diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go index 09f41a836..604c00a8f 100644 --- a/internal/ethapi/api.go +++ b/internal/ethapi/api.go @@ -1162,12 +1162,30 @@ func (s *BlockChainAPI) Call(ctx context.Context, args TransactionArgs, blockNrO return result.Return(), result.Err } +// executeEstimate is a helper that executes the transaction under a given gas limit and returns +// true if the transaction fails for a reason that might be related to not enough gas. A non-nil +// error means execution failed due to reasons unrelated to the gas limit. +func executeEstimate(ctx context.Context, b Backend, args TransactionArgs, state *state.StateDB, header *types.Header, gasCap uint64, gasLimit uint64) (bool, *core.ExecutionResult, error) { + args.Gas = (*hexutil.Uint64)(&gasLimit) + result, err := doCall(ctx, b, args, state, header, nil, nil, 0, gasCap) + if err != nil { + if errors.Is(err, core.ErrIntrinsicGas) { + return true, nil, nil // Special case, raise gas limit + } + return true, nil, err // Bail out + } + return result.Failed(), result, nil +} + +// DoEstimateGas returns the lowest possible gas limit that allows the transaction to run +// successfully at block `blockNrOrHash`. It returns error if the transaction would revert, or if +// there are unexpected failures. The gas limit is capped by both `args.Gas` (if non-nil & +// non-zero) and `gasCap` (if non-zero). func DoEstimateGas(ctx context.Context, b Backend, args TransactionArgs, blockNrOrHash rpc.BlockNumberOrHash, overrides *StateOverride, gasCap uint64) (hexutil.Uint64, error) { - // Binary search the gas requirement, as it may be higher than the amount used + // Binary search the gas limit, as it may need to be higher than the amount used var ( - lo uint64 = params.TxGas - 1 - hi uint64 - cap uint64 + lo uint64 // lowest-known gas limit where tx execution fails + hi uint64 // lowest-known gas limit where tx execution succeeds ) // Use zero address if sender unspecified. if args.From == nil { @@ -1198,16 +1216,17 @@ func DoEstimateGas(ctx context.Context, b Backend, args TransactionArgs, blockNr } else { feeCap = common.Big0 } + + state, header, err := b.StateAndHeaderByNumberOrHash(ctx, blockNrOrHash) + if state == nil || err != nil { + return 0, err + } + if err := overrides.Apply(state); err != nil { + return 0, err + } + // Recap the highest gas limit with account's available balance. if feeCap.BitLen() != 0 { - state, _, err := b.StateAndHeaderByNumberOrHash(ctx, blockNrOrHash) - if err != nil { - return 0, err - } - err = overrides.Apply(state) - if err != nil { - return 0, err - } balance := state.GetBalance(*args.From) // from can't be nil available := new(big.Int).Set(balance) if args.Value != nil { @@ -1234,39 +1253,42 @@ func DoEstimateGas(ctx context.Context, b Backend, args TransactionArgs, blockNr log.Warn("Caller gas above allowance, capping", "requested", hi, "cap", gasCap) hi = gasCap } - cap = hi - // Create a helper to check if a gas allowance results in an executable transaction - executable := func(gas uint64, state *state.StateDB, header *types.Header) (bool, *core.ExecutionResult, error) { - args.Gas = (*hexutil.Uint64)(&gas) - - result, err := doCall(ctx, b, args, state, header, nil, nil, 0, gasCap) - if err != nil { - if errors.Is(err, core.ErrIntrinsicGas) { - return true, nil, nil // Special case, raise gas limit - } - return true, nil, err // Bail out - } - return result.Failed(), result, nil - } - state, header, err := b.StateAndHeaderByNumberOrHash(ctx, blockNrOrHash) - if state == nil || err != nil { - return 0, err - } - err = overrides.Apply(state) + // We first execute the transaction at the highest allowable gas limit, since if this fails we + // can return error immediately. + failed, result, err := executeEstimate(ctx, b, args, state.Copy(), header, gasCap, hi) if err != nil { return 0, err } - // Execute the binary search and hone in on an executable gas limit - for lo+1 < hi { - s := state.Copy() - mid := (hi + lo) / 2 - failed, _, err := executable(mid, s, header) + if failed { + if result != nil && result.Err != vm.ErrOutOfGas { + if len(result.Revert()) > 0 { + return 0, newRevertError(result) + } + return 0, result.Err + } + return 0, fmt.Errorf("gas required exceeds allowance (%d)", hi) + } + // For almost any transaction, the gas consumed by the unconstrained execution above + // lower-bounds the gas limit required for it to succeed. One exception is those txs that + // explicitly check gas remaining in order to successfully execute within a given limit, but we + // probably don't want to return a lowest possible gas limit for these cases anyway. + lo = result.UsedGas - 1 - // If the error is not nil(consensus error), it means the provided message - // call or transaction will never be accepted no matter how much gas it is - // assigned. Return the error directly, don't struggle any more. + // Binary search for the smallest gas limit that allows the tx to execute successfully. + for lo+1 < hi { + mid := (hi + lo) / 2 + if mid > lo*2 { + // Most txs don't need much higher gas limit than their gas used, and most txs don't + // require near the full block limit of gas, so the selection of where to bisect the + // range here is skewed to favor the low side. + mid = lo * 2 + } + failed, _, err = executeEstimate(ctx, b, args, state.Copy(), header, gasCap, mid) if err != nil { + // This should not happen under normal conditions since if we make it this far the + // transaction had run without error at least once before. + log.Error("execution error in estimate gas", "err", err) return 0, err } if failed { @@ -1275,28 +1297,14 @@ func DoEstimateGas(ctx context.Context, b Backend, args TransactionArgs, blockNr hi = mid } } - // Reject the transaction as invalid if it still fails at the highest allowance - if hi == cap { - failed, result, err := executable(hi, state, header) - if err != nil { - return 0, err - } - if failed { - if result != nil && result.Err != vm.ErrOutOfGas { - if len(result.Revert()) > 0 { - return 0, newRevertError(result) - } - return 0, result.Err - } - // Otherwise, the specified gas cap is too low - return 0, fmt.Errorf("gas required exceeds allowance (%d)", cap) - } - } return hexutil.Uint64(hi), nil } -// EstimateGas returns an estimate of the amount of gas needed to execute the -// given transaction against the current pending block. +// EstimateGas returns the lowest possible gas limit that allows the transaction to run +// successfully at block `blockNrOrHash`, or the latest block if `blockNrOrHash` is unspecified. It +// returns error if the transaction would revert or if there are unexpected failures. The returned +// value is capped by both `args.Gas` (if non-nil & non-zero) and the backend's RPCGasCap +// configuration (if non-zero). func (s *BlockChainAPI) EstimateGas(ctx context.Context, args TransactionArgs, blockNrOrHash *rpc.BlockNumberOrHash, overrides *StateOverride) (hexutil.Uint64, error) { bNrOrHash := rpc.BlockNumberOrHashWithNumber(rpc.LatestBlockNumber) if blockNrOrHash != nil {