buildbucket: put_batch endpoint

appengine/cr-buildbucket/service.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import datetime
 import itertools
 import json
 import logging
 import urlparse
 
@@ skipping 117 matching lines @@
     )
     if lease_expiration_date is not None:
       build.lease_expiration_date = lease_expiration_date
       build.leasee = auth.get_current_identity()
       build.regenerate_lease_key()
     build.put()
     logging.info(
         'Build %s was created by %s', build.key.id(), identity.to_bytes())
     return build
 
+  @ndb.transactional(xg=True)  # pylint: disable=no-value-for-parameter

[Vadim Sh., 2015/04/14 18:56:40]

I don't think adding them all transactionally is a good idea:
1) Weird unavoidable limit of 25.
2) It is slow, with 25 groups probably very slow (have you tried it?).

One way of not triggering already triggered builds on retry is to introduce a
new "client_operation_id" into API that server can use to identify retries. E.g.
put_batch([builds], operation_id) -> ([triggered], [existing]). Then from client
point of view put_batch(..., some client id) is essentially idempotent.

[nodir, 2015/04/14 22:13:05]

Done.

+  def add_batch(self, build_params):
+    """Adds multiple builds in a cross-group transaction.
+
+    Args:
+      build_params: list of dicts, where each dict contains parameters for
+        add() method.
+
+    Returns:
+      List of builds.
+    """
+    if len(build_params) > 25:
+      # Cross-group transactions support up to 25 entity groups.
+      raise errors.InvalidInputError('Cannot add more than 25 builds at a time')
+    builds = []
+    for i, req in enumerate(build_params):
+      try:
+        builds.append(self.add(**req))
+      except errors.Error as ex:
+        msg = 'Error in build request %d: %s' % (i, ex.message)
+        raise type(ex)(msg)
+    return builds
+
   def get(self, build_id):
     """Gets a build by |build_id|.
 
     Requires the current user to have permissions to view the build.
     """
     build = model.Build.get_by_id(build_id)
     if not build:
       return None
     identity = auth.get_current_identity()
     if not acl.can_view_build(build, identity):
@@ skipping 457 matching lines @@
 
   def reset_expired_builds(self):
     """For all building expired builds, resets their lease_key and state."""
     q = model.Build.query(
         model.Build.is_leased == True,
         model.Build.lease_expiration_date <= datetime.datetime.utcnow(),
     )
     for key in q.iter(keys_only=True):
       if self._reset_expired_build(key):  # pragma: no branch
         logging.info('Expired build %s was reset' % key.id())