Merge pull request #411 from nwestfall/asynclock_release

Implement Disposable.Create in "AsyncLock" to prevent multiple disposes
reactiveui · Oct 1, 2018 · 72321b9 · 72321b9
2 parents 54ba92e + d6c95d6
commit 72321b9
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Showing 2 changed files with 19 additions and 6 deletions.
diff --git a/src/Akavache.Sqlite3/AsyncLock.cs b/src/Akavache.Sqlite3/AsyncLock.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Threading;
 using System.Threading.Tasks;
+using System.Reactive.Disposables;
 
 namespace Akavache.Sqlite3.Internal
 {
@@ -20,11 +21,11 @@ public AsyncLock()
             var wait = m_semaphore.WaitAsync(ct);
 
             // Happy path. We synchronously acquired the lock.
-            if (wait.IsCompleted && !wait.IsFaulted)
+            if (wait.IsCompleted && !wait.IsFaulted && !wait.IsCanceled)
                 return m_releaser;
-
+            
             return wait
-                .ContinueWith((_, state) => (IDisposable)state,
+                .ContinueWith((task, state) => task.IsCanceled ? null : (IDisposable)state,
                     m_releaser.Result, ct,
                     TaskContinuationOptions.ExecuteSynchronously, TaskScheduler.Default);
         }

diff --git a/src/Akavache.Sqlite3/OperationQueue.cs b/src/Akavache.Sqlite3/OperationQueue.cs
@@ -89,6 +89,10 @@ public IDisposable Start()
                         break;
                     }
 
+                    //Verify lock was acquired
+                    if(@lock == null)
+                        break;
+
                     using (@lock)
                     {
                         // NB: We special-case the first item because we want to 
@@ -141,10 +145,14 @@ public IDisposable Start()
                 } 
                 catch (OperationCanceledException) { }
 
-                using (flushLock.LockAsync().Result)
+                try 
                 {
-                    FlushInternal();
+                    using(flushLock.LockAsync().Result)
+                    {
+                        FlushInternal();
+                    }
                 }
+                catch(OperationCanceledException) { }
 
                 start = null;
             }));
@@ -240,7 +248,11 @@ public AsyncSubject<Unit> Vacuum()
                     var lockTask = flushLock.LockAsync(shouldQuit.Token);
                     operationQueue.Add(OperationQueueItem.CreateUnit(OperationType.DoNothing));
 
-                    @lock = await lockTask;
+                    try 
+                    {
+                        @lock = await lockTask;
+                    }
+                    catch(OperationCanceledException) { }
 
                     var deleteOp = OperationQueueItem.CreateUnit(OperationType.DeleteExpiredSqliteOperation);
                     operationQueue.Add(deleteOp);