Notification settings stack fix

[s0170071]

@TD-er would you be please so kind and replace in webserver.ino three occurences of :

NotificationSettingsStruct NotificationSettings;
with

    NotificationSettingsStruct* NotificationSettingsStruct_ptr =new NotificationSettingsStruct;
    NotificationSettingsStruct& NotificationSettings = *NotificationSettingsStruct_ptr ;

that moves that temporary struct to heap. Clicking the notifications tab and setting an email notifications brings the stack down to 1700 (was 500 before)
Don't forget to delete() afterwards.
Sorry for asking, but creating pull requests takes me at least half an hour ;-)

Thanks.

Edit:
There are more potential replacements like

ControllerSettingsStruct ControllerSettings;
with

    ControllerSettingsStruct* ControllerSettings_ptr =new ControllerSettingsStruct;
    ControllerSettingsStruct& ControllerSettings = *ControllerSettings_ptr ;

There are some more hidden in the code, e.g. comtrollers. You find them best if you search for "ControllerSettingsStruct " with a space char at the end of the search string.

[s0170071]

Ah and another important observation I would like to share.
The local variables (those that go to the stack) increase the stack watermark at the BEGINNING of a function even if they are DECLARED LATER on somewhere in the function or even more local in a loop or an if clause.

Seems the compiler prepares for the worst case, which makes sense. But if you go hunting for stack usage, that is very irritating. Took me a while to figure out.

[TD-er]

I will replace the occurrences. I think I will make a macro for it, which makes changing back later a lot easier ;) (and then you only have a single line to replace)

About the second post.
That's how C++ compiler does work. It allocates all members in that scope on the stack when you enter a scope.
This is also one of the reasons why it is important to initialize members in the same order as they are defined, when you initialize them in the constructor before entering the { } part.

[TD-er]

Oh and by the way, I think I will use some kind of smart pointer for this, to make sure the object gets destructed.

[s0170071]

That's how C++ compiler does work. It allocates all members in that scope on the stack when you enter a scope.

I found it allocates all of these variables on the stack before they come into scope.
You can see this in handle_notifications.

[TD-er]

Yep, a call to a function, for example, will allocate the items on the stack and only then enter the function.
But it looks like you're already looking into it at quite an impressive level of detail :)

[s0170071]

It's important to know if you debug memory usage with printfs...

[TD-er]

I added a pull req. for NotificationSettings and ControllerSettings.
I'm still thinking about how to do the CustomTaskSettings, since that is variable in dimensions.
See all plugins which call LoadCustomTaskSettings or SaveCustomTaskSettings

[uzi18]

It's time to check performane loos/rise of this change.
@TD-er what do You think?