add CrossProcessLockError::LockDirtied

Author: Hywan

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

@@ -240,6 +240,11 @@ where
         // function, to avoid multiple reentrant calls.
         let mut _attempt = self.locking_attempt.lock().await;
 
+        // The lock is already dirtied? Let's stop here.
+        if self.is_dirty() {
+            return Err(CrossProcessLockError::LockDirtied);
+        }
+
         // If another thread obtained the lock, make sure to only superficially increase
         // the number of holders, and carry on.
         if self.num_holders.load(Ordering::SeqCst) > 0 {
@@ -274,6 +279,8 @@ where
                         "The lock has been acquired, but it's been dirtied!"
                     );
                     self.is_dirty.store(true, Ordering::SeqCst);
+
+                    return Err(CrossProcessLockError::LockDirtied);
                 }
 
                 // This was the same generation, no problem.
@@ -340,6 +347,11 @@ where
                     }
                 }
 
+                // The lock has been dirtied. Exit the loop.
+                if this.is_dirty() {
+                    break;
+                }
+
                 sleep(Duration::from_millis(EXTEND_LEASE_EVERY_MS)).await;
 
                 match this
@@ -459,6 +471,11 @@ pub enum CrossProcessLockError {
     #[error("a lock timed out")]
     LockTimeout,
 
+    /// The lock has been dirtied, i.e. it means another process took the lock
+    /// while this process was holding it.
+    #[error("a lock has been dirtied")]
+    LockDirtied,
+
     #[error(transparent)]
     #[cfg(not(target_family = "wasm"))]
     TryLockError(#[from] Box<dyn Error + Send + Sync>),