Try to ensure we'll have a truly random postfix

While it is very improbable, it seemed fairly straight forward to add
a small bit of code to ensure the temporary file name is random and
won't clash with another host, pid or thread potentially working on
the same object.

BUG: XXXXXX (https://bugzilla.redhat.com/show_bug.cgi?id=XXXXXX)

Change-Id: I862021b725efbfe58b98754c4470aef4882eb8f7
Signed-off-by: Peter Portante <peter.portante@redhat.com>
Reviewed-on: http://review.gluster.org/5671
Reviewed-by: Luis Pabon <lpabon@redhat.com>
Tested-by: Luis Pabon <lpabon@redhat.com>

gluster/swift/obj/diskfile.py

@@ -17,10 +17,16 @@ import os
 import stat
 import fcntl
 import errno
-import random
+try:
+    from random import SystemRandom
+    random = SystemRandom()
+except ImportError:
+    import random
 import logging
+from socket import gethostname
 from hashlib import md5
 from eventlet import sleep
+from greenlet import getcurrent
 from contextlib import contextmanager
 from swift.common.utils import TRUE_VALUES, drop_buffer_cache, ThreadPool
 from swift.common.exceptions import DiskFileNotExist, DiskFileError, \
@@ -53,6 +59,9 @@ DISALLOWED_HEADERS = set('content-length content-type deleted etag'.split())
 MAX_RENAME_ATTEMPTS = 10
 MAX_OPEN_ATTEMPTS = 10
 
+_cur_pid = str(os.getpid())
+_cur_host = str(gethostname())
+
 
 def _random_sleep():
     sleep(random.uniform(0.5, 0.15))
@@ -623,9 +632,11 @@ class DiskFile(SwiftDiskFile):
         # Assume the full directory path exists to the file already, and
         # construct the proper name for the temporary file.
         attempts = 1
+        cur_thread = str(getcurrent())
         while True:
-            tmpfile = '.' + self._obj + '.' + md5(self._obj +
-                      str(random.random())).hexdigest()
+            postfix = md5(self._obj + _cur_host + _cur_pid + cur_thread
+                          + str(random.random())).hexdigest()
+            tmpfile = '.' + self._obj + '.' + postfix
             tmppath = os.path.join(self.put_datadir, tmpfile)
             try:
                 fd = do_open(tmppath,