Lua script of redis

Redis And Lua Script

1.Redis Script Introduction

Redis Script use Lua Interpreter to execute the script ,Reids Supported by inline Lua Environmental Science .

2.eval

The common command to execute a script is EVAL.
Parameter description ：
1.script： The argument is a segment Lua 5.1 Script program . Scripts don't have to ( Should not be ) Define as a Lua function .
2.numkeys： Used to specify the number of key name parameters .
3.key [key …]： from EVAL The third parameter starts to count , Represents those used in scripts Redis key (key), These key name parameters can be found in Lua Through global variables KEYS Array , use 1 Form access for the base address ( KEYS[1] , KEYS[2] , And so on ).
4.arg [arg …]： Additional parameters , stay Lua Through global variables ARGV Array access , The form of access and KEYS Variables like ( ARGV[1] 、 ARGV[2] , And so on ).

EVAL script numkeys key [key ...] arg [arg ...]

3.evalsha

Evalsha The command is based on the given sha1 Check code , Executing scripts cached in the server .
Parameter description ：
1.script： The argument is a segment Lua 5.1 Script program . Scripts don't have to ( Should not be ) Define as a Lua function .
2.numkeys： Used to specify the number of key name parameters .
3.key [key …]： from EVAL The third parameter starts to count , Represents those used in scripts Redis key (key), These key name parameters can be found in Lua Through global variables KEYS Array , use 1 Form access for the base address ( KEYS[1] , KEYS[2] , And so on ).
4.arg [arg …]： Additional parameters , stay Lua Through global variables ARGV Array access , The form of access and KEYS Variables like ( ARGV[1] 、 ARGV[2] , So

 EVALSHA sha1 numkeys key [key ...] arg [arg ...] 

4.script kill

Script kill The command is used to kill the currently running Lua Script , If and only if the script does not perform any write operations , This order will take effect .
This command is mainly used to terminate long running scripts , Like one because BUG And the script with infinite loop .
SCRIPT KILL After performing , The currently running script will be killed , The client executing this script will run from EVAL Exit from the command block , And receive an error as the return value .
Return value ： Always returns OK

SCRIPT KILL

5.script load

Redis Script Load The command is used to put the script script Add to script cache , But the script is not executed immediately .
EVAL The command also adds the script to the script cache , But it immediately evaluates the input script .
If the given script is already in the cache , Then do nothing .
After the script is added to the cache , adopt EVALSHA command , You can use script SHA1 Checksum to invoke this script .
Scripts can stay in the cache for an infinite amount of time , Until the execution of SCRIPT FLUSH until .
Return value ： Of a given script SHA1 The checksum

SCRIPT LOAD script

6.script exists

Script Exists Command is used to verify whether the specified script has been saved in the cache .

Return value ：
A list of , contain 0 and 1 , The former means that the script does not exist in the cache , The latter means that the script is already in the cache .
The elements in the list and the given SHA1 Check and keep the corresponding relationship , For example, the value of the third element in the list represents the third SHA1 The state of the script specified by the checksum in the cache .

SCRIPT EXISTS sha1 [sha1 ...]

7.script flush

Flush The command is used to clear all Lua Script cache .
Return value ： Always returns OK

 SCRIPT FLUSH