Struct FallbackChainService 

pub struct FallbackChainService { /* private fields */ }

A ScrapingService that tries multiple inner services in priority order, automatically routing around open circuit breakers and failed services.

Construct via FallbackChainService::builder().

Example

use std::sync::Arc;
use std::time::Duration;
use stygian_graph::adapters::fallback::FallbackChainService;
use stygian_graph::adapters::noop::NoopService;
use stygian_graph::adapters::resilience::CircuitBreakerImpl;
use stygian_graph::ports::ScrapingService;

let chain = FallbackChainService::builder()
    .add(Arc::new(NoopService), CircuitBreakerImpl::new(5, Duration::from_secs(60)))
    .build();

assert_eq!(chain.name(), "fallback-chain");

Implementations

impl FallbackChainService

pub const fn builder() -> FallbackChainBuilder

Return a FallbackChainBuilder for ergonomic construction.

Example

use stygian_graph::adapters::fallback::FallbackChainService;

let builder = FallbackChainService::builder();

pub const fn len(&self) -> usize

Return the number of services in this chain.

Example

use std::sync::Arc;
use std::time::Duration;
use stygian_graph::adapters::fallback::FallbackChainService;
use stygian_graph::adapters::noop::NoopService;
use stygian_graph::adapters::resilience::CircuitBreakerImpl;

let chain = FallbackChainService::builder()
    .add(Arc::new(NoopService), CircuitBreakerImpl::new(3, Duration::from_secs(30)))
    .add(Arc::new(NoopService), CircuitBreakerImpl::new(3, Duration::from_secs(30)))
    .build();

assert_eq!(chain.len(), 2);

pub const fn is_empty(&self) -> bool

Return true when no services are registered.

An empty chain always returns ServiceError::Unavailable.

Example

use stygian_graph::adapters::fallback::FallbackChainService;

let chain = FallbackChainService::builder().build();
assert!(chain.is_empty());

Trait Implementations

impl ScrapingService for FallbackChainService

fn execute<'life0, 'async_trait>( &'life0 self, input: ServiceInput, ) -> Pin<Box<dyn Future<Output = Result<ServiceOutput>> + Send + 'async_trait>>

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

Execute the fallback chain.

Tries each registered service in order, respecting circuit breaker state. Returns the first successful result, or the last error if all services fail.

fn name(&self) -> &'static str

Service name for identification in logs and metrics