Making thousands of HTTP requests simultaneously inevitably results in some
failing or the server being overwhelmed, so limit how many can be made at once
(currently to the arbitrary cap of 5) and enqueue any further requests.
* When refreshing the token, look up the user in a way that doesn't suffer
from #1586
Expose a means of looking up a user by identity and server to avoid
problems if the same user identity exists for multiple servers, which
can happen when connecting to the same server via different hostnames.
* Return undefined if the user doesn't exist rather than returning an object wrapping a null SyncUser.
* Adding method Realm.Sync.User.authenticate()
* Adding JWT provider support to Realm.Sync.User.authenticate()
* Adding password provider support to Realm.Sync.User.authenticate()
being open with a different schema version
In order to correctly open read-only synchronized Realms, `Realm.open`
would open the Realm without specifying a schema or schema version, wait
for any remote changes to be downloaded (if appropriate), and then
re-open the Realm with the specified schema and schema version. This
would lead to an exception about the Realm being open with a different
schema version if the Realm had previously been opened with a different
schema version, due to the way `RealmCoordinator` caches information
about the schema of open Realms.
We address this by making two changes:
1. `Realm.open` for non-synchronized Realms no longer goes through
`_waitForDownload`. This means the dance described above where the Realm
is opened twice is not used for local Realms.
2. `_waitForDownload` no longer keeps the `Realm` alive until after its
callback has returned. It instead keeps the `SyncSession` alive. This is
sufficient to avoid the connection being torn down and having to
reconnect when `_waitForDownload`'s callback later opens the Realm with
the correct schema and schema version, while also allowing for
`RealmCoordinator`'s cached information to be cleared when the
schemaless Realm is closed prior to the Realm being reopened.
In addition, tests have been added that reproduced the problem in both a
local and sync context.