args=None):

test/unit/common/test_utils.py

@@ -1043,54 +1043,58 @@ class TestUtils(unittest.TestCase):
         handler = logging.StreamHandler(sio)
         logger = logging.getLogger()
         logger.addHandler(handler)
-        lfo = utils.LoggerFileObject(logger)
+        lfo_stdout = utils.LoggerFileObject(logger)
+        lfo_stderr = utils.LoggerFileObject(logger)
+        lfo_stderr = utils.LoggerFileObject(logger, 'STDERR')
         print 'test1'
         self.assertEquals(sio.getvalue(), '')
-        sys.stdout = lfo
+        sys.stdout = lfo_stdout
         print 'test2'
         self.assertEquals(sio.getvalue(), 'STDOUT: test2\n')
-        sys.stderr = lfo
+        sys.stderr = lfo_stderr
         print >> sys.stderr, 'test4'
-        self.assertEquals(sio.getvalue(), 'STDOUT: test2\nSTDOUT: test4\n')
+        self.assertEquals(sio.getvalue(), 'STDOUT: test2\nSTDERR: test4\n')
         sys.stdout = orig_stdout
         print 'test5'
-        self.assertEquals(sio.getvalue(), 'STDOUT: test2\nSTDOUT: test4\n')
+        self.assertEquals(sio.getvalue(), 'STDOUT: test2\nSTDERR: test4\n')
         print >> sys.stderr, 'test6'
-        self.assertEquals(sio.getvalue(), 'STDOUT: test2\nSTDOUT: test4\n'
-                          'STDOUT: test6\n')
+        self.assertEquals(sio.getvalue(), 'STDOUT: test2\nSTDERR: test4\n'
+                          'STDERR: test6\n')
         sys.stderr = orig_stderr
         print 'test8'
-        self.assertEquals(sio.getvalue(), 'STDOUT: test2\nSTDOUT: test4\n'
-                          'STDOUT: test6\n')
-        lfo.writelines(['a', 'b', 'c'])
-        self.assertEquals(sio.getvalue(), 'STDOUT: test2\nSTDOUT: test4\n'
-                          'STDOUT: test6\nSTDOUT: a#012b#012c\n')
-        lfo.close()
-        lfo.write('d')
-        self.assertEquals(sio.getvalue(), 'STDOUT: test2\nSTDOUT: test4\n'
-                          'STDOUT: test6\nSTDOUT: a#012b#012c\nSTDOUT: d\n')
-        lfo.flush()
-        self.assertEquals(sio.getvalue(), 'STDOUT: test2\nSTDOUT: test4\n'
-                          'STDOUT: test6\nSTDOUT: a#012b#012c\nSTDOUT: d\n')
-        got_exc = False
-        try:
-            for line in lfo:
-                pass
-        except Exception:
-            got_exc = True
-        self.assert_(got_exc)
-        got_exc = False
-        try:
-            for line in lfo.xreadlines():
-                pass
-        except Exception:
-            got_exc = True
-        self.assert_(got_exc)
-        self.assertRaises(IOError, lfo.read)
-        self.assertRaises(IOError, lfo.read, 1024)
-        self.assertRaises(IOError, lfo.readline)
-        self.assertRaises(IOError, lfo.readline, 1024)
-        lfo.tell()
+        self.assertEquals(sio.getvalue(), 'STDOUT: test2\nSTDERR: test4\n'
+                          'STDERR: test6\n')
+        lfo_stdout.writelines(['a', 'b', 'c'])
+        self.assertEquals(sio.getvalue(), 'STDOUT: test2\nSTDERR: test4\n'
+                          'STDERR: test6\nSTDOUT: a#012b#012c\n')
+        lfo_stdout.close()
+        lfo_stderr.close()
+        lfo_stdout.write('d')
+        self.assertEquals(sio.getvalue(), 'STDOUT: test2\nSTDERR: test4\n'
+                          'STDERR: test6\nSTDOUT: a#012b#012c\nSTDOUT: d\n')
+        lfo_stdout.flush()
+        self.assertEquals(sio.getvalue(), 'STDOUT: test2\nSTDERR: test4\n'
+                          'STDERR: test6\nSTDOUT: a#012b#012c\nSTDOUT: d\n')
+        for lfo in (lfo_stdout, lfo_stderr):
+            got_exc = False
+            try:
+                for line in lfo:
+                    pass
+            except Exception:
+                got_exc = True
+            self.assert_(got_exc)
+            got_exc = False
+            try:
+                for line in lfo.xreadlines():
+                    pass
+            except Exception:
+                got_exc = True
+            self.assert_(got_exc)
+            self.assertRaises(IOError, lfo.read)
+            self.assertRaises(IOError, lfo.read, 1024)
+            self.assertRaises(IOError, lfo.readline)
+            self.assertRaises(IOError, lfo.readline, 1024)
+            lfo.tell()
 
     def test_parse_options(self):
         # Get a file that is definitely on disk