The perfect combination of Redis and Spring Boot: the black technology of Lua scripting

Source: blog.csdn.net/Mrxiao_bo/article/details/133783127

There once was a magician who was good at combining two powerful tools, Spring Boot and Redis, into an amazing combination. His magic weapon is Redis’s Lua script.

Today, we will uncover the secrets of this magician and explore how to use Lua scripts in Spring Boot projects to unlock new possibilities and improve performance. If you’ve been looking for ways to improve your applications, this blog will reveal the magic.

Part 1: Introduction to Lua script

When it comes to Lua programming, here is a detailed explanation of the 12 key concepts mentioned above, with Lua code examples to help you gain a deeper understanding of this programming language:

Comments:

Comments are used in Lua to add instructions and annotations. Single-line comments start with --, and multi-line comments use --[[ ... ]].

-- This is a single line comment

--[[
    This is a multiline comment
    Can span multiple lines
]]

Variables:

Variables do not need to be explicitly typed in Lua. Use the local keyword to create local variables, and global variables are declared directly.

local age = 30
name = "John" -- global variable

Data type:

Basic data types include integers, floating point numbers, strings, Boolean values, and nil.

Table is a very flexible data structure.

local num = 42
local str = "Hello, Lua!"
local flag = true
local empty = nil
local person = { name = "John", age = 30 }

Control structure:

Conditional statements: Use if, else, and elseif to implement conditional branches.

if age < 18 then
    print("underage")
elseif age >= 18 and age < 65 then
    print("adult")
else
    print("senior")
end

Loop structure: Lua supports for loop, while loop and repeat…until loop.

for i = 1, 5 do
    print(i)
end

local count = 0
while count < 3 do
    print("Number of loops: " .. count)
    count = count + 1
end

repeat
    print("Execute at least once")
until count > 5

Function:

Functions are defined in Lua using the function keyword, which can accept parameters and return values.

function add(a, b)
    return a + b
end

local result = add(5, 3)
print("5 + 3 = " .. result)

Table:

Tables are the core data structure of Lua and are defined using curly braces {}.

Tables can contain key-value pairs, and keys and values can be of any data type.

local person = { name = "John", age = 30, hobbies = {"Reading", "Gaming"} }
print("Name:" .. person.name)
print("Age:" .. person.age)

Module:

Lua supports modular programming, allowing related functions to be encapsulated in independent modules and loaded through the require keyword. The example is slightly complex, please refer to the standard usage of Lua modules for detailed examples.

String operations:

Lua provides many string processing functions, such as string.sub for intercepting substrings, string.find for finding substrings in a string, etc.

local text = "Lua programming"
local sub = string.sub(text, 1, 3)
print(sub) -- output "Lua"

Error handling:

Error handling usually uses pcall functions to wrap code blocks that may throw exceptions to catch and handle errors. This is usually used with assert.

local success, result = pcall(function()
    error("An error occurred!")
end)

if success then
    print("Execution successful")
else
    print("Error message: " .. result)
end

Standard library:

The Lua standard library contains rich functions, such as file operations, network programming, regular expressions, time processing, etc. You can use these functions through built-in modules, such as io, socket, etc.

”

In summary, Lua is a flexible programming language whose simplicity and powerful tabular data structures make it widely useful in a variety of applications. These sample codes should help to better understand the basic concepts and syntax of Lua.

Part 2: Why choose Lua script

The use of Lua scripts in Redis has many advantages, making it ideal for performing complex operations. Here are some of the main reasons:

  • Performance:

Lua scripts are executed in Redis, avoiding multiple communications between the client and the server. This can reduce network overhead and improve performance, especially when multiple Redis commands need to be executed to complete an operation. Atomicity: Redis guarantees atomic execution of Lua scripts without worrying about race conditions or concurrency issues.

  • Transaction:

Lua scripts can be used with Redis transactions to ensure atomic execution of a series of commands. This allows you to treat multiple operations as a single transaction, and either all succeed or all fail.

  • Complex operations:

Lua scripts provide a way to perform complex operations in Redis, allowing you to combine multiple Redis commands in a single script. This is useful for handling complex business logic, such as calculating and updating distributed counters, implementing custom data structures, etc.

  • Atomic lock:

Using Lua scripts, you can implement complex atomic locks instead of just using Redis’s SETNX (set if not exists) command. This is very important for the implementation of distributed locks.

  • Reduce network overhead:

For large batches of data processing, Lua scripts can reduce the number of round trips between the client and the server, thereby significantly reducing network overhead.

  • Reduce server load:

By moving complex calculations to the server side, the burden on the client can be relieved and the load on the server can be reduced.

  • Native support:

Redis natively supports Lua scripts, so no additional plugins or extensions are required.

  • Readability and maintainability:

Lua script is a common scripting language that is easy to write and maintain. Encapsulating complex logic in scripts helps improve code readability.

”

In short, the advantage of Lua scripts in Redis is that it can perform complex operations atomically, reduce network communication, improve performance, reduce server load, and improve code readability. This makes it ideal for performing a range of complex operations, especially in distributed systems where high performance and scalability are required. Through Lua scripts, Redis not only becomes a key-value store, but can also perform complex data operations.

Part 3: Application scenarios of lua script

Lua scripts have a wide range of application scenarios in Redis. The following are some example scenarios showing the practical use of Lua scripts:

1. Cache update:

Scenario: Store some data in the cache, but need to update this data periodically or based on conditions while ensuring that no concurrency issues occur during updates.

Example: Using Lua scripts, you can atomically check the freshness of data and, if updated, recalculate the data and update the cache in one atomic operation.

local cacheKey = KEYS[1] -- Get the cache key
local data = redis.call('GET', cacheKey) -- Try to get data from cache
if not data then
    --The data is not in the cache, recalculate and set
    data = calculateData()
    redis.call('SET', cacheKey, data)
end
return data

2. Atomic operations:

Scenario: Multiple Redis commands need to be executed as an atomic operation to ensure that they will not be interrupted in a multi-threaded or multi-process environment.

Example: Using Lua scripts, you can combine multiple commands into an atomic operation, such as implementing distributed locks, counters, rankings, etc.

local key = KEYS[1] -- Get the key name
local value = ARGV[1] -- Get parameter value
local current = redis.call('GET', key) -- Get the current value
if not current or tonumber(current) < tonumber(value) then
    -- If the current value does not exist or the new value is greater, set the new value
    redis.call('SET', key, value)
end

3. Data processing:

Scenario: Complex processing of data in Redis is required, such as statistics, filtering, aggregation, etc.

Example: Using Lua scripts, you can perform complex data processing in Redis without having to transfer the data to the client for processing, reducing network overhead.

local keyPattern = ARGV[1] -- Get the matching pattern of the key name
local keys = redis.call('KEYS', keyPattern) -- Get matching keys
local result = {}
for i, key in ipairs(keys) do
    local data = redis.call('GET', key) -- Get the data corresponding to each key
    -- Process data and add to results
    table.insert(result, processData(data))
end
return result

4. Distributed lock:

Scenario: Implement a lock mechanism in a distributed system to ensure that only one client can perform critical operations.

Example: Using a Lua script, you can atomically try to acquire a lock, avoiding race conditions, and then release the lock when complete.

local lockKey = KEYS[1] -- Get the key name of the lock
local lockValue = ARGV[1] -- Get the lock value
local lockTimeout = ARGV[2] -- timeout for acquiring lock
if redis.call('SET', lockKey, lockValue, 'NX', 'PX', lockTimeout) then
    -- The lock is acquired successfully and key operations are performed.
    --...
    redis.call('DEL', lockKey) -- Release the lock
    return true
else
    return false -- Unable to acquire lock

These scenarios are just one of the applications of Lua scripts in Redis. Lua scripts allow you to perform more complex operations in Redis without requiring multiple network communications, thereby improving performance and scalability while ensuring data consistency and atomicity. This makes Lua a powerful tool for Redis for handling various distributed system needs.

Part 4: Implementation of Lua script in Spring Boot

Implementing the execution of Lua scripts in Spring Boot mainly involves the use of Spring Data Redis and Lettuce (or Jedis) clients. Here are the steps and examples for writing, loading, and executing Lua scripts:

  • Add dependencies:

First, in the pom.xml of the Spring Boot project, add the dependencies of Spring Data Redis and Lettuce (or Jedis).

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<dependency>
    <groupId>io.lettuce.core</groupId>
    <artifactId>lettuce-core</artifactId> <!-- Or use Jedis -->
</dependency>

  • Configure Redis connection:

Configure Redis connection properties in application.properties or application.yml, including host, port, password, etc.

spring.redis.host=127.0.0.1
spring.redis.port=6379
spring.redis.password=yourPassword

  • Create Lua script:

Create a Lua script to do what you need. Save the script in a suitable location in your Spring Boot project.

For example, suppose you have a Lua script file myscript.lua that implements a simple calculation:

local a = tonumber(ARGV[1])
local b = tonumber(ARGV[2])
return a + b

  • Write Java code:

In a Spring Boot application, write Java code to load and execute Lua scripts. Use StringRedisTemplate or LettuceConnectionFactory provided by Spring Data Redis.

Two different examples are provided to execute Lua scripts, one is to run Lua script strings directly, and the other is to run script files. Here are examples of both:

Run Lua script string:

@Service
public class LuaScriptService {
    @Autowired
    private StringRedisTemplate stringRedisTemplate;

    public Integer executeLuaScriptFromString() {
        String luaScript = "local a = tonumber(ARGV[1])\\
local b = tonumber(ARGV[2])\\
return a + b";
        RedisScript<Integer> script = new DefaultRedisScript<>(luaScript, Integer.class);
        String[] keys = new String[0]; // Normally, there is no KEYS part
        Object[] args = new Object[]{10, 20}; // Parameters passed to Lua script
        Integer result = stringRedisTemplate.execute(script, keys, args);
        return result;
    }
}

Run Lua script file:

First, save the Lua script to a file, such as myscript.lua.

Then, create a Java class to load and run the script file:

@Service
public class LuaScriptService {
    @Autowired
    private StringRedisTemplate stringRedisTemplate;

    @Autowired
    private ResourceLoader resourceLoader;

    public Integer executeLuaScriptFromFile() {
        Resource resource = resourceLoader.getResource("classpath:myscript.lua");
        String luaScript;
        try {
            luaScript = new String(resource.getInputStream().readAllBytes());
        } catch (Exception e) {
            throw new RuntimeException("Unable to read Lua script file.");
        }
        
        RedisScript<Integer> script = new DefaultRedisScript<>(luaScript, Integer.class);
        String[] keys = new String[0]; // Normally, there is no KEYS part
        Object[] args = new Object[]{10, 20}; // Parameters passed to Lua script
        Integer result = stringRedisTemplate.execute(script, keys, args);
        return result;
    }
}

With both examples, you can choose how you want to execute the Lua script, whether to define the script string directly in the Java code, or to read the script from a file.

  • Run the application:

Start the Spring Boot application, and then call the executeLuaScript method in LuaScriptService to execute the Lua script.

In this example, we first inject StringRedisTemplate, then create a RedisScript object, passing the Lua script and the desired result type. In the execute method, we pass the parameters required in the Lua script. This method will load and execute the Lua script and return the results.

Through these steps, you can write, load and execute Lua scripts in Spring Boot applications. This enables you to perform custom operations in Redis, giving you greater control and scaling of your application.

Part 5: Lua scripting to improve the performance of Spring Boot applications

Using Lua scripts can significantly improve the performance of Spring Boot applications, especially when it comes to interacting with Redis. Here are a few ways how to use Lua scripts to achieve performance optimization:

1. Reduce network overhead:

  • Redis is an in-memory database, data is stored in memory, and network communication is usually one of the performance bottlenecks of Redis operations. By using Lua scripts, you can combine multiple operations into a single atomic operation, thereby reducing the number of network round-trips. This is useful for situations where multiple Redis commands need to be executed to complete one operation.

2. Atomic operations:

  • The execution of a Lua script is atomic, which means that no other client can interject other operations during the execution of the Lua script. This makes Lua scripts very useful when implementing atomic operations such as distributed locks, counters, leaderboards, etc.

For example, consider a counter scenario where multiple clients need to atomically increment the count. Using Lua scripts you can implement atomic increment:

local key = KEYS[1]
local increment = ARGV[1]
return redis.call('INCRBY', key, increment)

3. Complex operations:

  • Lua scripts allow you to perform complex data processing on the Redis server side. This reduces the overhead of transferring data to the client for processing and allows you to perform more complex logic in Redis, thus improving performance.

For example, you can use a Lua script to process data stored in multiple keys and return aggregated results:

local total = 0
for _, key in ipairs(KEYS) do
    local value = redis.call('GET', key)
    total = total + tonumber(value)
end
return total

4. Affairs:

  • Using transactions with Lua scripts ensures atomic execution of a series of Redis commands. This is important for situations where a set of operations either all succeed or all fail.

For example, you can use a Lua script to perform a series of update operations within a transaction, and if one of the operations fails, the entire transaction will be rolled back:

local key1 = KEYS[1]
local key2 = KEYS[2]
local value = ARGV[1]

redis.call('SET', key1, value)
redis.call('INCRBY', key2, value)

-- If any step here fails, the entire transaction will be rolled back

”

In summary, using Lua scripts can greatly improve the performance between Spring Boot applications and Redis. It reduces network overhead, allows for atomic operations, performs complex operations, and implements transactions, which all help improve application performance and scalability. Therefore, Lua scripts are a powerful tool for performance optimization when interacting with Redis.

Part 6: Error handling and security

Handling errors in Lua scripts and ensuring security are very important when interacting with Redis. Here are some suggestions on how to deal with these issues:

Error handling:

  • Error return value: A Lua script may encounter errors during execution, such as syntax errors in the script itself, or certain operations in the script failing. After Redis executes the Lua script, it will return the execution result of the script. You can check this result to see if there are any errors, usually the return value is a specific error identifier. For example, if the script executes successfully, the return value is usually OK, otherwise there will be a corresponding error message.

  • Exception handling: In a Spring Boot application, you can use exception handling to capture exceptions that may be thrown when Redis executes scripts. Spring Data Redis provides some exception classes, such as RedisScriptExecutionException, for handling errors during script execution. You can use a try-catch block to catch these exceptions and take appropriate action, such as logging an error message or performing an alternate action.

Security:

  • Parameter validation: Always validate the parameters passed to the Lua script before executing it. Make sure the parameters are legal and do not contain malicious code. Avoid passing untrusted user input directly to Lua scripts as it may contain malicious Lua code.

  • Restrict permissions: Configure appropriate permissions on the Redis server to restrict the execution of Lua scripts. Ensure that only authorized users can execute scripts and that scripts that perform destructive or unsafe operations are not allowed.

  • Whitelist: If you allow dynamic loading of Lua scripts, ensure that only trusted scripts can be executed. You can create a whitelist to only allow scripts in the whitelist to be executed to prevent unaudited scripts from being executed.

  • Sandbox mode: Some Redis client libraries support running Lua scripts in sandbox mode to restrict their access and execution permissions. In sandbox mode, scripts cannot perform dangerous operations such as file access.

  • Monitoring log: Records information related to the execution of Lua scripts by Redis, including who executed the script and the content of the executed script. This helps track execution and identify potential security issues.

In summary, it is very important to handle errors and ensure security in Lua scripts. With proper error handling and security measures, you can ensure that Lua scripts do not introduce potential problems when interacting with Redis and improve the stability and security of your application.

Part 7: Best Practices and Recommendations

To successfully use Lua scripts in Spring Boot projects to implement Redis functions, the following are some best practices and suggestions:

Maintain documentation and comments:

  • Keep documentation and comments of Lua scripts and related code clear and concise. This helps other developers understand the purpose and usage of the script.

Parameter validation:

  • Always validate arguments passed to Lua scripts. Make sure they are legitimate, safe, and do not contain malicious code.

Whitelist:

  • If possible, it is recommended to create a whitelist that only allows audited scripts to execute. This helps prevent unauthorized script execution.

Error handling:

  • Implement appropriate error handling mechanisms for Lua script execution. Catch and handle exceptions that may occur during execution so that error messages can be logged or appropriate actions can be taken.

Test:

  • Be sure to thoroughly unit test Lua scripts before actual use. Ensure scripts execute as expected and have expected behavior under various circumstances.

Permission Control:

  • Implement appropriate permission control on the Redis server to restrict the execution of Lua scripts. Only allow authorized users or applications to execute scripts and avoid performing dangerous operations.

Performance optimization:

  • Use Lua scripts to reduce network overhead, perform atomic operations, and handle complex operations to improve performance. Make sure the script effectively reduces the number of interactions with the Redis server.

Version Management:

  • Implement version management of Lua scripts so that changes to the script can be easily tracked and rolled back.

Monitoring and logging:

  • When Redis executes the Lua script, record relevant information and monitor the execution. This helps track performance and security issues.

Backup plan:

  • For critical operations, consider implementing backup and fault-tolerance solutions to prevent script execution failure or Redis failure.

Appropriate use of Lua scripts:

  • Lua scripting is a powerful tool, but it should not be abused. Use it only when atomicity, performance optimization, or complex operations are required.

Learn Lua programming:

  • If you are not familiar with the Lua programming language, it is recommended to learn the basics of Lua to better write and understand Lua scripts.

By following these best practices and recommendations, you can use Lua scripts to implement Redis functions more safely and efficiently, and ensure that your Spring Boot project’s interaction with Redis is reliable and maintainable.

d208338687f5886f1d70111677f2b41b.png

Recommended in the past

Use Redis to query “people nearby”

The company has been using a multi-account unified login solution for more than 3 years. It is universal and stable!

Interviewer: How many TCP connections can a server support? Asked for a large piece. . .

After only changing five lines of code, the interface throughput increased by more than 10 times! Cool!

1f2d61ad5a884bbb05b393b4b62f69b4.gif

The knowledge points of the article match the official knowledge files, and you can further learn related knowledge. Java Skill TreeHomepageOverview 139,106 people are learning the system