README.md

asyncio

As the name suggests, this a very simple async reader and writer for interacting with files in a non-blocking way from R. It runs the file I/O in a separate thread and uses the promises as an API to eventually return the result of the operation.

Installation

Note: This package is not yet on CRAN and is still just an experiment. You will also need rustc and cargo installed in your system to compile the Rust code.

# With remotes
remotes::install_github("ixpantia/asyncio")
# With pak
pak::pak("ixpantia/asyncio")

Usage

This package works best when used inside a plumber API or any other async environment like Shiny. Here is an example of how to use it in a Plumber API to asynchronously read and write to a file.

library(asyncio)
library(promises)

options(asyncio.threads = 10)
temp_file <- tempfile()

#* @post /write
#* @param line The line to write to the file
#* @parser text
function(line) {
  asyncWriteLines(line, temp_file, append = TRUE) %...>% {
    paste("You wrote:", ., "bytes to the file")
  } %...!% {
    paste("Failed to write to the file:", .)
  }
}

#* @get /read
function() {
  asyncReadLines(temp_file) %...!% {
    paste("Failed to read from the file, try writing something first:", .)
  }
}

Changing the number of worker threads

asyncio uses actual operating system threads, not additional R proccesses, therefore spawning additional threads is not as expensive as it would be if using the future package. You can change the number of worker threads by setting the option asyncio.threads before calling any of the async functions.

By default, asyncio.threads is set to 4. You can change it like this:

options(asyncio.threads = 10)

Improvements

1. Add more file reading functions.
2. Add more options for the file reading functions.
3. Add other I/O operations like TCP, UDP, etc.