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use crate::errors::*;
use crate::messages::*;
use crate::pool::*;
use crate::row::*;
use crate::types::*;
use std::collections::VecDeque;
use std::sync::Arc;
use tokio::sync::Mutex;
pub struct RowStream {
qid: i64,
fields: BoltList,
state: State,
fetch_size: usize,
buffer: VecDeque<Row>,
connection: Arc<Mutex<ManagedConnection>>,
}
#[derive(Copy, Clone, PartialEq, Debug)]
enum State {
Ready,
Streaming,
Buffered,
Complete,
}
impl RowStream {
pub(crate) fn new(
qid: i64,
fields: BoltList,
fetch_size: usize,
connection: Arc<Mutex<ManagedConnection>>,
) -> RowStream {
RowStream {
qid,
fields,
connection,
fetch_size,
state: State::Ready,
buffer: VecDeque::with_capacity(fetch_size),
}
}
pub async fn next(&mut self) -> Result<Option<Row>> {
let mut connection = self.connection.lock().await;
loop {
match self.state {
State::Ready => {
let pull = BoltRequest::pull(self.fetch_size, self.qid);
connection.send(pull).await?;
self.state = State::Streaming;
}
State::Streaming => match connection.recv().await {
Ok(BoltResponse::SuccessMessage(s)) => {
if s.get("has_more").unwrap_or(false) {
self.state = State::Buffered;
} else {
self.state = State::Complete;
}
}
Ok(BoltResponse::RecordMessage(record)) => {
let row = Row::new(self.fields.clone(), record.data);
self.buffer.push_back(row);
}
msg => {
return Err(Error::UnexpectedMessage(format!(
"unexpected response for PULL: {:?}",
msg
)))
}
},
State::Buffered => {
if !self.buffer.is_empty() {
return Ok(self.buffer.pop_front());
}
self.state = State::Ready;
}
State::Complete => {
return Ok(self.buffer.pop_front());
}
}
}
}
}