This commit restructures the map session in to a struct
holding the state of what is needed during its lifetime.
For streaming sessions, the event loop is structured a
bit differently not hammering the clients with updates
but rather batching them over a short, configurable time
which should significantly improve cpu usage, and potentially
flakyness.
The use of Patch updates has been dialed back a little as
it does not look like its a 100% ready for prime time. Nodes
are now updated with full changes, except for a few things
like online status.
Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>
This commits removes the locks used to guard data integrity for the
database and replaces them with Transactions, turns out that SQL had
a way to deal with this all along.
This reduces the complexity we had with multiple locks that might stack
or recurse (database, nofitifer, mapper). All notifications and state
updates are now triggered _after_ a database change.
Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>
