Support top down query (#331)

* support top down query

* review feedbacks

ipc/provider/src/lib.rs

@@ -14,6 +14,7 @@ use fvm_shared::{
 use ipc_identity::{
     EthKeyAddress, EvmKeyStore, KeyStore, KeyStoreConfig, PersistentKeyStore, Wallet,
 };
+use ipc_sdk::staking::StakingChangeRequest;
 use ipc_sdk::{
     cross::CrossMsg,
     subnet::{ConsensusType, ConstructParams},
@@ -534,6 +535,33 @@ impl IpcProvider {
         conn.manager().chain_head_height().await
     }
 
+    /// Obtain the genesis epoch of the input subnet.
+    pub async fn genesis_epoch(&self, subnet: &SubnetID) -> anyhow::Result<ChainEpoch> {
+        let parent = subnet.parent().ok_or_else(|| anyhow!("no parent found"))?;
+        let conn = match self.connection(&parent) {
+            None => return Err(anyhow!("parent subnet config not found")),
+            Some(conn) => conn,
+        };
+        conn.manager().genesis_epoch(subnet).await
+    }
+
+    /// Get the changes in subnet validators. This is fetched from parent.
+    pub async fn get_validator_changeset(
+        &self,
+        subnet: &SubnetID,
+        start: ChainEpoch,
+        end: ChainEpoch,
+    ) -> anyhow::Result<Vec<StakingChangeRequest>> {
+        let conn = match self.connection(subnet) {
+            None => return Err(anyhow!("target subnet not found")),
+            Some(conn) => conn,
+        };
+
+        conn.manager()
+            .get_validator_changeset(subnet, start, end)
+            .await
+    }
+
     pub async fn get_top_down_msgs(
         &self,
         subnet: &SubnetID,
@@ -572,6 +600,15 @@ impl IpcProvider {
 
         conn.manager().get_chain_id().await
     }
+
+    pub async fn get_chain_head_height(&self, subnet: &SubnetID) -> anyhow::Result<ChainEpoch> {
+        let conn = match self.connection(subnet) {
+            None => return Err(anyhow!("target subnet not found")),
+            Some(conn) => conn,
+        };
+
+        conn.manager().chain_head_height().await
+    }
 }
 
 /// Lotus JSON keytype format

ipc/provider/src/manager/evm/manager.rs

@@ -70,6 +70,23 @@ struct IPCContractInfo {
 
 #[async_trait]
 impl TopDownCheckpointQuery for EthSubnetManager {
+    async fn genesis_epoch(&self, subnet_id: &SubnetID) -> Result<ChainEpoch> {
+        let address = contract_address_from_subnet(subnet_id)?;
+        log::info!("querying genesis epoch in evm subnet contract: {address:}");
+
+        let evm_subnet_id = gateway_getter_facet::SubnetID::try_from(subnet_id)?;
+
+        let contract = gateway_getter_facet::GatewayGetterFacet::new(
+            self.ipc_contract_info.gateway_addr,
+            Arc::new(self.ipc_contract_info.provider.clone()),
+        );
+        let (exists, subnet) = contract.get_subnet(evm_subnet_id).call().await?;
+        if !exists {
+            return Err(anyhow!("subnet: {} does not exists", subnet_id));
+        }
+        Ok(subnet.genesis_epoch.as_u64() as ChainEpoch)
+    }
+
     async fn chain_head_height(&self) -> Result<ChainEpoch> {
         let block = self
             .ipc_contract_info

ipc/provider/src/manager/subnet.rs

@@ -128,6 +128,8 @@ pub trait SubnetManager: Send + Sync + TopDownCheckpointQuery {
 /// Trait to interact with a subnet to query the necessary information for top down checkpoint.
 #[async_trait]
 pub trait TopDownCheckpointQuery: Send + Sync {
+    /// Returns the genesis epoch that the subnet is created in parent network
+    async fn genesis_epoch(&self, subnet_id: &SubnetID) -> Result<ChainEpoch>;
     /// Returns the chain head height
     async fn chain_head_height(&self) -> Result<ChainEpoch>;
     /// Returns the list of top down messages