feat(f3): prefetch the power table of every parent tipset

chain/lf3/ec.go

@@ -15,6 +15,7 @@ import (
 	"github.com/filecoin-project/go-f3/gpbft"
 	"github.com/filecoin-project/go-state-types/abi"
 
+	"github.com/filecoin-project/lotus/build/buildconstants"
 	"github.com/filecoin-project/lotus/chain"
 	"github.com/filecoin-project/lotus/chain/actors/builtin/miner"
 	"github.com/filecoin-project/lotus/chain/actors/builtin/power"
@@ -95,6 +96,29 @@ func (ts *f3TipSet) Timestamp() time.Time {
 	return time.Time{}
 }
 
+func (ec *ecWrapper) runPrefetcher(ctx context.Context) {
+	// We have a loop here because we'll be automatically unsubscribed if we're too slow.
+	for {
+		headChanges := ec.chainStore.SubHeadChanges(ctx)
+		for changes := range headChanges {
+			for _, head := range changes {
+				if head.Type == store.HCRevert {
+					continue
+				}
+				// We do one job at a time because we're just pre-fetching here. If,
+				// e.g., we end up in "catch up" mode, we'll be unsubscribed (too
+				// slow) then we'll try again after we wait for one block.
+				_, _ = ec.getPowerTableLotusTSK(ctx, head.Val.Parents())
+			}
+		}
+		select {
+		case <-time.After(time.Duration(buildconstants.BlockDelaySecs) * time.Second):
+		case <-ctx.Done():
+			return
+		}
+	}
+}
+
 // GetTipsetByEpoch should return a tipset before the one requested if the requested
 // tipset does not exist due to null epochs
 func (ec *ecWrapper) GetTipsetByEpoch(ctx context.Context, epoch int64) (ec.TipSet, error) {

chain/lf3/f3.go

@@ -106,20 +106,38 @@ func New(mctx helpers.MetricsCtx, lc fx.Lifecycle, params F3Params) (*F3, error)
 		OnStop:  fff.inner.Stop,
 	})
 
-	// Start signing F3 messages.
 	lCtx, cancel := context.WithCancel(mctx)
-	doneCh := make(chan struct{})
+
+	// start EC wrapper power-table prefetch logic.
+	donePrefetchingCh := make(chan struct{})
+	lc.Append(fx.Hook{
+		OnStart: func(context.Context) error {
+			go func() {
+				defer close(donePrefetchingCh)
+				ec.runPrefetcher(lCtx)
+			}()
+			return nil
+		},
+		OnStop: func(context.Context) error {
+			cancel()
+			<-donePrefetchingCh
+			return nil
+		},
+	})
+
+	// Start signing F3 messages.
+	doneSigningCh := make(chan struct{})
 	lc.Append(fx.Hook{
 		OnStart: func(context.Context) error {
 			go func() {
-				defer close(doneCh)
+				defer close(doneSigningCh)
 				fff.runSigningLoop(lCtx)
 			}()
 			return nil
 		},
 		OnStop: func(context.Context) error {
 			cancel()
-			<-doneCh
+			<-doneSigningCh
 			return nil
 		},
 	})