fix: API module; delay sending commands to EvseManager until it is ready

[james-ctc]

Describe your changes

The API module can send commands to EvseManager before the manager has completed initialisation.
When this happens there is a potential for the manager to dereference a null pointer and terminate.

This change holds requests to EvseManagers until they have all responded with ready.

Issue ticket number and link

Checklist before requesting a review

• I have performed a self-review of my code
• I have made corresponding changes to the documentation
• I read the contribution documentation and made sure that my changes meet its requirements

[Pietfried]

These changes rely on the fact that each EvseManager publishes ready only once (which is currently given). Instead of using a counter that counts down you could actually check for each EVSE individually (e.g. by using a map).

[james-ctc]

@Pietfried updated the approach so that an EVSE manager can be ready multiple times and not cause an issue.

[MarzellT]

For consistency reasons I would explicitly use this here since it's been used everywhere else too

Suggested change

	evse_manager_ready = this->r_evse_manager.size();
	this->evse_manager_ready = this->r_evse_manager.size();

[james-ctc]

this-> is commonly needed for lambdas. Elsewhere this-> should not be added unless is is actually required.

[MarzellT]

I agree, I just think it might be better to have a consistent style and this has been used throughout this file to refer to class members not just in lambdas

[MarzellT]

I think it would be cleaner to use a bool instead of an integer here since this would better reflect the intent. I also think I would make an explicit check in the cpp file like so:

evse_manager_ready = this->r_evse_manager.size() == 0;

Suggested change

	std::int16_t evse_manager_ready{0};
	bool evse_manager_ready{0};

[james-ctc]

r_evse_manager.size() will never equal 0.

  evse_manager:
    interface: evse_manager
    min_connections: 1
    max_connections: 128

If there are 10 EVSE managers then r_evse_manager.size() == 10
evse_manager_ready is set to 10 and decremented when a manager becomes ready.
evse_manager_ready being 0 or less means that at least 10 ready messages have been received.

[MarzellT]

Alright :) then I must have misunderstood how this variable works