added latch timestamp updates

inventory_provider/tasks/common.py

 import json
 import logging
+import time
 
 import jsonschema
 import redis
@@ -87,17 +88,24 @@ def update_latch_status(config, pending=False, failure=False):
     logger.debug('updating latch status: pending={}, failure={}'.format(
         pending, failure))
 
+    now = time.time()
     for db in config['redis-databases']:
         r = _get_redis(config, dbid=db)
         latch = get_latch(r)
         if not latch:
             continue
+        if not pending and not failure:
+            if not latch['pending'] and not latch['failure']:
+                logger.error(
+                    'updating latch for db {db} with pending=failure=True, '
+                    f'but latch is already {latch}')
+            latch['timestamp'] = now
         latch['pending'] = pending
         latch['failure'] = failure
         r.set('db:latch', json.dumps(latch))
 
 
-def set_latch(config, new_current, new_next):
+def set_latch(config, new_current, new_next, timestamp):
 
     logger.debug('setting latch: new current={}, new next={}'.format(
         new_current, new_next))
@@ -108,7 +116,8 @@ def set_latch(config, new_current, new_next):
             'next': new_next,
             'this': db,
             'pending': False,
-            'failure': False
+            'failure': False,
+            'timestamp': timestamp
         }
 
         r = _get_redis(config, dbid=db)
@@ -130,7 +139,11 @@ def latch_db(config):
     next_idx = db_ids.index(latch['next'])
     next_idx = (next_idx + 1) % len(db_ids)
 
-    set_latch(config, new_current=latch['next'], new_next=db_ids[next_idx])
+    set_latch(
+        config,
+        new_current=latch['next'],
+        new_next=db_ids[next_idx],
+        timestamp=time.time())
 
 
 def _get_redis(config, dbid=None):

inventory_provider/tasks/worker.py

@@ -541,7 +541,8 @@ def _erase_next_db(config):
         set_latch(
             config,
             new_current=saved_latch['current'],
-            new_next=saved_latch['next'])
+            new_next=saved_latch['next'],
+            timestamp=saved_latch.get('timestamp', 0))
 
 
 @app.task(base=InventoryTask, bind=True, name='internal_refresh_phase_2')