Merge pull request #2133 from navis/log4j-shudown-callback

callbacks registered to Log4jShutdown is not executed when stop is called

common/src/main/java/io/druid/common/config/Log4jShutdown.java

@@ -19,19 +19,21 @@
 
 package io.druid.common.config;
 
+import com.google.common.base.Throwables;
 import org.apache.logging.log4j.core.util.Cancellable;
 import org.apache.logging.log4j.core.util.ShutdownCallbackRegistry;
 
+import javax.annotation.concurrent.GuardedBy;
 import java.util.Queue;
 import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.concurrent.atomic.AtomicReference;
 
 public class Log4jShutdown implements ShutdownCallbackRegistry, org.apache.logging.log4j.core.LifeCycle
 {
-  private final AtomicReference<State> state = new AtomicReference<>(State.INITIALIZED);
+  private static final long SHUTDOWN_WAIT_TIMEOUT = 60000;
+
+  private final SynchronizedStateHolder state = new SynchronizedStateHolder(State.INITIALIZED);
   private final Queue<Runnable> shutdownCallbacks = new ConcurrentLinkedQueue<>();
-  private final AtomicBoolean callbacksRun = new AtomicBoolean(false);
 
   @Override
   public Cancellable addShutdownCallback(final Runnable callback)
@@ -95,21 +97,23 @@ public class Log4jShutdown implements ShutdownCallbackRegistry, org.apache.loggi
   @Override
   public void stop()
   {
-    if (callbacksRun.get()) {
+    if (!state.compareAndSet(State.STARTED, State.STOPPING)) {
+      State current = state.waitForTransition(State.STOPPING, State.STOPPED, SHUTDOWN_WAIT_TIMEOUT);
+      if (current != State.STOPPED) {
+        throw new IllegalStateException(String.format("Expected state [%s] found [%s]", State.STARTED, current));
+      }
       return;
     }
-    if (!state.compareAndSet(State.STARTED, State.STOPPED)) {
-      throw new IllegalStateException(String.format("Expected state [%s] found [%s]", State.STARTED, state.get()));
+    try {
+      runCallbacks();
+    }
+    finally {
+      state.compareAndSet(State.STOPPING, State.STOPPED);
     }
   }
 
-  public void runCallbacks()
+  private void runCallbacks()
   {
-    if (!callbacksRun.compareAndSet(false, true)) {
-      // Already run, skip
-      return;
-    }
-    stop();
     RuntimeException e = null;
     for (Runnable callback = shutdownCallbacks.poll(); callback != null; callback = shutdownCallbacks.poll()) {
       try {
@@ -138,4 +142,60 @@ public class Log4jShutdown implements ShutdownCallbackRegistry, org.apache.loggi
   {
     return State.STOPPED.equals(getState());
   }
+
+  private static class SynchronizedStateHolder
+  {
+    @GuardedBy("this")
+    private State current;
+
+    private SynchronizedStateHolder(State initial) {
+      current = initial;
+    }
+
+    private synchronized boolean compareAndSet(State expected, State transition)
+    {
+      if (current == expected) {
+        return transition(transition);
+      }
+      return false;
+    }
+
+    /**
+     * if current state is `expected`, wait it to be changed into `transition` state for `timeout` msec.
+     * if it's not, return current state immediately.
+     *
+     * @return current state
+     */
+    private synchronized State waitForTransition(State expected, State transition, long timeout)
+    {
+      if (current == expected) {
+        long remaining = timeout;
+        try {
+          long prev = System.currentTimeMillis();
+          while (current != transition && remaining > 0) {
+            wait(remaining);
+            long now = System.currentTimeMillis();
+            remaining -= now - prev;
+            prev = now;
+          }
+        }
+        catch (InterruptedException e) {
+          throw Throwables.propagate(e);
+        }
+      }
+      return current;
+    }
+
+    private synchronized boolean transition(State transition)
+    {
+      current = transition;
+      notifyAll();
+      return true;
+    }
+
+    private synchronized State get()
+    {
+      return current;
+    }
+  }
 }

services/src/main/java/io/druid/cli/CliPeon.java

@@ -233,8 +233,7 @@ public class CliPeon extends GuiceRunnable
       Injector injector = makeInjector();
       try {
         final Lifecycle lifecycle = initLifecycle(injector);
-        Runtime.getRuntime().addShutdownHook(
-            new Thread(
+        final Thread hook = new Thread(
             new Runnable()
             {
               @Override
@@ -244,8 +243,8 @@ public class CliPeon extends GuiceRunnable
                 lifecycle.stop();
               }
             }
-            )
         );
+        Runtime.getRuntime().addShutdownHook(hook);
         injector.getInstance(ExecutorLifecycle.class).join();
 
         // Sanity check to help debug unexpected non-daemon threads
@@ -258,6 +257,7 @@ public class CliPeon extends GuiceRunnable
 
         // Explicitly call lifecycle stop, dont rely on shutdown hook.
         lifecycle.stop();
+        Runtime.getRuntime().removeShutdownHook(hook);
       }
       catch (Throwable t) {
         log.error(t, "Error when starting up.  Failing.");