75 lines
2.2 KiB
Rust
75 lines
2.2 KiB
Rust
//! Tower service layer for batch processing.
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use std::{fmt, marker::PhantomData};
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use tower::layer::Layer;
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use tower::Service;
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use super::{service::Batch, BatchControl};
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/// Adds a layer performing batch processing of requests.
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///
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/// The default Tokio executor is used to run the given service,
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/// which means that this layer can only be used on the Tokio runtime.
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///
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/// See the module documentation for more details.
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pub struct BatchLayer<Request> {
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max_items_in_batch: usize,
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max_batches: Option<usize>,
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max_latency: std::time::Duration,
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// TODO: is the variance correct here?
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// https://doc.rust-lang.org/1.33.0/nomicon/subtyping.html#variance
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// https://doc.rust-lang.org/nomicon/phantom-data.html#table-of-phantomdata-patterns
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_handles_requests: PhantomData<fn(Request)>,
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}
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impl<Request> BatchLayer<Request> {
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/// Creates a new `BatchLayer`.
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///
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/// The wrapper is responsible for telling the inner service when to flush a
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/// batch of requests. See [`Batch::new()`] for details.
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pub fn new(
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max_items_in_batch: usize,
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max_batches: impl Into<Option<usize>>,
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max_latency: std::time::Duration,
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) -> Self {
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BatchLayer {
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max_items_in_batch,
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max_batches: max_batches.into(),
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max_latency,
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_handles_requests: PhantomData,
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}
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}
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}
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impl<S, Request> Layer<S> for BatchLayer<Request>
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where
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S: Service<BatchControl<Request>> + Send + 'static,
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S::Future: Send,
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S::Response: Send,
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S::Error: Into<crate::BoxError> + Send + Sync,
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Request: Send + 'static,
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{
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type Service = Batch<S, Request>;
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fn layer(&self, service: S) -> Self::Service {
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Batch::new(
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service,
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self.max_items_in_batch,
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self.max_batches,
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self.max_latency,
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)
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}
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}
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impl<Request> fmt::Debug for BatchLayer<Request> {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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f.debug_struct("BufferLayer")
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.field("max_items_in_batch", &self.max_items_in_batch)
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.field("max_batches", &self.max_batches)
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.field("max_latency", &self.max_latency)
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.finish()
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}
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}
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