Discovered while working on https://github.com/matrix-org/synapse/pull/13589 and I had all the messages at the same timestamp in the tests.

Part of https://github.com/matrix-org/matrix-spec-proposals/pull/3030

Complement tests: https://github.com/matrix-org/complement/pull/457

This has been the same as a generic_worker since #6964, so let's get rid of it.

Fixes #3717

It can be authenticated with the worker_replication_secret setting,
but is always unencrypted.

We incorrectly didn't use the returned `Responder` if the client had
disconnected, which meant that the resource used by the Responder
wasn't correctly released.

In particular, this exhausted the thread pools so that *all* requests
timed out.

Media downloaded as part of a URL preview is normally deleted after two days.
However, while a background database migration is running, the process is
stopped. A long-running database migration can therefore cause the media
store to fill up with old preview files.

This logic was added in #2697 to make sure that we didn't try to run the expiry
without an index on `local_media_repository.created_ts`; the original logic that
needs that index was added in #2478 (in `get_url_cache_media_before`, as
amended by 93247a42), and is still present.

Given that the background update was added before Synapse v1.0.0, just drop
this check and assume the index exists.

By using `execute_values` instead of `execute_batch`.

* Fix rate limit metrics registering twice and misreporting

Fix https://github.com/matrix-org/synapse/issues/13641

* Fix lints

* Add changelog

* Document `metrics_name=None`.

Optimize how we calculate `likely_domains` during backfill because I've seen this take 17s in production just to `get_current_state` which is used to `get_domains_from_state` (see case [*2. Loading tons of events* in the `/messages` investigation issue](https://github.com/matrix-org/synapse/issues/13356)).

There are 3 ways we currently calculate hosts that are in the room:

 1. `get_current_state` -> `get_domains_from_state`
    - Used in `backfill` to calculate `likely_domains` and `/timestamp_to_event` because it was cargo-culted from `backfill`
    - This one is being eliminated in favor of `get_current_hosts_in_room` in this PR 
 1. `get_current_hosts_in_room`
    - Used for other federation things like sending read receipts and typing indicators
 1. `get_hosts_in_room_at_events`
    - Used when pushing out events over federation to other servers in the `_process_event_queue_loop`

Fix https://github.com/matrix-org/synapse/issues/13626

Part of https://github.com/matrix-org/synapse/issues/13356

Mentioned in [internal doc](https://docs.google.com/document/d/1lvUoVfYUiy6UaHB6Rb4HicjaJAU40-APue9Q4vzuW3c/edit#bookmark=id.2tvwz3yhcafh)


### Query performance

#### Before

The query from `get_current_state` sucks just because we have to get all 80k events. And we see almost the exact same performance locally trying to get all of these events (16s vs 17s):
```
synapse=# SELECT type, state_key, event_id FROM current_state_events WHERE room_id = '!OGEhHVWSdvArJzumhm:matrix.org';
Time: 16035.612 ms (00:16.036)

synapse=# SELECT type, state_key, event_id FROM current_state_events WHERE room_id = '!OGEhHVWSdvArJzumhm:matrix.org';
Time: 4243.237 ms (00:04.243)
```

But what about `get_current_hosts_in_room`: When there is 8M rows in the `current_state_events` table, the previous query in `get_current_hosts_in_room` took 13s from complete freshness (when the events were first added). But takes 930ms after a Postgres restart or 390ms if running back to back to back.

```sh
$ psql synapse
synapse=# \timing on
synapse=# SELECT COUNT(DISTINCT substring(state_key FROM '@[^:]*:(.*)$'))
FROM current_state_events
WHERE
    type = 'm.room.member'
    AND membership = 'join'
    AND room_id = '!OGEhHVWSdvArJzumhm:matrix.org';
 count
-------
  4130
(1 row)

Time: 13181.598 ms (00:13.182)

synapse=# SELECT COUNT(*) from current_state_events where room_id = '!OGEhHVWSdvArJzumhm:matrix.org';
 count
-------
 80814

synapse=# SELECT COUNT(*) from current_state_events;
  count
---------
 8162847

synapse=# SELECT pg_size_pretty( pg_total_relation_size('current_state_events') );
 pg_size_pretty
----------------
 4702 MB
```

#### After

I'm not sure how long it takes from complete freshness as I only really get that opportunity once (maybe restarting computer but that's cumbersome) and it's not really relevant to normal operating times. Maybe you get closer to the fresh times the more access variability there is so that Postgres caches aren't as exact. Update: The longest I've seen this run for is 6.4s and 4.5s after a computer restart.

After a Postgres restart, it takes 330ms and running back to back takes 260ms.

```sh
$ psql synapse
synapse=# \timing on
Timing is on.
synapse=# SELECT
    substring(c.state_key FROM '@[^:]*:(.*)$') as host
FROM current_state_events c
/* Get the depth of the event from the events table */
INNER JOIN events AS e USING (event_id)
WHERE
    c.type = 'm.room.member'
    AND c.membership = 'join'
    AND c.room_id = '!OGEhHVWSdvArJzumhm:matrix.org'
GROUP BY host
ORDER BY min(e.depth) ASC;
Time: 333.800 ms
```

#### Going further

To improve things further we could add a `limit` parameter to `get_current_hosts_in_room`. Realistically, we don't need 4k domains to choose from because there is no way we're going to query that many before we a) probably get an answer or b) we give up. 

Another thing we can do is optimize the query to use a index skip scan:

 - https://wiki.postgresql.org/wiki/Loose_indexscan
 - Index Skip Scan, https://commitfest.postgresql.org/37/1741/
 - https://www.timescale.com/blog/how-we-made-distinct-queries-up-to-8000x-faster-on-postgresql/

Since github always scrolls to the bottom of any test output, let's put the
failed tests last and hide any successful packages.

Update a bunch of the documentation for user registration, add some cross
links, etc.

If things like the signing key file are missing, let's just try to generate
them on startup.

Again, this is useful for k8s-like deployments where we just want to generate
keys on the first run.

* Update debian packaging to debhelper version 12

Don't call dh_installinit anymore, because it has been deprecated, and use
dh_installsystemd instead of dh_systemd_enable for the same reason.

Signed-off-by: Jörg Behrmann <behrmann@physik.fu-berlin.de>

* Drop preinst script

It was used for reasons of interactions of dh_systemd_start and dh_installinit,
which have both be deprecated

Signed-off-by: Jörg Behrmann <behrmann@physik.fu-berlin.de>

* Drop /etc/default file

It was no longer being installed.

* Remove debian/compat file

This is managed by the control file nowadays

Fixes #9927

Signed-off-by: Brad Murray <brad@beeper.com>

Otherwise the files of the synapse user are readable by the nobody user, which
is unsafe.

Signed-off-by: Jörg Behrmann <behrmann@physik.fu-berlin.de>

A new `registration_shared_secret_path` option. This is kinda handy for k8s deployments and things.

Fixes https://github.com/matrix-org/synapse/issues/3672:
`https://localhost:8448` is virtually never right.

GitHub appears to be deprecating addProjectNextItem by not allowing it to be used alongside projectV2 to get the project ID, so switching to using addProjectV2ItemById instead.

Split off from https://github.com/matrix-org/synapse/pull/13561

Part of https://github.com/matrix-org/synapse/issues/13356

Mentioned in [internal doc](https://docs.google.com/document/d/1lvUoVfYUiy6UaHB6Rb4HicjaJAU40-APue9Q4vzuW3c/edit#bookmark=id.2tvwz3yhcafh)

See https://github.com/matrix-org/synapse/pull/13575#discussion_r953023755

Directly lookup local membership instead of getting all members in a room first (`get_users_in_room` mis-use) (#13608)

See https://github.com/matrix-org/synapse/pull/13575#discussion_r953023755

When loading current ids, sort by `stream_id` to avoid incorrect overwrite and avoid errors caused by sorting alphabetical instance name which can be `null` (#13585)

When loading current ids, sort by stream ID so that we don't want to overwrite the `current_position` of an instance to a lower stream ID than we're actually at ([discussion](https://github.com/matrix-org/synapse/pull/13585#discussion_r951795379)). Previously, it sorted alphabetically by instance name which can be `null` and throw errors but more importantly, accomplishes nothing.

Fixes the following startup error which is why I started looking into this area:

```
$ poetry run synapse_homeserver --config-path homeserver.yaml
****************************************************************
 Error during initialisation:
    '<' not supported between instances of 'NoneType' and 'str'
 There may be more information in the logs.
****************************************************************
```

Somehow my database ended up looking like the following, notice the `instance_name` is `null` in the db, and we can't sort `NoneType` things. Another question is why do we see the `instance_name` as `null` sometimes instead of `master` in monolith mode?
```
$ psql synapse
synapse=# SELECT * FROM stream_positions;
   stream_name   | instance_name | stream_id
-----------------+---------------+-----------
 account_data    | master        |      1242
 events          | master        |      1787
 to_device       | master        |        58
 presence_stream | master        |    485638
 receipts        | master        |       341
 backfill        | master        |   -139106
(6 rows)
synapse=# SELECT instance_name, stream_id FROM receipts_linearized;
 instance_name | stream_id
---------------+-----------
               |       211
               |         3
               |         4
               |       212
               |       213
               |       224
               |       228
               |       164
               |       313
               |       253
               |        38
               |       321
               |       324
               |       189
               |       192
               |       193
               |       194
               |       195
               |       197
               |       198
               |       275
               |        79
               |       339
               |       340
               |        82
               |       341
               |        84
               |        85
               |        91
               |       119
```

Use dedicated `get_local_users_in_room` to find local users when calculating `join_authorised_via_users_server` of a `/make_join` request (#13606)

Use dedicated `get_local_users_in_room` to find local users when calculating `join_authorised_via_users_server` ("the authorising user for joining a restricted room") of a `/make_join` request.

Found while working on https://github.com/matrix-org/synapse/pull/13575#discussion_r953023755 but it's not related.

Co-authored-by: David Robertson <davidr@element.io>

Set up automation to move newly opened issues in GitHub to the issue triage board.

Faster Room Joins: fix `/make_knock` blocking indefinitely when the room in question is a partial-stated room. (#13583)

Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>

Instrument `_check_sigs_and_hash_and_fetch` to trace time spent in child concurrent calls because I've see `_check_sigs_and_hash_and_fetch` take [10.41s to process 100 events](https://github.com/matrix-org/synapse/issues/13587)

Fix https://github.com/matrix-org/synapse/issues/13587

Part of https://github.com/matrix-org/synapse/issues/13356

Co-authored-by: Sean Quah <8349537+squahtx@users.noreply.github.com>

This speeds things up by ~2x.

The vast majority of the time is now spent in `LruCache` moving things around the linked lists.

We do this via two things:
1. Don't create a deferred per-key during bulk set operations in `DeferredCache`. Instead, only create them if a subsequent caller asks for the key.
2. Add a bulk lookup API to `DeferredCache` rather than use a loop.

Broke in #13573. 

Linking the help article may prevent confusion regarding the creation of the necessary rule using auth0.

Synapse 1.66.0rc1 (2022-08-23)
==============================

This release removes the ability for homeservers to delegate email ownership
verification and password reset confirmation to identity servers. This removal
was originally planned for Synapse 1.64, but was later deferred until now.

See the [upgrade notes](https://matrix-org.github.io/synapse/v1.66/upgrade.html#upgrading-to-v1660) for more details.

Features
--------

- Improve validation of request bodies for the following client-server API endpoints: [`/account/password`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3accountpassword), [`/account/password/email/requestToken`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3accountpasswordemailrequesttoken), [`/account/deactivate`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3accountdeactivate) and [`/account/3pid/email/requestToken`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3account3pidemailrequesttoken). ([\#13188](https://github.com/matrix-org/synapse/issues/13188), [\#13563](https://github.com/matrix-org/synapse/issues/13563))
- Add forgotten status to [Room Details Admin API](https://matrix-org.github.io/synapse/latest/admin_api/rooms.html#room-details-api). ([\#13503](https://github.com/matrix-org/synapse/issues/13503))
- Add an experimental implementation for [MSC3852 (Expose user agents on `Device`)](https://github.com/matrix-org/matrix-spec-proposals/pull/3852). ([\#13549](https://github.com/matrix-org/synapse/issues/13549))
- Add `org.matrix.msc2716v4` experimental room version with updated content fields. Part of [MSC2716 (Importing history)](https://github.com/matrix-org/matrix-spec-proposals/pull/2716).  ([\#13551](https://github.com/matrix-org/synapse/issues/13551))
- Add support for compression to federation responses. ([\#13537](https://github.com/matrix-org/synapse/issues/13537))
- Improve performance of sending messages in rooms with thousands of local users. ([\#13522](https://github.com/matrix-org/synapse/issues/13522), [\#13547](https://github.com/matrix-org/synapse/issues/13547))

Bugfixes
--------

- Faster room joins: make `/joined_members` block whilst the room is partial stated. ([\#13514](https://github.com/matrix-org/synapse/issues/13514))
- Fix a bug introduced in Synapse 1.21.0 where the [`/event_reports` Admin API](https://matrix-org.github.io/synapse/develop/admin_api/event_reports.html) could return a total count which was larger than the number of results you can actually query for. ([\#13525](https://github.com/matrix-org/synapse/issues/13525))
- Fix a bug introduced in Synapse 1.52.0 where sending server notices fails if `max_avatar_size` or `allowed_avatar_mimetypes` is set and not `system_mxid_avatar_url`. ([\#13566](https://github.com/matrix-org/synapse/issues/13566))
- Fix a bug where the `opentracing.force_tracing_for_users` config option would not apply to [`/sendToDevice`](https://spec.matrix.org/v1.3/client-server-api/#put_matrixclientv3sendtodeviceeventtypetxnid) and [`/keys/upload`](https://spec.matrix.org/v1.3/client-server-api/#post_matrixclientv3keysupload) requests. ([\#13574](https://github.com/matrix-org/synapse/issues/13574))

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

- Add `openssl` example for generating registration HMAC digest. ([\#13472](https://github.com/matrix-org/synapse/issues/13472))
- Tidy up Synapse's README. ([\#13491](https://github.com/matrix-org/synapse/issues/13491))
- Document that event purging related to the `redaction_retention_period` config option is executed only every 5 minutes. ([\#13492](https://github.com/matrix-org/synapse/issues/13492))
- Add a warning to retention documentation regarding the possibility of database corruption. ([\#13497](https://github.com/matrix-org/synapse/issues/13497))
- Document that the `DOCKER_BUILDKIT=1` flag is needed to build the docker image. ([\#13515](https://github.com/matrix-org/synapse/issues/13515))
- Add missing links in `user_consent` section of configuration manual. ([\#13536](https://github.com/matrix-org/synapse/issues/13536))
- Fix the doc and some warnings that were referring to the nonexistent `custom_templates_directory` setting (instead of `custom_template_directory`). ([\#13538](https://github.com/matrix-org/synapse/issues/13538))

Deprecations and Removals
-------------------------

- Remove the ability for homeservers to delegate email ownership verification
  and password reset confirmation to identity servers. See [upgrade notes](https://matrix-org.github.io/synapse/v1.66/upgrade.html#upgrading-to-v1660) for more details.

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

- Update the rejected state of events during de-partial-stating. ([\#13459](https://github.com/matrix-org/synapse/issues/13459))
- Avoid blocking lazy-loading `/sync`s during partial joins due to remote memberships. Pull remote memberships from auth events instead of the room state. ([\#13477](https://github.com/matrix-org/synapse/issues/13477))
- Refuse to start when faster joins is enabled on a deployment with workers, since worker configurations are not currently supported. ([\#13531](https://github.com/matrix-org/synapse/issues/13531))

- Allow use of both `@trace` and `@tag_args` stacked on the same function. ([\#13453](https://github.com/matrix-org/synapse/issues/13453))
- Instrument the federation/backfill part of `/messages` for understandable traces in Jaeger. ([\#13489](https://github.com/matrix-org/synapse/issues/13489))
- Instrument `FederationStateIdsServlet` (`/state_ids`) for understandable traces in Jaeger. ([\#13499](https://github.com/matrix-org/synapse/issues/13499), [\#13554](https://github.com/matrix-org/synapse/issues/13554))
- Track HTTP response times over 10 seconds from `/messages` (`synapse_room_message_list_rest_servlet_response_time_seconds`). ([\#13533](https://github.com/matrix-org/synapse/issues/13533))
- Add metrics to track how the rate limiter is affecting requests (sleep/reject). ([\#13534](https://github.com/matrix-org/synapse/issues/13534), [\#13541](https://github.com/matrix-org/synapse/issues/13541))
- Add metrics to time how long it takes us to do backfill processing (`synapse_federation_backfill_processing_before_time_seconds`, `synapse_federation_backfill_processing_after_time_seconds`). ([\#13535](https://github.com/matrix-org/synapse/issues/13535), [\#13584](https://github.com/matrix-org/synapse/issues/13584))
- Add metrics to track rate limiter queue timing (`synapse_rate_limit_queue_wait_time_seconds`). ([\#13544](https://github.com/matrix-org/synapse/issues/13544))
- Update metrics to track `/messages` response time by room size. ([\#13545](https://github.com/matrix-org/synapse/issues/13545))

- Refactor methods in `synapse.api.auth.Auth` to use `Requester` objects everywhere instead of user IDs. ([\#13024](https://github.com/matrix-org/synapse/issues/13024))
- Clean-up tests for notifications. ([\#13471](https://github.com/matrix-org/synapse/issues/13471))
- Add some miscellaneous comments to document sync, especially around `compute_state_delta`. ([\#13474](https://github.com/matrix-org/synapse/issues/13474))
- Use literals in place of `HTTPStatus` constants in tests. ([\#13479](https://github.com/matrix-org/synapse/issues/13479), [\#13488](https://github.com/matrix-org/synapse/issues/13488))
- Add comments about how event push actions are rotated. ([\#13485](https://github.com/matrix-org/synapse/issues/13485))
- Modify HTML template content to better support mobile devices' screen sizes. ([\#13493](https://github.com/matrix-org/synapse/issues/13493))
- Add a linter script which will reject non-strict types in Pydantic models. ([\#13502](https://github.com/matrix-org/synapse/issues/13502))
- Reduce the number of tests using legacy TCP replication. ([\#13543](https://github.com/matrix-org/synapse/issues/13543))
- Allow specifying additional request fields when using the `HomeServerTestCase.login` helper method. ([\#13549](https://github.com/matrix-org/synapse/issues/13549))
- Make `HomeServerTestCase` load any configured homeserver modules automatically. ([\#13558](https://github.com/matrix-org/synapse/issues/13558))