feat: compute a better gas limit for recursive external contract calls

2023-02-03 20:40:18 +00:00
parent b46258d0bf
commit 03b419e3d4
7 changed files with 278 additions and 14 deletions
@@ -24,6 +24,7 @@ import (
 	"github.com/filecoin-project/go-state-types/builtin/v10/eam"
 	"github.com/filecoin-project/go-state-types/builtin/v10/evm"
 	"github.com/filecoin-project/go-state-types/crypto"
+	"github.com/filecoin-project/go-state-types/exitcode"

 	"github.com/filecoin-project/lotus/api"
 	"github.com/filecoin-project/lotus/build"
@@ -809,12 +810,137 @@ func (a *EthModule) EthEstimateGas(ctx context.Context, tx ethtypes.EthCall) (et
 	// gas estimation actually run.
 	msg.GasLimit = 0

-	msg, err = a.GasAPI.GasEstimateMessageGas(ctx, msg, nil, types.EmptyTSK)
+	ts := a.Chain.GetHeaviestTipSet()
+	msg, err = a.GasAPI.GasEstimateMessageGas(ctx, msg, nil, ts.Key())
 	if err != nil {
-		return ethtypes.EthUint64(0), err
+		return ethtypes.EthUint64(0), xerrors.Errorf("failed to estimate gas: %w", err)
 	}

-	return ethtypes.EthUint64(msg.GasLimit), nil
+	expectedGas, err := ethGasSearch(ctx, a.Chain, a.Stmgr, a.Mpool, msg, ts)
+	if err != nil {
+		log.Errorw("expected gas", "err", err)
+	}
+
+	return ethtypes.EthUint64(expectedGas), nil
+}
+
+// gasSearch does an exponential search to find a gas value to execute the
+// message with. It first finds a high gas limit that allows the message to execute
+// by doubling the previous gas limit until it succeeds then does a binary
+// search till it gets within a range of 1%
+func gasSearch(
+	ctx context.Context,
+	smgr *stmgr.StateManager,
+	msgIn *types.Message,
+	priorMsgs []types.ChainMsg,
+	ts *types.TipSet,
+) (int64, error) {
+	msg := *msgIn
+
+	high := msg.GasLimit
+	low := msg.GasLimit
+
+	canSucceed := func(limit int64) (bool, error) {
+		msg.GasLimit = limit
+
+		res, err := smgr.CallWithGas(ctx, &msg, priorMsgs, ts)
+		if err != nil {
+			return false, xerrors.Errorf("CallWithGas failed: %w", err)
+		}
+
+		if res.MsgRct.ExitCode.IsSuccess() {
+			return true, nil
+		}
+
+		return false, nil
+	}
+
+	for {
+		ok, err := canSucceed(high)
+		if err != nil {
+			return -1, xerrors.Errorf("searching for high gas limit failed: %w", err)
+		}
+		if ok {
+			break
+		}
+
+		low = high
+		high = high * 2
+
+		if high > build.BlockGasLimit {
+			high = build.BlockGasLimit
+			break
+		}
+	}
+
+	checkThreshold := high / 100
+	for (high - low) > checkThreshold {
+		median := (low + high) / 2
+		ok, err := canSucceed(median)
+		if err != nil {
+			return -1, xerrors.Errorf("searching for optimal gas limit failed: %w", err)
+		}
+
+		if ok {
+			high = median
+		} else {
+			low = median
+		}
+
+		checkThreshold = median / 100
+	}
+
+	return high, nil
+}
+
+func traceContainsExitCode(et types.ExecutionTrace, ex exitcode.ExitCode) bool {
+	if et.MsgRct.ExitCode == ex {
+		return true
+	}
+
+	for _, et := range et.Subcalls {
+		if traceContainsExitCode(et, ex) {
+			return true
+		}
+	}
+
+	return false
+}
+
+// ethGasSearch executes a message for gas estimation using the previously estimated gas.
+// If the message fails due to an out of gas error then a gas search is performed.
+// See gasSearch.
+func ethGasSearch(
+	ctx context.Context,
+	cstore *store.ChainStore,
+	smgr *stmgr.StateManager,
+	mpool *messagepool.MessagePool,
+	msgIn *types.Message,
+	ts *types.TipSet,
+) (int64, error) {
+	msg := *msgIn
+	currTs := ts
+
+	res, priorMsgs, ts, err := gasEstimateCallWithGas(ctx, cstore, smgr, mpool, &msg, currTs)
+	if err != nil {
+		return -1, xerrors.Errorf("gas estimation failed: %w", err)
+	}
+
+	if res.MsgRct.ExitCode.IsSuccess() {
+		return msg.GasLimit, nil
+	}
+
+	if traceContainsExitCode(res.ExecutionTrace, exitcode.SysErrOutOfGas) {
+		ret, err := gasSearch(ctx, smgr, &msg, priorMsgs, ts)
+		if err != nil {
+			return -1, xerrors.Errorf("gas estimation search failed: %w", err)
+		}
+
+		ret = int64(float64(ret) * mpool.GetConfig().GasLimitOverestimation)
+		return ret, nil
+	}
+
+	return -1, xerrors.Errorf("message execution failed: exit %s, reason: %s", res.MsgRct.ExitCode, res.Error)
 }

 func (a *EthModule) EthCall(ctx context.Context, tx ethtypes.EthCall, blkParam string) (ethtypes.EthBytes, error) {
@@ -248,22 +248,23 @@ func (m *GasModule) GasEstimateGasLimit(ctx context.Context, msgIn *types.Messag
 	}
 	return gasEstimateGasLimit(ctx, m.Chain, m.Stmgr, m.Mpool, msgIn, ts)
 }
-func gasEstimateGasLimit(
+
+// gasEstimateCallWithGas invokes a message "msgIn" on the earliest available tipset with pending
+// messages in the message pool. The function returns the result of the message invocation, the
+// pending messages, the tipset used for the invocation, and an error if occurred.
+// The returned information can be used to make subsequent calls to CallWithGas with the same parameters.
+func gasEstimateCallWithGas(
 	ctx context.Context,
 	cstore *store.ChainStore,
 	smgr *stmgr.StateManager,
 	mpool *messagepool.MessagePool,
 	msgIn *types.Message,
 	currTs *types.TipSet,
-) (int64, error) {
+) (*api.InvocResult, []types.ChainMsg, *types.TipSet, error) {
 	msg := *msgIn
-	msg.GasLimit = build.BlockGasLimit
-	msg.GasFeeCap = big.Zero()
-	msg.GasPremium = big.Zero()
-
 	fromA, err := smgr.ResolveToDeterministicAddress(ctx, msgIn.From, currTs)
 	if err != nil {
-		return -1, xerrors.Errorf("getting key address: %w", err)
+		return nil, []types.ChainMsg{}, nil, xerrors.Errorf("getting key address: %w", err)
 	}

 	pending, ts := mpool.PendingFor(ctx, fromA)
@@ -284,12 +285,34 @@ func gasEstimateGasLimit(
 		}
 		ts, err = cstore.GetTipSetFromKey(ctx, ts.Parents())
 		if err != nil {
-			return -1, xerrors.Errorf("getting parent tipset: %w", err)
+			return nil, []types.ChainMsg{}, nil, xerrors.Errorf("getting parent tipset: %w", err)
 		}
 	}
 	if err != nil {
-		return -1, xerrors.Errorf("CallWithGas failed: %w", err)
+		return nil, []types.ChainMsg{}, nil, xerrors.Errorf("CallWithGas failed: %w", err)
 	}
+
+	return res, priorMsgs, ts, nil
+}
+
+func gasEstimateGasLimit(
+	ctx context.Context,
+	cstore *store.ChainStore,
+	smgr *stmgr.StateManager,
+	mpool *messagepool.MessagePool,
+	msgIn *types.Message,
+	currTs *types.TipSet,
+) (int64, error) {
+	msg := *msgIn
+	msg.GasLimit = build.BlockGasLimit
+	msg.GasFeeCap = big.Zero()
+	msg.GasPremium = big.Zero()
+
+	res, _, ts, err := gasEstimateCallWithGas(ctx, cstore, smgr, mpool, &msg, currTs)
+	if err != nil {
+		return -1, xerrors.Errorf("gas estimation failed: %w", err)
+	}
+
 	if res.MsgRct.ExitCode == exitcode.SysErrOutOfGas {
 		return -1, &api.ErrOutOfGas{}
 	}
@@ -300,6 +323,8 @@ func gasEstimateGasLimit(

 	ret := res.MsgRct.GasUsed

+	log.Infow("GasEstimateMessageGas CallWithGas Result", "GasUsed", ret, "ExitCode", res.MsgRct.ExitCode)
+
 	transitionalMulti := 1.0
 	// Overestimate gas around the upgrade
 	if ts.Height() <= build.UpgradeSkyrHeight && (build.UpgradeSkyrHeight-ts.Height() <= 20) {