feat(rpc): implement Filecoin.ChainTipSetWeight (#4192)

Co-authored-by: Aatif Syed <38045910+aatifsyed@users.noreply.github.com>

src/rpc/auth_layer.rs

@@ -56,6 +56,7 @@ static ACCESS_MAP: Lazy<HashMap<&str, Access>> = Lazy::new(|| {
     access.insert(chain::ChainGetTipSet::NAME, Access::Read);
     access.insert(chain::ChainSetHead::NAME, Access::Admin);
     access.insert(chain::ChainGetMinBaseFee::NAME, Access::Admin);
+    access.insert(chain::ChainTipSetWeight::NAME, Access::Read);
     access.insert(chain::ChainGetMessagesInTipset::NAME, Access::Read);
     access.insert(chain::ChainGetParentMessages::NAME, Access::Read);
     access.insert(chain::CHAIN_NOTIFY, Access::Read);

src/rpc/methods/chain.rs

@@ -27,6 +27,7 @@ use fvm_ipld_encoding::{CborStore, RawBytes};
 use hex::ToHex;
 use jsonrpsee::types::error::ErrorObjectOwned;
 use jsonrpsee::types::Params;
+use num::BigInt;
 use once_cell::sync::Lazy;
 use schemars::JsonSchema;
 use serde::{Deserialize, Serialize};
@@ -57,6 +58,7 @@ macro_rules! for_each_method {
         $callback!(crate::rpc::chain::ChainGetTipSet);
         $callback!(crate::rpc::chain::ChainSetHead);
         $callback!(crate::rpc::chain::ChainGetMinBaseFee);
+        $callback!(crate::rpc::chain::ChainTipSetWeight);
     };
 }
 pub(crate) use for_each_method;
@@ -637,6 +639,25 @@ impl RpcMethod<1> for ChainGetMinBaseFee {
     }
 }
 
+pub enum ChainTipSetWeight {}
+impl RpcMethod<1> for ChainTipSetWeight {
+    const NAME: &'static str = "Filecoin.ChainTipSetWeight";
+    const PARAM_NAMES: [&'static str; 1] = ["tsk"];
+    const API_VERSION: ApiVersion = ApiVersion::V0;
+
+    type Params = (LotusJson<ApiTipsetKey>,);
+    type Ok = LotusJson<BigInt>;
+
+    async fn handle(
+        ctx: Ctx<impl Blockstore>,
+        (LotusJson(ApiTipsetKey(tsk)),): Self::Params,
+    ) -> Result<Self::Ok, ServerError> {
+        let tsk = ctx.chain_store.load_required_tipset_or_heaviest(&tsk)?;
+        let weight = crate::fil_cns::weight(ctx.chain_store.blockstore(), &tsk)?;
+        Ok(LotusJson(weight))
+    }
+}
+
 pub const CHAIN_NOTIFY: &str = "Filecoin.ChainNotify";
 pub(crate) fn chain_notify<DB: Blockstore>(
     _params: Params<'_>,

src/rpc_client/chain_ops.rs

@@ -3,6 +3,10 @@
 
 use super::{ApiInfo, RpcRequest};
 
+/// Client calls should use [`crate::rpc::RpcMethod`]'s way of constructing [`RpcRequest`].
+/// `Filecoin.ChainNotify` is an exception because it is a subscription method, so falls outside
+/// of that abstraction.
+/// See <https://github.com/ChainSafe/forest/issues/4032> for more information.
 impl ApiInfo {
     pub fn chain_notify_req() -> RpcRequest<()> {
         RpcRequest::new(crate::rpc::chain::CHAIN_NOTIFY, ())

src/tool/subcommands/api_cmd.rs

@@ -628,6 +628,9 @@ fn snapshot_tests(store: Arc<ManyCar>, n_tipsets: usize) -> anyhow::Result<Vec<R
                 tipset.key().into(),
             ),
         ));
+        tests.push(RpcTest::identity_raw(ChainTipSetWeight::request((
+            LotusJson(tipset.key().into()),
+        ))?));
         for block in tipset.block_headers() {
             let block_cid = (*block.cid()).into();
             tests.extend([