FileSystem
=========

A file change watcher wrapper based on [fs](https://github.com/synrc/fs)

## System Support

- Mac fsevent
- Linux, FreeBSD and OpenBSD inotify
- Windows inotify-win

NOTE:

        On Linux, FreeBSD and OpenBSD you need to install inotify-tools.
        On Macos 10.14, you need run `open /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg` to compile `mac_listener`.

## Usage

Put `file_system` in the `deps` and `application` part of your mix.exs

``` elixir
defmodule Excellent.Mixfile do
  use Mix.Project

  def project do
  ...
  end

  defp deps do
    [
      { :file_system, "~> 0.2", only: :test },
    ]
  end
  ...
end
```


### Subscription API

You can spawn a worker and subscribe to events from it:

```elixir
{:ok, pid} = FileSystem.start_link(dirs: ["/path/to/some/files"])
FileSystem.subscribe(pid)
```

or

```elixir
{:ok, pid} = FileSystem.start_link(dirs: ["/path/to/some/files"], name: :my_monitor_name)
FileSystem.subscribe(:my_monitor_name)
```

The pid you subscribed from will now receive messages like

```
{:file_event, worker_pid, {file_path, events}}
```
and
```
{:file_event, worker_pid, :stop}
```

### Example with GenServer

```elixir
defmodule Watcher do
  use GenServer

  def start_link(args) do
    GenServer.start_link(__MODULE__, args)
  end

  def init(args) do
    {:ok, watcher_pid} = FileSystem.start_link(args)
    FileSystem.subscribe(watcher_pid)
    {:ok, %{watcher_pid: watcher_pid}}
  end

  def handle_info({:file_event, watcher_pid, {path, events}}, %{watcher_pid: watcher_pid}=state) do
    # YOUR OWN LOGIC FOR PATH AND EVENTS
    {:noreply, state}
  end

  def handle_info({:file_event, watcher_pid, :stop}, %{watcher_pid: watcher_pid}=state) do
    # YOUR OWN LOGIC WHEN MONITOR STOP
    {:noreply, state}
  end
end
```


## Tweaking behaviour via extra arguments

For each platform, you can pass extra arguments to the underlying listener process.

Each backend support different extra arguments, check backend module documentation for more information.

Here is an example to get instant notifications on file changes for Mac OS X:

```elixir
FileSystem.start_link(dirs: ["/path/to/some/files"], latency: 0, watch_root: true)
```