Struct GenericHandler 

pub struct GenericHandler { /* private fields */ }

Closure-based CallbackHandler for ad-hoc observability hooks.

Unset hooks delegate to the generic lifecycle layer, matching the CallbackHandler trait defaults (e.g. an unset on_llm_start forwards to on_run_start).

Implementations

impl GenericHandler

pub fn new() -> Self

Create a handler with no hooks set.

pub fn with_run_start( self, f: impl Fn(&RunTree) + Send + Sync + 'static, ) -> Self

Set the generic run-start hook.

pub fn with_run_end(self, f: impl Fn(&RunTree) + Send + Sync + 'static) -> Self

Set the generic run-end hook.

pub fn with_run_error( self, f: impl Fn(&RunTree, &str) + Send + Sync + 'static, ) -> Self

Set the generic run-error hook.

pub fn with_llm_start( self, f: impl Fn(&RunTree, &[Message]) + Send + Sync + 'static, ) -> Self

Set the LLM start hook (falls back to the run-start hook when unset).

pub fn with_llm_end( self, f: impl Fn(&RunTree, &str) + Send + Sync + 'static, ) -> Self

Set the LLM end hook (falls back to the run-end hook when unset).

pub fn with_llm_new_token( self, f: impl Fn(&RunTree, &str) + Send + Sync + 'static, ) -> Self

Set the streaming-token hook (default: no-op).

pub fn with_llm_thinking( self, f: impl Fn(&RunTree, &str) + Send + Sync + 'static, ) -> Self

Set the extended-thinking token hook (default: no-op).

pub fn with_tool_start( self, f: impl Fn(&RunTree, &str, &str) + Send + Sync + 'static, ) -> Self

Set the tool start hook (falls back to the run-start hook when unset).

pub fn with_retriever_start( self, f: impl Fn(&RunTree, &str) + Send + Sync + 'static, ) -> Self

Set the retriever start hook (falls back to the run-start hook when unset).

Trait Implementations

impl CallbackHandler for GenericHandler

fn on_run_start<'life0, 'life1, 'async_trait>( &'life0 self, run: &'life1 RunTree, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Called when any run starts

fn on_run_end<'life0, 'life1, 'async_trait>( &'life0 self, run: &'life1 RunTree, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Called when a run ends successfully

fn on_run_error<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, run: &'life1 RunTree, error: &'life2 str, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called when a run fails

fn on_llm_start<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, run: &'life1 RunTree, messages: &'life2 [Message], ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called when an LLM starts

fn on_llm_end<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, run: &'life1 RunTree, response: &'life2 str, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called when an LLM ends

fn on_llm_new_token<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, run: &'life1 RunTree, token: &'life2 str, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called for each new token during streaming

fn on_llm_thinking<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, run: &'life1 RunTree, thinking: &'life2 str, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called for each thinking token during streaming (extended thinking).

fn on_tool_start<'life0, 'life1, 'life2, 'life3, 'async_trait>( &'life0 self, run: &'life1 RunTree, tool_name: &'life2 str, input: &'life3 str, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait, 'life3: 'async_trait,

Called when a tool starts

fn on_retriever_start<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, run: &'life1 RunTree, query: &'life2 str, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called when a retriever starts

fn on_llm_error<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, run: &'life1 RunTree, error: &'life2 str, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called when an LLM errors

fn on_chain_start<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, run: &'life1 RunTree, _inputs: &'life2 Value, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called when a chain starts

fn on_chain_end<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, run: &'life1 RunTree, _outputs: &'life2 Value, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called when a chain ends

fn on_chain_error<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, run: &'life1 RunTree, error: &'life2 str, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called when a chain errors

fn on_tool_end<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, run: &'life1 RunTree, _output: &'life2 str, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called when a tool ends

fn on_tool_error<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, run: &'life1 RunTree, error: &'life2 str, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called when a tool errors

fn on_retriever_end<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, run: &'life1 RunTree, _documents: &'life2 [Value], ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called when a retriever ends

fn on_retriever_error<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, run: &'life1 RunTree, error: &'life2 str, ) -> Pin<Box<dyn Future<Output = ()> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait,

Called when a retriever errors

impl Default for GenericHandler

fn default() -> GenericHandler

Returns the “default value” for a type.