feat: fall back to EC if F3 finalized tipeset is older than 900 epochs

CHANGELOG.md

@@ -13,6 +13,8 @@
 - fix(deps): fix Ledger hardware wallet support ([filecoin-project/lotus#13048](https://github.com/filecoin-project/lotus/pull/13048))
 - fix(eth): always return nil for eth transactions not found ([filecoin-project/lotus#12999](https://github.com/filecoin-project/lotus/pull/12999))
 - feat: add gas to application metric reporting `vm/applyblocks_early_gas`, `vm/applyblocks_messages_gas`, `vm/applyblocks_cron_gas` ([filecoin-project/lotus#13030](https://github.com/filecoin-project/lotus/pull/13030))
+- feat: fall back to EC if F3 finalized tipeset is older than 900 epochs ([filecoin-project/lotus#13066](https://github.com/filecoin-project/lotus/pull/13066))
+
 
 ### Experimental v2 APIs with F3 awareness
 

itests/api_v2_test.go

@@ -133,6 +133,18 @@ func TestAPIV2_ThroughRPC(t *testing.T) {
 				wantTipSet:         tipSetAtHeight(f3FinalizedEpoch),
 				wantResponseStatus: http.StatusOK,
 			},
+			{
+				name: "old f3 finalized falls back to ec",
+				when: func(t *testing.T) {
+					mockF3.Running = true
+					mockF3.Finalizing = true
+					mockF3.LatestCertErr = nil
+					mockF3.LatestCert = plausibleCertAt(t, targetHeight-policy.ChainFinality-5)
+				},
+				request:            `{"jsonrpc":"2.0","method":"Filecoin.ChainGetTipSet","params":[{"tag":"finalized"}],"id":1}`,
+				wantTipSet:         tipSetAtHeight(targetHeight - policy.ChainFinality),
+				wantResponseStatus: http.StatusOK,
+			},
 			{
 				name: "safe tag is ec safe distance when more recent than f3 finalized",
 				when: func(t *testing.T) {

node/impl/full/chain_v2.go

@@ -8,6 +8,7 @@ import (
 	"golang.org/x/xerrors"
 
 	"github.com/filecoin-project/go-f3"
+	"github.com/filecoin-project/go-state-types/abi"
 
 	"github.com/filecoin-project/lotus/api"
 	"github.com/filecoin-project/lotus/build/buildconstants"
@@ -107,7 +108,21 @@ func (cm *ChainModuleV2) getLatestFinalizedTipset(ctx context.Context) (*types.T
 	}
 
 	// Extract the finalized tipeset from the certificate.
-	tsk, err := types.TipSetKeyFromBytes(cert.ECChain.Head().Key)
+	latestF3FinalizedTipSet := cert.ECChain.Head()
+
+	// Fall back to EC finality if the latest F3 finalized tipset is older than EC finality.
+	latestF3FinalizedEpoch := abi.ChainEpoch(latestF3FinalizedTipSet.Epoch)
+	head := cm.Chain.GetHeaviestTipSet()
+	if head == nil {
+		return nil, xerrors.New("no known heaviest tipset")
+	}
+	if head.Height()-latestF3FinalizedEpoch > policy.ChainFinality {
+		log.Debugw("Latest F3 finalized tipset is older than EC finality, falling back to EC finality", "headEpoch", head.Height(), "latestF3FinalizedEpoch", latestF3FinalizedEpoch)
+		return cm.getECFinalized(ctx)
+	}
+
+	// All good, load the latest F3 finalized tipset.
+	tsk, err := types.TipSetKeyFromBytes(latestF3FinalizedTipSet.Key)
 	if err != nil {
 		return nil, xerrors.Errorf("decoding latest f3 cert tipset key: %w", err)
 	}