Redis transaction operation commands and execution operations (code)

The content of this article is about the commands and execution operations (code) of Redis transaction operations. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

Preface

This article mainly studies the transaction operation of redis

Command

multi and exec

• Command Line

127.0.0.1:6379> multi
OK
127.0.0.1:6379> incr total
QUEUED
127.0.0.1:6379> incr len
QUEUED
127.0.0.1:6379> exec
1) (integer) 2
2) (integer) 2
127.0.0.1:6379> get total
"2"
127.0.0.1:6379> get len
"2"

• lettuce instance

    @Test
    public void testMultiExec(){
        RedisClient client = RedisClient.create("redis://192.168.99.100:6379/0");
        StatefulRedisConnection<string> connection = client.connect();
        RedisCommands<string> syncCommands = connection.sync();

        syncCommands.set("hello","1");
        syncCommands.set("world","2");

        syncCommands.multi();
        syncCommands.incr("hello");
        syncCommands.incr("world");

        //DefaultTransactionResult[wasRolledBack=false,result=[1, 2, 1, 3, 1]]
        TransactionResult transactionResult = syncCommands.exec();
        System.out.println(transactionResult);
        System.out.println(syncCommands.get("hello"));
        System.out.println(syncCommands.get("world"));
    }</string></string>

partially executes the

• command Row

127.0.0.1:6379> multi
OK
127.0.0.1:6379> set a hello
QUEUED
127.0.0.1:6379> set b world
QUEUED
127.0.0.1:6379> incr a
QUEUED
127.0.0.1:6379> set c part
QUEUED
127.0.0.1:6379> exec
1) OK
2) OK
3) (error) ERR value is not an integer or out of range
4) OK
127.0.0.1:6379> get a
"hello"
127.0.0.1:6379> get b
"world"
127.0.0.1:6379> get c
"part"

• lettuce instance

    @Test
    public void testMultiExecError(){
        RedisClient client = RedisClient.create("redis://192.168.99.100:6379/0");
        StatefulRedisConnection<string> connection = client.connect();
        RedisCommands<string> syncCommands = connection.sync();

        syncCommands.multi();
        syncCommands.set("a","hello");
        syncCommands.set("b","world");
        syncCommands.incr("a");
        syncCommands.set("c","part");
        //DefaultTransactionResult[wasRolledBack=false,result=[OK, OK, io.lettuce.core.RedisCommandExecutionException: ERR value is not an integer or out of range, OK, 1]]
        TransactionResult transactionResult = syncCommands.exec();
        System.out.println(transactionResult);
        System.out.println(syncCommands.get("a"));
        System.out.println(syncCommands.get("b"));
        System.out.println(syncCommands.get("c"));
    }</string></string>

multi with discard

• Command line

127.0.0.1:6379> set sum 1
OK
127.0.0.1:6379> multi
OK
127.0.0.1:6379> incr sum
QUEUED
127.0.0.1:6379> discard
OK
127.0.0.1:6379> get sum
"1"

• lettuce instance

    @Test
    public void testMultiDiscard(){
        RedisClient client = RedisClient.create("redis://192.168.99.100:6379/0");
        StatefulRedisConnection<string> connection = client.connect();
        RedisCommands<string> syncCommands = connection.sync();
        syncCommands.incr("key1");
        syncCommands.multi();
        syncCommands.incr("key1");
        //需要有multi才可以执行discard，成功返回OK
        String result = syncCommands.discard();
        System.out.println(result);
        System.out.println(syncCommands.get("key1"));
    }</string></string>

check and set

    @Test
    public void testWatch(){
        RedisClient client = RedisClient.create("redis://192.168.99.100:6379/0");
        StatefulRedisConnection<string> connection = client.connect();
        RedisCommands<string> syncCommands = connection.sync();

        String key = "key";
        syncCommands.watch(key);

        //another connection
        StatefulRedisConnection<string> conn2 = client.connect();
        RedisCommands<string> syncCommands2 = conn2.sync();
        syncCommands2.set(key, "a");

        syncCommands.multi();
        syncCommands.append(key, "b");
        //DefaultTransactionResult [wasRolledBack=true, responses=0]
        TransactionResult transactionResult = syncCommands.exec();
        System.out.println(transactionResult);

        System.out.println(syncCommands.get(key));
    }</string></string></string></string>

Summary

• reids provides multi exec/discard instructions, similar to open commit/rollback transaction, but exec will not roll when it encounters errors such as type operations. The commands that should be executed successfully will still be executed successfully, and the commands that should fail will still be executed successfully. Failure

• multi exec guarantees that as long as the exec command is successfully executed, a series of commands in the transaction can be executed. If the exec is not received by the server due to network problems, etc., Then a series of commands in the transaction will not be executed

• discard can only be used after calling multi. This command will clear the transaction queue of commands waiting to be executed

• Redis provides the watch command, which can be used with multi exec to implement an optimistic locking mechanism similar to the database. Once the watch key is updated by other clients, the entire exec operation fails

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