Struct TokenUsage 

pub struct TokenUsage {
    pub prompt_tokens: u32,
    pub completion_tokens: u32,
    pub total_tokens: u32,
    pub cache_hit_tokens: u32,
    pub cache_miss_tokens: u32,
    pub reasoning_tokens: u32,
}

Token usage data from an LLM response.

Fields

prompt_tokens: u32

completion_tokens: u32

total_tokens: u32

cache_hit_tokens: u32

Input tokens served from the provider’s prompt cache.

Invariant (normalised across providers): cache_hit_tokens + cache_miss_tokens == total input tokens. A “hit” is a token read from cache; everything else processed for the prompt (fresh input and tokens written to cache) counts as a “miss”. This lets consumers compute a cache-hit rate as cache_hit / (cache_hit + cache_miss) uniformly, regardless of which provider reported the usage. DeepSeek already reports the split this way (prompt_tokens = hit + miss); Anthropic reports input_tokens, cache_read_input_tokens and cache_creation_input_tokens separately, so its parser folds input + creation into cache_miss_tokens.

cache_miss_tokens: u32

reasoning_tokens: u32

Reasoning / thinking tokens emitted by models that support extended thinking (DeepSeek R1, OpenAI o1, Anthropic extended thinking). Adds to the cost total because the model spent compute producing them. Default 0 for models that don’t report this separately.

Implementations

impl TokenUsage

pub fn accumulate(self, other: TokenUsage) -> TokenUsage

Saturating element-wise sum. Used to accumulate across LLM calls.

Trait Implementations

impl Clone for TokenUsage

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 TokenUsage

impl Debug for TokenUsage

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

Formats the value using the given formatter.

impl Default for TokenUsage

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for TokenUsage

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Eq for TokenUsage

impl PartialEq for TokenUsage

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

Equality operator ==.

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

Inequality operator !=.

impl Serialize for TokenUsage

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

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for TokenUsage