mirror of https://github.com/mastodon/flodgatt
168 lines
5.3 KiB
Rust
168 lines
5.3 KiB
Rust
//! Receives data from Redis, sorts it by `ClientAgent`, and stores it until
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//! polled by the correct `ClientAgent`. Also manages sububscriptions and
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//! unsubscriptions to/from Redis.
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mod err;
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mod message_queues;
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pub use err::ReceiverErr;
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pub use message_queues::{MessageQueues, MsgQueue};
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use super::redis::{redis_connection::RedisCmd, RedisConn};
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use crate::{
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config,
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messages::Event,
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parse_client_request::{Stream, Subscription, Timeline},
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};
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use futures::{Async, Poll};
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use std::{
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collections::HashMap,
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result,
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sync::{Arc, Mutex},
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};
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use uuid::Uuid;
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type Result<T> = result::Result<T, ReceiverErr>;
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/// The item that streams from Redis and is polled by the `ClientAgent`
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#[derive(Debug)]
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pub struct Receiver {
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redis_connection: RedisConn,
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pub msg_queues: MessageQueues,
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clients_per_timeline: HashMap<Timeline, i32>,
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}
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impl Receiver {
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/// Create a new `Receiver`, with its own Redis connections (but, as yet, no
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/// active subscriptions).
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pub fn try_from(redis_cfg: config::RedisConfig) -> Result<Self> {
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let redis_connection = RedisConn::new(redis_cfg)?;
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Ok(Self {
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redis_connection,
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msg_queues: MessageQueues(HashMap::new()),
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clients_per_timeline: HashMap::new(),
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})
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}
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pub fn into_arc(self) -> Arc<Mutex<Self>> {
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Arc::new(Mutex::new(self))
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}
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/// Assigns the `Receiver` a new timeline to monitor and runs other
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/// first-time setup.
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pub fn add_subscription(&mut self, subscription: &Subscription) -> Result<()> {
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let (tag, tl) = (subscription.hashtag_name.clone(), subscription.timeline);
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if let (Some(hashtag), Timeline(Stream::Hashtag(id), _, _)) = (tag, tl) {
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self.redis_connection.update_cache(hashtag, id);
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};
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self.msg_queues.insert(subscription.id, MsgQueue::new(tl));
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let number_of_subscriptions = self
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.clients_per_timeline
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.entry(tl)
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.and_modify(|n| *n += 1)
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.or_insert(1);
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use RedisCmd::*;
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if *number_of_subscriptions == 1 {
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self.redis_connection.send_cmd(Subscribe, &tl)?
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};
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Ok(())
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}
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pub fn remove_subscription(&mut self, subscription: &Subscription) -> Result<()> {
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let tl = subscription.timeline;
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self.msg_queues.remove(&subscription.id);
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let number_of_subscriptions = self
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.clients_per_timeline
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.entry(tl)
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.and_modify(|n| *n -= 1)
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.or_insert_with(|| {
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log::error!(
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"Attempted to unsubscribe from a timeline to which you were not subscribed: {:?}",
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tl
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);
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0
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});
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use RedisCmd::*;
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if *number_of_subscriptions == 0 {
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self.redis_connection.send_cmd(Unsubscribe, &tl)?;
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self.clients_per_timeline.remove_entry(&tl);
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};
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Ok(())
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}
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/// Returns the oldest message in the `ClientAgent`'s queue (if any).
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///
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/// Note: This method does **not** poll Redis every time, because polling
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/// Redis is significantly more time consuming that simply returning the
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/// message already in a queue. Thus, we only poll Redis if it has not
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/// been polled lately.
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pub fn poll_for(&mut self, id: Uuid, timeline: Timeline) -> Poll<Option<Event>, ReceiverErr> {
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loop {
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match self.redis_connection.poll_redis() {
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Ok(Async::Ready(Some((timeline, event)))) => {
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self.msg_queues
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.values_mut()
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.filter(|msg_queue| msg_queue.timeline == timeline)
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.for_each(|msg_queue| {
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msg_queue.messages.push_back(event.clone());
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});
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}
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Ok(Async::NotReady) => break,
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Ok(Async::Ready(None)) => (),
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Err(err) => Err(err)?,
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}
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}
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// If the `msg_queue` being polled has any new messages, return the first (oldest) one
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match self.msg_queues.get_mut(&id) {
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Some(msg_q) => match msg_q.messages.pop_front() {
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Some(event) => Ok(Async::Ready(Some(event))),
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None => Ok(Async::NotReady),
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},
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None => {
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log::error!("Polled a MsgQueue that had not been set up. Setting it up now.");
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self.msg_queues.insert(id, MsgQueue::new(timeline));
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Ok(Async::NotReady)
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}
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}
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}
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pub fn count_connections(&self) -> String {
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format!(
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"Current connections: {}",
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self.clients_per_timeline.values().sum::<i32>()
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)
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}
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pub fn list_connections(&self) -> String {
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let max_len = self
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.clients_per_timeline
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.keys()
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.fold(0, |acc, el| acc.max(format!("{:?}:", el).len()));
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self.clients_per_timeline
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.iter()
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.map(|(tl, n)| {
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let tl_txt = format!("{:?}:", tl);
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format!("{:>1$} {2}\n", tl_txt, max_len, n)
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})
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.collect()
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}
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pub fn queue_length(&self) -> String {
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format!(
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"Longest MessageQueue: {}",
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self.msg_queues
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.0
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.values()
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.fold(0, |acc, el| acc.max(el.messages.len()))
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)
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}
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}
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