fix: avoid manual poll impl for accounts events

deltachat-ffi/src/lib.rs

@@ -3576,7 +3576,7 @@ pub unsafe extern "C" fn dc_accounts_get_next_event(
     if emitter.is_null() {
         return ptr::null_mut();
     }
-    let emitter = &*emitter;
+    let emitter = &mut *emitter;
 
     emitter
         .recv_sync()

src/accounts.rs

@@ -1,10 +1,8 @@
 use std::collections::BTreeMap;
-use std::pin::Pin;
-use std::sync::atomic::{AtomicBool, Ordering};
-use std::task::{Context as TaskContext, Poll};
 
 use async_std::fs;
 use async_std::path::PathBuf;
+use async_std::prelude::*;
 use async_std::sync::{Arc, RwLock};
 use uuid::Uuid;
 
@@ -225,61 +223,42 @@ impl Accounts {
 
     /// Unified event emitter.
     pub async fn get_event_emitter(&self) -> EventEmitter {
-        let emitters = self
+        let emitters: Vec<_> = self
             .accounts
             .read()
             .await
             .iter()
-            .map(|(id, a)| EmitterWrapper {
+            .map(|(_id, a)| a.get_event_emitter())
-                id: *id,
-                emitter: a.get_event_emitter(),
-                done: AtomicBool::new(false),
-            })
             .collect();
 
-        EventEmitter(emitters)
+        EventEmitter(futures::stream::select_all(emitters))
     }
 }
 
+#[derive(Debug)]
+pub struct EventEmitter(futures::stream::SelectAll<crate::events::EventEmitter>);
+
 impl EventEmitter {
-    /// Blocking recv of an event. Return `None` if the `Sender` has been droped.
+    /// Blocking recv of an event. Return `None` if all `Sender`s have been droped.
-    pub fn recv_sync(&self) -> Option<Event> {
+    pub fn recv_sync(&mut self) -> Option<Event> {
         async_std::task::block_on(self.recv())
     }
 
-    /// Async recv of an event. Return `None` if the `Sender` has been droped.
+    /// Async recv of an event. Return `None` if all `Sender`s have been droped.
-    pub async fn recv(&self) -> Option<Event> {
+    pub async fn recv(&mut self) -> Option<Event> {
-        futures::future::poll_fn(|cx| Pin::new(self).recv_poll(cx)).await
+        self.0.next().await
-    }
-
-    fn recv_poll(self: Pin<&Self>, _cx: &mut TaskContext<'_>) -> Poll<Option<Event>> {
-        for e in &*self.0 {
-            if e.done.load(Ordering::Acquire) {
-                // skip emitters that are already done
-                continue;
-            }
-
-            match e.emitter.try_recv() {
-                Ok(event) => return Poll::Ready(Some(event)),
-                Err(async_std::sync::TryRecvError::Disconnected) => {
-                    e.done.store(true, Ordering::Release);
-                }
-                Err(async_std::sync::TryRecvError::Empty) => {}
-            }
-        }
-
-        Poll::Pending
     }
 }
 
-#[derive(Debug)]
+impl async_std::stream::Stream for EventEmitter {
-pub struct EventEmitter(Vec<EmitterWrapper>);
+    type Item = Event;
 
-#[derive(Debug)]
+    fn poll_next(
-struct EmitterWrapper {
+        mut self: std::pin::Pin<&mut Self>,
-    id: u32,
+        cx: &mut std::task::Context<'_>,
-    emitter: crate::events::EventEmitter,
+    ) -> std::task::Poll<Option<Self::Item>> {
-    done: AtomicBool,
+        std::pin::Pin::new(&mut self.0).poll_next(cx)
+    }
 }
 
 pub const CONFIG_NAME: &str = "accounts.toml";

src/events.rs

@@ -58,12 +58,18 @@ impl EventEmitter {
 
     /// Async recv of an event. Return `None` if the `Sender` has been droped.
     pub async fn recv(&self) -> Option<Event> {
-        // TODO: change once we can use async channels internally.
         self.0.recv().await.ok()
     }
+}
 
-    pub fn try_recv(&self) -> Result<Event, async_std::sync::TryRecvError> {
+impl async_std::stream::Stream for EventEmitter {
-        self.0.try_recv()
+    type Item = Event;
+
+    fn poll_next(
+        mut self: std::pin::Pin<&mut Self>,
+        cx: &mut std::task::Context<'_>,
+    ) -> std::task::Poll<Option<Self::Item>> {
+        std::pin::Pin::new(&mut self.0).poll_next(cx)
     }
 }