Inspector improvement: page load profiler for services and more

[ebruchez]

See also #2169 and #3534.

A recurring issue is gaining data about a slow-loading page. In a few concrete cases we've had, slow user-defined services are to blame. But it's hard to know about this without inspecting log files.

We should have a way to load a page in a "profiling" mode. This can be done:

• with the Form Builder Test mode
• as well as for a deployed form
  • exactly how, and how to access this information, is TBD

Here is the information we'd like to have:

• total page load time on the server
• total time spent in user-defined service calls
  • and which services are running
• total time spent in Form Runner persistence layer
• total time spent in Form Runner proper
  • document initialization
  • refreshes
  • actions
  • and possibly more

The result could be shown in two ways:

• stored in memory, for retrieval by an admin view
• shown directly as a pane on the loaded page (but only if enabled, of course)

[ebruchez]

As a first step, even just gathering the info and logging it in a compact form could help.

[ebruchez]

I made some improvements to the XForms Inspector. I notice that it has a "Console" mode, which allows dispatching fr-messages events to the inspector and have them show there. This doesn't appear to be used anywhere in our code base.

We could use this feature, or an improvement of it, to output this kind of information.

[ebruchez]

Moved this comment to separate issue #5846.

[ebruchez]

Moved this comment to separate issue #5846.

[ebruchez]

Moved this comment to separate issue #5845.

[ebruchez]

Also for Form Runner actions, including action syntax!