From 3d3c26fa0c797b6ebae73e8b2f335df50da4ef72 Mon Sep 17 00:00:00 2001
From: Jakub Sztandera <kubuxu@protocol.ai>
Date: Thu, 10 Jun 2021 19:04:15 +0200
Subject: [PATCH] Add lookback limit

Signed-off-by: Jakub Sztandera <kubuxu@protocol.ai>
---
 cmd/lotus-sim/info.go                  | 61 ++++++++++++++------------
 cmd/lotus-sim/simulation/simulation.go |  8 +++-
 2 files changed, 41 insertions(+), 28 deletions(-)

diff --git a/cmd/lotus-sim/info.go b/cmd/lotus-sim/info.go
index d87b3da63..252642eea 100644
--- a/cmd/lotus-sim/info.go
+++ b/cmd/lotus-sim/info.go
@@ -101,6 +101,12 @@ var infoSimCommand = &cli.Command{
 var infoCommitGasSimCommand = &cli.Command{
 	Name:        "commit-gas",
 	Description: "Output information about the gas for committs",
+	Flags: []cli.Flag{
+		&cli.Int64Flag{
+			Name:  "lookback",
+			Value: 0,
+		},
+	},
 	Action: func(cctx *cli.Context) error {
 		log := func(f string, i ...interface{}) {
 			fmt.Fprintf(os.Stderr, f, i...)
@@ -119,38 +125,39 @@ var infoCommitGasSimCommand = &cli.Command{
 		var gasAgg, proofsAgg uint64
 		var gasAggMax, proofsAggMax uint64
 
-		sim.Walk(cctx.Context, func(sm *stmgr.StateManager, ts *types.TipSet, stCid cid.Cid,
-			messages []*simulation.AppliedMessage) error {
-			for _, m := range messages {
-				if m.ExitCode != exitcode.Ok {
-					continue
-				}
-				if m.Method == builtin.MethodsMiner.ProveCommitAggregate {
-					param := miner.ProveCommitAggregateParams{}
-					err := param.UnmarshalCBOR(bytes.NewReader(m.Params))
-					if err != nil {
-						log("failed to decode params: %+v", err)
-						return nil
+		sim.Walk(cctx.Context, cctx.Int64("lookback"),
+			func(sm *stmgr.StateManager, ts *types.TipSet, stCid cid.Cid,
+				messages []*simulation.AppliedMessage) error {
+				for _, m := range messages {
+					if m.ExitCode != exitcode.Ok {
+						continue
 					}
-					c, err := param.SectorNumbers.Count()
-					if err != nil {
-						log("failed to count sectors")
-						return nil
+					if m.Method == builtin.MethodsMiner.ProveCommitAggregate {
+						param := miner.ProveCommitAggregateParams{}
+						err := param.UnmarshalCBOR(bytes.NewReader(m.Params))
+						if err != nil {
+							log("failed to decode params: %+v", err)
+							return nil
+						}
+						c, err := param.SectorNumbers.Count()
+						if err != nil {
+							log("failed to count sectors")
+							return nil
+						}
+						gasAgg += uint64(m.GasUsed)
+						proofsAgg += c
+						if c == 819 {
+							gasAggMax += uint64(m.GasUsed)
+							proofsAggMax += c
+						}
 					}
-					gasAgg += uint64(m.GasUsed)
-					proofsAgg += c
-					if c == 819 {
-						gasAggMax += uint64(m.GasUsed)
-						proofsAggMax += c
+
+					if m.Method == builtin.MethodsMiner.ProveCommitSector {
 					}
 				}
 
-				if m.Method == builtin.MethodsMiner.ProveCommitSector {
-				}
-			}
-
-			return nil
-		})
+				return nil
+			})
 		idealGassUsed := float64(gasAggMax) / float64(proofsAggMax) * float64(proofsAgg)
 
 		fmt.Printf("Gas usage efficiency in comparison to all 819: %f%%\n", 100*idealGassUsed/float64(gasAgg))
diff --git a/cmd/lotus-sim/simulation/simulation.go b/cmd/lotus-sim/simulation/simulation.go
index 2d8b4f388..ab021ddd5 100644
--- a/cmd/lotus-sim/simulation/simulation.go
+++ b/cmd/lotus-sim/simulation/simulation.go
@@ -286,6 +286,7 @@ type AppliedMessage struct {
 // Walk walks the simulation's chain from the current head back to the first tipset.
 func (sim *Simulation) Walk(
 	ctx context.Context,
+	maxLookback int64,
 	cb func(sm *stmgr.StateManager,
 		ts *types.TipSet,
 		stCid cid.Cid,
@@ -297,7 +298,12 @@ func (sim *Simulation) Walk(
 	if err != nil {
 		return err
 	}
-	for !ts.Equals(sim.start) && ctx.Err() == nil {
+	minEpoch := abi.ChainEpoch(0)
+	if maxLookback != 0 {
+		minEpoch = ts.Height() - abi.ChainEpoch(maxLookback)
+	}
+
+	for !ts.Equals(sim.start) && ctx.Err() == nil && ts.Height() > minEpoch {
 		msgs, err := sim.Chainstore.MessagesForTipset(ts)
 		if err != nil {
 			return err