Struct Usage 

pub struct Usage {
    pub input_tokens: u32,
    pub output_tokens: u32,
    pub cache_read_tokens: Option<u32>,
    pub cache_creation_tokens: Option<u32>,
}

Token usage for one model response.

Convention, uniform across every provider mapping: input_tokens is the full, cache-inclusive prompt size. It always contains cache_read_tokens as a subset (verified live: OpenAI/OpenRouter/DeepSeek report it inside prompt_tokens; the Anthropic mapping adds it back since that API reports input net of cache). cache_creation_tokens is likewise inside input_tokens for providers that report cache writes (Anthropic); the OpenAI-style providers we use don’t report writes at all. So Usage::total (input + output) is the context-window occupancy.

For cost, the cache buckets bill at different rates, so subtract them from the input rate instead of charging the full rate twice: cost = (input - cache_read - cache_creation)·p_in + cache_read·p_cache_read + cache_creation·p_cache_write + output·p_out.

Fields

input_tokens: u32

Full prompt tokens, cache-inclusive (a superset of the two cache fields).

output_tokens: u32

Generated output (completion) tokens.

cache_read_tokens: Option<u32>

Subset of input_tokens served from the prompt cache (cheaper rate).

cache_creation_tokens: Option<u32>

Subset of input_tokens written into the prompt cache (surcharge rate).

Implementations

impl Usage

pub fn new(input_tokens: u32, output_tokens: u32) -> Self

pub fn total(&self) -> u32

Context-window occupancy: the full (cache-inclusive) prompt plus output.

Trait Implementations

impl Add for Usage

type Output = Usage

The resulting type after applying the + operator.

fn add(self, other: Usage) -> Usage

Performs the + operation.

impl AddAssign for Usage

fn add_assign(&mut self, other: Usage)

Performs the += operation.

impl Clone for Usage

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Usage

impl Debug for Usage

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

Formats the value using the given formatter.

impl Default for Usage

fn default() -> Self

Returns the “default value” for a type.

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

where Usage: Default,

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

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.