@ -42,6 +42,8 @@ type Options struct {
Chain core . ChainContext // Chain context to access past block hashes
Chain core . ChainContext // Chain context to access past block hashes
Header * types . Header // Header defining the block context to execute in
Header * types . Header // Header defining the block context to execute in
State * state . StateDB // Pre-state on top of which to estimate the gas
State * state . StateDB // Pre-state on top of which to estimate the gas
ErrorRatio float64 // Allowed overestimation ratio for faster estimation termination
}
}
// Estimate returns the lowest possible gas limit that allows the transaction to
// Estimate returns the lowest possible gas limit that allows the transaction to
@ -86,16 +88,28 @@ func Estimate(ctx context.Context, call *core.Message, opts *Options, gasCap uin
if transfer == nil {
if transfer == nil {
transfer = new ( big . Int )
transfer = new ( big . Int )
}
}
log . Warn ( "Gas estimation capped by limited funds" , "original" , hi , "balance" , balance ,
log . Debug ( "Gas estimation capped by limited funds" , "original" , hi , "balance" , balance ,
"sent" , transfer , "maxFeePerGas" , feeCap , "fundable" , allowance )
"sent" , transfer , "maxFeePerGas" , feeCap , "fundable" , allowance )
hi = allowance . Uint64 ( )
hi = allowance . Uint64 ( )
}
}
}
}
// Recap the highest gas allowance with specified gascap.
// Recap the highest gas allowance with specified gascap.
if gasCap != 0 && hi > gasCap {
if gasCap != 0 && hi > gasCap {
log . Warn ( "Caller gas above allowance, capping" , "requested" , hi , "cap" , gasCap )
log . Debug ( "Caller gas above allowance, capping" , "requested" , hi , "cap" , gasCap )
hi = gasCap
hi = gasCap
}
}
// If the transaction is a plain value transfer, short circuit estimation and
// directly try 21000. Returning 21000 without any execution is dangerous as
// some tx field combos might bump the price up even for plain transfers (e.g.
// unused access list items). Ever so slightly wasteful, but safer overall.
if len ( call . Data ) == 0 {
if call . To != nil && opts . State . GetCodeSize ( * call . To ) == 0 {
failed , _ , err := execute ( ctx , call , opts , params . TxGas )
if ! failed && err == nil {
return params . TxGas , nil , nil
}
}
}
// We first execute the transaction at the highest allowable gas limit, since if this fails we
// We first execute the transaction at the highest allowable gas limit, since if this fails we
// can return error immediately.
// can return error immediately.
failed , result , err := execute ( ctx , call , opts , hi )
failed , result , err := execute ( ctx , call , opts , hi )
@ -115,8 +129,35 @@ func Estimate(ctx context.Context, call *core.Message, opts *Options, gasCap uin
// limit for these cases anyway.
// limit for these cases anyway.
lo = result . UsedGas - 1
lo = result . UsedGas - 1
// There's a fairly high chance for the transaction to execute successfully
// with gasLimit set to the first execution's usedGas + gasRefund. Explicitly
// check that gas amount and use as a limit for the binary search.
optimisticGasLimit := ( result . UsedGas + result . RefundedGas + params . CallStipend ) * 64 / 63
if optimisticGasLimit < hi {
failed , _ , err = execute ( ctx , call , opts , optimisticGasLimit )
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 = optimisticGasLimit
} else {
hi = optimisticGasLimit
}
}
// Binary search for the smallest gas limit that allows the tx to execute successfully.
// Binary search for the smallest gas limit that allows the tx to execute successfully.
for lo + 1 < hi {
for lo + 1 < hi {
if opts . ErrorRatio > 0 {
// It is a bit pointless to return a perfect estimation, as changing
// network conditions require the caller to bump it up anyway. Since
// wallets tend to use 20-25% bump, allowing a small approximation
// error is fine (as long as it's upwards).
if float64 ( hi - lo ) / float64 ( hi ) < opts . ErrorRatio {
break
}
}
mid := ( hi + lo ) / 2
mid := ( hi + lo ) / 2
if mid > lo * 2 {
if mid > lo * 2 {
// Most txs don't need much higher gas limit than their gas used, and most txs don't
// Most txs don't need much higher gas limit than their gas used, and most txs don't