From 9595101065f25dc02e3256f4977d87953b61c1b1 Mon Sep 17 00:00:00 2001
From: Damien Elmes <gpg@ankiweb.net>
Date: Thu, 7 Sep 2023 14:10:50 +1000
Subject: [PATCH] Wrap backend in an outer Arc

Necessary to allow backend commands that run in the background instead
of blocking.
---
 rslib/src/backend/mod.rs  | 37 +++++++++++++++++++++++++------------
 rslib/src/backend/sync.rs |  9 +++------
 rslib/src/progress.rs     |  4 ----
 3 files changed, 28 insertions(+), 22 deletions(-)

diff --git a/rslib/src/backend/mod.rs b/rslib/src/backend/mod.rs
index 441d35f72..eb611dafd 100644
--- a/rslib/src/backend/mod.rs
+++ b/rslib/src/backend/mod.rs
@@ -14,11 +14,13 @@ mod import_export;
 mod ops;
 mod sync;
 
+use std::ops::Deref;
 use std::result;
 use std::sync::Arc;
 use std::sync::Mutex;
 use std::thread::JoinHandle;
 
+use futures::future::AbortHandle;
 use once_cell::sync::OnceCell;
 use prost::Message;
 use reqwest::Client;
@@ -28,20 +30,31 @@ use tokio::runtime::Runtime;
 use crate::backend::dbproxy::db_command_bytes;
 use crate::backend::sync::SyncState;
 use crate::prelude::*;
-use crate::progress::AbortHandleSlot;
 use crate::progress::Progress;
 use crate::progress::ProgressState;
 use crate::progress::ThrottlingProgressHandler;
 
-pub struct Backend {
-    col: Arc<Mutex<Option<Collection>>>,
+#[derive(Clone)]
+#[repr(transparent)]
+pub struct Backend(Arc<BackendInner>);
+
+impl Deref for Backend {
+    type Target = BackendInner;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+pub struct BackendInner {
+    col: Mutex<Option<Collection>>,
     pub(crate) tr: I18n,
     server: bool,
-    sync_abort: AbortHandleSlot,
+    sync_abort: Mutex<Option<AbortHandle>>,
     progress_state: Arc<Mutex<ProgressState>>,
     runtime: OnceCell<Runtime>,
-    state: Arc<Mutex<BackendState>>,
-    backup_task: Arc<Mutex<Option<JoinHandle<Result<()>>>>>,
+    state: Mutex<BackendState>,
+    backup_task: Mutex<Option<JoinHandle<Result<()>>>>,
     web_client: OnceCell<Client>,
 }
 
@@ -64,20 +77,20 @@ pub fn init_backend(init_msg: &[u8]) -> result::Result<Backend, String> {
 
 impl Backend {
     pub fn new(tr: I18n, server: bool) -> Backend {
-        Backend {
-            col: Arc::new(Mutex::new(None)),
+        Backend(Arc::new(BackendInner {
+            col: Mutex::new(None),
             tr,
             server,
-            sync_abort: Arc::new(Mutex::new(None)),
+            sync_abort: Mutex::new(None),
             progress_state: Arc::new(Mutex::new(ProgressState {
                 want_abort: false,
                 last_progress: None,
             })),
             runtime: OnceCell::new(),
-            state: Arc::new(Mutex::new(BackendState::default())),
-            backup_task: Arc::new(Mutex::new(None)),
+            state: Mutex::new(BackendState::default()),
+            backup_task: Mutex::new(None),
             web_client: OnceCell::new(),
-        }
+        }))
     }
 
     pub fn i18n(&self) -> &I18n {
diff --git a/rslib/src/backend/sync.rs b/rslib/src/backend/sync.rs
index 234c66a84..0e3a345cc 100644
--- a/rslib/src/backend/sync.rs
+++ b/rslib/src/backend/sync.rs
@@ -1,8 +1,6 @@
 // Copyright: Ankitects Pty Ltd and contributors
 // License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 
-use std::sync::Arc;
-
 use anki_proto::sync::sync_status_response::Required;
 use anki_proto::sync::SyncStatusResponse;
 use futures::future::AbortHandle;
@@ -13,7 +11,6 @@ use tracing::warn;
 
 use super::Backend;
 use crate::prelude::*;
-use crate::progress::AbortHandleSlot;
 use crate::sync::collection::normal::ClientSyncState;
 use crate::sync::collection::normal::SyncActionRequired;
 use crate::sync::collection::normal::SyncOutput;
@@ -154,7 +151,7 @@ impl Backend {
     fn sync_abort_handle(
         &self,
     ) -> Result<(
-        scopeguard::ScopeGuard<AbortHandleSlot, impl FnOnce(AbortHandleSlot)>,
+        scopeguard::ScopeGuard<Backend, impl FnOnce(Backend)>,
         AbortRegistration,
     )> {
         let (abort_handle, abort_reg) = AbortHandle::new_pair();
@@ -171,8 +168,8 @@ impl Backend {
             );
         }
         // Clear the abort handle after the caller is done and drops the guard.
-        let guard = scopeguard::guard(Arc::clone(&self.sync_abort), |sync_abort| {
-            sync_abort.lock().unwrap().take();
+        let guard = scopeguard::guard(self.clone(), |backend| {
+            backend.sync_abort.lock().unwrap().take();
         });
         Ok((guard, abort_reg))
     }
diff --git a/rslib/src/progress.rs b/rslib/src/progress.rs
index 25e115d29..644a4d29f 100644
--- a/rslib/src/progress.rs
+++ b/rslib/src/progress.rs
@@ -8,7 +8,6 @@ use std::sync::Mutex;
 use anki_i18n::I18n;
 use anki_proto::collection::progress::ComputeRetention;
 use anki_proto::collection::progress::ComputeWeights;
-use futures::future::AbortHandle;
 
 use crate::dbcheck::DatabaseCheckProgress;
 use crate::error::AnkiError;
@@ -123,9 +122,6 @@ pub struct ProgressState {
     pub last_progress: Option<Progress>,
 }
 
-// fixme: this should support multiple abort handles.
-pub(crate) type AbortHandleSlot = Arc<Mutex<Option<AbortHandle>>>;
-
 #[derive(Clone, Copy, Debug)]
 pub enum Progress {
     MediaSync(MediaSyncProgress),