It's just a thin wrapper around two ID gens to make `get_current_token`
and `get_next` return tuples. This can easily be replaced by calling the
appropriate methods on the underlying ID gens directly.

* Updated docs: Added note about missing 308 redirect support.

* Added changelog

The function is used for two purposes: 1) for subscribers of streams to
get a token they can use to get further updates with, and 2) for
replication to track position of the writers of the stream.

For streams with a single writer the two scenarios produce the same
result, however the situation becomes complicated for streams with
multiple writers. The current `MultiWriterIdGenerator` does not
correctly handle the first case (which is not an issue as its only used
for the `caches` stream which nothing subscribes to outside of
replication).

Closes: https://github.com/matrix-org/synapse/issues/6766

Equivalent Sydent PR: https://github.com/matrix-org/sydent/pull/309

I believe it's now time to remove the extra allowed `:` from `client_secret` parameters.

Turns out that part of the codebase (synapse.config.server) checks for this key explicitly. Remove that check.

Fixes https://github.com/matrix-org/synapse/issues/6583

Signed-off-by: Olivier Wilkinson (reivilibre) <olivier@librepush.net>

Synapse 1.19.0rc1 (2020-08-13)
==============================

Removal warning
---------------

As outlined in the [previous release](https://github.com/matrix-org/synapse/releases/tag/v1.18.0), we are no longer publishing Docker images with the `-py3` tag suffix. On top of that, we have also removed the `latest-py3` tag. Please see [the announcement in the upgrade notes for 1.18.0](https://github.com/matrix-org/synapse/blob/develop/UPGRADE.rst#upgrading-to-v1180).

Features
--------

- Add option to allow server admins to join rooms which fail complexity checks. Contributed by @lugino-emeritus. ([\#7902](https://github.com/matrix-org/synapse/issues/7902))
- Add an option to purge room or not with delete room admin endpoint (`POST /_synapse/admin/v1/rooms/<room_id>/delete`). Contributed by @dklimpel. ([\#7964](https://github.com/matrix-org/synapse/issues/7964))
- Add rate limiting to users joining rooms. ([\#8008](https://github.com/matrix-org/synapse/issues/8008))
- Add a `/health` endpoint to every configured HTTP listener that can be used as a health check endpoint by load balancers. ([\#8048](https://github.com/matrix-org/synapse/issues/8048))
- Allow login to be blocked based on the values of SAML attributes. ([\#8052](https://github.com/matrix-org/synapse/issues/8052))
- Allow guest access to the `GET /_matrix/client/r0/rooms/{room_id}/members` endpoint, according to MSC2689. Contributed by Awesome Technologies Innovationslabor GmbH. ([\#7314](https://github.com/matrix-org/synapse/issues/7314))

Bugfixes
--------

- Fix a bug introduced in Synapse v1.7.2 which caused inaccurate membership counts in the room directory. ([\#7977](https://github.com/matrix-org/synapse/issues/7977))
- Fix a long standing bug: 'Duplicate key value violates unique constraint "event_relations_id"' when message retention is configured. ([\#7978](https://github.com/matrix-org/synapse/issues/7978))
- Fix "no create event in auth events" when trying to reject invitation after inviter leaves. Bug introduced in Synapse v1.10.0. ([\#7980](https://github.com/matrix-org/synapse/issues/7980))
- Fix various comments and minor discrepencies in server notices code. ([\#7996](https://github.com/matrix-org/synapse/issues/7996))
- Fix a long standing bug where HTTP HEAD requests resulted in a 400 error. ([\#7999](https://github.com/matrix-org/synapse/issues/7999))
- Fix a long-standing bug which caused two copies of some log lines to be written when synctl was used along with a MemoryHandler logger. ([\#8011](https://github.com/matrix-org/synapse/issues/8011), [\#8012](https://github.com/matrix-org/synapse/issues/8012))

Updates to the Docker image
---------------------------

- We no longer publish Docker images with the `-py3` tag suffix, as [announced in the upgrade notes](https://github.com/matrix-org/synapse/blob/develop/UPGRADE.rst#upgrading-to-v1180). ([\#8056](https://github.com/matrix-org/synapse/issues/8056))

Improved Documentation
----------------------

- Document how to set up a client .well-known file and fix several pieces of outdated documentation. ([\#7899](https://github.com/matrix-org/synapse/issues/7899))
- Improve workers docs. ([\#7990](https://github.com/matrix-org/synapse/issues/7990), [\#8000](https://github.com/matrix-org/synapse/issues/8000))
- Fix typo in `docs/workers.md`. ([\#7992](https://github.com/matrix-org/synapse/issues/7992))
- Add documentation for how to undo a room shutdown. ([\#7998](https://github.com/matrix-org/synapse/issues/7998), [\#8010](https://github.com/matrix-org/synapse/issues/8010))

Internal Changes
----------------

- Reduce the amount of whitespace in JSON stored and sent in responses. Contributed by David Vo. ([\#7372](https://github.com/matrix-org/synapse/issues/7372))
- Switch to the JSON implementation from the standard library and bump the minimum version of the canonicaljson library to 1.2.0. ([\#7936](https://github.com/matrix-org/synapse/issues/7936), [\#7979](https://github.com/matrix-org/synapse/issues/7979))
- Convert various parts of the codebase to async/await. ([\#7947](https://github.com/matrix-org/synapse/issues/7947), [\#7948](https://github.com/matrix-org/synapse/issues/7948), [\#7949](https://github.com/matrix-org/synapse/issues/7949), [\#7951](https://github.com/matrix-org/synapse/issues/7951), [\#7963](https://github.com/matrix-org/synapse/issues/7963), [\#7973](https://github.com/matrix-org/synapse/issues/7973), [\#7975](https://github.com/matrix-org/synapse/issues/7975), [\#7976](https://github.com/matrix-org/synapse/issues/7976), [\#7981](https://github.com/matrix-org/synapse/issues/7981), [\#7987](https://github.com/matrix-org/synapse/issues/7987), [\#7989](https://github.com/matrix-org/synapse/issues/7989), [\#8003](https://github.com/matrix-org/synapse/issues/8003), [\#8014](https://github.com/matrix-org/synapse/issues/8014), [\#8016](https://github.com/matrix-org/synapse/issues/8016), [\#8027](https://github.com/matrix-org/synapse/issues/8027), [\#8031](https://github.com/matrix-org/synapse/issues/8031), [\#8032](https://github.com/matrix-org/synapse/issues/8032), [\#8035](https://github.com/matrix-org/synapse/issues/8035), [\#8042](https://github.com/matrix-org/synapse/issues/8042), [\#8044](https://github.com/matrix-org/synapse/issues/8044), [\#8045](https://github.com/matrix-org/synapse/issues/8045), [\#8061](https://github.com/matrix-org/synapse/issues/8061), [\#8062](https://github.com/matrix-org/synapse/issues/8062), [\#8063](https://github.com/matrix-org/synapse/issues/8063), [\#8066](https://github.com/matrix-org/synapse/issues/8066), [\#8069](https://github.com/matrix-org/synapse/issues/8069), [\#8070](https://github.com/matrix-org/synapse/issues/8070))
- Move some database-related log lines from the default logger to the database/transaction loggers. ([\#7952](https://github.com/matrix-org/synapse/issues/7952))
- Add a script to detect source code files using non-unix line terminators. ([\#7965](https://github.com/matrix-org/synapse/issues/7965), [\#7970](https://github.com/matrix-org/synapse/issues/7970))
- Log the SAML session ID during creation. ([\#7971](https://github.com/matrix-org/synapse/issues/7971))
- Implement new experimental push rules for some users. ([\#7997](https://github.com/matrix-org/synapse/issues/7997))
- Remove redundant and unreliable signature check for v1 Identity Service lookup responses. ([\#8001](https://github.com/matrix-org/synapse/issues/8001))
- Improve the performance of the register endpoint. ([\#8009](https://github.com/matrix-org/synapse/issues/8009))
- Reduce less useful output in the newsfragment CI step. Add a link to the changelog section of the contributing guide on error. ([\#8024](https://github.com/matrix-org/synapse/issues/8024))
- Rename storage layer objects to be more sensible. ([\#8033](https://github.com/matrix-org/synapse/issues/8033))
- Change the default log config to reduce disk I/O and storage for new servers. ([\#8040](https://github.com/matrix-org/synapse/issues/8040))
- Add an assertion on `prev_events` in `create_new_client_event`. ([\#8041](https://github.com/matrix-org/synapse/issues/8041))
- Add a comment to `ServerContextFactory` about the use of `SSLv23_METHOD`. ([\#8043](https://github.com/matrix-org/synapse/issues/8043))
- Log `OPTIONS` requests at `DEBUG` rather than `INFO` level to reduce amount logged at `INFO`. ([\#8049](https://github.com/matrix-org/synapse/issues/8049))
- Reduce amount of outbound request logging at `INFO` level. ([\#8050](https://github.com/matrix-org/synapse/issues/8050))
- It is no longer necessary to explicitly define `filters` in the logging configuration. (Continuing to do so is redundant but harmless.) ([\#8051](https://github.com/matrix-org/synapse/issues/8051))
- Add and improve type hints. ([\#8058](https://github.com/matrix-org/synapse/issues/8058), [\#8064](https://github.com/matrix-org/synapse/issues/8064), [\#8060](https://github.com/matrix-org/synapse/issues/8060), [\#8067](https://github.com/matrix-org/synapse/issues/8067))

Signed-off-by: Olivier Wilkinson (reivilibre) <olivier@librepush.net>

Signed-off-by: Olivier Wilkinson (reivilibre) <olivier@librepush.net>

Signed-off-by: Olivier Wilkinson (reivilibre) <olivier@librepush.net>

If we got an error persisting an event, we would try to remove the push actions
asynchronously, which would lead to a 'Re-starting finished log context'
warning.

I don't think there's any need for this to be asynchronous.

* Empty federation transmission queues when we are backing off.

Fixes #7828.

Signed-off-by: Olivier Wilkinson (reivilibre) <olivier@librepush.net>

* Address feedback

Signed-off-by: Olivier Wilkinson (reivilibre) <olivier@librepush.net>

* Reword newsfile