com.godmao.mqbroker.handler.TopicSyncMessageEncoderHandler Maven / Gradle / Ivy

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package com.godmao.mqbroker.handler;

import com.godmao.mqbroker.message.TopicSyncMessage;
import com.godmao.netty.handler.AbstractEncoderHandler;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufAllocator;
import io.netty.channel.ChannelHandler;

import java.nio.charset.StandardCharsets;
import java.util.HashMap;
import java.util.Map;

/**
 * 同步主题消息处理器
 */
@ChannelHandler.Sharable
public class TopicSyncMessageEncoderHandler extends AbstractEncoderHandler {

    public static final TopicSyncMessageEncoderHandler INSTANCE = new TopicSyncMessageEncoderHandler();

    @Override
    public ByteBuf encode(TopicSyncMessage msg) {
        final Map topicCount = msg.getTopicCount();
        final int topicCount_size = topicCount.size();
        // 预估缓冲区大小
        int estimatedSize = 14;// cmd(1 byte) + version(8 bytes) + replace(1 bytes) + size(4 bytes)
        final Map topicByteCount = new HashMap<>(topicCount_size);
        for (Map.Entry entry : topicCount.entrySet()) {
            final byte[] topic_bytes = entry.getKey().getBytes(StandardCharsets.UTF_8);
            topicByteCount.put(topic_bytes, entry.getValue());
            estimatedSize += 4 + topic_bytes.length;
        }

        final ByteBuf byteBuf = ByteBufAllocator.DEFAULT.buffer(estimatedSize);
        byteBuf.writeByte(msg.getCmd());      // 1
        byteBuf.writeLong(msg.getVersion());  // 8
        byteBuf.writeBoolean(msg.isReplace());// 1
        byteBuf.writeInt(topicCount_size);    // 4

        for (Map.Entry entry : topicByteCount.entrySet()) {
            final byte[] topic_bytes = entry.getKey();
            byteBuf.writeInt(topic_bytes.length);
            byteBuf.writeBytes(topic_bytes);
            byteBuf.writeInt(entry.getValue());
        }
        return byteBuf;
    }
}