X-Git-Url: https://git.opendaylight.org/gerrit/gitweb?a=blobdiff_plain;f=common%2Futil%2Fsrc%2Fmain%2Fjava%2Forg%2Fopendaylight%2Fyangtools%2Futil%2Fconcurrent%2FDeadlockDetectingListeningExecutorService.java;h=fad71a93525e9d33b4951a71d2e80f63f6d28719;hb=c24d6e2f39acbb11e22b5676bb7481ed52bec461;hp=011872d6b138d9edbaf28869524121bd859f0b43;hpb=b655d5e1807cf5fca0f8a4c0ecc8da565bd923c7;p=yangtools.git

diff --git a/common/util/src/main/java/org/opendaylight/yangtools/util/concurrent/DeadlockDetectingListeningExecutorService.java b/common/util/src/main/java/org/opendaylight/yangtools/util/concurrent/DeadlockDetectingListeningExecutorService.java
index 011872d6b1..fad71a9352 100644
--- a/common/util/src/main/java/org/opendaylight/yangtools/util/concurrent/DeadlockDetectingListeningExecutorService.java
+++ b/common/util/src/main/java/org/opendaylight/yangtools/util/concurrent/DeadlockDetectingListeningExecutorService.java
@@ -8,9 +8,8 @@
 
 package org.opendaylight.yangtools.util.concurrent;
 
-import static com.google.common.base.Preconditions.checkNotNull;
-
-import com.google.common.base.Function;
+import com.google.common.base.Preconditions;
+import com.google.common.base.Supplier;
 import com.google.common.util.concurrent.ForwardingListenableFuture;
 import com.google.common.util.concurrent.ListenableFuture;
 import java.util.concurrent.Callable;
@@ -19,14 +18,14 @@ import java.util.concurrent.Executor;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
-
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
 /**
  * An implementation of ListeningExecutorService that attempts to detect deadlock scenarios that
- * could occur if clients invoke the returned Future's <ode>get</code> methods synchronously.
- * <p>
- * Deadlock scenarios are most apt to occur with a backing single-threaded executor where setting of
+ * could occur if clients invoke the returned Future's <code>get</code> methods synchronously.
+ *
+ * <p>Deadlock scenarios are most apt to occur with a backing single-threaded executor where setting of
  * the Future's result is executed on the single thread. Here's a scenario:
  * <ul>
  * <li>Client code is currently executing in an executor's single thread.</li>
@@ -36,95 +35,117 @@ import javax.annotation.Nullable;
  * The second submitted task will never execute since the single thread is currently executing
  * the client code which is blocked waiting for the submitted task to complete. Thus, deadlock has
  * occurred.
- * <p>
- * This class prevents this scenario via the use of a ThreadLocal variable. When a task is invoked,
+ *
+ * <p>This class prevents this scenario via the use of a ThreadLocal variable. When a task is invoked,
  * the ThreadLocal is set and, when a task completes, the ThreadLocal is cleared. Futures returned
  * from this class override the <code>get</code> methods to check if the ThreadLocal is set. If it is,
  * an ExecutionException is thrown with a custom cause.
  *
+ * <p>Note that the ThreadLocal is not removed automatically, so some state may be left hanging off of
+ * threads which have encountered this class. If you need to clean that state up, use
+ * {@link #cleanStateForCurrentThread()}.
+ *
  * @author Thomas Pantelis
+ * @author Robert Varga
  */
 public class DeadlockDetectingListeningExecutorService extends AsyncNotifyingListeningExecutorService {
-    private final ThreadLocal<Boolean> deadlockDetector = new ThreadLocal<>();
-    private final Function<Void, Exception> deadlockExceptionFunction;
+    /*
+     * We cannot use a static field simply because our API contract allows nesting, which means some
+     * tasks may be submitted to underlay and some to overlay service -- and the two cases need to
+     * be discerned reliably.
+     */
+    private final SettableBooleanThreadLocal deadlockDetector = new SettableBooleanThreadLocal();
+    private final Supplier<Exception> deadlockExceptionFunction;
 
     /**
      * Constructor.
      *
      * @param delegate the backing ExecutorService.
-     * @param deadlockExceptionFunction Function that returns an Exception instance to set as the
+     * @param deadlockExceptionSupplier Supplier that returns an Exception instance to set as the
      *             cause of the ExecutionException when a deadlock is detected.
      */
-    public DeadlockDetectingListeningExecutorService( ExecutorService delegate,
-                                          Function<Void,Exception> deadlockExceptionFunction ) {
-        this(delegate, deadlockExceptionFunction, null);
+    public DeadlockDetectingListeningExecutorService(final ExecutorService delegate,
+            @Nonnull final Supplier<Exception> deadlockExceptionSupplier) {
+        this(delegate, deadlockExceptionSupplier, null);
     }
 
     /**
      * Constructor.
      *
      * @param delegate the backing ExecutorService.
-     * @param deadlockExceptionFunction Function that returns an Exception instance to set as the
+     * @param deadlockExceptionSupplier Supplier that returns an Exception instance to set as the
      *             cause of the ExecutionException when a deadlock is detected.
      * @param listenableFutureExecutor the executor used to run listener callbacks asynchronously.
      *             If null, no executor is used.
      */
-    public DeadlockDetectingListeningExecutorService( ExecutorService delegate,
-                                          Function<Void,Exception> deadlockExceptionFunction,
-                                          @Nullable Executor listenableFutureExecutor ) {
+    public DeadlockDetectingListeningExecutorService(final ExecutorService delegate,
+            @Nonnull final Supplier<Exception> deadlockExceptionSupplier,
+            @Nullable final Executor listenableFutureExecutor ) {
         super(delegate, listenableFutureExecutor);
-        this.deadlockExceptionFunction = checkNotNull(deadlockExceptionFunction);
+        this.deadlockExceptionFunction = Preconditions.checkNotNull(deadlockExceptionSupplier);
     }
 
     @Override
-    public void execute( Runnable command ){
+    public void execute(@Nonnull final Runnable command) {
         getDelegate().execute(wrapRunnable(command));
     }
 
+    @Nonnull
     @Override
-    public <T> ListenableFuture<T> submit( Callable<T> task ){
+    public <T> ListenableFuture<T> submit(final Callable<T> task) {
         return wrapListenableFuture(super.submit(wrapCallable(task)));
     }
 
+    @Nonnull
     @Override
-    public ListenableFuture<?> submit( Runnable task ){
+    public ListenableFuture<?> submit(final Runnable task) {
         return wrapListenableFuture(super.submit(wrapRunnable(task)));
     }
 
+    @Nonnull
     @Override
-    public <T> ListenableFuture<T> submit( Runnable task, T result ){
+    public <T> ListenableFuture<T> submit(final Runnable task, final T result) {
         return wrapListenableFuture(super.submit(wrapRunnable(task), result));
     }
 
+    /**
+     * Remove the state this instance may have attached to the calling thread. If no state
+     * was attached this method does nothing.
+     */
+    public void cleanStateForCurrentThread() {
+        deadlockDetector.remove();
+    }
+
+    private SettableBoolean primeDetector() {
+        final SettableBoolean b = deadlockDetector.get();
+        Preconditions.checkState(!b.isSet(), "Detector for {} has already been primed", this);
+        b.set();
+        return b;
+    }
+
     private Runnable wrapRunnable(final Runnable task) {
-        return new Runnable() {
-            @Override
-            public void run() {
-                deadlockDetector.set(Boolean.TRUE);
-                try {
-                    task.run();
-                } finally {
-                    deadlockDetector.remove();
-                }
+        return () -> {
+            final SettableBoolean b = primeDetector();
+            try {
+                task.run();
+            } finally {
+                b.reset();
             }
         };
     }
 
     private <T> Callable<T> wrapCallable(final Callable<T> delagate) {
-        return new Callable<T>() {
-            @Override
-            public T call() throws Exception {
-                deadlockDetector.set(Boolean.TRUE);
-                try {
-                    return delagate.call();
-                } finally {
-                    deadlockDetector.remove();
-                }
+        return () -> {
+            final SettableBoolean b = primeDetector();
+            try {
+                return delagate.call();
+            } finally {
+                b.reset();
             }
         };
     }
 
-    private <T> ListenableFuture<T> wrapListenableFuture(final ListenableFuture<T> delegate ) {
+    private <T> ListenableFuture<T> wrapListenableFuture(final ListenableFuture<T> delegate) {
         /*
          * This creates a forwarding Future that overrides calls to get(...) to check, via the
          * ThreadLocal, if the caller is doing a blocking call on a thread from this executor. If
@@ -141,16 +162,16 @@ public class DeadlockDetectingListeningExecutorService extends AsyncNotifyingLis
             }
 
             @Override
-            public T get(final long timeout, final TimeUnit unit)
+            public T get(final long timeout, @Nonnull final TimeUnit unit)
                     throws InterruptedException, ExecutionException, TimeoutException {
                 checkDeadLockDetectorTL();
                 return super.get(timeout, unit);
             }
 
             void checkDeadLockDetectorTL() throws ExecutionException {
-                if (deadlockDetector.get() != null) {
+                if (deadlockDetector.get().isSet()) {
                     throw new ExecutionException("A potential deadlock was detected.",
-                            deadlockExceptionFunction.apply(null));
+                            deadlockExceptionFunction.get());
                 }
             }
         };