diff options
Diffstat (limited to 'internal')
| -rw-r--r-- | internal/ethapi/api.go | 39 |
1 files changed, 26 insertions, 13 deletions
diff --git a/internal/ethapi/api.go b/internal/ethapi/api.go index 1ffb5a180..59a29d722 100644 --- a/internal/ethapi/api.go +++ b/internal/ethapi/api.go @@ -649,12 +649,14 @@ func (s *PublicBlockChainAPI) Call(ctx context.Context, args CallArgs, blockNr r return (hexutil.Bytes)(result), err } -// EstimateGas returns an estimate of the amount of gas needed to execute the given transaction. +// EstimateGas returns an estimate of the amount of gas needed to execute the +// given transaction against the current pending block. func (s *PublicBlockChainAPI) EstimateGas(ctx context.Context, args CallArgs) (*hexutil.Big, error) { - // Binary search the gas requirement, as it may be higher than the amount used + // Determine the lowest and highest possible gas limits to binary search in between var ( - lo uint64 = params.TxGas - 1 - hi uint64 + lo uint64 = params.TxGas - 1 + hi uint64 + cap uint64 ) if (*big.Int)(&args.Gas).Uint64() >= params.TxGas { hi = (*big.Int)(&args.Gas).Uint64() @@ -666,20 +668,31 @@ func (s *PublicBlockChainAPI) EstimateGas(ctx context.Context, args CallArgs) (* } hi = block.GasLimit().Uint64() } - for lo+1 < hi { - // Take a guess at the gas, and check transaction validity - mid := (hi + lo) / 2 - (*big.Int)(&args.Gas).SetUint64(mid) + cap = hi + // Create a helper to check if a gas allowance results in an executable transaction + executable := func(gas uint64) bool { + (*big.Int)(&args.Gas).SetUint64(gas) _, _, failed, err := s.doCall(ctx, args, rpc.PendingBlockNumber, vm.Config{}) - - // If the transaction became invalid or execution failed, raise the gas limit if err != nil || failed { + return false + } + return true + } + // Execute the binary search and hone in on an executable gas limit + for lo+1 < hi { + mid := (hi + lo) / 2 + if !executable(mid) { lo = mid - continue + } else { + hi = mid + } + } + // Reject the transaction as invalid if it still fails at the highest allowance + if hi == cap { + if !executable(hi) { + return nil, fmt.Errorf("gas required exceeds allowance or always failing transaction") } - // Otherwise assume the transaction succeeded, lower the gas limit - hi = mid } return (*hexutil.Big)(new(big.Int).SetUint64(hi)), nil } |