fix header level

Dex isn't yet [1,2] a certified OpenID Provider implementation. As of today, it's not on the list maintained by the OpenID Foundation. [3]

[1] https://github.com/dexidp/dex/issues/42
[2] https://github.com/dexidp/dex/issues/262
[3] https://openid.net/certification/

* Add note to postgres doc about hugepages

* Newsfragment

* Add check to catch syanpse master process starting when workers are configured

* add test to verify that starting master process with worker config raises error

* newsfragment

* specify config.worker.worker_app in check

* update test

* report specific config option that triggered the error

Co-authored-by: reivilibre <oliverw@matrix.org>

* clarify error message

Co-authored-by: reivilibre <oliverw@matrix.org>

Co-authored-by: reivilibre <oliverw@matrix.org>

Co-authored-by: reivilibre <oliverw@matrix.org>

Per updates to MSC2675 which now states that bundled
aggregations should be included from the `/relations`
endpoint.

When all entries in an `LruCache` have a size of 0 according to the
provided `size_callback`, and `drop_from_cache` is called on a cache
node, the node would be unlinked from the LRU linked list but remain in
the cache dictionary. An assertion would be later be tripped due to the
inconsistency.

Avoid unintentionally calling `__len__` and use a strict `is None`
check instead when unwrapping the weak reference.

The tests helpers automatically convert dictionaries to
JSON payloads, no need to do it manually for each
test.

If you're trying to shut down Synapse, it's rather handy if it *actually* shuts
down before you move on.

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

Refactor `backfilled` into specific behavior function arguments (`_persist_events_and_state_updates`) (#11417)

Part of https://github.com/matrix-org/synapse/issues/11300

Call stack:

 - `_persist_events_and_state_updates` (added `use_negative_stream_ordering`)
    - `_persist_events_txn`
       - `_update_room_depths_txn` (added `update_room_forward_stream_ordering`)
       - `_update_metadata_tables_txn`
          - `_store_room_members_txn` (added `inhibit_local_membership_updates`)

Using keyword-only arguments (`*`) to reduce the mistakes from `backfilled` being left as a positional argument somewhere and being interpreted wrong by our new arguments.

This also makes additional updates where the implementation
had drifted from the approved MSC.

Unstable endpoints will be removed at a later data.

Co-authored-by: Brendan Abolivier <babolivier@matrix.org>

This does not remove the unstable field and still parses both.
Handling of the unstable field will need to be removed in the
future.

If we tried to request multiple keys for the same server, we would end up
dropping some of those requests.

Signed-off-by: Tulir Asokan <tulir@beeper.com>

This would have caught the bug #11438 introduced in #11217 and fixed in #11439.

Since e81fa926, Synapse depends on
the use_float flag which has been introduced in ijson 3.1 and
is not available in 3.0. This is known to cause runtime errors
with send_join.

Signed-off-by: Daniel Molkentin <danimo@infra.run>

Co-authored-by: Daniel Molkentin <danimo@infra.run>

Update MSC2918 refresh token support to confirm with the latest revision: accept the `refresh_tokens` parameter in the request body rather than in the URL parameters. (#11430)

Also refactor the stream ID trackers/generators a bit and try to
document them better.

Support expiry of refresh tokens and expiry of the overall session when refresh tokens are in use. (#11425)

The intent is to iterate through all the worker ports and only
report healthy when all are healthy, starting with the main process.

The previous fix for the ongoing event fetches counter
(8eec25a1) was both insufficient and
incorrect.

When the database is unreachable, `_do_fetch` never gets run and so
`_event_fetch_ongoing` is never decremented.

The previous fix also moved the `_event_fetch_ongoing` decrement outside
of the `_event_fetch_lock` which allowed race conditions to corrupt the
counter.

This change makes mypy complain if the constants are ever reassigned,
and, more usefully, makes mypy type them as `Literal`s instead of `str`s,
allowing code of the following form to pass mypy:
```py
def do_something(membership: Literal["join", "leave"], ...): ...

do_something(Membership.JOIN, ...)
```