Features

• 🚀 High Performance: Leverages mmap for memory-mapped file I/O, significantly outperforming react-native-fs. Built on the new React Native architecture with NitroModules, it enables zero-copy operations and direct ArrayBuffer access.
• 🛠️ Simple API: Easily read, write or append files using the Mmfile or EncryptedMmfile objects.
• 🔒 Encryption: Supports AES-128, AES-192, and AES-256 in CTR mode for real-time encryption/decryption and random access. The cipher is implemented in C++ and optimized for performance using NEON (ARM) and AES-NI (Intel) instructions.
• 📦 Zero Dependencies: No external libraries required—pure, efficient native code.
• 📱 Cross-Platform: Seamlessly works on both iOS and Android

Performance

To compare the performance of react-native-mmfile to the most popular React Native storage modules react-native-mmkv and react-native-fs, the following benchmark measures the total time it takes to write a file of 1MB by appending chunks of varying sizes (16 bytes to 1MB).

*) It's important to note that MMKV is not a file-based storage solution, but rather a key-value store and doesn't offer an append operation, so it had to overwrite the file each time, but even in a single write operation, it was still slower than react-native-mmfile.

Installation

bun add react-native-mmfile react-native-nitro-modules
cd ios && pod install

[!NOTE] Supported Android ABIs. The native code is built for arm64-v8a, armeabi-v7a and x86_64. The 32-bit armeabi-v7a library exists for 64-bit ARMv8 CPUs that run a 32-bit Android (e.g. the Samsung Galaxy A13): it executes in AArch32 but still uses the hardware AES instructions, so it requires the ARMv8 Cryptography Extensions. If your app pins reactNativeArchitectures in android/gradle.properties, make sure armeabi-v7a is included.

Minimum SDK is 28 (Android 9). Every pre-ARMv8 32-bit CPU (which lacks the AES instructions) tops out at Android 8.1, so this floor guarantees the armeabi-v7a library only ever runs on a CPU that supports it — and keeps the app off the long-EOL Android 8. Consuming apps must therefore use minSdkVersion >= 28.

Usage

import { Mmfile } from '@d4l/react-native-mmfile';

// encode 'Hello World' to ArrayBuffer using UTF-8 encoding
const data = new TextEncoder().encode('Hello World').buffer;

let file = Mmfile.openMmfile('hello.txt');
file.append(data);
file.close();

Documentation

• Full API reference
• Nitro Modules — The easiest and fastest way to write React Native modules, Medium article

Example App

The example app demonstrates the usage of react-native-mmfile and can be found in the example directory. To run the example app, follow these steps:

cd example
npm run preinstall
npm install

# For Android
npm run android 

# For iOS
cd ios
pod install
npm run ios     

Run Tests

To run the tests, you need to install GoogleTests first, e.g. with Homebrew:

brew install googletest

And then use the following commands:

cd cpp/tests
mkdir build
cd build
cmake ..
cmake --build .
ctest

License

MIT