Add a configuration number getter (#867)

Co-authored-by: Jorge M. Soares <[email protected]>

contracts/src/gateway/GatewayGetterFacet.sol

@@ -6,6 +6,7 @@ import {QuorumInfo} from "../structs/Quorum.sol";
 import {SubnetID, Subnet} from "../structs/Subnet.sol";
 import {Membership} from "../structs/Subnet.sol";
 import {LibGateway} from "../lib/LibGateway.sol";
+import {LibStaking} from "../lib/LibStaking.sol";
 import {LibQuorum} from "../lib/LibQuorum.sol";
 import {GatewayActorStorage} from "../lib/LibGatewayActorStorage.sol";
 import {SubnetIDHelper} from "../lib/SubnetIDHelper.sol";
@@ -20,6 +21,12 @@ contract GatewayGetterFacet {
     using EnumerableSet for EnumerableSet.AddressSet;
     using EnumerableSet for EnumerableSet.Bytes32Set;
 
+    /// @notice Returns the next and start configuration numbers in the validator changes.
+    /// The configuration numbers are from changes made in the parent.
+    function getValidatorConfigurationNumbers() external view returns (uint64, uint64) {
+        return LibStaking.getConfigurationNumbers();
+    }
+
     /// @notice Returns code commit SHA where this contract is from.
     function getCommitSha() external view returns (bytes32) {
         return s.commitSha;

contracts/src/gateway/router/TopDownFinalityFacet.sol

@@ -35,6 +35,15 @@ contract TopDownFinalityFacet is GatewayActorModifiers {
         s.validatorsTracker.batchStoreChange(changeRequests);
     }
 
+    /// @notice Returns the next and start configuration numbers in the tracker of changes
+    /// from the parent in the child gateway
+    function getTrackerConfigurationNumbers() external view returns (uint64, uint64) {
+        return (
+            s.validatorsTracker.changes.nextConfigurationNumber,
+            s.validatorsTracker.changes.startConfigurationNumber
+        );
+    }
+
     /// @notice Apply all changes committed through the commitment of parent finality.
     /// @return configurationNumber The configuration number of the changes set that has been confirmed.
     function applyFinalityChanges() external systemActorOnly returns (uint64) {