Add RedisEncoderBenchmark

Motivation:
Add a benchmark to measure RedisEncoder's performance

Modifications:
- Add RedisEncoderBenchmark

Result:
JMH benchmark exists to measure RedisEncoder's performance.

microbench/pom.xml

@@ -73,6 +73,11 @@
       <artifactId>netty-codec-http2</artifactId>
       <version>${project.version}</version>
     </dependency>
+    <dependency>
+      <groupId>${project.groupId}</groupId>
+      <artifactId>netty-codec-redis</artifactId>
+      <version>${project.version}</version>
+    </dependency>
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>

microbench/src/main/java/io/netty/microbench/redis/RedisEncoderBenchmark.java

@@ -0,0 +1,101 @@
+/*
+ * Copyright 2016 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.
+ */
+package io.netty.microbench.redis;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.PooledByteBufAllocator;
+import io.netty.buffer.Unpooled;
+import io.netty.buffer.UnpooledByteBufAllocator;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelPromise;
+import io.netty.handler.codec.redis.ArrayRedisMessage;
+import io.netty.handler.codec.redis.FullBulkStringRedisMessage;
+import io.netty.handler.codec.redis.RedisEncoder;
+import io.netty.handler.codec.redis.RedisMessage;
+import io.netty.microbench.channel.EmbeddedChannelWriteReleaseHandlerContext;
+import io.netty.microbench.util.AbstractMicrobenchmark;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Level;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Param;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.TearDown;
+import org.openjdk.jmh.annotations.Threads;
+import org.openjdk.jmh.annotations.Warmup;
+
+import java.util.ArrayList;
+import java.util.List;
+
+@State(Scope.Benchmark)
+@Fork(1)
+@Threads(1)
+@Warmup(iterations = 5)
+@Measurement(iterations = 5)
+public class RedisEncoderBenchmark extends AbstractMicrobenchmark {
+    private RedisEncoder encoder;
+    private ByteBuf content;
+    private ChannelHandlerContext context;
+    private ArrayRedisMessage redisArray;
+
+    @Param({ "true", "false" })
+    public boolean pooledAllocator;
+
+    @Param({ "true", "false" })
+    public boolean voidPromise;
+
+    @Param({ "50", "200", "1000" })
+    public int arraySize;
+
+    @Setup(Level.Trial)
+    public void setup() {
+        byte[] bytes = new byte[256];
+        content = Unpooled.buffer(bytes.length);
+        content.writeBytes(bytes);
+        ByteBuf testContent = Unpooled.unreleasableBuffer(content.asReadOnly());
+
+        List<RedisMessage> rList = new ArrayList<RedisMessage>(arraySize);
+        for (int i = 0; i < arraySize; ++i) {
+            rList.add(new FullBulkStringRedisMessage(testContent));
+        }
+        redisArray = new ArrayRedisMessage(rList);
+        encoder = new RedisEncoder();
+        context = new EmbeddedChannelWriteReleaseHandlerContext(pooledAllocator ? PooledByteBufAllocator.DEFAULT :
+                UnpooledByteBufAllocator.DEFAULT, encoder) {
+            @Override
+            protected void handleException(Throwable t) {
+                handleUnexpectedException(t);
+            }
+        };
+    }
+
+    @TearDown(Level.Trial)
+    public void teardown() {
+        content.release();
+        content = null;
+    }
+
+    @Benchmark
+    public void writeArray() throws Exception {
+        encoder.write(context, redisArray.retain(), newPromise());
+    }
+
+    private ChannelPromise newPromise() {
+        return voidPromise ? context.voidPromise() : context.newPromise();
+    }
+}

microbench/src/main/java/io/netty/microbench/redis/package-info.java

@@ -0,0 +1,19 @@
+/*
+ * Copyright 2016 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.
+ */
+/**
+ * Benchmarks for {@link io.netty.handler.codec.redis}.
+ */
+package io.netty.microbench.redis;