use crate::com::AsError;
use futures::{Async, AsyncSink, Future, Sink, Stream};
use std::collections::VecDeque;
use crate::proxy::standalone::Request;
const MAX_PIPELINE: usize = 128;
#[derive(Eq, PartialEq)]
enum State {
Running,
Closing,
Closed,
}
impl State {
fn is_closing(&self) -> bool {
self == &State::Closing
}
fn is_closed(&self) -> bool {
self == &State::Closed
}
}
pub struct Back<T, I, O, R>
where
T: Request,
I: Stream<Item = T, Error = ()>,
O: Sink<SinkItem = T, SinkError = AsError>,
R: Stream<Item = T::Reply, Error = AsError>,
{
#[allow(unused)]
cluster: String,
addr: String,
state: State,
store: Option<T>,
cmdq: VecDeque<T>,
input: I,
output: O,
recv: R,
}
impl<T, I, O, R> Back<T, I, O, R>
where
T: Request,
I: Stream<Item = T, Error = ()>,
O: Sink<SinkItem = T, SinkError = AsError>,
R: Stream<Item = T::Reply, Error = AsError>,
{
pub fn new(cluster: String, addr: String, input: I, output: O, recv: R) -> Back<T, I, O, R> {
Back {
cluster,
addr,
input,
output,
recv,
state: State::Running,
store: None,
cmdq: VecDeque::with_capacity(MAX_PIPELINE),
}
}
fn try_forward(&mut self) -> Result<Async<State>, AsError> {
let mut count = 0;
let mut ret_state = State::Running;
for _ in 0..MAX_PIPELINE {
if let Some(cmd) = self.store.take() {
let rcmd = cmd.clone();
match self.output.start_send(cmd) {
Ok(AsyncSink::NotReady(cmd)) => {
self.store = Some(cmd);
break;
}
Ok(AsyncSink::Ready) => {
count += 1;
#[cfg(feature = "metrics")]
rcmd.mark_remote(&self.cluster);
self.cmdq.push_back(rcmd);
}
Err(err) => {
error!(
"fail to send cmd to backend to {} due to {}",
self.addr, err
);
rcmd.set_error(&err);
return Err(err);
}
}
}
match self.input.poll() {
Ok(Async::Ready(Some(cmd))) => {
self.store = Some(cmd);
}
Ok(Async::Ready(None)) => {
ret_state = State::Closing;
break;
}
Ok(Async::NotReady) => {
break;
}
Err(_) => unreachable!(),
}
}
if count > 0 {
self.output.poll_complete()?;
return Ok(Async::Ready(ret_state));
} else {
return Ok(Async::NotReady);
}
}
fn try_recv(&mut self) -> Result<Async<()>, AsError> {
let mut count = 0usize;
for _ in 0..MAX_PIPELINE {
if self.cmdq.is_empty() {
break;
}
let msg = match self.recv.poll() {
Ok(Async::Ready(Some(msg))) => {
count += 1;
msg
}
Ok(Async::Ready(None)) => {
return Err(AsError::BackendClosedError(self.addr.clone()));
}
Ok(Async::NotReady) => {
break;
}
Err(err) => {
error!("fail to recv from backend connection due {:?}", err);
return Err(err.into());
}
};
let cmd = self.cmdq.pop_front().expect("cmdq never be empty");
cmd.set_reply(msg);
}
if count > 0 {
Ok(Async::Ready(()))
} else {
Ok(Async::NotReady)
}
}
fn on_closed(&mut self) {
for cmd in self.cmdq.drain(0..) {
cmd.set_error(&AsError::BackendClosedError(self.addr.clone()));
}
if let Some(cmd) = self.store.take() {
cmd.set_error(&AsError::BackendClosedError(self.addr.clone()));
}
loop {
match self.input.poll() {
Ok(Async::Ready(Some(cmd))) => {
cmd.set_error(&AsError::BackendClosedError(self.addr.clone()));
}
Ok(Async::Ready(None)) | Ok(Async::NotReady) => {
break;
}
Err(_) => unreachable!(),
}
}
}
}
impl<T, I, O, R> Future for Back<T, I, O, R>
where
T: Request,
I: Stream<Item = T, Error = ()>,
O: Sink<SinkItem = T, SinkError = AsError>,
R: Stream<Item = T::Reply, Error = AsError>,
{
type Item = ();
type Error = ();
fn poll(&mut self) -> Result<Async<Self::Item>, Self::Error> {
let mut can_recv = true;
let mut can_forward = true;
loop {
if self.state.is_closing() {
debug!("backend {} is closing", self.addr);
self.on_closed();
self.state = State::Closed;
}
if self.state.is_closed() {
debug!("backend {} is closed", self.addr);
return Ok(Async::Ready(()));
}
if !can_recv && !can_forward {
return Ok(Async::NotReady);
}
if can_recv {
match self.try_recv() {
Ok(Async::NotReady) => {
can_recv = false;
}
Ok(Async::Ready(_)) => {
can_forward = true;
}
Err(err) => {
warn!("backend {} recv is error {}", self.addr, err);
self.state = State::Closing;
continue;
}
}
}
if can_forward {
match self.try_forward() {
Ok(Async::NotReady) => {
can_forward = false;
}
Ok(Async::Ready(State::Closing)) => {
self.state = State::Closing;
}
Ok(Async::Ready(_)) => {
can_recv = true;
}
Err(err) => {
warn!("backend {} forward is error {}", self.addr, err);
self.state = State::Closing;
continue;
}
}
}
}
}
}
pub struct Blackhole<T, S>
where
T: Request,
S: Stream<Item = T>,
{
addr: String,
input: S,
}
impl<T, S> Blackhole<T, S>
where
T: Request,
S: Stream<Item = T>,
{
pub fn new(addr: String, input: S) -> Blackhole<T, S> {
Blackhole { addr, input }
}
}
impl<T, S> Future for Blackhole<T, S>
where
T: Request,
S: Stream<Item = T>,
{
type Item = ();
type Error = ();
fn poll(&mut self) -> Result<Async<Self::Item>, Self::Error> {
loop {
match self.input.poll() {
Ok(Async::Ready(Some(cmd))) => {
cmd.set_error(&AsError::BackendClosedError(self.addr.clone()));
}
Ok(Async::Ready(None)) => {
return Ok(Async::Ready(()));
}
Ok(Async::NotReady) => {
return Ok(Async::NotReady);
}
Err(_) => {
unreachable!("rx chan is never be fail");
}
}
}
}
}