fix(core,fuse): a deleted file's trash is not held back by its create (B171)

A file deleted after its create was sent keeps the op as a trash. The op
kept the create's attempts and backoff, and the drain recorded the failure
of a create attempt still on the wire on the row that was by then the trash.
The trash waited out the create's backoff.

The trash starts due, as a create that becomes a revision does, and the
drain records a failed attempt only if the op is still the kind it ran as
(`Db::record_attempt_failure`).

crates/pdfs-core/src/db/ops.rs

@@ -151,6 +151,7 @@ fn drop_doomed_ops(tx: &rusqlite::Transaction<'_>, uid: &str) -> Result<Vec<Stri
             "{DOOMED}
              UPDATE pending_op
              SET kind = 'trash', issue = NULL,
+                 attempts = 0, last_error = NULL, next_attempt_at = 0,
                  parent_uid = CASE WHEN {PARENT_NOW} LIKE '{LOCAL_VOLUME}~%' THEN NULL
                                    ELSE {PARENT_NOW} END,
                  parent_lid = CASE WHEN {PARENT_NOW} LIKE '{LOCAL_VOLUME}~%' THEN NULL
@@ -1276,6 +1277,31 @@ impl Db {
     /// A rename with a newer one queued behind it ([`Db::enqueue_op`]) is
     /// dropped instead: retried, it could land after the newer one and undo it.
     pub fn record_op_failure(&self, id: i64, error: &str, next_attempt_at: i64) -> Result<()> {
+        self.record_failure(id, None, error, next_attempt_at)
+    }
+
+    /// [`Db::record_op_failure`] for an attempt at op `id` as a `kind` op. An
+    /// op that has become another kind while the attempt ran is left as it
+    /// is: a create deleted on the wire is a trash now, and the create's
+    /// failure would hold the trash back for the create's backoff
+    /// (`docs/BUGS.md` B171).
+    pub fn record_attempt_failure(
+        &self,
+        id: i64,
+        kind: &str,
+        error: &str,
+        next_attempt_at: i64,
+    ) -> Result<()> {
+        self.record_failure(id, Some(kind), error, next_attempt_at)
+    }
+
+    fn record_failure(
+        &self,
+        id: i64,
+        kind: Option<&str>,
+        error: &str,
+        next_attempt_at: i64,
+    ) -> Result<()> {
         let conn = self.conn.lock();
         if drop_replaced_rename(&conn, id)? {
             return Ok(());
@@ -1284,8 +1310,8 @@ impl Db {
             "UPDATE pending_op
              SET attempts = attempts + 1, last_error = ?2, next_attempt_at = ?3,
                  access_deferred_since = 0
-             WHERE id = ?1",
-            params![id, error, next_attempt_at],
+             WHERE id = ?1 AND (?4 IS NULL OR kind = ?4)",
+            params![id, error, next_attempt_at, kind],
         )?;
         Ok(())
     }

crates/pdfs-core/src/db/tests.rs

@@ -3726,6 +3726,61 @@ fn a_create_withdrawn_after_it_failed_queues_a_trash_that_keeps_its_blob() {
     assert!(db.pending_ops().unwrap().is_empty());
 }
 
+/// A create deleted after it was sent becomes a trash in its place. The
+/// create's backoff, and the failure of an attempt still on the wire, are the
+/// create's: the trash is due at once (`docs/BUGS.md` B171).
+#[test]
+fn a_create_deleted_after_it_was_sent_leaves_a_trash_that_is_due_at_once() {
+    let db = Db::open_in_memory().unwrap();
+    let parent = uid("parent").to_string();
+    let create = |local: &str| {
+        db.enqueue_op(&PendingOp {
+            id: 0,
+            kind: OP_CREATE.to_string(),
+            uid: local.to_string(),
+            parent_uid: Some(parent.clone()),
+            name: Some(format!("{local}.txt")),
+            blob_path: Some(format!("/staging/{local}")),
+            meta_json: Some("{}".to_string()),
+            created_at: 1,
+            attempts: 0,
+            last_error: None,
+            next_attempt_at: 0,
+        })
+        .unwrap()
+        .0
+    };
+    let failed = create("local~failed");
+    db.record_attempt_failure(failed, OP_CREATE, "no answer", 50_000)
+        .unwrap();
+    let sending = create("local~sending");
+    assert_eq!(
+        db.claim_next_due_op(10).unwrap().map(|op| op.id),
+        Some(sending)
+    );
+
+    db.delete_ops_for_uid("local~failed").unwrap();
+    db.delete_ops_for_uid("local~sending").unwrap();
+    db.record_attempt_failure(sending, OP_CREATE, "No such file or directory", 50_000)
+        .unwrap();
+
+    let ops = db.pending_ops().unwrap();
+    assert_eq!(ops.len(), 2);
+    for op in &ops {
+        assert_eq!(op.kind, OP_TRASH);
+        assert_eq!((op.attempts, op.last_error.as_deref()), (0, None), "{op:?}");
+        assert_eq!(op.next_attempt_at, 0, "{op:?}");
+    }
+    db.record_attempt_failure(failed, OP_TRASH, "offline", 50_000)
+        .unwrap();
+    let trash = db
+        .pending_ops()
+        .unwrap()
+        .into_iter()
+        .find(|op| op.id == failed);
+    assert_eq!(trash.map(|op| op.attempts), Some(1));
+}
+
 #[test]
 fn a_landed_placeholder_never_overwrites_the_server_copy() {
     let db = Db::open_in_memory().unwrap();

crates/pdfs-fuse/src/drain.rs

@@ -394,8 +394,9 @@ impl Core {
                         .min(DRAIN_BACKOFF_MAX)
                 };
                 warn!(uid = %op.uid, attempts, error = %err_str, "pending upload failed; will retry");
-                if let Err(e) = self.db.record_op_failure(
+                if let Err(e) = self.db.record_attempt_failure(
                     op.id,
+                    &op.kind,
                     &err_str,
                     now_millis() + backoff.as_millis() as i64,
                 ) {