429 responses are cached

[lukebarnard1]

Requests/responses such as

warn: matrix-appservice-bridge [-] PUT http://localhost:8080/_matrix/client/r0/rooms/!mhAdlVvCyQdKdmuIlm%3Alocalhost%3A8480/send/m.room.message/m1484159120283.7 (@_twitter_1344951:localhost:8480) HTTP 429 Error: {"errcode":"M_LIMIT_EXCEEDED","error":"Too Many Requests","retry_after_ms":1480}

have been observed running the twitter bridge against a local synapse. These appear to by cached responses and despite the js-sdk retrying after the given number of retry_after_ms, what appears to be a cached response.

It would be best not to cache these so that the js-sdk doesn't retry for as long as the request is cached.

[ara4n]

It looks like the HttpTransactionCache layer is blindly caching HTTP responses for 30-60mins regardless of whether they are error codes or not. @erikjohnston / @NegativeMjark is this deliberate?

[kegsay]

Most likely not. I touched it last to convert it to using ObservableDeferreds. We should be doing rate limit checks well before then but I guess we don't.

[kegsay]

I have fixed this: #1913