# Debouncer [](https://travis-ci.com/dominicletz/debouncer)
Debouncer module to reduce frequency of function calls to alerts, updates and similar. It supports four different modes:
* `apply()` - For delayed triggers, e.g. to trigger an __autocomplete__ action
* `immediate()` - For reducing frequency of events, the first event per interval is delivered immediately, e.g. trigger __data processing tasks__
* `immediate2()` - Similiar to immediate but never delays events, either forwards them or ignores them, e.g. to trigger __alert emails__
* `delay()` - Only triggers an event after the timeout period, any further event delays the trigger. E.g. to detect data streams that __ended actvitiy__
## Usage Example
```elixir
Debouncer.apply(SomeKey, fn() ->
IO.puts("Hello World, debounced will appear in 5 seconds")
end)
```
```elixir
Debouncer.immediate(OtherKey, fn() ->
IO.puts("Hello World, will appear immediate, but not again within 5 seconds")
end)
```
## Behaviour Graph
```
EVENT X1---X2------X3-------X4----------
TIMEOUT ----------|----------|----------|-
===============================================
apply() ----------X2---------X3---------X4
immediate() X1--------X2---------X3---------X4
immediate2() X1-----------X3-------------------
delay() --------------------------------X4
```
This graph represents when the different variants fire an event respectively on a timeline. In code the first line would look like this:
```elixir
fn ->
Debouncer.apply(SomeKey, fn() -> IO.puts("X1") end, 1000)
Process.sleep(500)
Debouncer.apply(SomeKey, fn() -> IO.puts("X2") end, 1000)
Process.sleep(800)
Debouncer.apply(SomeKey, fn() -> IO.puts("X3") end, 1000)
Process.sleep(900)
Debouncer.apply(SomeKey, fn() -> IO.puts("X4") end, 1000)
Process.sleep(1200)
end.()
> X2
> X3
> X4
```
## Installation
The debouncer can be installed by adding `debouncer` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:debouncer, "~> 0.1"}
]
end
```
The debouncer is an application and will start a GenServer to trigger the events. To include the Application in your release add it to your extra applications:
```elixir
def application do
[
mod: {Your.Application, []},
extra_applications: [:debouncer]
]
end
```
If it's not started it will try to start itself on usage.
The docs can be found at [https://hexdocs.pm/debouncer](https://hexdocs.pm/debouncer).
## Remarks
The `delay()` behaviour should be the same as in Michal Muskalas Debounce implementation https://github.com/michalmuskala/debounce
