Struct soroban_env_host::budget::CostModel

pub struct CostModel {
    pub const_param: u64,
    pub log_param: u64,
    pub log_base_param: u64,
    pub lin_param: u64,
    pub quad_param: u64,
}

We provide a general “cost model” object that evaluates a general expression:

f(x) = a + blog_i(x) + cx + d*(x^2)

Where a, b, c, d, and i are all “fixed” parameters at construction time (extracted from an on-chain cost schedule, so technically not totally fixed) and x is some abstract input variable – say, event counts or object sizes – provided at runtime.

The log base i is also rounded-up to its nearest power of 2, since we implement that term using bit count instructions.

The same CostModel type (applied to different parameters and variables) is used for calculating memory as well as CPU time. We hope this expression is capable of modeling any of the costs we want to measure at runtime.

The parameters for a CostModel are calibrated empirically. See this crate’s benchmarks for more details.

Fields

const_param: u64

log_param: u64

log_base_param: u64

lin_param: u64

quad_param: u64

Implementations

impl CostModel

pub fn evaluate(&self, input: u64) -> u64

Trait Implementations

impl Clone for CostModel

fn clone(&self) -> CostModel

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for CostModel

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for CostModel

fn default() -> CostModel

Returns the “default value” for a type.

impl Hash for CostModel

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)where
    H: Hasher,
    Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for CostModel

fn cmp(&self, other: &CostModel) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Selfwhere
    Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Selfwhere
    Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Selfwhere
    Self: Sized + PartialOrd<Self>,

Restrict a value to a certain interval.

impl PartialEq<CostModel> for CostModel

fn eq(&self, other: &CostModel) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd<CostModel> for CostModel

fn partial_cmp(&self, other: &CostModel) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl Eq for CostModel

impl StructuralEq for CostModel

impl StructuralPartialEq for CostModel