From ca571b0ec3674cd477e9da5f8e9d20c4dfcaf58b Mon Sep 17 00:00:00 2001 From: Erik Johnston Date: Fri, 27 Oct 2017 11:57:27 +0100 Subject: [PATCH] Add jitter to validity period of attestations This helps ensure that the renewals of attestations are spread out more evenly. --- synapse/groups/attestations.py | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/synapse/groups/attestations.py b/synapse/groups/attestations.py index b751cf5e4..fc5f92121 100644 --- a/synapse/groups/attestations.py +++ b/synapse/groups/attestations.py @@ -13,6 +13,8 @@ # See the License for the specific language governing permissions and # limitations under the License. +import random + from twisted.internet import defer from synapse.api.errors import SynapseError @@ -25,6 +27,11 @@ from signedjson.sign import sign_json # Default validity duration for new attestations we create DEFAULT_ATTESTATION_LENGTH_MS = 3 * 24 * 60 * 60 * 1000 +# We add some jitter to the validity duration of attestations so that if we +# add lots of users at once we don't need to renew them all at once. +# The jitter is a multiplier picked randomly between the first and second number +DEFAULT_ATTESTATION_JITTER = (0.9, 1.3) + # Start trying to update our attestations when they come this close to expiring UPDATE_ATTESTATION_TIME_MS = 1 * 24 * 60 * 60 * 1000 @@ -73,10 +80,14 @@ class GroupAttestationSigning(object): """Create an attestation for the group_id and user_id with default validity length. """ + validity_period = DEFAULT_ATTESTATION_LENGTH_MS + validity_period *= random.uniform(*DEFAULT_ATTESTATION_JITTER) + valid_until_ms = int(self.clock.time_msec() + validity_period) + return sign_json({ "group_id": group_id, "user_id": user_id, - "valid_until_ms": self.clock.time_msec() + DEFAULT_ATTESTATION_LENGTH_MS, + "valid_until_ms": valid_until_ms, }, self.server_name, self.signing_key)