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use std::{
hash::Hash,
io::IoSlice,
marker::PhantomData,
pin::Pin,
sync::Arc,
task::{Context, Poll},
time::Duration,
};
use async_trait::async_trait;
use chrono::Utc;
use futures::{io, join, pin_mut, AsyncRead, AsyncWrite, Stream, StreamExt, TryFutureExt};
use smtp_message::Email;
#[derive(serde::Deserialize, serde::Serialize)]
pub struct MailMetadata<U> {
pub from: Option<Email>,
pub to: Email,
pub metadata: U,
}
pub use smtp_queue_types::{QueueId, ScheduleInfo};
#[async_trait]
pub trait Config<U, StorageError>: 'static + Send + Sync {
async fn next_interval(&self, s: ScheduleInfo) -> Option<Duration>;
async fn log_storage_error(&self, err: StorageError, id: Option<QueueId>);
async fn log_found_inflight(&self, inflight: QueueId);
async fn log_found_pending_cleanup(&self, pcm: QueueId);
async fn log_queued_mail_vanished(&self, id: QueueId);
async fn log_inflight_mail_vanished(&self, id: QueueId);
async fn log_pending_cleanup_mail_vanished(&self, id: QueueId);
async fn log_too_big_duration(&self, id: QueueId, too_big: Duration, new: Duration);
fn found_inflight_check_delay(&self) -> Duration {
Duration::from_secs(3600)
}
fn io_error_next_retry_delay(&self, d: Duration) -> Duration {
if d < Duration::from_secs(30) {
Duration::from_secs(60)
} else {
d.mul_f64(2.0)
}
}
}
#[async_trait]
pub trait Storage<U>: 'static + Send + Sync {
type Error: Send + std::error::Error;
type QueuedMail: QueuedMail;
type InflightMail: InflightMail;
type PendingCleanupMail: PendingCleanupMail;
type QueueLister: Send + Stream<Item = Result<Self::QueuedMail, (Self::Error, Option<QueueId>)>>;
type InflightLister: Send
+ Stream<Item = Result<Self::InflightMail, (Self::Error, Option<QueueId>)>>;
type PendingCleanupLister: Send
+ Stream<Item = Result<Self::PendingCleanupMail, (Self::Error, Option<QueueId>)>>;
type Enqueuer: StorageEnqueuer<U, Self, Self::QueuedMail>;
type Reader: Send + AsyncRead;
async fn list_queue(&self) -> Self::QueueLister;
async fn find_inflight(&self) -> Self::InflightLister;
async fn find_pending_cleanup(&self) -> Self::PendingCleanupLister;
async fn read_inflight(
&self,
mail: &Self::InflightMail,
) -> Result<(MailMetadata<U>, Self::Reader), Self::Error>;
async fn enqueue(&self) -> Result<Self::Enqueuer, Self::Error>;
async fn reschedule(
&self,
mail: &mut Self::QueuedMail,
schedule: ScheduleInfo,
) -> Result<(), Self::Error>;
async fn send_start(
&self,
mail: Self::QueuedMail,
) -> Result<Option<Self::InflightMail>, (Self::QueuedMail, Self::Error)>;
async fn send_done(
&self,
mail: Self::InflightMail,
) -> Result<Option<Self::PendingCleanupMail>, (Self::InflightMail, Self::Error)>;
async fn send_cancel(
&self,
mail: Self::InflightMail,
) -> Result<Option<Self::QueuedMail>, (Self::InflightMail, Self::Error)>;
async fn drop(
&self,
mail: Self::QueuedMail,
) -> Result<Option<Self::PendingCleanupMail>, (Self::QueuedMail, Self::Error)>;
async fn cleanup(
&self,
mail: Self::PendingCleanupMail,
) -> Result<bool, (Self::PendingCleanupMail, Self::Error)>;
}
pub trait QueuedMail: Send + Sync {
fn id(&self) -> QueueId;
fn schedule(&self) -> ScheduleInfo;
}
pub trait InflightMail: Send + Sync {
fn id(&self) -> QueueId;
}
pub trait PendingCleanupMail: Send + Sync {
fn id(&self) -> QueueId;
}
#[async_trait]
pub trait StorageEnqueuer<U, S, QueuedMail>: Send + AsyncWrite
where
S: ?Sized + Storage<U>,
{
async fn commit(
self,
destinations: Vec<(MailMetadata<U>, ScheduleInfo)>,
) -> Result<Vec<QueuedMail>, S::Error>;
}
pub enum TransportFailure {
Local,
NetworkTransient,
MailTransient,
MailboxTransient,
MailSystemTransient,
MailPermanent,
MailboxPermanent,
MailSystemPermanent,
}
#[async_trait]
pub trait Transport<U>: 'static + Send + Sync {
type Destination: Send + Sync + Eq + Hash;
type Sender: TransportSender<U>;
async fn destination(
&self,
meta: &MailMetadata<U>,
) -> Result<Self::Destination, TransportFailure>;
async fn connect(&self, dest: &Self::Destination) -> Result<Self::Sender, TransportFailure>;
}
#[async_trait]
pub trait TransportSender<U>: 'static + Send {
async fn send<Reader>(
&mut self,
meta: &MailMetadata<U>,
mail: Reader,
) -> Result<(), TransportFailure>
where
Reader: Send + AsyncRead;
}
const INTERVAL_ON_TOO_BIG_DURATION: Duration = Duration::from_secs(4 * 3600);
struct QueueImpl<C, S, T> {
executor: Arc<smol::Executor<'static>>,
config: C,
storage: S,
transport: T,
}
pub struct Queue<U, C, S, T> {
q: Arc<QueueImpl<C, S, T>>,
phantom: PhantomData<U>,
}
macro_rules! io_retry_loop {
($this:ident, $init:expr, | $mail:ident | $e:expr) => {{
let mut delay = Duration::from_secs(0);
let mut $mail = $init;
loop {
match $e {
Ok(v) => {
break v;
}
Err((mail, e)) => {
$this.q.config.log_storage_error(e, Some(mail.id())).await;
$mail = mail;
}
}
smol::Timer::after(delay).await;
delay = $this.q.config.io_error_next_retry_delay(delay);
}
}};
}
macro_rules! io_retry_loop_raw {
($this:ident, $id:expr, $e:expr) => {{
let mut delay = Duration::from_secs(0);
loop {
match $e {
Ok(v) => {
break v;
}
Err(e) => {
$this.q.config.log_storage_error(e, Some($id)).await;
}
}
smol::Timer::after(delay).await;
delay = $this.q.config.io_error_next_retry_delay(delay);
}
}};
}
impl<U, C, S, T> Queue<U, C, S, T>
where
U: 'static + Send + Sync,
C: Config<U, S::Error>,
S: Storage<U>,
T: Transport<U>,
{
async fn cleanup(&self, pcm: S::PendingCleanupMail) {
let id = pcm.id();
let cleanup_successful = io_retry_loop!(self, pcm, |p| self.q.storage.cleanup(p).await);
if !cleanup_successful {
self.q.config.log_pending_cleanup_mail_vanished(id).await;
}
}
}
impl<U, C, S, T> Queue<U, C, S, T>
where
U: 'static + Send + Sync,
C: Config<U, S::Error>,
S: Storage<U>,
T: Transport<U>,
{
pub async fn new(
executor: Arc<smol::Executor<'static>>,
config: C,
storage: S,
transport: T,
) -> Queue<U, C, S, T> {
let this = Queue {
q: Arc::new(QueueImpl {
executor,
config,
storage,
transport,
}),
phantom: PhantomData,
};
join!(this.scan_inflight(), this.scan_pending_cleanup());
let this2 = this.clone();
this.q
.executor
.spawn(async move { this2.scan_queue().await })
.detach();
this
}
pub async fn enqueue(&self) -> Result<Enqueuer<U, C, S, T>, S::Error> {
Ok(Enqueuer {
queue: self.clone(),
enqueuer: Some(self.q.storage.enqueue().await?),
})
}
async fn scan_inflight(&self) {
let found_inflight_stream = self.q.storage.find_inflight().await;
pin_mut!(found_inflight_stream);
while let Some(inflight) = found_inflight_stream.next().await {
match inflight {
Err((e, id)) => self.q.config.log_storage_error(e, id).await,
Ok(inflight) => {
self.q.config.log_found_inflight(inflight.id()).await;
let this = self.clone();
self.q
.executor
.spawn(async move {
smol::Timer::after(this.q.config.found_inflight_check_delay()).await;
let queued = io_retry_loop!(this, inflight, |i| this
.q
.storage
.send_cancel(i)
.await);
if let Some(queued) = queued {
this.send(queued).await
} else {
}
})
.detach();
}
}
}
}
async fn scan_queue(&self) {
let queued_stream = self.q.storage.list_queue().await;
pin_mut!(queued_stream);
while let Some(queued) = queued_stream.next().await {
match queued {
Err((e, id)) => self.q.config.log_storage_error(e, id).await,
Ok(queued) => {
let this = self.clone();
self.q
.executor
.spawn(async move {
this.send(queued).await;
})
.detach();
}
}
}
}
async fn scan_pending_cleanup(&self) {
let pcm_stream = self.q.storage.find_pending_cleanup().await;
pin_mut!(pcm_stream);
while let Some(pcm) = pcm_stream.next().await {
match pcm {
Err((e, id)) => self.q.config.log_storage_error(e, id).await,
Ok(pcm) => {
self.q.config.log_found_pending_cleanup(pcm.id()).await;
let this = self.clone();
self.q
.executor
.spawn(async move {
this.cleanup(pcm).await;
})
.detach();
}
}
}
}
async fn send(&self, mail: S::QueuedMail) {
let mut mail = mail;
loop {
const ZERO_DURATION: Duration = Duration::from_secs(0);
let wait_time = (mail.schedule().at - Utc::now())
.to_std()
.unwrap_or(ZERO_DURATION);
smol::Timer::after(wait_time).await;
match self.try_send(mail).await {
Ok(()) => return,
Err(m) => mail = m,
}
let this_attempt = Utc::now();
match self.q.config.next_interval(mail.schedule()).await {
Some(next_interval) => {
let next_interval = match chrono::Duration::from_std(next_interval) {
Ok(i) => i,
Err(_) => {
let new_next_interval = INTERVAL_ON_TOO_BIG_DURATION;
self.q
.config
.log_too_big_duration(mail.id(), next_interval, new_next_interval)
.await;
chrono::Duration::from_std(new_next_interval).unwrap()
}
};
let next_attempt = this_attempt + next_interval;
let schedule = ScheduleInfo {
at: next_attempt,
last_attempt: Some(this_attempt),
};
io_retry_loop_raw!(
self,
mail.id(),
self.q.storage.reschedule(&mut mail, schedule).await
);
}
None => {
let id = mail.id();
let pcm = io_retry_loop!(self, mail, |m| self.q.storage.drop(m).await);
let pcm = match pcm {
Some(pcm) => pcm,
None => {
self.q.config.log_queued_mail_vanished(id).await;
return;
}
};
self.cleanup(pcm).await;
return;
}
}
}
}
async fn try_send(&self, mail: S::QueuedMail) -> Result<(), S::QueuedMail> {
let id = mail.id();
let inflight = io_retry_loop!(self, mail, |m| self.q.storage.send_start(m).await);
let inflight = match inflight {
Some(inflight) => inflight,
None => {
self.q.config.log_queued_mail_vanished(id).await;
return Ok(());
}
};
let (inflight, meta, reader) = io_retry_loop!(self, inflight, |i| match self
.q
.storage
.read_inflight(&i)
.await
{
Ok((m, r)) => Ok((i, m, r)),
Err(e) => Err((i, e)),
});
let meta_ref = &meta;
let send_attempt = self
.q
.transport
.destination(&meta)
.and_then(|dest| async move { self.q.transport.connect(&dest).await })
.and_then(|mut sender| async move { sender.send(meta_ref, reader).await })
.await;
match send_attempt {
Ok(()) => {
let pcm = io_retry_loop!(self, inflight, |i| self.q.storage.send_done(i).await);
match pcm {
Some(pcm) => {
self.cleanup(pcm).await;
}
None => {
self.q.config.log_queued_mail_vanished(id).await;
}
};
return Ok(());
}
Err(_e) => {
}
}
let id = inflight.id();
let queued = io_retry_loop!(self, inflight, |i| self.q.storage.send_cancel(i).await);
match queued {
Some(queued) => Err(queued),
None => {
self.q.config.log_inflight_mail_vanished(id).await;
Ok(())
}
}
}
}
impl<U, C, S, T> Clone for Queue<U, C, S, T> {
fn clone(&self) -> Self {
Self {
q: self.q.clone(),
phantom: self.phantom,
}
}
}
pub struct Enqueuer<U, C, S, T>
where
S: Storage<U>,
{
queue: Queue<U, C, S, T>,
enqueuer: Option<S::Enqueuer>,
}
impl<U, C, S, T> Enqueuer<U, C, S, T>
where
U: 'static + Send + Sync,
C: Config<U, S::Error>,
S: Storage<U>,
T: Transport<U>,
{
pub async fn commit(
self,
destinations: Vec<(MailMetadata<U>, ScheduleInfo)>,
) -> Result<(), S::Error> {
let mut this = self;
let mails = this.enqueuer.take().unwrap().commit(destinations).await?;
for mail in mails {
let q = this.queue.clone();
this.queue
.q
.executor
.spawn(async move { q.send(mail).await })
.detach();
}
Ok(())
}
}
impl<U, C, S, T> AsyncWrite for Enqueuer<U, C, S, T>
where
U: 'static + Send + Sync,
C: Config<U, S::Error>,
S: Storage<U>,
T: Transport<U>,
{
fn poll_write(self: Pin<&mut Self>, cx: &mut Context, buf: &[u8]) -> Poll<io::Result<usize>> {
unsafe {
self.map_unchecked_mut(|s| {
s.enqueuer
.as_mut()
.expect("Tried writing to enqueuer after having committed it")
})
}
.poll_write(cx, buf)
}
fn poll_flush(self: Pin<&mut Self>, cx: &mut Context) -> Poll<io::Result<()>> {
unsafe {
self.map_unchecked_mut(|s| {
s.enqueuer
.as_mut()
.expect("Tried writing to enqueuer after having committed it")
})
}
.poll_flush(cx)
}
fn poll_close(self: Pin<&mut Self>, cx: &mut Context) -> Poll<io::Result<()>> {
unsafe {
self.map_unchecked_mut(|s| {
s.enqueuer
.as_mut()
.expect("Tried writing to enqueuer after having committed it")
})
}
.poll_close(cx)
}
fn poll_write_vectored(
self: Pin<&mut Self>,
cx: &mut Context,
bufs: &[IoSlice],
) -> Poll<io::Result<usize>> {
unsafe {
self.map_unchecked_mut(|s| {
s.enqueuer
.as_mut()
.expect("Tried writing to enqueuer after having committed it")
})
}
.poll_write_vectored(cx, bufs)
}
}