deploy: 9a0a651

plumbing/database_and_runtime.html

@@ -230,19 +230,23 @@ <h2 id="incrementing-the-revision-counter-and-getting-mutable-access-to-the-jars
         loop {
             self.runtime.set_cancellation_flag();
 
+            // Acquire lock before we check if we have unique access to the jars.
+            // If we do not yet have unique access, we will go to sleep and wait for
+            // the snapshots to be dropped, which will signal the cond var associated
+            // with this lock.
+            //
+            // NB: We have to acquire the lock first to ensure that we can check for
+            // unique access and go to sleep waiting on the condvar atomically,
+            // as described in PR #474.
+            let mut guard = self.shared.noti_lock.lock();
             // If we have unique access to the jars, we are done.
             if Arc::get_mut(self.shared.jars.as_mut().unwrap()).is_some() {
                 return;
             }
 
             // Otherwise, wait until some other storage entities have dropped.
-            // We create a mutex here because the cvar api requires it, but we
-            // don't really need one as the data being protected is actually
-            // the jars above.
             //
             // The cvar `self.shared.cvar` is notified by the `Drop` impl.
-            let mutex = parking_lot::Mutex::new(());
-            let mut guard = mutex.lock();
             self.shared.cvar.wait(&amp;mut guard);
         }
     }

plumbing/jars_and_ingredients.html

@@ -340,6 +340,7 @@ <h3 id="initializing-the-database"><a class="header" href="#initializing-the-dat
             shared: Shared {
                 jars: Some(Arc::from(jars)),
                 cvar: Arc::new(Default::default()),
+                noti_lock: Arc::new(parking_lot::Mutex::new(())),
             },
             routes: Arc::new(routes),
             runtime: Runtime::default(),

print.html

@@ -1846,6 +1846,7 @@ <h3 id="initializing-the-database"><a class="header" href="#initializing-the-dat
             shared: Shared {
                 jars: Some(Arc::from(jars)),
                 cvar: Arc::new(Default::default()),
+                noti_lock: Arc::new(parking_lot::Mutex::new(())),
             },
             routes: Arc::new(routes),
             runtime: Runtime::default(),
@@ -1978,19 +1979,23 @@ <h2 id="incrementing-the-revision-counter-and-getting-mutable-access-to-the-jars
         loop {
             self.runtime.set_cancellation_flag();
 
+            // Acquire lock before we check if we have unique access to the jars.
+            // If we do not yet have unique access, we will go to sleep and wait for
+            // the snapshots to be dropped, which will signal the cond var associated
+            // with this lock.
+            //
+            // NB: We have to acquire the lock first to ensure that we can check for
+            // unique access and go to sleep waiting on the condvar atomically,
+            // as described in PR #474.
+            let mut guard = self.shared.noti_lock.lock();
             // If we have unique access to the jars, we are done.
             if Arc::get_mut(self.shared.jars.as_mut().unwrap()).is_some() {
                 return;
             }
 
             // Otherwise, wait until some other storage entities have dropped.
-            // We create a mutex here because the cvar api requires it, but we
-            // don't really need one as the data being protected is actually
-            // the jars above.
             //
             // The cvar `self.shared.cvar` is notified by the `Drop` impl.
-            let mutex = parking_lot::Mutex::new(());
-            let mut guard = mutex.lock();
             self.shared.cvar.wait(&amp;mut guard);
         }
     }