wait_ro (wait until read-only) and
wait_rw (wait until read-write) functions
are useful during server initialization.
To see whether a function is already in read-only or read-write mode, check box.info.ro.
A particular use is for box.once().
For example, when a replica is initializing, it may call
box.once() function while the server is still in
read-only mode, and fail to make changes that are necessary
only once before the replica is fully initialized.
This could cause conflicts between a master and a replica
if the master is in read-write mode and the replica is in
Waiting until “read only mode = false” solves this problem.
Below is a list of all
box.info.ro is true
box.info.ro is false
|Create a “schema_init trigger”
|Create a “shutdown trigger”
|Create a trigger executed on different stages of a node recovery or initial configuration
|Create a trigger executed every time the current state of a replica set node in regard to leader election changes
|Set a timeout in seconds for the
|Check if recovery has finished
|Wait, then choose replication leader
|Revoke the leader role from the instance
|Make the instance a bootstrap leader of a replica set