dbalabka/dag

Directed acyclic graph of tasks implementation based on Amphp promises

This experimental library helps to organize tasks and its dependencies. Amphp framework support provide ability to execute tasks asynchronously.

Following example show basic usage:

$taskDag = (new TaskGraph())
    
    // root task in graph (there might be multiple root tasks)
    ->addTask(new ClosureTask('1', function () {
        echo $this->name;
    }))
    
    // these two tasks were be executed only after task with name '1'
    // the order of execution is not guaranteed
    ->addTask(new ClosureTask('2', function () {
        echo 2;
    }, ['1'])) 
    ->addTask(new ClosureTask('3', function () {
        echo 3;
    }, ['1']))

    // this is the last task in graph (there might be multiple leaf tasks)
    ->addTask(new ClosureTask('4', function () {
        echo 4;
    }, ['3', '2']));

Amp\Loop::run($taskDag); // will output "1234"

The visualization of the execution graph will be following:

     +------+
   +-+Task 1+-+
   | +------+ |
   |          |
+--v---+  +---v--+
|Task 2|  |Task 3|
+--+---+  +---+--+
   |          |
   | +------+ |
   +->Task 4<-+
     +------+