Crate napi

High level NodeJS N-API binding

napi-rs provides minimal overhead to write N-API modules in Rust.

Feature flags

libuv

With libuv feature, you can execute a rust future in libuv in NodeJS, and return a promise object.

use std::thread;
use std::fs;

use futures::prelude::*;
use futures::channel::oneshot;
use napi::{CallContext, Result, JsString, JsObject, Status, Error};

#[js_function(1)]
pub fn uv_read_file(ctx: CallContext) -> Result<JsObject> {
  let path = ctx.get::<JsString>(0)?;
  let (sender, receiver) = oneshot::channel();
  let p = path.as_str()?.to_owned();
  thread::spawn(|| {
    let res = fs::read(p).map_err(|e| Error::new(Status::Unknown, format!("{}", e)));
    sender.send(res).expect("Send data failed");
  });
  ctx.env.execute(receiver.map_err(|e| Error::new(Status::Unknown, format!("{}", e))).map(|x| x.and_then(|x| x)), |&mut env, data| {
    env.create_buffer_with_data(data)
  })
}

tokio_rt

With tokio_rt feature, napi-rs provides a tokio runtime in an additional thread. And you can easily run tokio future in it and return promise.

use futures::prelude::*;
use napi::{CallContext, Error, JsObject, JsString, Result, Status};
use tokio;

#[js_function(1)]
pub fn tokio_readfile(ctx: CallContext) -> Result<JsObject> {
  let js_filepath = ctx.get::<JsString>(0)?;
  let path_str = js_filepath.as_str()?;
  ctx.env.execute_tokio_future(
    tokio::fs::read(path_str.to_owned())
      .map(|v| v.map_err(|e| Error::new(Status::Unknown, format!("failed to read file, {}", e)))),
    |&mut env, data| env.create_buffer_with_data(data),
  )
}

Tokio channel in napi-rs buffer size is default 100.

You can adjust it via NAPI_RS_TOKIO_CHANNEL_BUFFER_SIZE environment variable

NAPI_RS_TOKIO_CHANNEL_BUFFER_SIZE=1000 node ./app.js

Re-exports

pub use napi_sys as sys;

Modules

threadsafe_function

Macros

register_module

register nodejs module

Structs

CallContext
Env
Error
JsArrayBuffer
JsBoolean
JsBuffer
JsExternal
JsFunction
JsNull
JsNumber
JsObject
JsString
JsSymbol
JsUndefined
JsUnknown
Module
NodeVersion
Property

Enums

Either
Status
ValueType

Traits

NapiValue
Task

Type Definitions

Callback
Result