Add last_accessed information to User and expose for robot accounts

Fixes https://jira.coreos.com/browse/QUAY-848

data/model/_basequery.py

@@ -1,11 +1,17 @@
-from peewee import fn
+import logging
+
+from peewee import fn, PeeweeException
 from cachetools import lru_cache
 
-from data.model import DataModelException
+from datetime import datetime, timedelta
+
+from data.model import DataModelException, config
 from data.database import (Repository, User, Team, TeamMember, RepositoryPermission, TeamRole,
                            Namespace, Visibility, ImageStorage, Image, RepositoryKind,
                            db_for_update)
 
+logger = logging.getLogger(__name__)
+
 def reduce_as_tree(queries_to_reduce):
   """ This method will split a list of queries into halves recursively until we reach individual
       queries, at which point it will start unioning the queries, or the already unioned subqueries.
@@ -164,3 +170,36 @@ def calculate_image_aggregate_size(ancestors_str, image_size, parent_image):
     return None
 
   return ancestor_size + image_size
+
+
+def update_last_accessed(token_or_user):
+  """ Updates the `last_accessed` field on the given token or user. If the existing field's value
+      is within the configured threshold, the update is skipped. """
+  threshold = timedelta(seconds=config.app_config.get('LAST_ACCESSED_UPDATE_THRESHOLD_S', 120))
+  if (token_or_user.last_accessed is not None and
+      datetime.utcnow() - token_or_user.last_accessed < threshold):
+    # Skip updating, as we don't want to put undue pressure on the database.
+    return
+
+  model_class = token_or_user.__class__
+  last_accessed = datetime.utcnow()
+
+  try:
+    (model_class
+     .update(last_accessed=last_accessed)
+     .where(model_class.id == token_or_user.id)
+     .execute())
+    token_or_user.last_accessed = last_accessed
+  except PeeweeException as ex:
+    # If there is any form of DB exception, only fail if strict logging is enabled.
+    strict_logging_disabled = config.app_config.get('ALLOW_PULLS_WITHOUT_STRICT_LOGGING')
+    if strict_logging_disabled:
+      data = {
+        'exception': ex,
+        'token_or_user': token_or_user.id,
+        'class': str(model_class),
+      }
+
+      logger.exception('update last_accessed for token/user failed', extra=data)
+    else:
+      raise