mirror of https://github.com/mastodon/flodgatt
129 lines
5.2 KiB
Rust
129 lines
5.2 KiB
Rust
//! Provides an interface between the `Warp` filters and the underlying
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//! mechanics of talking with Redis/managing multiple threads.
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//!
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//! The `ClientAgent`'s interface is very simple. All you can do with it is:
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//! * Create a totally new `ClientAgent` with no shared data;
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//! * Clone an existing `ClientAgent`, sharing the `Receiver`;
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//! * Manage an new timeline/user pair; or
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//! * Poll an existing `ClientAgent` to see if there are any new messages
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//! for clients
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//!
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//! When you poll the `ClientAgent`, it is responsible for polling internal data
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//! structures, getting any updates from Redis, and then filtering out any updates
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//! that should be excluded by relevant filters.
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//!
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//! Because `StreamManagers` are lightweight data structures that do not directly
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//! communicate with Redis, it we create a new `ClientAgent` for
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//! each new client connection (each in its own thread).use super::{message::Message, receiver::Receiver}
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use super::receiver::{Receiver, ReceiverErr};
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use crate::{
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messages::Event,
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parse_client_request::{Stream::Public, Subscription, Timeline},
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};
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use futures::{
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Async::{self, NotReady, Ready},
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Poll,
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};
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use std::sync::{Arc, Mutex, MutexGuard};
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/// Struct for managing all Redis streams.
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#[derive(Clone, Debug)]
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pub struct ClientAgent {
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receiver: Arc<Mutex<Receiver>>,
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pub subscription: Subscription,
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}
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impl ClientAgent {
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pub fn new(receiver: Arc<Mutex<Receiver>>, subscription: &Subscription) -> Self {
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ClientAgent {
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receiver,
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subscription: subscription.clone(),
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}
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}
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/// Initializes the `ClientAgent` with a unique ID associated with a specific user's
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/// subscription. Also passes values to the `Receiver` for it's initialization.
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///
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/// Note that this *may or may not* result in a new Redis connection.
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/// If the server has already subscribed to the timeline on behalf of
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/// a different user, the `Receiver` is responsible for figuring
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/// that out and avoiding duplicated connections. Thus, it is safe to
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/// use this method for each new client connection.
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pub fn subscribe(&mut self) {
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let mut receiver = self.lock_receiver();
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receiver
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.add_subscription(&self.subscription)
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.unwrap_or_else(|e| log::error!("Could not subscribe to the Redis channel: {}", e))
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}
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pub fn disconnect(&self) -> futures::future::FutureResult<bool, tokio::timer::Error> {
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let mut receiver = self.lock_receiver();
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receiver
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.remove_subscription(&self.subscription)
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.unwrap_or_else(|e| log::error!("Could not unsubscribe from: {}", e));
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futures::future::ok(false)
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}
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fn lock_receiver(&self) -> MutexGuard<Receiver> {
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match self.receiver.lock() {
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Ok(inner) => inner,
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Err(e) => {
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log::error!(
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"Another thread crashed: {}\n
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Attempting to continue, possibly with invalid data",
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e
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);
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e.into_inner()
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}
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}
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}
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}
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/// The stream that the `ClientAgent` manages. `Poll` is the only method implemented.
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impl futures::stream::Stream for ClientAgent {
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type Item = Event;
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type Error = ReceiverErr;
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/// Checks for any new messages that should be sent to the client.
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///
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/// The `ClientAgent` polls the `Receiver` and replies
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/// with `Ok(Ready(Some(Value)))` if there is a new message to send to
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/// the client. If there is no new message or if the new message should be
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/// filtered out based on one of the user's filters, then the `ClientAgent`
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/// replies with `Ok(NotReady)`. The `ClientAgent` bubles up any
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/// errors from the underlying data structures.
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fn poll(&mut self) -> Poll<Option<Self::Item>, Self::Error> {
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let result = {
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let mut receiver = self.lock_receiver();
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receiver.poll_for(self.subscription.id, self.subscription.timeline)
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};
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let timeline = &self.subscription.timeline;
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let allowed_langs = &self.subscription.allowed_langs;
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let blocks = &self.subscription.blocks;
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let (send, block) = (|msg| Ok(Ready(Some(msg))), Ok(NotReady));
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use crate::messages::{CheckedEvent::Update, Event::*};
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match result {
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Ok(Async::Ready(Some(event))) => match event {
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TypeSafe(Update { payload, queued_at }) => match timeline {
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Timeline(Public, _, _) if payload.language_not(allowed_langs) => block,
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_ if payload.involves_any(blocks) => block,
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_ => send(TypeSafe(Update { payload, queued_at })),
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},
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TypeSafe(non_update) => send(Event::TypeSafe(non_update)),
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Dynamic(event) if event.event == "update" => match timeline {
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Timeline(Public, _, _) if event.language_not(allowed_langs) => block,
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_ if event.involves_any(blocks) => block,
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_ => send(Dynamic(event)),
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},
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Dynamic(non_update) => send(Dynamic(non_update)),
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},
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Ok(Ready(None)) => Ok(Ready(None)),
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Ok(NotReady) => Ok(NotReady),
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Err(e) => Err(e),
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}
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}
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}
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