allow aborting a media sync while http req in flight

The progress handling code needs a rethink, as we now have two separate
ways to flag that the media sync should abort. In the future, it may
make sense to switch to polling the backend for progress, instead of
passing a callback in.

proto/backend.proto

@@ -55,6 +55,7 @@ message BackendInput {
         Empty all_deck_config = 43;
         Empty new_deck_config = 44;
         int64 remove_deck_config = 45;
+        Empty abort_media_sync = 46;
     }
 }
 
@@ -70,6 +71,7 @@ message BackendOutput {
         string format_time_span = 31;
         string studied_today = 32;
         string congrats_learn_msg = 33;
+        Empty abort_media_sync = 46;
 
         // fallible commands
         TemplateRequirementsOut template_requirements = 16;

pylib/anki/rsbackend.py

@@ -519,6 +519,9 @@ class RustBackend:
     def remove_deck_config(self, dcid: int) -> None:
         self._run_command(pb.BackendInput(remove_deck_config=dcid))
 
+    def abort_media_sync(self):
+        self._run_command(pb.BackendInput(abort_media_sync=pb.Empty()))
+
 
 def translate_string_in(
     key: TR, **kwargs: Union[str, int, float]

qt/aqt/mediasync.py

@@ -123,6 +123,7 @@ class MediaSyncer:
             return
         self._log_and_notify(tr(TR.SYNC_MEDIA_ABORTING))
         self._want_stop = True
+        self.mw.col.backend.abort_media_sync()
 
     def is_syncing(self) -> bool:
         return self._syncing

rslib/Cargo.toml

@@ -39,6 +39,7 @@ slog-envlogger = "2.2.0"
 serde_repr = "0.1.5"
 num_enum = "0.4.2"
 unicase = "2.6.0"
+futures = "0.3.4"
 
 # pinned until rusqlite 0.22 comes out
 [target.'cfg(target_vendor="apple")'.dependencies.rusqlite]

rslib/src/backend/mod.rs

@@ -30,6 +30,7 @@ use crate::timestamp::TimestampSecs;
 use crate::types::Usn;
 use crate::{backend_proto as pb, log};
 use fluent::FluentValue;
+use futures::future::{AbortHandle, Abortable};
 use log::error;
 use prost::Message;
 use std::collections::{HashMap, HashSet};
@@ -47,6 +48,7 @@ pub struct Backend {
     progress_callback: Option<ProtoProgressCallback>,
     i18n: I18n,
     server: bool,
+    media_sync_abort: Option<AbortHandle>,
 }
 
 enum Progress<'a> {
@@ -135,6 +137,7 @@ impl Backend {
             progress_callback: None,
             i18n,
             server,
+            media_sync_abort: None,
         }
     }
 
@@ -274,6 +277,10 @@ impl Backend {
                 self.remove_deck_config(dcid)?;
                 OValue::RemoveDeckConfig(pb::Empty {})
             }
+            Value::AbortMediaSync(_) => {
+                self.abort_media_sync();
+                OValue::AbortMediaSync(pb::Empty {})
+            }
         })
     }
 
@@ -481,9 +488,7 @@ impl Backend {
         })
     }
 
-    // fixme: will block other db access
-
-    fn sync_media(&self, input: SyncMediaIn) -> Result<()> {
+    fn sync_media(&mut self, input: SyncMediaIn) -> Result<()> {
         let mut guard = self.col.lock().unwrap();
 
         let col = guard.as_mut().unwrap();
@@ -503,19 +508,38 @@ impl Backend {
     }
 
     fn sync_media_inner(
-        &self,
+        &mut self,
         input: pb::SyncMediaIn,
         folder: PathBuf,
         db: PathBuf,
         log: Logger,
     ) -> Result<()> {
+        let (abort_handle, abort_reg) = AbortHandle::new_pair();
+        self.media_sync_abort = Some(abort_handle);
+
         let callback = |progress: &MediaSyncProgress| {
             self.fire_progress_callback(Progress::MediaSync(progress))
         };
 
         let mgr = MediaManager::new(&folder, &db)?;
         let mut rt = Runtime::new().unwrap();
-        rt.block_on(mgr.sync_media(callback, &input.endpoint, &input.hkey, log))
+        let sync_fut = mgr.sync_media(callback, &input.endpoint, &input.hkey, log);
+        let abortable_sync = Abortable::new(sync_fut, abort_reg);
+        let ret = match rt.block_on(abortable_sync) {
+            Ok(sync_result) => sync_result,
+            Err(_) => {
+                // aborted sync
+                Ok(())
+            }
+        };
+        self.media_sync_abort = None;
+        ret
+    }
+
+    fn abort_media_sync(&mut self) {
+        if let Some(handle) = self.media_sync_abort.take() {
+            handle.abort();
+        }
     }
 
     fn check_media(&self) -> Result<pb::MediaCheckOut> {