From 1e28e0bb03c6911a691d7125cb8c5e41faac2eab Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?P=C3=A9ter=20Szil=C3=A1gyi?= Date: Mon, 27 Nov 2023 16:20:09 +0200 Subject: [PATCH] eth/gasestimator, internal/ethapi: move gas estimator out of rpc (#28600) --- eth/gasestimator/gasestimator.go | 194 +++++++++++++++++++++++++++++++ internal/ethapi/api.go | 149 ++++-------------------- internal/ethapi/api_test.go | 8 +- 3 files changed, 222 insertions(+), 129 deletions(-) create mode 100644 eth/gasestimator/gasestimator.go diff --git a/eth/gasestimator/gasestimator.go b/eth/gasestimator/gasestimator.go new file mode 100644 index 0000000000..3e74b5b08b --- /dev/null +++ b/eth/gasestimator/gasestimator.go @@ -0,0 +1,194 @@ +// Copyright 2023 The go-ethereum Authors +// This file is part of the go-ethereum library. +// +// The go-ethereum library is free software: you can redistribute it and/or modify +// it under the terms of the GNU Lesser General Public License as published by +// the Free Software Foundation, either version 3 of the License, or +// (at your option) any later version. +// +// The go-ethereum library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU Lesser General Public License for more details. +// +// You should have received a copy of the GNU Lesser General Public License +// along with the go-ethereum library. If not, see . + +package gasestimator + +import ( + "context" + "errors" + "fmt" + "math" + "math/big" + + "github.com/ethereum/go-ethereum/common" + "github.com/ethereum/go-ethereum/core" + "github.com/ethereum/go-ethereum/core/state" + "github.com/ethereum/go-ethereum/core/types" + "github.com/ethereum/go-ethereum/core/vm" + "github.com/ethereum/go-ethereum/log" + "github.com/ethereum/go-ethereum/params" +) + +// Options are the contextual parameters to execute the requested call. +// +// Whilst it would be possible to pass a blockchain object that aggregates all +// these together, it would be excessively hard to test. Splitting the parts out +// allows testing without needing a proper live chain. +type Options struct { + Config *params.ChainConfig // Chain configuration for hard fork selection + Chain core.ChainContext // Chain context to access past block hashes + Header *types.Header // Header defining the block context to execute in + State *state.StateDB // Pre-state on top of which to estimate the gas +} + +// Estimate returns the lowest possible gas limit that allows the transaction to +// run successfully with the provided context optons. It returns an error if the +// transaction would always revert, or if there are unexpected failures. +func Estimate(ctx context.Context, call *core.Message, opts *Options, gasCap uint64) (uint64, []byte, error) { + // Binary search the gas limit, as it may need to be higher than the amount used + var ( + lo uint64 // lowest-known gas limit where tx execution fails + hi uint64 // lowest-known gas limit where tx execution succeeds + ) + // Determine the highest gas limit can be used during the estimation. + hi = opts.Header.GasLimit + if call.GasLimit >= params.TxGas { + hi = call.GasLimit + } + // Normalize the max fee per gas the call is willing to spend. + var feeCap *big.Int + if call.GasFeeCap != nil { + feeCap = call.GasFeeCap + } else if call.GasPrice != nil { + feeCap = call.GasPrice + } else { + feeCap = common.Big0 + } + // Recap the highest gas limit with account's available balance. + if feeCap.BitLen() != 0 { + balance := opts.State.GetBalance(call.From) + + available := new(big.Int).Set(balance) + if call.Value != nil { + if call.Value.Cmp(available) >= 0 { + return 0, nil, core.ErrInsufficientFundsForTransfer + } + available.Sub(available, call.Value) + } + allowance := new(big.Int).Div(available, feeCap) + + // If the allowance is larger than maximum uint64, skip checking + if allowance.IsUint64() && hi > allowance.Uint64() { + transfer := call.Value + if transfer == nil { + transfer = new(big.Int) + } + log.Warn("Gas estimation capped by limited funds", "original", hi, "balance", balance, + "sent", transfer, "maxFeePerGas", feeCap, "fundable", allowance) + hi = allowance.Uint64() + } + } + // Recap the highest gas allowance with specified gascap. + if gasCap != 0 && hi > gasCap { + log.Warn("Caller gas above allowance, capping", "requested", hi, "cap", gasCap) + hi = gasCap + } + // We first execute the transaction at the highest allowable gas limit, since if this fails we + // can return error immediately. + failed, result, err := execute(ctx, call, opts, hi) + if err != nil { + return 0, nil, err + } + if failed { + if result != nil && !errors.Is(result.Err, vm.ErrOutOfGas) { + return 0, result.Revert(), result.Err + } + return 0, nil, 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 that explicitly check gas remaining in order to execute within a + // given limit, but we probably don't want to return the lowest possible gas + // limit for these cases anyway. + lo = result.UsedGas - 1 + + // 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 = execute(ctx, call, opts, 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, nil, err + } + if failed { + lo = mid + } else { + hi = mid + } + } + return hi, nil, nil +} + +// execute 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 execute(ctx context.Context, call *core.Message, opts *Options, gasLimit uint64) (bool, *core.ExecutionResult, error) { + // Configure the call for this specific execution (and revert the change after) + defer func(gas uint64) { call.GasLimit = gas }(call.GasLimit) + call.GasLimit = gasLimit + + // Execute the call and separate execution faults caused by a lack of gas or + // other non-fixable conditions + result, err := run(ctx, call, opts) + 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 +} + +// run assembles the EVM as defined by the consensus rules and runs the requested +// call invocation. +func run(ctx context.Context, call *core.Message, opts *Options) (*core.ExecutionResult, error) { + // Assemble the call and the call context + var ( + msgContext = core.NewEVMTxContext(call) + evmContext = core.NewEVMBlockContext(opts.Header, opts.Chain, nil) + + dirtyState = opts.State.Copy() + evm = vm.NewEVM(evmContext, msgContext, dirtyState, opts.Config, vm.Config{NoBaseFee: true}) + ) + // Monitor the outer context and interrupt the EVM upon cancellation. To avoid + // a dangling goroutine until the outer estimation finishes, create an internal + // context for the lifetime of this method call. + ctx, cancel := context.WithCancel(ctx) + defer cancel() + + go func() { + <-ctx.Done() + evm.Cancel() + }() + // Execute the call, returning a wrapped error or the result + result, err := core.ApplyMessage(evm, call, new(core.GasPool).AddGas(math.MaxUint64)) + if vmerr := dirtyState.Error(); vmerr != nil { + return nil, vmerr + } + if err != nil { + return result, fmt.Errorf("failed with %d gas: %w", call.GasLimit, err) + } + return result, nil +} diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go index 89c132ddee..f322132769 100644 --- a/internal/ethapi/api.go +++ b/internal/ethapi/api.go @@ -40,6 +40,7 @@ import ( "github.com/ethereum/go-ethereum/core/types" "github.com/ethereum/go-ethereum/core/vm" "github.com/ethereum/go-ethereum/crypto" + "github.com/ethereum/go-ethereum/eth/gasestimator" "github.com/ethereum/go-ethereum/eth/tracers/logger" "github.com/ethereum/go-ethereum/log" "github.com/ethereum/go-ethereum/p2p" @@ -1120,15 +1121,16 @@ func DoCall(ctx context.Context, b Backend, args TransactionArgs, blockNrOrHash return doCall(ctx, b, args, state, header, overrides, blockOverrides, timeout, globalGasCap) } -func newRevertError(result *core.ExecutionResult) *revertError { - reason, errUnpack := abi.UnpackRevert(result.Revert()) - err := errors.New("execution reverted") +func newRevertError(revert []byte) *revertError { + err := vm.ErrExecutionReverted + + reason, errUnpack := abi.UnpackRevert(revert) if errUnpack == nil { - err = fmt.Errorf("execution reverted: %v", reason) + err = fmt.Errorf("%w: %v", vm.ErrExecutionReverted, reason) } return &revertError{ error: err, - reason: hexutil.Encode(result.Revert()), + reason: hexutil.Encode(revert), } } @@ -1167,147 +1169,44 @@ func (s *BlockChainAPI) Call(ctx context.Context, args TransactionArgs, blockNrO } // If the result contains a revert reason, try to unpack and return it. if len(result.Revert()) > 0 { - return nil, newRevertError(result) + return nil, newRevertError(result.Revert()) } 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 limit, as it may need to be higher than the amount used - var ( - 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 { - args.From = new(common.Address) - } - // Determine the highest gas limit can be used during the estimation. - if args.Gas != nil && uint64(*args.Gas) >= params.TxGas { - hi = uint64(*args.Gas) - } else { - // Retrieve the block to act as the gas ceiling - block, err := b.BlockByNumberOrHash(ctx, blockNrOrHash) - if err != nil { - return 0, err - } - if block == nil { - return 0, errors.New("block not found") - } - hi = block.GasLimit() - } - // Normalize the max fee per gas the call is willing to spend. - var feeCap *big.Int - if args.GasPrice != nil && (args.MaxFeePerGas != nil || args.MaxPriorityFeePerGas != nil) { - return 0, errors.New("both gasPrice and (maxFeePerGas or maxPriorityFeePerGas) specified") - } else if args.GasPrice != nil { - feeCap = args.GasPrice.ToInt() - } else if args.MaxFeePerGas != nil { - feeCap = args.MaxFeePerGas.ToInt() - } else { - feeCap = common.Big0 - } - + // Retrieve the base state and mutate it with any overrides state, header, err := b.StateAndHeaderByNumberOrHash(ctx, blockNrOrHash) if state == nil || err != nil { return 0, err } - if err := overrides.Apply(state); err != nil { + if err = overrides.Apply(state); err != nil { return 0, err } - - // Recap the highest gas limit with account's available balance. - if feeCap.BitLen() != 0 { - balance := state.GetBalance(*args.From) // from can't be nil - available := new(big.Int).Set(balance) - if args.Value != nil { - if args.Value.ToInt().Cmp(available) >= 0 { - return 0, core.ErrInsufficientFundsForTransfer - } - available.Sub(available, args.Value.ToInt()) - } - allowance := new(big.Int).Div(available, feeCap) - - // If the allowance is larger than maximum uint64, skip checking - if allowance.IsUint64() && hi > allowance.Uint64() { - transfer := args.Value - if transfer == nil { - transfer = new(hexutil.Big) - } - log.Warn("Gas estimation capped by limited funds", "original", hi, "balance", balance, - "sent", transfer.ToInt(), "maxFeePerGas", feeCap, "fundable", allowance) - hi = allowance.Uint64() - } + // Construct the gas estimator option from the user input + opts := &gasestimator.Options{ + Config: b.ChainConfig(), + Chain: NewChainContext(ctx, b), + Header: header, + State: state, } - // Recap the highest gas allowance with specified gascap. - if gasCap != 0 && hi > gasCap { - log.Warn("Caller gas above allowance, capping", "requested", hi, "cap", gasCap) - hi = gasCap - } - - // 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) + // Run the gas estimation andwrap any revertals into a custom return + call, err := args.ToMessage(gasCap, header.BaseFee) if err != nil { return 0, err } - if failed { - if result != nil && !errors.Is(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 - - // 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 { - lo = mid - } else { - hi = mid + estimate, revert, err := gasestimator.Estimate(ctx, call, opts, gasCap) + if err != nil { + if len(revert) > 0 { + return 0, newRevertError(revert) } + return 0, err } - return hexutil.Uint64(hi), nil + return hexutil.Uint64(estimate), nil } // EstimateGas returns the lowest possible gas limit that allows the transaction to run diff --git a/internal/ethapi/api_test.go b/internal/ethapi/api_test.go index 4a7694737e..9b08fd8d42 100644 --- a/internal/ethapi/api_test.go +++ b/internal/ethapi/api_test.go @@ -910,18 +910,18 @@ func TestCall(t *testing.T) { } } -type Account struct { +type account struct { key *ecdsa.PrivateKey addr common.Address } -func newAccounts(n int) (accounts []Account) { +func newAccounts(n int) (accounts []account) { for i := 0; i < n; i++ { key, _ := crypto.GenerateKey() addr := crypto.PubkeyToAddress(key.PublicKey) - accounts = append(accounts, Account{key: key, addr: addr}) + accounts = append(accounts, account{key: key, addr: addr}) } - slices.SortFunc(accounts, func(a, b Account) int { return a.addr.Cmp(b.addr) }) + slices.SortFunc(accounts, func(a, b account) int { return a.addr.Cmp(b.addr) }) return accounts }