wesichain_core/
fallbacks.rs

1use std::sync::Arc;
2
3use crate::{Runnable, StreamEvent, WesichainError};
4use async_trait::async_trait;
5use futures::stream::BoxStream;
6
7pub struct RunnableWithFallbacks<Input, Output> {
8    primary: Arc<dyn Runnable<Input, Output> + Send + Sync>,
9    fallbacks: Vec<Arc<dyn Runnable<Input, Output> + Send + Sync>>,
10}
11
12impl<Input, Output> RunnableWithFallbacks<Input, Output> {
13    pub fn new(
14        primary: Arc<dyn Runnable<Input, Output> + Send + Sync>,
15        fallbacks: Vec<Arc<dyn Runnable<Input, Output> + Send + Sync>>,
16    ) -> Self {
17        Self { primary, fallbacks }
18    }
19}
20
21#[async_trait]
22impl<Input, Output> Runnable<Input, Output> for RunnableWithFallbacks<Input, Output>
23where
24    Input: Clone + Send + Sync + 'static,
25    Output: Send + Sync + 'static,
26{
27    async fn invoke(&self, input: Input) -> Result<Output, WesichainError> {
28        let mut last_error = match self.primary.invoke(input.clone()).await {
29            Ok(output) => return Ok(output),
30            Err(e) => e,
31        };
32
33        for fallback in &self.fallbacks {
34            match fallback.invoke(input.clone()).await {
35                Ok(output) => return Ok(output),
36                Err(e) => last_error = e,
37            }
38        }
39
40        Err(last_error)
41    }
42
43    fn stream(&self, input: Input) -> BoxStream<'_, Result<StreamEvent, WesichainError>> {
44        // Streaming support for fallbacks is tricky (state reset).
45        // Delegating to primary stream for now, but ignoring fallbacks in stream mode?
46        // Or if primary fails stream, we can't easily switch to fallback stream mid-stream.
47        // So we just stream primary.
48        self.primary.stream(input)
49    }
50
51    fn to_serializable(&self) -> Option<crate::serde::SerializableRunnable> {
52        let primary = Box::new(self.primary.to_serializable()?);
53        let mut fallbacks = Vec::new();
54        for f in &self.fallbacks {
55            fallbacks.push(f.to_serializable()?);
56        }
57        Some(crate::serde::SerializableRunnable::Fallbacks { primary, fallbacks })
58    }
59}
wesichain_core/fallbacks.rs

wesichain_core/
fallbacks.rs
