* Pull Sentinel out of LoggingContext

... and drop a few unnecessary references to it

* Factor out LoggingContext.current_context

move `current_context` and `set_context` out to top-level functions.

Mostly this means that I can more easily trace what's actually referring to
LoggingContext, but I think it's generally neater.

* move copy-to-parent into `stop`

this really just makes `start` and `stop` more symetric. It also means that it
behaves correctly if you manually `set_log_context` rather than using the
context manager.

* Replace `LoggingContext.alive` with `finished`

Turn `alive` into `finished` and make it a bit better defined.

Build the same service URL when requesting the CAS ticket and when calling the proxyValidate URL.

Signed-off-by: Kartikaya Gupta <kats@trevize.staktrace.com>

This just helps keep the rows closer to their streams, so that it's easier to
see what the format of each stream is.

Synapse 1.12.0 (2020-03-23)
===========================

No significant changes since 1.12.0rc1.

Debian packages and Docker images are rebuilt using the latest versions of
dependency libraries, including Twisted 20.3.0. **Please see security advisory
below**.

Security advisory
-----------------

Synapse may be vulnerable to request-smuggling attacks when it is used with a
reverse-proxy. The vulnerabilties are fixed in Twisted 20.3.0, and are
described in
[CVE-2020-10108](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-10108)
and
[CVE-2020-10109](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-10109).
For a good introduction to this class of request-smuggling attacks, see
https://portswigger.net/research/http-desync-attacks-request-smuggling-reborn.

We are not aware of these vulnerabilities being exploited in the wild, and
do not believe that they are exploitable with current versions of any reverse
proxies. Nevertheless, we recommend that all Synapse administrators ensure that
they have the latest versions of the Twisted library to ensure that their
installation remains secure.

* Administrators using the [`matrix.org` Docker
  image](https://hub.docker.com/r/matrixdotorg/synapse/) or the [Debian/Ubuntu
  packages from
  `matrix.org`](https://github.com/matrix-org/synapse/blob/master/INSTALL.md#matrixorg-packages)
  should ensure that they have version 1.12.0 installed: these images include
  Twisted 20.3.0.
* Administrators who have [installed Synapse from
  source](https://github.com/matrix-org/synapse/blob/master/INSTALL.md#installing-from-source)
  should upgrade Twisted within their virtualenv by running:
  ```sh
  <path_to_virtualenv>/bin/pip install 'Twisted>=20.3.0'
  ```
* Administrators who have installed Synapse from distribution packages should
  consult the information from their distributions.

The `matrix.org` Synapse instance was not vulnerable to these vulnerabilities.

Advance notice of change to the default `git` branch for Synapse
----------------------------------------------------------------

Currently, the default `git` branch for Synapse is `master`, which tracks the
latest release.

After the release of Synapse 1.13.0, we intend to change this default to
`develop`, which is the development tip. This is more consistent with common
practice and modern `git` usage.

Although we try to keep `develop` in a stable state, there may be occasions
where regressions creep in. Developers and distributors who have scripts which
run builds using the default branch of `Synapse` should therefore consider
pinning their scripts to `master`.

Synapse 1.12.0rc1 (2020-03-19)
==============================

Features
--------

- Changes related to room alias management ([MSC2432](https://github.com/matrix-org/matrix-doc/pull/2432)):
  - Publishing/removing a room from the room directory now requires the user to have a power level capable of modifying the canonical alias, instead of the room aliases. ([\#6965](https://github.com/matrix-org/synapse/issues/6965))
  - Validate the `alt_aliases` property of canonical alias events. ([\#6971](https://github.com/matrix-org/synapse/issues/6971))
  - Users with a power level sufficient to modify the canonical alias of a room can now delete room aliases. ([\#6986](https://github.com/matrix-org/synapse/issues/6986))
  - Implement updated authorization rules and redaction rules for aliases events, from [MSC2261](https://github.com/matrix-org/matrix-doc/pull/2261) and [MSC2432](https://github.com/matrix-org/matrix-doc/pull/2432). ([\#7037](https://github.com/matrix-org/synapse/issues/7037))
  - Stop sending m.room.aliases events during room creation and upgrade. ([\#6941](https://github.com/matrix-org/synapse/issues/6941))
  - Synapse no longer uses room alias events to calculate room names for push notifications. ([\#6966](https://github.com/matrix-org/synapse/issues/6966))
  - The room list endpoint no longer returns a list of aliases. ([\#6970](https://github.com/matrix-org/synapse/issues/6970))
  - Remove special handling of aliases events from [MSC2260](https://github.com/matrix-org/matrix-doc/pull/2260) added in v1.10.0rc1. ([\#7034](https://github.com/matrix-org/synapse/issues/7034))
- Expose the `synctl`, `hash_password` and `generate_config` commands in the snapcraft package. Contributed by @devec0. ([\#6315](https://github.com/matrix-org/synapse/issues/6315))
- Check that server_name is correctly set before running database updates. ([\#6982](https://github.com/matrix-org/synapse/issues/6982))
- Break down monthly active users by `appservice_id` and emit via Prometheus. ([\#7030](https://github.com/matrix-org/synapse/issues/7030))
- Render a configurable and comprehensible error page if something goes wrong during the SAML2 authentication process. ([\#7058](https://github.com/matrix-org/synapse/issues/7058), [\#7067](https://github.com/matrix-org/synapse/issues/7067))
- Add an optional parameter to control whether other sessions are logged out when a user's password is modified. ([\#7085](https://github.com/matrix-org/synapse/issues/7085))
- Add prometheus metrics for the number of active pushers. ([\#7103](https://github.com/matrix-org/synapse/issues/7103), [\#7106](https://github.com/matrix-org/synapse/issues/7106))
- Improve performance when making HTTPS requests to sygnal, sydent, etc, by sharing the SSL context object between connections. ([\#7094](https://github.com/matrix-org/synapse/issues/7094))

Bugfixes
--------

- When a user's profile is updated via the admin API, also generate a displayname/avatar update for that user in each room. ([\#6572](https://github.com/matrix-org/synapse/issues/6572))
- Fix a couple of bugs in email configuration handling. ([\#6962](https://github.com/matrix-org/synapse/issues/6962))
- Fix an issue affecting worker-based deployments where replication would stop working, necessitating a full restart, after joining a large room. ([\#6967](https://github.com/matrix-org/synapse/issues/6967))
- Fix `duplicate key` error which was logged when rejoining a room over federation. ([\#6968](https://github.com/matrix-org/synapse/issues/6968))
- Prevent user from setting 'deactivated' to anything other than a bool on the v2 PUT /users Admin API. ([\#6990](https://github.com/matrix-org/synapse/issues/6990))
- Fix py35-old CI by using native tox package. ([\#7018](https://github.com/matrix-org/synapse/issues/7018))
- Fix a bug causing `org.matrix.dummy_event` to be included in responses from `/sync`. ([\#7035](https://github.com/matrix-org/synapse/issues/7035))
- Fix a bug that renders UTF-8 text files incorrectly when loaded from media. Contributed by @TheStranjer. ([\#7044](https://github.com/matrix-org/synapse/issues/7044))
- Fix a bug that would cause Synapse to respond with an error about event visibility if a client tried to request the state of a room at a given token. ([\#7066](https://github.com/matrix-org/synapse/issues/7066))
- Repair a data-corruption issue which was introduced in Synapse 1.10, and fixed in Synapse 1.11, and which could cause `/sync` to return with 404 errors about missing events and unknown rooms. ([\#7070](https://github.com/matrix-org/synapse/issues/7070))
- Fix a bug causing account validity renewal emails to be sent even if the feature is turned off in some cases. ([\#7074](https://github.com/matrix-org/synapse/issues/7074))

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

- Updated CentOS8 install instructions. Contributed by Richard Kellner. ([\#6925](https://github.com/matrix-org/synapse/issues/6925))
- Fix `POSTGRES_INITDB_ARGS` in the `contrib/docker/docker-compose.yml` example docker-compose configuration. ([\#6984](https://github.com/matrix-org/synapse/issues/6984))
- Change date in [INSTALL.md](./INSTALL.md#tls-certificates) for last date of getting TLS certificates to November 2019. ([\#7015](https://github.com/matrix-org/synapse/issues/7015))
- Document that the fallback auth endpoints must be routed to the same worker node as the register endpoints. ([\#7048](https://github.com/matrix-org/synapse/issues/7048))

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

- Remove the unused query_auth federation endpoint per [MSC2451](https://github.com/matrix-org/matrix-doc/pull/2451). ([\#7026](https://github.com/matrix-org/synapse/issues/7026))

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

- Add type hints to `logging/context.py`. ([\#6309](https://github.com/matrix-org/synapse/issues/6309))
- Add some clarifications to `README.md` in the database schema directory. ([\#6615](https://github.com/matrix-org/synapse/issues/6615))
- Refactoring work in preparation for changing the event redaction algorithm. ([\#6874](https://github.com/matrix-org/synapse/issues/6874), [\#6875](https://github.com/matrix-org/synapse/issues/6875), [\#6983](https://github.com/matrix-org/synapse/issues/6983), [\#7003](https://github.com/matrix-org/synapse/issues/7003))
- Improve performance of v2 state resolution for large rooms. ([\#6952](https://github.com/matrix-org/synapse/issues/6952), [\#7095](https://github.com/matrix-org/synapse/issues/7095))
- Reduce time spent doing GC, by freezing objects on startup. ([\#6953](https://github.com/matrix-org/synapse/issues/6953))
- Minor perfermance fixes to `get_auth_chain_ids`. ([\#6954](https://github.com/matrix-org/synapse/issues/6954))
- Don't record remote cross-signing keys in the `devices` table. ([\#6956](https://github.com/matrix-org/synapse/issues/6956))
- Use flake8-comprehensions to enforce good hygiene of list/set/dict comprehensions. ([\#6957](https://github.com/matrix-org/synapse/issues/6957))
- Merge worker apps together. ([\#6964](https://github.com/matrix-org/synapse/issues/6964), [\#7002](https://github.com/matrix-org/synapse/issues/7002), [\#7055](https://github.com/matrix-org/synapse/issues/7055), [\#7104](https://github.com/matrix-org/synapse/issues/7104))
- Remove redundant `store_room` call from `FederationHandler._process_received_pdu`. ([\#6979](https://github.com/matrix-org/synapse/issues/6979))
- Update warning for incorrect database collation/ctype to include link to documentation. ([\#6985](https://github.com/matrix-org/synapse/issues/6985))
- Add some type annotations to the database storage classes. ([\#6987](https://github.com/matrix-org/synapse/issues/6987))
- Port `synapse.handlers.presence` to async/await. ([\#6991](https://github.com/matrix-org/synapse/issues/6991), [\#7019](https://github.com/matrix-org/synapse/issues/7019))
- Add some type annotations to the federation base & client classes. ([\#6995](https://github.com/matrix-org/synapse/issues/6995))
- Port `synapse.rest.keys` to async/await. ([\#7020](https://github.com/matrix-org/synapse/issues/7020))
- Add a type check to `is_verified` when processing room keys. ([\#7045](https://github.com/matrix-org/synapse/issues/7045))
- Add type annotations and comments to the auth handler. ([\#7063](https://github.com/matrix-org/synapse/issues/7063))

`groups` != `receipts`

Introduced in #6964

Attempts to clarify the sample config for databases, and add some stuff about
tcp keepalives to `postgres.md`.

* Add 'device_lists_outbound_pokes' as extra table.

This makes sure we check all the relevant tables to get the current max
stream ID.

Currently not doing so isn't problematic as the max stream ID in
`device_lists_outbound_pokes` is the same as in `device_lists_stream`,
however that will change.

* Change device lists stream to have one row per id.

This will make it possible to process the streams more incrementally,
avoiding having to process large chunks at once.

* Change device list replication to match new semantics.

Instead of sending down batches of user ID/host tuples, send down a row
per entity (user ID or host).

* Newsfile

* Remove handling of multiple rows per ID

* Fix worker handling

* Comments from review

add a lock to try to make this metric actually work

This should be safe to do on all workers/masters because it is guarded by
a config option which will ensure it is only actually done on the worker
assigned as a pusher.

It was originally implemented by pulling the full auth chain of all
state sets out of the database and doing set comparison. However, that
can take a lot work if the state and auth chains are large.

Instead, lets try and fetch the auth chains at the same time and
calculate the difference on the fly, allowing us to bail early if all
the auth chains converge. Assuming that the auth chains do converge more
often than not, this should improve performance. Hopefully.

Extends #5794 etc to the SimpleHttpClient so that it also applies to non-federation requests.

Fixes #7092.

fix broken link

Fixes #7043

This reverts commit 54dd2862, reversing
changes made to 6640460d.

Fixes #7065 

This is basically the same as https://github.com/matrix-org/synapse/pull/6847 except it tries to populate events from `state_events` rather than `current_state_events`, since the latter might have been cleared from the state of some rooms too early, leaving them with a `NULL` room version.