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use serde::de::DeserializeOwned;
use serde_json;
use nakadi::model::{EventType, PartitionId};
#[derive(Debug)]
pub enum ProcessingStatus {
Processed(Option<usize>),
Failed { reason: String },
}
impl ProcessingStatus {
pub fn processed_no_hint() -> ProcessingStatus {
ProcessingStatus::Processed(None)
}
pub fn processed(num_events_hint: usize) -> ProcessingStatus {
ProcessingStatus::Processed(Some(num_events_hint))
}
pub fn failed<T: Into<String>>(reason: T) -> ProcessingStatus {
ProcessingStatus::Failed {
reason: reason.into(),
}
}
}
pub trait BatchHandler {
fn handle(&mut self, event_type: EventType, events: &[u8]) -> ProcessingStatus;
}
#[derive(Debug, Fail)]
#[fail(display = "{}", message)]
pub struct CreateHandlerError {
pub message: String,
}
pub trait HandlerFactory {
type Handler: BatchHandler + Send + 'static;
fn create_handler(&self, partition: &PartitionId) -> Result<Self::Handler, CreateHandlerError>;
}
pub enum TypedProcessingStatus {
Processed,
Failed { reason: String },
}
pub trait TypedBatchHandler {
type Event: DeserializeOwned;
fn handle(&mut self, events: Vec<Self::Event>) -> TypedProcessingStatus;
}
impl<T, E> BatchHandler for T
where
T: TypedBatchHandler<Event = E>,
E: DeserializeOwned,
{
fn handle(&mut self, event_type: EventType, events: &[u8]) -> ProcessingStatus {
let events: Vec<E> = match serde_json::from_slice(events) {
Ok(events) => events,
Err(err) => {
return ProcessingStatus::Failed {
reason: format!(
"Could not deserialize events(event type: {}): {}",
event_type.0, err
),
}
}
};
let n = events.len();
match TypedBatchHandler::handle(self, events) {
TypedProcessingStatus::Processed => ProcessingStatus::processed(n),
TypedProcessingStatus::Failed { reason } => ProcessingStatus::Failed { reason },
}
}
}