Signals

A Signal is a way to decouple between a subject(dispatcher) and the observers(listeners) in distributed event handling systems.

Setup

Step 1. Add it in your root build.gradle at the end of repositories:

allprojects {
	repositories {
		...
		maven { url 'https://jitpack.io' }
	}
}

Step 2. Add the dependency

dependencies {
    implementation 'com.github.gazman-sdk:signals:1.5'
}

Kotlin example

fun interface Chat{
    fun onNewMessage(s:String)    
}

class Foo{
    val chatSignal = Signals.signal(Chat::class)
    
    fun bar(){
        chatSignal.addListener { s-> Log.d("chat", s) } // logs all the messaged to Logcat
    }
}

class Foo2{
    val chatSignal = Signals.signal(Chat::class)
    
    fun bar2(){
        chatSignal.dispatcher.onNewMessage("Hello from Foo2") // dispatches "Hello from Foo2" message to all the listeners
    }
}

Java example

interface Chat{
    void onNewMessage(String s);    
}

class Foo{
    Signal<Chat> chatSignal = Signals.signal(Chat.class);
    
    void bar(){
        chatSignal.addListener( s-> Log.d("chat", s) ); // logs all the messaged to Logcat
    }
}

class Foo2{
    Signal<Chat> chatSignal = Signals.signal(Chat.class);
    
    void bar2(){
        chatSignal.dispatcher.onNewMessage("Hello from Foo2"); // dispatches "Hello from Foo2" message to all the listeners
    }
}

The Signal is automatically created from the Chat interface. It allows Foo to register for it and Foo2 to dispatch new messages without interaction.

Signal API

Register/Unregister listeners

• addListener(listener) - registers a listeners for this signal
• addListenerOnce(listener) - registers a listeners for this signal and unregister it after the first dispatch
• removeListener(listener) - removes a listener that was registered using one of the methods above

Dispatch events

• dispatcher - property from the interface-type used to create this Signal. When it is invoked, it is propagating to all the listeners.
• setInvoker(executor/handler) - by default, all the listeners, will be executed synchronously over the dispatcher thread. You can change this behavior by using an explicit executor/handler to execute all the calls for listeners

SignalsHelper

A helper class to unregister all the signals at once.

• addListener(class, listener)
• addListenerOnce(class, listener)
• removeListener(class, listener)
• removeAll() - Removes all the listeners registered via this SignalsHelper

G

G is a super light utility class to simplify the work with Signals.

• G.app - app context. It is automatically obtained via a ContentProvider during the Application creation
• G.main - Main handler
• G.CE - A multithreaded cached executor

Behavior

• Signals support modification during iteration. You can add and remove listeners during the dispatch phase, and it will take effect immediately. See the ListenersList implementation for details, as well as ListenersListTest
• Signals is thread-safe, you can add/remove/clear and dispatch in a multithreaded environment