refactor(sdk,common): Move JoinHandleExt inside matrix-sdk-common.

This patch moves the `JoinHandleExt` trait and the
`AbortOnDrop` type from `matrix_sdk::sliding_sync::utils` into
`matrix_sdk_common::executor`. This is going to be useful for other
modules.

Author: Hywan

crates/matrix-sdk-common/src/executor.rs

@@ -14,11 +14,17 @@
 
 //! Abstraction over an executor so we can spawn tasks under Wasm the same way
 //! we do usually.
-
+//!
 //! On non Wasm platforms, this re-exports parts of tokio directly.  For Wasm,
 //! we provide a single-threaded solution that matches the interface that tokio
 //! provides as a drop in replacement.
 
+use std::{
+    future::Future,
+    pin::Pin,
+    task::{Context, Poll},
+};
+
 #[cfg(not(target_family = "wasm"))]
 mod sys {
     pub use tokio::{
@@ -141,6 +147,41 @@ mod sys {
 
 pub use sys::*;
 
+/// A type ensuring a task is aborted on drop.
+#[derive(Debug)]
+pub struct AbortOnDrop<T>(JoinHandle<T>);
+
+impl<T> AbortOnDrop<T> {
+    pub fn new(join_handle: JoinHandle<T>) -> Self {
+        Self(join_handle)
+    }
+}
+
+impl<T> Drop for AbortOnDrop<T> {
+    fn drop(&mut self) {
+        self.0.abort();
+    }
+}
+
+impl<T: 'static> Future for AbortOnDrop<T> {
+    type Output = Result<T, JoinError>;
+
+    fn poll(mut self: Pin<&mut Self>, context: &mut Context<'_>) -> Poll<Self::Output> {
+        Pin::new(&mut self.0).poll(context)
+    }
+}
+
+/// Trait to create an [`AbortOnDrop`] from a [`JoinHandle`].
+pub trait JoinHandleExt<T> {
+    fn abort_on_drop(self) -> AbortOnDrop<T>;
+}
+
+impl<T> JoinHandleExt<T> for JoinHandle<T> {
+    fn abort_on_drop(self) -> AbortOnDrop<T> {
+        AbortOnDrop::new(self)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use assert_matches::assert_matches;

crates/matrix-sdk/src/sliding_sync/mod.rs

@@ -21,7 +21,6 @@ mod client;
 mod error;
 mod list;
 mod sticky_parameters;
-mod utils;
 
 use std::{
     collections::{btree_map::Entry, BTreeMap},
@@ -35,6 +34,8 @@ use async_stream::stream;
 pub use client::{Version, VersionBuilder};
 use futures_core::stream::Stream;
 use matrix_sdk_base::RequestedRequiredStates;
+#[cfg(feature = "e2e-encryption")]
+use matrix_sdk_common::executor::JoinHandleExt as _;
 use matrix_sdk_common::{executor::spawn, timer};
 use ruma::{
     api::client::{error::ErrorKind, sync::sync_events::v5 as http},
@@ -47,8 +48,6 @@ use tokio::{
 };
 use tracing::{debug, error, info, instrument, trace, warn, Instrument, Span};
 
-#[cfg(feature = "e2e-encryption")]
-use self::utils::JoinHandleExt as _;
 pub use self::{builder::*, client::VersionBuilderError, error::*, list::*};
 use self::{
     cache::restore_sliding_sync_state,