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use bytes::Bytes;
use futures_util::stream::Stream;
use log::error;
use std::{pin::Pin, task::Poll};
mod error;
mod event;
pub use error::Error;
pub use event::{Change, ChangeEvent, Event, FinishedEvent};
pub struct ChangesStream {
buffer: Vec<u8>,
source: Pin<Box<dyn Stream<Item = reqwest::Result<Bytes>> + Send>>,
}
impl ChangesStream {
pub async fn new(db: String) -> Result<ChangesStream, Error> {
let res = reqwest::get(&db).await.map_err(Error::RequestFailed)?;
let status = res.status();
if !status.is_success() {
return Err(Error::InvalidStatus(status));
}
let source = Pin::new(Box::new(res.bytes_stream()));
Ok(ChangesStream {
buffer: vec![],
source,
})
}
}
impl Stream for ChangesStream {
type Item = Result<Event, Error>;
fn poll_next(
mut self: std::pin::Pin<&mut Self>,
cx: &mut std::task::Context<'_>,
) -> std::task::Poll<Option<Self::Item>> {
loop {
let line_break_pos = self
.buffer
.iter()
.enumerate()
.find(|(_pos, b)| **b == 0x0A)
.map(|(pos, _b)| pos);
if let Some(line_break_pos) = line_break_pos {
let mut line = self.buffer.drain(0..=line_break_pos).collect::<Vec<_>>();
if line.len() < 15 {
continue;
}
line.remove(line.len() - 1);
if line[line.len() - 1] == 0x0D {
line.remove(line.len() - 1);
}
if line[line.len() - 1] == 0x2C {
line.remove(line.len() - 1);
}
let result = match serde_json::from_slice(line.as_slice()) {
Err(err) => Err(Error::ParsingFailed(
err,
String::from_utf8(line).unwrap_or_default(),
)),
Ok(json) => {
let event: Event = json;
Ok(event)
}
};
return Poll::Ready(Some(result));
} else {
match Stream::poll_next(self.source.as_mut(), cx) {
Poll::Pending => return Poll::Pending,
Poll::Ready(None) => return Poll::Ready(None),
Poll::Ready(Some(Ok(chunk))) => self.buffer.append(&mut chunk.to_vec()),
Poll::Ready(Some(Err(err))) => {
error!("Error getting next chunk: {:?}", err);
return Poll::Ready(None);
}
};
}
}
}
}