Library uses file-based mmap to store key-values

This is a Rust version of MMKV.

By default, this lib uses CRC8 to check data integrity.

If include feature encryption, this lib will encrypt the data with AES-EAX.

MMKV is thread-safe but cannot guarantee cross-process data consistency (still under development). If you want to use it in a cross-process scenario, please ensure that there is no competing write.

How to use

Add dependency:

cargo add mmkv

And use MMKV directly:

use mmkv::MMKV;

fn main() {
    // initialize it with a directory, 
    // the library will crate a file,
    // named "mini_mmkv" under this dir
    MMKV::initialize(".");
    MMKV::put_i32("key1", 1);
    // Ok(1)
    println!("{:?}", MMKV::get_i32("key1"));
    MMKV::put_str("key1", "value");
    // Err(Error::KeyNotFound), cause "key1" was override by put_str
    println!("{:?}", MMKV::get_i32("key1"));
    // Ok("value")
    println!("{:?}", MMKV::get_str("key1"));
    MMKV::put_bool("key1", true);
    // Ok(true)
    println!("{:?}", MMKV::get_bool("key1"));
    // close the instance if you need to re-initialize with different config.
    // MMKV::close();
    // clear all related data to free disk space, this call will also close the instance.
    // MMKV::clear_data();
}

Use with encryption feature

Add dependency:

cargo add mmkv --features encryption

Then init MMKV with an encryption credential:

MMKV::initialize(".", "88C51C536176AD8A8EE4A06F62EE897E")

Encryption will greatly reduce the efficiency of reading and writing, and will also increase the file size, use at your own risk!

Use in Android projects

Add lib dependency to gradle:

dependencies {
    implementation("net.yangkx:mmkv:0.2.4")
    // Or another one with encryption feature
    // implementation("net.yangkx:mmkv-encrypt:0.2.4")
}

Use the kotlin API:

class MyApplication : Application() {
    override fun onCreate() {
        super.onCreate()
        val dir = this.getDir("mmkv", Context.MODE_PRIVATE)
        MMKV.initialize(dir.absolutePath)
        // If you are using mmkv with encryption
        // MMKV.initialize(dir.absolutePath, "88C51C536176AD8A8EE4A06F62EE897E")
    }
}

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = ActivityMainBinding.inflate(layoutInflater)
        setContentView(binding.root)
        MMKV.putString("first_key", "first value")
        MMKV.putInt("second_key", 1024)
        MMKV.putBool("third_key", true)
        binding.string.text = MMKV.getString("first_key", "default")
        binding.integer.text = MMKV.getInt("second_key", 0).toString()
        binding.bool.text = MMKV.getBool("third_key", false).toString()
    }
}

Check the android demo for more detail.

Use in iOS project

Since this repo is using git-lfs, and SwiftPM doesn't support git-lfs(check this issue), You need to clone this repo to your machine, and add path-to-this-repo/ios/MMKV as a Swift package to your project. Then add code to your App.swift:

import SwiftUI
import MMKV

@main
struct MMKVDemoApp: App {
    init() {
        initMMKV()
    }
    var body: some Scene {
        ...
    }
}

func initMMKV() {
    let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
    let documentsDirectory = paths[0]
    let docURL = URL(string: documentsDirectory)!
    let dataPath = docURL.appendingPathComponent("mmkv")
    if !FileManager.default.fileExists(atPath: dataPath.path) {
        do {
            try FileManager.default.createDirectory(atPath: dataPath.path, withIntermediateDirectories: true, attributes: nil)
        } catch {
            print(error.localizedDescription)
        }
    }
    MMKV.shared.initialize(dir: dataPath.path)
}

And then you can use MMKV API directly:

import SwiftUI
import MMKV

struct ContentView: View {
    @State var textContent: String = "Hello, world!"
    var body: some View {
        Text(textContent)
            .onTapGesture {
                let value = MMKV.shared.getInt32(key: "int_key").unwrap(defalutValue: 0)
                MMKV.shared.putInt32(key: "int_key", value: value + 1).unwrap(defalutValue: ())
                textContent = MMKV.shared.getInt32(key: "int_key").unwrap(defalutValue: 0).formatted()
            }
    }
}

Check the ios demo for more detail.