mirror of https://github.com/mastodon/flodgatt
131 lines
4.1 KiB
Rust
131 lines
4.1 KiB
Rust
//! Interfacing with Redis and stream the results on to the `StreamManager`
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use crate::user::User;
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use futures::stream::Stream;
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use futures::{Async, Poll};
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use log::info;
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use regex::Regex;
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use serde_json::Value;
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use std::collections::{HashMap, VecDeque};
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use tokio::io::{AsyncRead, Error};
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use uuid::Uuid;
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use std::io::{Read, Write};
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use std::net::TcpStream;
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use std::time::Duration;
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/// The item that streams from Redis and is polled by the `StreamManger`
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#[derive(Debug)]
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pub struct Receiver {
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stream: TcpStream,
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tl: String,
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pub user: User,
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polled_by: Uuid,
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msg_queue: HashMap<Uuid, VecDeque<Value>>,
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}
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impl Receiver {
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pub fn new() -> Self {
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let stream = TcpStream::connect("127.0.0.1:6379").unwrap();
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stream
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.set_read_timeout(Some(Duration::from_millis(10)))
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.unwrap();
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Self {
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stream,
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tl: String::new(),
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user: User::public(),
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polled_by: Uuid::new_v4(),
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msg_queue: HashMap::new(),
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}
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}
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/// Update the `StreamManager` that is currently polling the `Receiver`
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pub fn set_polled_by(&mut self, id: Uuid) -> &Self {
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self.polled_by = id;
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self
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}
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/// Send a subscribe command to the Redis PubSub
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pub fn subscribe(&mut self, tl: &str) {
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let subscribe_cmd = redis_cmd_from("subscribe", &tl);
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info!("Subscribing to {}", &tl);
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self.stream
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.write_all(&subscribe_cmd)
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.expect("Can subscribe to Redis");
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}
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/// Send an unsubscribe command to the Redis PubSub
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pub fn unsubscribe(&mut self, tl: &str) {
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let unsubscribe_cmd = redis_cmd_from("unsubscribe", &tl);
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info!("Subscribing to {}", &tl);
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self.stream
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.write_all(&unsubscribe_cmd)
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.expect("Can unsubscribe from Redis");
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}
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}
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impl Stream for Receiver {
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type Item = Value;
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type Error = Error;
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fn poll(&mut self) -> Poll<Option<Value>, Self::Error> {
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let mut buffer = vec![0u8; 3000];
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let polled_by = self.polled_by;
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self.msg_queue
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.entry(polled_by)
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.or_insert_with(VecDeque::new);
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info!("Being polled by StreamManager with uuid: {}", polled_by);
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let mut async_stream = AsyncReadableStream(&mut self.stream);
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if let Async::Ready(num_bytes_read) = async_stream.poll_read(&mut buffer)? {
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// capture everything between `{` and `}` as potential JSON
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// TODO: figure out if `(?x)` is needed
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let re = Regex::new(r"(?P<json>\{.*\})").expect("Valid hard-coded regex");
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if let Some(cap) = re.captures(&String::from_utf8_lossy(&buffer[..num_bytes_read])) {
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let json: Value = serde_json::from_str(&cap["json"].to_string().clone())?;
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for value in self.msg_queue.values_mut() {
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value.push_back(json.clone());
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}
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}
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}
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if let Some(value) = self.msg_queue.entry(polled_by).or_default().pop_front() {
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Ok(Async::Ready(Some(value)))
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} else {
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Ok(Async::NotReady)
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}
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}
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}
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impl Drop for Receiver {
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fn drop(&mut self) {
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let timeline = self.tl.clone();
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self.unsubscribe(&timeline);
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}
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}
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struct AsyncReadableStream<'a>(&'a mut TcpStream);
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impl<'a> Read for AsyncReadableStream<'a> {
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fn read(&mut self, buffer: &mut [u8]) -> Result<usize, std::io::Error> {
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self.0.read(buffer)
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}
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}
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impl<'a> AsyncRead for AsyncReadableStream<'a> {
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fn poll_read(&mut self, buf: &mut [u8]) -> Poll<usize, std::io::Error> {
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match self.read(buf) {
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Ok(t) => Ok(Async::Ready(t)),
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Err(_) => Ok(Async::NotReady),
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}
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}
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}
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fn redis_cmd_from(cmd: impl std::fmt::Display, timeline: impl std::fmt::Display) -> Vec<u8> {
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let (cmd, arg) = (cmd.to_string(), format!("timeline:{}", timeline));
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format!(
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"*2\r\n${cmd_length}\r\n{cmd}\r\n${arg_length}\r\n{arg}\r\n",
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cmd_length = cmd.len(),
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cmd = cmd,
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arg_length = arg.len(),
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arg = arg
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)
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.as_bytes()
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.to_owned()
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}
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