Add async_pending_last time to object.recon

The async_pending count isn't near as useful when we don't know how out
of date it is.

Change-Id: I3e5e904ffc0eba7a7e141e1c2d9f9840e4952041

bin/swift-recon-cron

@@ -18,6 +18,7 @@ swift-recon-cron.py
 
 import os
 import sys
+import time
 
 from eventlet import Timeout
 
@@ -65,7 +66,10 @@ def main():
     try:
         with lock_path(lock_dir):
             asyncs = get_async_count(device_dir, logger)
-            dump_recon_cache({'async_pending': asyncs}, cache_file, logger)
+            dump_recon_cache({
+                'async_pending': asyncs,
+                'async_pending_last': time.time(),
+            }, cache_file, logger)
     except (Exception, Timeout) as err:
         msg = 'Exception during recon-cron while accessing devices'
         logger.exception(msg)

swift/common/middleware/recon.py

@@ -81,7 +81,7 @@ class ReconMiddleware(object):
         try:
             with openr(cache_file, 'r') as f:
                 recondata = json.load(f)
-                return dict((key, recondata.get(key)) for key in cache_keys)
+                return {key: recondata.get(key) for key in cache_keys}
         except IOError as err:
             if err.errno == errno.ENOENT and ignore_missing:
                 pass
@@ -132,7 +132,7 @@ class ReconMiddleware(object):
 
     def get_async_info(self):
         """get # of async pendings"""
-        return self._from_recon_cache(['async_pending'],
+        return self._from_recon_cache(['async_pending', 'async_pending_last'],
                                       self.object_recon_cache)
 
     def get_driveaudit_error(self):

test/unit/common/middleware/test_recon.py

@@ -22,6 +22,7 @@ import os
 from posix import stat_result, statvfs_result
 from shutil import rmtree
 import tempfile
+import time
 import unittest
 from unittest import TestCase
 
@@ -676,13 +677,14 @@ class TestReconSuccess(TestCase):
         self.assertEqual(rv, meminfo_resp)
 
     def test_get_async_info(self):
-        from_cache_response = {'async_pending': 5}
+        now = time.time()
+        from_cache_response = {'async_pending': 5, 'async_pending_last': now}
         self.fakecache.fakeout = from_cache_response
         rv = self.app.get_async_info()
         self.assertEqual(self.fakecache.fakeout_calls,
-                         [((['async_pending'],
+                         [((['async_pending', 'async_pending_last'],
                              '/var/cache/swift/object.recon'), {})])
-        self.assertEqual(rv, {'async_pending': 5})
+        self.assertEqual(rv, {'async_pending': 5, 'async_pending_last': now})
 
     def test_get_replication_info_account(self):
         from_cache_response = {