vishna/watchservice-ktx

Kotlin API wrapper for Java's WatchService powered with Channels and Coroutines. a.k.a. KWatchChannel

watchservice-ktx

Kotlin API wrapper for Java's WatchService powered with Channels and Coroutines. a.k.a. KWatchChannel

Getting started

This repository is hosted via jitpack since it's by far the easiest delivery method while also being pretty transparent to the developer.

Make sure you have added jitpack to the list of your repositories:

maven("https://jitpack.io")

Then simply add the watchservice-ktx dependency

dependencies {
  compile("com.github.vishna:watchservice-ktx:master-SNAPSHOT")
}

Example usage

val currentDirectory  = File(System.getProperty("user.dir"))

val watchChannel = currentDirectory.asWatchChannel()

launch {
  watchChannel.consumeEach { event ->
    // do something with event
  }
}

// once you no longer need this channel, make sure you close it
watchChannel.close()

For more documentation on API see watchservice.kt or check out the medium article

watchservice-ktx's Issues

Should it use `Dispatchers.IO` given that the watcher service blocks the thread permanently?

1. scope should be a mandatory parameter and should be a custom CoroutineScope with a single thread executor service
2. scope.launch(Dispatchers.IO) should be replaced with scope.launch

take() blocks indefinitely

It looks like the core loop is using up a lot more CPU than it should due to a busy-wait, correct? Would it be better to sleep between iterations?

Btw, thanks for the blog post and WatchService example! Even though I don't know Kotlin, I found it easy to follow.

ClassNotFoundException

I am getting this error

  at(KWatchChannel.java:2)


Please help me solve this.

Handling of large file being written to the watched folder

When large files are being written into a watched folder over some network, there is a possiblity that a partial file is received for processing in the consumer.

There are multiple ways to handle this, but the easiest to ensure that the file's modified timestamp does not change for more than n seconds (e.g. 5 secs) and then send the event over the channel for processing.

Removal of subfolder results into the watcher not being able to react to any other future events

This is essentially because event.file.isDirectory on a path representing a deleted folder will always return false