Instead of using the cache invalidation replication stream to invalidate
the _get_presence_cache, we can instead rely on the presence replication
stream. This reduces the amount of replication traffic considerably.
synapse
This is necessary for replicating the data in synapse to be visible to a
separate service because presence and typing notifications aren't stored
in a database so won't be visible to another process.
This API can be used to either get the raw data by requesting the tables
themselves or to just receive notifications for updates by following the
streams meta-stream.
Returns updates for each table requested a JSON array of arrays with a
row for each row in the table.
Each table is prefixed by a header row with the: name of the table,
current stream_id position for the table, number of rows, number of
columns and the names of the columns.
This is followed by the rows that have been added to the server since
the requester last asked.
The API has a timeout and is hooked up to the notifier so that a slave
can long poll for updates.
Rather than loading them lazily. This allows us to remove all
the yield statements and spurious arguments for the get_next
methods.
It also allows us to replace all instances of get_next_txn with
get_next since get_next no longer needs to access the db.
Amber Brown