Struct Usage 

pub struct Usage {
    pub input_tokens: u64,
    pub output_tokens: u64,
    pub reasoning_tokens: Option<u64>,
    pub cache_read_tokens: Option<u64>,
    pub cache_write_tokens: Option<u64>,
}

Token counts for a single request/response pair.

Fields

input_tokens: u64

Tokens consumed by the prompt (messages + system + tool defs).

output_tokens: u64

Tokens produced by the model’s response.

reasoning_tokens: Option<u64>

Tokens used for chain-of-thought reasoning, if applicable.

cache_read_tokens: Option<u64>

Tokens served from the provider’s prompt cache (reducing cost).

cache_write_tokens: Option<u64>

Tokens written into the provider’s prompt cache for future reuse.

Implementations

impl Usage

pub fn total_tokens(&self) -> u64

Total tokens across all categories.

Sums input_tokens, output_tokens, and all optional fields (reasoning_tokens, cache_read_tokens, cache_write_tokens), treating None as zero. Uses saturating arithmetic.

Trait Implementations

impl Add for Usage

fn add(self, rhs: Self) -> Self

Adds two Usage records field-by-field.

Mandatory fields use saturating addition. Optional fields are summed when both are Some, preserved when one is Some, and remain None when both are None.

type Output = Usage

The resulting type after applying the + operator.

impl AddAssign<&Usage> for Usage

fn add_assign(&mut self, rhs: &Self)

Adds another Usage to this one in-place without cloning.

This is more efficient than AddAssign<Usage> when you have a reference.

impl AddAssign for Usage

fn add_assign(&mut self, rhs: Self)

Performs the += operation.

impl Clone for Usage

fn clone(&self) -> Usage

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Usage

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

Formats the value using the given formatter.

impl Default for Usage

fn default() -> Usage

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Usage

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for Usage

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

Tests for self and other values to be equal, and is used by ==.

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

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

impl Serialize for Usage

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl Eq for Usage

impl StructuralPartialEq for Usage