@screamingvoid/leveldown v0.1.0

@screamingvoid/leveldown

Native (C++) LevelDB bindings for React Native, implemented as JSI module. Fully abstract-leveldown compatible. Partially compatible with leveldown extended API.

For documentation, see abstract-leveldown README, public API section. As full safety is not guaranteed when using these bindings, it's recommended to use levelup to avoid accidental crashes.

Speed and Binary Data

As these binding are implemented as JSI module, the speed of operations should be pretty good. I haven't run the benchmarks yet, but it should perform close to maximum speed of native LevelDB.

Again, as this is a JSI module, there's no marshalling/serialization happening for binary data. In fact, I chose buffer as the native JavaScript format and while strings and other data types are supported, they are first converted to Uint8Array's before being passed to native code.

For maximum performance you should stick to Buffer keys/values, to avoid serialization penalty.

Sync/Async

As levelup/abstract-leveldown offer only async API, so these bindings do too.

We do implement { sync: true } option for write operations from leveldown extended API. This does NOT make the call synchronous, but it does ensure that when the callback is called/promise resolves, all changes have been written to disk.

Note for developers

The C++ binding is fully synchronous in a sense that all calls are synchronous. The JavaScript API achieves asynchronicity through the use of setImmediate calls.

What this means is that if you have a use case for synchronous access, you can implements synchronous JavaScript API using the same native code.

If you do, pull requests are welcome. Do open an issue or drop me an email for coordination then.

As I have no need for synchronous access and limited time/resources I probably won't be implementing this myself.

Leveldown Extended API

I'd like to support all of leveldown's additional methods, not in abstract-leveldown API. However as I do not have the time to implement and test them, that's a goal for the future.

As it is, we support the { sync: true } option and one additional method, namely approximateSize. If you implement any others - pull requests are very welcome. Do add the tests if you do.