Meaning of Tree.sleep()

[MatteoAlbi]

My question is why do we need to add a sleep interval in the tick cycle of the tree?

[MatteoAlbi]

Answer from @facontidavide :

Since the concept of ticking a tree is basically "polling", we don't want to consume 100% of the cpu, bombarding an asynchronous action with ticks.

The smart thing we do is that the proposed sleep is actually a std::condition_variable in disguise.

So, contrariwise to a regular sleep, it can be interrupted if a wake up signal is sent

[MatteoAlbi]

And in which cases a wake up signal is sent? Moreover, what could actually happen by shortening the sleep period?

[facontidavide]

A well implemented asynchornous action with its own thread, should invoke emitWakeUpSignal when it is ready.

For instance, imagine that you asynchronous Action is waiting for a reply from a server (in its own thread).
As soon as this reply is reached, you should call emitWakeUpSignal to notify that you are ready to be complete your action in the next tick.