Submodule box.ctl
The 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
a 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
read-only mode.
Waiting until “read only mode = false” solves this problem.
Below is a list of all box.ctl functions.
| Name | Use |
|---|---|
| box.ctl.wait_ro() | Wait until box.info.ro is true |
| box.ctl.wait_rw() | Wait until box.info.ro is false |
| box.ctl.on_schema_init() | Create a “schema_init trigger” |
| box.ctl.on_shutdown() | Create a “shutdown trigger” |
| box.ctl.on_recovery_state() | Create a trigger executed on different stages of a node recovery or initial configuration |
| box.ctl.on_election() | Create a trigger executed every time the current state of a replica set node in regard to leader election changes |
| box.ctl.set_on_shutdown_timeout() | Set a timeout in seconds for the on_shutdown trigger |
| box.ctl.is_recovery_finished() | Check if recovery has finished |
| box.ctl.promote() | Wait, then choose replication leader |
| box.ctl.demote() | Revoke the leader role from the instance |