DOM Scheduler for read/write tasks #

API #

Scheduler #

The scheduler algorithm is quite simple and looks like this:

while (writeTasks.isNotEmpty) {
  while (writeTasks.isNotEmpty) {
     writeTasks.removeFirst().start();
     runMicrotasks();
  }
  while (readTasks.isNotEmpty) {
    readTasks.removeFirst().start();
    runMicrotasks();
  }
}
while (afterTasks.isNotEmpty) {
  afterTasks.removeFirst().start();
  runMicrotasks();
}

It will perform write and read tasks in batches until there are no write or read tasks left.

Write tasks sorted by their priority, and the tasks with the lowest value in the priority property are executed first. It is implemented this way because most of the time tasks priority will be its depth in the DOM.

Scheduler runs in its own Zone and intercepts all microtasks, this way it is possible to use Futures to track dependencies between tasks.

Frame get nextFrame

Returns Frame that contains tasks for the next animation frame.

Frame get currentFrame

Returns Frame that contains tasks for the current animation frame.

Zone get zone

Returns Scheduler Zone.

Frame #

Future write([int priority = maxPriority])

Returns Future that will be completed when Scheduler starts executing write tasks with this priority.

Future read()

Returns Future that will be completed when Scheduler starts executing read tasks.

Future after()

Returns Future that will be completed when Scheduler finishes executing all write and read tasks.

Notes #

If you are planning to use something else for the write priority and not depth of the node in the DOM tree, please let me know. Right now it is implemented in a way that is better suited for depth, and will behave badly for sparse values.