Struct LatencyMiddleware 

pub struct LatencyMiddleware { /* private fields */ }

Middleware that records latency metrics for tool calls.

Stores ToolLatency entries that can be retrieved via LatencyMiddleware::tool_latencies. Thread-safe and suitable for use across async tasks.

Examples

use gemini_adk_rs::middleware::{LatencyMiddleware, Middleware};
use gemini_genai_rs::prelude::FunctionCall;

let lat = LatencyMiddleware::new();
// In an async context:
lat.before_tool(&call).await.unwrap();
// ... tool executes ...
lat.after_tool(&call, &result).await.unwrap();
let records = lat.tool_latencies();
println!("Tool {} took {:?}", records[0].name, records[0].elapsed);

Implementations

impl LatencyMiddleware

pub fn new() -> Self

Create a new latency middleware with empty records.

pub fn tool_latencies(&self) -> Vec<ToolLatency>

Returns a snapshot of all recorded tool latencies.

pub fn clear(&self)

Clears all recorded latencies and in-flight state.

Trait Implementations

impl Default for LatencyMiddleware

fn default() -> Self

Returns the “default value” for a type.

impl Middleware for LatencyMiddleware

fn name(&self) -> &str

Unique name for this middleware (used in logging/debugging).

fn before_tool<'life0, 'life1, 'async_trait>( &'life0 self, call: &'life1 FunctionCall, ) -> Pin<Box<dyn Future<Output = Result<(), AgentError>> + Send + 'async_trait>>

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

Called before a tool is invoked.

fn after_tool<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, call: &'life1 FunctionCall, _result: &'life2 Value, ) -> Pin<Box<dyn Future<Output = Result<(), AgentError>> + Send + 'async_trait>>

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

Called after a tool completes successfully.

fn on_tool_error<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, call: &'life1 FunctionCall, _err: &'life2 ToolError, ) -> Pin<Box<dyn Future<Output = Result<(), AgentError>> + Send + 'async_trait>>

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

Called when a tool execution fails.

fn before_agent<'life0, 'life1, 'async_trait>( &'life0 self, _ctx: &'life1 InvocationContext, ) -> Pin<Box<dyn Future<Output = Result<(), AgentError>> + Send + 'async_trait>>

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

Called before an agent begins execution.

fn after_agent<'life0, 'life1, 'async_trait>( &'life0 self, _ctx: &'life1 InvocationContext, ) -> Pin<Box<dyn Future<Output = Result<(), AgentError>> + Send + 'async_trait>>

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

Called after an agent completes execution.

fn on_event<'life0, 'life1, 'async_trait>( &'life0 self, _event: &'life1 AgentEvent, ) -> Pin<Box<dyn Future<Output = Result<(), AgentError>> + Send + 'async_trait>>

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

Called when an agent event is emitted.

fn on_error<'life0, 'life1, 'async_trait>( &'life0 self, _err: &'life1 AgentError, ) -> Pin<Box<dyn Future<Output = Result<(), AgentError>> + Send + 'async_trait>>

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

Called when an agent error occurs.

fn before_model<'life0, 'life1, 'async_trait>( &'life0 self, _request: &'life1 LlmRequest, ) -> Pin<Box<dyn Future<Output = Result<Option<LlmResponse>, AgentError>> + Send + 'async_trait>>

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

Called before an LLM model call is made. Return Some(LlmResponse) to skip the LLM call and use the returned response instead (e.g., for caching, guardrails). Return None to proceed.

fn after_model<'life0, 'life1, 'life2, 'async_trait>( &'life0 self, _request: &'life1 LlmRequest, _response: &'life2 LlmResponse, ) -> Pin<Box<dyn Future<Output = Result<Option<LlmResponse>, AgentError>> + Send + 'async_trait>>

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

Called after an LLM model call completes. Return Some(LlmResponse) to replace the model’s response (e.g., for output filtering, safety). Return None to use the original response.

fn transform_request<'life0, 'life1, 'async_trait>( &'life0 self, _request: &'life1 mut LlmRequest, ) -> Pin<Box<dyn Future<Output = Result<(), AgentError>> + Send + 'async_trait>>

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

Called with the fully-built request before it is sent to the model, allowing in-place mutation (e.g. trimming or rewriting conversation history). Runs ahead of Middleware::before_model. This mirrors the mutable before_model_callback request hook in the ADK Python SDK.

fn timeout(&self) -> Option<Duration>

Maximum wall-clock duration this middleware imposes on the agent run. None (the default) means no limit. The agent enforces the tightest timeout across its middleware chain by bounding the whole run.