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#![deny(missing_debug_implementations)]
#![deny(rustdoc::broken_intra_doc_links)]
#![cfg_attr(test, deny(warnings))]
#![warn(rust_2018_idioms)]
use std::{error::Error as StdError, fmt, future::Future, pin::Pin};
use thiserror::Error;
use tokio::sync::{
broadcast,
mpsc::{self, error::SendError},
oneshot,
};
use msr_core::audit::Activity;
pub trait Plugin {
type Message;
type Event;
fn message_sender(&self) -> MessageSender<Self::Message>;
fn subscribe_events(&self) -> BroadcastReceiver<Self::Event>;
fn run(self) -> MessageLoop;
}
#[allow(missing_debug_implementations)]
pub struct PluginContainer<M, E> {
pub ports: PluginPorts<M, E>,
pub message_loop: MessageLoop,
}
impl<M, E> Plugin for PluginContainer<M, E> {
type Message = M;
type Event = PublishedEvent<E>;
fn message_sender(&self) -> MessageSender<Self::Message> {
self.ports.message_tx.clone()
}
fn subscribe_events(&self) -> BroadcastReceiver<Self::Event> {
self.ports.event_subscriber.subscribe()
}
fn run(self) -> MessageLoop {
self.message_loop
}
}
pub type MessageLoop = Pin<Box<dyn Future<Output = ()> + Send + 'static>>;
#[allow(missing_debug_implementations)]
pub struct PluginPorts<M, E> {
pub message_tx: MessageSender<M>,
pub event_subscriber: EventSubscriber<E>,
}
#[derive(Error, Debug)]
pub enum PluginError<E: StdError> {
#[error("communication error")]
Communication,
#[error("internal error: {0}")]
Internal(E),
}
pub type PluginResult<T, E> = Result<T, PluginError<E>>;
pub type MessageSender<T> = mpsc::UnboundedSender<T>;
pub type MessageReceiver<T> = mpsc::UnboundedReceiver<T>;
pub fn message_channel<T>() -> (MessageSender<T>, MessageReceiver<T>) {
mpsc::unbounded_channel()
}
pub type ReplySender<T> = oneshot::Sender<T>;
pub type ReplyReceiver<T> = oneshot::Receiver<T>;
pub fn reply_channel<T>() -> (oneshot::Sender<T>, oneshot::Receiver<T>) {
oneshot::channel()
}
pub type ResultSender<T, E> = ReplySender<Result<T, E>>;
pub type ResultReceiver<T, E> = ReplyReceiver<Result<T, E>>;
type BroadcastSender<T> = broadcast::Sender<T>;
type BroadcastReceiver<T> = broadcast::Receiver<T>;
#[derive(Debug, Clone)]
pub struct BroadcastSubscriber<T> {
sender: BroadcastSender<T>,
}
impl<T> BroadcastSubscriber<T> {
pub fn new(sender: BroadcastSender<T>) -> Self {
Self { sender }
}
pub fn subscribe(&self) -> BroadcastReceiver<T> {
self.sender.subscribe()
}
}
pub fn broadcast_channel<T>(channel_capacity: usize) -> (BroadcastSender<T>, BroadcastSubscriber<T>)
where
T: Clone,
{
let (tx, _) = broadcast::channel(channel_capacity);
let subscriber = BroadcastSubscriber::new(tx.clone());
(tx, subscriber)
}
pub type EventPublisherIndexValue = usize;
#[derive(Debug, Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub struct EventPublisherIndex(EventPublisherIndexValue);
impl EventPublisherIndex {
pub const fn from_value(value: EventPublisherIndexValue) -> Self {
Self(value)
}
pub const fn to_value(self) -> EventPublisherIndexValue {
self.0
}
}
impl From<EventPublisherIndexValue> for EventPublisherIndex {
fn from(from: EventPublisherIndexValue) -> Self {
Self::from_value(from)
}
}
impl From<EventPublisherIndex> for EventPublisherIndexValue {
fn from(from: EventPublisherIndex) -> Self {
from.to_value()
}
}
#[derive(Debug, Clone)]
pub struct PublishedEvent<E> {
pub published: Activity<EventPublisherIndex>,
pub payload: E,
}
pub type EventSender<E> = broadcast::Sender<PublishedEvent<E>>;
pub type EventReceiver<E> = broadcast::Receiver<PublishedEvent<E>>;
pub type EventSubscriber<E> = BroadcastSubscriber<PublishedEvent<E>>;
pub fn event_channel<E>(channel_capacity: usize) -> (EventSender<E>, EventSubscriber<E>)
where
E: Clone,
{
broadcast_channel(channel_capacity)
}
#[derive(Debug, Clone)]
pub struct EventPubSub<E> {
publisher_index: EventPublisherIndex,
event_tx: EventSender<E>,
}
impl<E> EventPubSub<E>
where
E: fmt::Debug + Clone,
{
pub fn new(
publisher_index: impl Into<EventPublisherIndex>,
channel_capacity: usize,
) -> (Self, EventSubscriber<E>) {
let (event_tx, event_subscriber) = event_channel(channel_capacity);
(
Self {
publisher_index: publisher_index.into(),
event_tx,
},
event_subscriber,
)
}
pub fn publish_event(&self, payload: E) {
let published = Activity::now(self.publisher_index);
let event = PublishedEvent { published, payload };
self.dispatch_event(event);
}
}
pub trait EventDispatcher<E> {
fn dispatch_event(&self, event: E);
}
impl<E> EventDispatcher<PublishedEvent<E>> for EventPubSub<E>
where
E: fmt::Debug + Clone,
{
fn dispatch_event(&self, event: PublishedEvent<E>) {
if let Err(event) = self.event_tx.send(event) {
log::debug!("No subscribers for published event {:?}", event);
}
}
}
pub fn send_message<M, E>(
message: impl Into<M>,
message_tx: &MessageSender<M>,
) -> PluginResult<(), E>
where
M: fmt::Debug,
E: StdError,
{
message_tx.send(message.into()).map_err(|send_error| {
let SendError(message) = send_error;
log::error!("Unexpected send error: Dropping message {:?}", message);
PluginError::Communication
})
}
pub fn send_reply<R>(reply_tx: ReplySender<R>, reply: impl Into<R>)
where
R: fmt::Debug,
{
if let Err(reply) = reply_tx.send(reply.into()) {
log::info!("Unexpected send error: Dropping reply {:?}", reply);
}
}
pub async fn receive_reply<R, E>(reply_rx: ReplyReceiver<R>) -> PluginResult<R, E>
where
E: StdError,
{
reply_rx.await.map_err(|receive_error| {
log::error!("No reply received: {}", receive_error);
PluginError::Communication
})
}
pub async fn send_message_receive_reply<M, R, E>(
message: impl Into<M>,
message_tx: &MessageSender<M>,
reply_rx: ReplyReceiver<R>,
) -> PluginResult<R, E>
where
M: fmt::Debug,
E: StdError,
{
send_message(message, message_tx)?;
receive_reply(reply_rx).await
}
pub async fn receive_result<R, E>(result_rx: ResultReceiver<R, E>) -> PluginResult<R, E>
where
E: StdError,
{
receive_reply(result_rx)
.await?
.map_err(PluginError::Internal)
}
pub async fn send_message_receive_result<M, R, E>(
message: impl Into<M>,
message_tx: &MessageSender<M>,
result_rx: ResultReceiver<R, E>,
) -> PluginResult<R, E>
where
M: fmt::Debug,
E: StdError,
{
send_message(message, message_tx)?;
receive_result(result_rx).await
}