Enum BackpressurePolicy 

pub enum BackpressurePolicy {
    Queue,
    Fail,
}

Core traits and types.

Always available regardless of feature flags. Includes:

• Agent - The fundamental trait for all agents
• Tool / Toolset - For extending agents with capabilities
• Session / State - For managing conversation context
• Event - For streaming agent responses
• AdkError / Result - Unified error handling Policy for handling excess tool calls when the concurrency limit is reached.

Determines whether tool calls that exceed the configured concurrency limit should wait in a queue or fail immediately.

Example

use adk_core::BackpressurePolicy;

// Default is Queue
let policy = BackpressurePolicy::default();
assert!(matches!(policy, BackpressurePolicy::Queue));

Variants

Queue

Queue excess calls until a permit becomes available.

This is the default policy. Tool calls will await until a semaphore permit is released by a completing tool execution.

Fail

Fail immediately with a concurrency limit error when no permit is available.

Use this when latency is more important than throughput — callers receive an immediate error rather than waiting indefinitely.

Trait Implementations

impl Clone for BackpressurePolicy

fn clone(&self) -> BackpressurePolicy

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for BackpressurePolicy

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

Formats the value using the given formatter.

impl Default for BackpressurePolicy

fn default() -> BackpressurePolicy

Returns the “default value” for a type.

impl Eq for BackpressurePolicy

impl PartialEq for BackpressurePolicy

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for BackpressurePolicy