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原文链接地址:『互联网架构』软件架构-redis的通信协议(protocol)(52)
redis的通信协议是什么?双方约定了一种编码方式,客户端将要发送的命令进行编码,然后服务端收到后,使用同样的协议进行解码,服务端处理完成后,再次编码返回给客户端,客户端解码拿到返回结果,这样就完成了一次通信。
(一)协议介绍
- 易于实现
- 可以高效地被计算机分析(parse)
- 可以很容易地被人类读懂
(二)编码后的字符标记解释
- For Simple Strings the first byte of the reply is "+" 回复
- For Errors the first byte of the reply is "-" 错误
- For Integers the first byte of the reply is ":" 整数
- For Bulk Strings the first byte of the reply is "$" 字符串
- For Arrays the first byte of the reply is "*" 数组
(三)模拟Redis客户端&分片
- 客户端
Jedis跟redis通讯很简单发送了socket,然后发送了resp这种‘暗语’进行通讯。
import java.io.IOException;
import java.io.InputStream;
import java.net.Socket;
public class RedisClient {
private Socket socket;
private String host;
private int port;
public RedisClient() throws IOException {
this.socket = new Socket("192.168.79.100",6379);
}
public RedisClient(String host, int port) {
this.host = host;
this.port = port;
try {
this.socket = new Socket(host,port);
} catch (IOException e) {
e.printStackTrace();
}
}
//set wk 2018
public String set( String key, String value) throws IOException {
//"*3\r\n$3\r\nset\r\n$2\r\nwk\r\n$4\r\n2018"
StringBuilder stringBuilder=new StringBuilder();
stringBuilder.append("*3").append("\r\n");
stringBuilder.append("$").append(CommandRedis.set.name().length()).append("\r\n");
stringBuilder.append(CommandRedis.set).append("\r\n");
stringBuilder.append("$").append(key.getBytes().length).append("\r\n");
stringBuilder.append(key).append("\r\n");
stringBuilder.append("$").append(value.getBytes().length).append("\r\n");
stringBuilder.append(value).append("\r\n");
socket.getOutputStream().write(stringBuilder.toString().getBytes());
byte[] b=new byte[2048];
socket.getInputStream().read(b);
return new String(b);
}
public String get( String key) throws IOException {
//"*3\r\n$3\r\nset\r\n$2\r\nwk\r\n$4\r\n2018"
StringBuilder stringBuilder=new StringBuilder();
stringBuilder.append("*2").append("\r\n");
stringBuilder.append("$").append(CommandRedis.get.name().length()).append("\r\n");
stringBuilder.append(CommandRedis.get).append("\r\n");
stringBuilder.append("$").append(key.getBytes().length).append("\r\n");
stringBuilder.append(key).append("\r\n");
socket.getOutputStream().write(stringBuilder.toString().getBytes());
byte[] b=new byte[2048];
socket.getInputStream().read(b);
return new String(b);
}
public String setnx(String key, String value) throws Exception {
StringBuffer stringBuffer = new StringBuffer();
stringBuffer.append("*3").append("\r\n");
stringBuffer.append("$5").append("\r\n");
stringBuffer.append("setnx").append("\r\n");
stringBuffer.append("$").append(key.getBytes().length).append("\r\n");
stringBuffer.append(key).append("\r\n");
stringBuffer.append("$").append(value.getBytes().length).append("\r\n");
stringBuffer.append(value).append("\r\n");
socket.getOutputStream().write(stringBuffer.toString().getBytes());
byte[] b = new byte[2048];
socket.getInputStream().read(b );
return new String(b);
}
// 管道
public void pipeline(String key)throws Exception {
StringBuffer stringBuffer = new StringBuffer();
stringBuffer.append("*2").append("\r\n");
stringBuffer.append("$"+CommandRedis.subscribe.name().length()).append("\r\n");
stringBuffer.append(CommandRedis.subscribe).append("\r\n");
stringBuffer.append("$").append(key.getBytes().length).append("\r\n");
stringBuffer.append(key).append("\r\n");
socket.getOutputStream().write(stringBuffer.toString().getBytes());
InputStream inputStream = socket.getInputStream();
while (true) {
byte[] b = new byte[2048];
inputStream.read(b );
System.out.println(new String(b));
}
}
//subscribe
public void subscribe(String key)throws Exception {
StringBuffer stringBuffer = new StringBuffer();
stringBuffer.append("*2").append("\r\n");
stringBuffer.append("$"+CommandRedis.subscribe.name().length()).append("\r\n");
stringBuffer.append(CommandRedis.subscribe).append("\r\n");
stringBuffer.append("$").append(key.getBytes().length).append("\r\n");
stringBuffer.append(key).append("\r\n");
socket.getOutputStream().write(stringBuffer.toString().getBytes());
InputStream inputStream = socket.getInputStream();
while (true) {
byte[] b = new byte[2048];
inputStream.read(b );
System.out.println(new String(b));
}
}
public void close(){
if(socket != null){
try {
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
public enum CommandRedis {
set,get,incr,subscribe
}
- 分片
RedisClient分片方式,简单模拟,理解概念分片。
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
public class TestRedisClient {
public static void main(String[] args) throws IOException {
/* RedisClient redisClient=new RedisClient();
System.out.println(redisClient.set("wk","悟空"));
System.out.println(redisClient.get("wk"));*/
List<RedisClient> pool=new ArrayList<>();
pool.add(new RedisClient("192.168.0.12",6379));
pool.add(new RedisClient("192.168.0.12",6380));
pool.add(new RedisClient("192.168.0.12",6381));
Crc16Sharding crc16Sharding=new Crc16Sharding(pool);
for (int i=0;i<100;i++){
String key="xx"+i;
RedisClient redisClient=crc16Sharding.crc16(key);
redisClient.set(key,i+"");
System.out.println(redisClient.get(key));
}
}
}
import com.sun.org.apache.xerces.internal.impl.xpath.regex.Match;
import java.util.List;
public class Crc16Sharding {
List<RedisClient> pool;
public Crc16Sharding(List<RedisClient> pool) {
this.pool = pool;
}
/**
* 通过一个key可以定位到一块 节点
* @param key
* @return
*/
public RedisClient crc16(String key){
int num=Math.abs(key.hashCode()%pool.size());
return pool.get(num);
/* if(key.length()<3){
return pool.get(0);
}else if(key.length()<6){
return pool.get(1);
}else{
return pool.get(2);
}*/
}
}
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
public class TestRedisClient {
public static void main(String[] args) throws IOException {
List<RedisClient> pool=new ArrayList<>();
pool.add(new RedisClient("192.168.0.12",6379));
pool.add(new RedisClient("192.168.0.12",6380));
pool.add(new RedisClient("192.168.0.12",6381));
Crc16Sharding crc16Sharding=new Crc16Sharding(pool);
for (int i=0;i<100;i++){
String key="xx"+i;
RedisClient redisClient=crc16Sharding.crc16(key);
redisClient.set(key,i+"");
System.out.println(redisClient.get(key));;
}
}
}
(四)redis使用技巧
- 如果是订单表,取的话也是通过唯一的订单号来进行,不要通过循环去redis里面取。
- 开关类型的放到本地的jvm内存中,尽量减少redis的压力。
- 避免使用慢查询 hgetall
- 存储redis的购物车,有的人都是很多的好几M的,几百个商品,redis存储的内容的压缩。减少通信的宽带。优化存储内容。
- 少用字符串存储,可以存储map格式放入redis。获取redis里面的map,直接通过key就可以取到对应的值。
(五)监控&运维
- Open-falcon
http://open-falcon.org/
open-falcon是小米开源监控系统,强大灵活的数据采集、采集、传输、绘制、查询、报警等。采用全部golang编写,portal和dashboard使用python编写。
- Redis-migrate-tool
https://github.com/vipshop/redis-migrate-tool
2年多没更新了,可以了解下
Redis-migrate-tool是唯品会开源针对redis数据运维工具。
支持单独、twemproxy集群、redis custer、aof、rdb文件迁移。支持实时迁移、异构迁移、过滤等功能。
PS:介绍了运维工具,redis通信的内容拼接,redis存储的技巧,redis正常的时候没问题,并发量大的时候一定要注意,在大流量的情况下,代码的细节至关重要!
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