Define a dedicated exception for performing blocking ops in event loop

transport/src/main/java/io/netty/channel/BlockingOperationException.java

@@ -0,0 +1,26 @@
+package io.netty.channel;
+
+/**
+ * An {@link IllegalStateException} which is raised when a user performed a blocking operation
+ * when the user is in an event loop thread.  If a blocking operation is performed in an event loop
+ * thread, the blocking operation will most likely enter a dead lock state, hence throwing this
+ * exception.
+ */
+public class BlockingOperationException extends IllegalStateException {
+
+    private static final long serialVersionUID = 2462223247762460301L;
+
+    public BlockingOperationException() {}
+
+    public BlockingOperationException(String s) {
+        super(s);
+    }
+
+    public BlockingOperationException(Throwable cause) {
+        super(cause);
+    }
+
+    public BlockingOperationException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

transport/src/main/java/io/netty/channel/DefaultChannelFuture.java

@@ -19,7 +19,6 @@ import static java.util.concurrent.TimeUnit.*;
 import io.netty.channel.AbstractChannel.FlushCheckpoint;
 import io.netty.logging.InternalLogger;
 import io.netty.logging.InternalLoggerFactory;
-import io.netty.util.internal.DeadLockProofWorker;
 
 import java.nio.channels.Channels;
 import java.util.ArrayList;
@@ -48,33 +47,6 @@ public class DefaultChannelFuture extends FlushCheckpoint implements ChannelFutu
 
     private static final Throwable CANCELLED = new Throwable();
 
-    private static volatile boolean useDeadLockChecker = true;
-    private static boolean disabledDeadLockCheckerOnce;
-
-    /**
-     * Returns {@code true} if and only if the dead lock checker is enabled.
-     */
-    public static boolean isUseDeadLockChecker() {
-        return useDeadLockChecker;
-    }
-
-    /**
-     * Enables or disables the dead lock checker.  It is not recommended to
-     * disable the dead lock checker.  Disable it at your own risk!
-     */
-    public static void setUseDeadLockChecker(boolean useDeadLockChecker) {
-        if (!useDeadLockChecker && !disabledDeadLockCheckerOnce) {
-            disabledDeadLockCheckerOnce = true;
-            if (logger.isDebugEnabled()) {
-                logger.debug(
-                        "The dead lock checker in " +
-                        DefaultChannelFuture.class.getSimpleName() +
-                        " has been disabled as requested at your own risk.");
-            }
-        }
-        DefaultChannelFuture.useDeadLockChecker = useDeadLockChecker;
-    }
-
     private final Channel channel;
     private final boolean cancellable;
 
@@ -350,12 +322,9 @@ public class DefaultChannelFuture extends FlushCheckpoint implements ChannelFutu
         }
     }
 
-    private static void checkDeadLock() {
-        if (isUseDeadLockChecker() && DeadLockProofWorker.PARENT.get() != null) {
-            throw new IllegalStateException(
-                    "await*() in I/O thread causes a dead lock or " +
-                    "sudden performance drop. Use addListener() instead or " +
-                    "call await*() from a different thread.");
+    private void checkDeadLock() {
+        if (channel().eventLoop().inEventLoop()) {
+            throw new BlockingOperationException();
         }
     }