check revision after loading

relay-server/src/services/project_redis.rs

@@ -91,25 +91,36 @@ impl RedisProjectSource {
  .query(&mut connection)
  .map_err(RedisError::Redis)?;
 
- let response = match raw_response_opt {
- Some(response) => {
- metric!(
- counter(RelayCounters::ProjectStateRedis) += 1,
- hit = "project_config"
- );
- let parsed = parse_redis_response(response.as_slice())?;
- ProjectState::from(parsed)
- }
- None => {
- metric!(
- counter(RelayCounters::ProjectStateRedis) += 1,
- hit = "false"
- );
- ProjectState::Pending
- }
+ let Some(response) = raw_response_opt else {
+ metric!(
+ counter(RelayCounters::ProjectStateRedis) += 1,
+ hit = "false"
+ );
+ return Ok(Some(ProjectState::Pending));
  };
 
- Ok(Some(response))
+ let response = ProjectState::from(parse_redis_response(response.as_slice())?);
+
+ // If we were passed a revision, check if we just loaded the same revision from Redis.
+ //
+ // We always want to keep the old revision alive if possible, since the already loaded
+ // version has already initialized caches.
+ //
+ // While this is theoretically possible this should always been handled using the above revision
+ // check using the additional Redis key.
+ if revision.is_some() && response.revision() == revision {
+ metric!(
+ counter(RelayCounters::ProjectStateRedis) += 1,
+ hit = "project_config_revision"
+ );
+ Ok(None)
+ } else {
+ metric!(
+ counter(RelayCounters::ProjectStateRedis) += 1,
+ hit = "project_config"
+ );
+ Ok(Some(response))
+ }
  }
 
  fn get_redis_project_config_key(&self, key: ProjectKey) -> String {

relay-server/src/statsd.rs

@@ -651,6 +651,8 @@ pub enum RelayCounters {
  /// - `hit`: One of:
  /// - `revision`: the cached version was validated to be up to date using its revision.
  /// - `project_config`: the request was handled by the cache.
+ /// - `project_config_revision`: the request was handled by the cache and the revision did
+ /// not change.
  /// - `false`: the request will be sent to the sentry endpoint.
  #[cfg(feature = "processing")]
  ProjectStateRedis,