redis-lua introduction, implementation of the principle of

 

 

1.redis-lua related commands

# Lua script execution 
EVAL Script numkeys Key [Key ...] Arg [Arg ...] 
EVALSHA sha1 numkeys Key [Key ...] Arg [Arg ...] 
# View the specified script has already been stored in the cache which . 
EXISTS Script SCRIPT [Script ...] 
# remove all scripts from the script cache. 
FLUSH SCRIPT 
# kill the currently running Lua script 
SCRIPT KILL 
# Lua script to add a memory 
SCRIPT LOAD script

 

2.redis execute Lua way

# 1.redis execute the script will be loaded into memory 
EVAL Script numkeys Key [Key ...] Arg [Arg ...] 
EVALSHA sha1 numkeys Key [Key ...] Arg [Arg ...] 
# 2. local execute the script will not be loaded into memory 
redis-cli --eval test.lua aaa, bbb

 

3. Implementation of the principle of Lua

Sha1 value is calculated according to a Lua script 
if there is sha1 redis memory to use memory 
to see # redis whether a lua script loads over 
SCRIPT EXISTS sha1 value

 

4. proof

 

SHA1 value calculated lua script

package plantomjs;


import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;


/**
 * @author
 * @since 2020—01-09
 */
public class PlanTomJs {


    public static void main(String[] args) throws NoSuchAlgorithmException {
        //lua 脚本
        String lua =
            "local getnum =  function( count )\n"
                + "\tif count == false then\n"
                + "\t\treturn 0 ;\n"
                + "\telse\t\n"
                + "\t\treturn count ; \n"
                + "\tend\n"
                + "\treturn 0 ;\n"
                + "end\t\n"
                + "local plan =  KEYS[1] ;\n"
                + "local result = redis.call('get', KEYS[2] );\n"
                + "local keywordPlan = KEYS[3] ;\n"
                + "local keywordResult = redis.call('get', KEYS[4] ) ;\n"
                + "\n"
                + "if tonumber(getnum(plan)) > tonumber(getnum(result)) and tonumber(getnum(keywordPlan)) > tonumber(getnum(keywordResult)) then\n"
                + " \tredis.call('incrby', KEYS[2]  , 1 );\n"
                + " \tredis.call('incrby', KEYS[4]  , 1 );\n"
                + " \tredis.call('expire', KEYS[2] , 60*60*24 );\n"
                + " \tredis.call('expire', KEYS[4] , 60*60*24 );\n"
                + " \treturn '1';\n"
                + " else\n"
                + " \treturn '0';\n"
                + " end\t\t\n"
                + "\n";
        System.out.println(getSha1(lua.getBytes()));


    }


    public static String getSha1(byte[] input) throws NoSuchAlgorithmException {
        MessageDigest mDigest = MessageDigest.getInstance("SHA1");
        byte[] result = mDigest.digest(input);
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < result.length; i++) {
            sb.append(Integer.toString((result[i] & 0xff) + 0x100, 16).substring(1));
        }
        return sb.toString();
    }
   

SHA1 value 8f8b5c2314b53cd128e2ead7b9e5d42f5f1eabe8

Indicating the presence redis memory

 

5. View redis -lua configuration

#Lua engine used memory size (in bytes)                	 
used_memory_lua: 46080       
# ditto                         	 
used_memory_lua_human: 45.00K 
#Lua script occupied memory size 
used_memory_scripts: 53784 
used_memory_scripts_human: 52.52K 
# memory loaded Lua script number 
number_of_cached_scripts: 95

 

Use redis-lua script (spring-data-redis) 6. Project in

private boolean ipLuaCheckCount(String ip, App app) {
        String lua = "\n"
                + "local result = redis.call('hget', KEYS[1] , ARGV[1])\n"
                + "if result == false then \n"
                + "\tresult = 0 ;\n"
                + "end\n"
                + "local num =  KEYS[2] \n"
                + "if tonumber(result) < tonumber(num) then\n"
                + "\tredis.call('hincrby', KEYS[1] ,ARGV[1] , 1 )\n"
                + "\tredis.call('expire', KEYS[1] , 60*60*24 )\n"
                + "\treturn '1' ;\n"
                + "else \n"
                + "\treturn '0' ; \n"
                + "end\n"
                + "\n";
        DefaultRedisScript<String> rs = new DefaultRedisScript<>();
        //设置脚本
        rs.setScriptText(lua);
        //定义返回类型。注意如果没有这个定义，spring不会返回结果
        rs.setResultType(String.class);
        RedisSerializer valueSerializer = jsonRedisTemplate.getValueSerializer();
        RedisSerializer stringSerializer = jsonRedisTemplate.getStringSerializer();
        List<String> keyList = new ArrayList<>();
        keyList.add(RedisKeys.ipMonitorResult(app.getId()));
        keyList.add(Objects.nonNull(app.getIpMonitorCount()) ? String.valueOf(app.getIpMonitorCount()) : String.valueOf(3));

        List<String> valsList = new ArrayList<>();
        valsList.add(ip);
        String restult = redisTemplate.execute(rs, valueSerializer, stringSerializer, keyList, valsList.toArray());
        if ("0".equals(restult)) {
            throw new ConnectException(ConnectExceptionEnum.IP_TASK_BE_ALREADY_FULL);
        }
        return true;
    }