CoIO

Kotlin Coroutines make asynchronous programming simple and efficient but there is no official library that provides IO operations in a coroutine. These operations, such as reading a file or sending data over a TCP connection, benefit heavily from coroutines because they can take relatively long and use few CPU resources. This library seeks to wrap existing Java non-blocking IO libraries to provide a uniform and simple API with coroutines.

Features

• Simple, lean stream interfaces with suspend read and write functions using ByteBuffers
• Supports file access
• Supports TCP servers and clients
• Supports UDP unicast and multicast
• Wrapping any stream with TLS

Alternatives

• Official Kotlin coroutine IO - Does not exist yet.
• Java blocking IO - Must be used with care in coroutines because the blocking operations can consume your worker threads. Consider using the IO Dispatcher.
• Java NIO - Efficient non-blocking operation available but steep learning curve and quite a bit of code needed to build coroutines.
• Java NIO2 - Nice asynchronous methods that can be easily wrapped into a coroutine.

Usage

TCP Server

val server = CoIOTcp.listen(8775)

for (connection in server) {
    launch {
        val buf = ByteBuffer.allocate(1024)
        connection.readFully(buf)
        buf.flip()
        connection.writeFully(buf)
    }
}