Crazy God redis notes 09

  Open transaction multi:

Order to join the team is to write other normal orders

Execute transaction is exec

Normal execution of business ！

Give up the business ：

Every time we finish our business , You need to restart the transaction next time you want to use it ：

 

Compiler exception （ Something is wrong with the code ！ There was a mistake in the order ！） All commands in the transaction will not be executed ！

 

Runtime exception （1/0）, If there are syntax errors in the transaction queue , So when you execute an order , Other commands can be executed normally , An error command throws an exception ！

 

monitor ！

 

Monitoring test ：

We watch our money, The normal execution success is like this .

Testing multithreaded modification values , Use watch Can be regarded as redis Optimistic lock operation of ！

Let's open another server

 

Our threads 2 Take out 10 block , The transaction has not been executed .

At this point, the thread 1 Recharge the balance to 1000 了 ：

 

Before we execute , Another transaction modifies the value , Our implementation failed ！

  Can we solve this problem ？

If the modification fails , Just get the latest value .

unwatch: If transaction execution fails , Just unlock it first .

watch： Get the latest value , Watch again ,select version

exec: Compare whether the monitored value has changed , If there is no change , Then it can be executed successfully , If you change, the implementation fails . Just repeat this operation .

During the interview redis Often ask optimistic lock .

 

Let's create a java Empty item ：

  Create a module.

First we need to import our jedis My bag ：

Coding test ：

Connect to database

Operation command

disconnect

 

We started our local redis:

 

frequently-used Api Let's just take a look at it directly. It's almost the same as the previous order ：

 

 

I won't write my own code here , Direct screenshot of crazy God's code .

 

 

 

 

 

 

  Let's use jedis Do a normal thing ：

 

 

 

 

We have a residue here, but we haven't emptied the cache .

We add flushdb:

 

 

We can use our... Now java To do all of us redis The function of . Next class we will go to springboot To integrate our redis.