Add ByteBuf.maxWritableBytes()

- Fixes #806

buffer/src/main/java/io/netty/buffer/AbstractByteBuf.java

@@ -1,3 +1,19 @@
+/*
+ * Copyright 2012 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+
 /*
  * Copyright 2012 The Netty Project
  *
@@ -124,6 +140,11 @@ public abstract class AbstractByteBuf implements ByteBuf {
         return capacity() - writerIndex;
     }
 
+    @Override
+    public int maxWritableBytes() {
+        return maxCapacity() - writerIndex;
+    }
+
     @Override
     public ByteBuf markReaderIndex() {
         markedReaderIndex = readerIndex;

buffer/src/main/java/io/netty/buffer/ByteBuf.java

@@ -1,3 +1,19 @@
+/*
+ * Copyright 2012 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+
 /*
  * Copyright 2012 The Netty Project
  *
@@ -380,6 +396,12 @@ public interface ByteBuf extends ChannelBuf, Comparable<ByteBuf> {
      */
     int writableBytes();
 
+    /**
+     * Returns the maximum possible number of writable bytes, which is equal to
+     * {@code (this.maxCapacity - this.writerIndex)}.
+     */
+    int maxWritableBytes();
+
     /**
      * Returns {@code true}
      * if and only if {@code (this.writerIndex - this.readerIndex)} is greater

buffer/src/main/java/io/netty/buffer/SwappedByteBuf.java

@@ -1,3 +1,19 @@
+/*
+ * Copyright 2012 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+
 /*
  * Copyright 2012 The Netty Project
  *
@@ -131,6 +147,11 @@ public final class SwappedByteBuf implements ByteBuf {
         return buf.writableBytes();
     }
 
+    @Override
+    public int maxWritableBytes() {
+        return buf.maxWritableBytes();
+    }
+
     @Override
     public boolean readable() {
         return buf.readable();

codec/src/main/java/io/netty/handler/codec/ReplayingDecoderBuffer.java

@@ -1,3 +1,19 @@
+/*
+ * Copyright 2012 The Netty Project
+ *
+ * The Netty Project licenses this file to you under the Apache License,
+ * version 2.0 (the "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at:
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+
 /*
  * Copyright 2012 The Netty Project
  *
@@ -731,6 +747,11 @@ final class ReplayingDecoderBuffer implements ByteBuf, Unsafe {
         return 0;
     }
 
+    @Override
+    public int maxWritableBytes() {
+        return 0;
+    }
+
     @Override
     public ByteBuf writeBoolean(boolean value) {
         throw new UnreplayableOperationException();