# README
x/signal
The signal module acts as a coordinating mechanism for the application on when it should transition from one app version to another. The application itself handles multiple versioned modules as well as migrations, however it requires some protocol for knowing which height to perform this upgrade as it is critical that all nodes upgrade at the same point.
Note: this module won't be used for upgrading from app version v1 to v2 but will be used for upgrading from v2 to v3 and onwards.
Concepts
- Total voting power: The sum of voting power for all validators.
- Voting power threshold: The amount of voting power that needs to signal for a particular version for an upgrade to take place. This is a percentage of the total voting power (usually 5/6).
State
This module persists a map in state from validator address to version that they are signalling for.
State Transitions
The map from validator address to version is updated when a validator signals for a version (SignalVersion) and after an upgrade takes place (ResetTally).
Messages
See types/msgs.go for the message types.
Client
CLI
celestia-appd query signal tally
celestia-appd tx signal signal
celestia-appd tx signal try-upgrade
gRPC
celestia.signal.v1.Query/VersionTally
grpcurl -plaintext localhost:9090 celestia.signal.v1.Query/VersionTally