*#Stop(): wait for own Checkable#ProcessCheckResult() to finish🏁

[Al2Klimov]

This is the very first and hardest step of the #10179 (comment) plan.

Checkable#ProcessCheckResult() now takes a CheckResultProducer::Ptr:

• 23c2365 Checkable#ProcessCheckResult(): discard CR or delay its producers shutdown

It tries to shared-lock the CheckResultProducer:

• Failure means the CheckResultProducer indicates it's already shutting down, so the not yet really started Checkable#ProcessCheckResult() fails and discards the CR
• Success means Checkable#ProcessCheckResult() can continue and on shutdown CheckResultProducer will wait for that

This implies that every component producing checks needs to implement CheckResultProducer:

• f86b8ba *#Stop(): wait for own Checkable#ProcessCheckResult()s to finish
• 84cb9d8 mkclass: inherit from Object like this: class T : virtual public Object

Finally, the CheckResultProducer::Ptr has "just" to be passed through from the CheckResultProducer itself to Checkable#ProcessCheckResult():

• a06b01a Unconditionally allow processing CheckResults in tests
• 3cbcbde LivestatusQuery#Execute(): take CheckResultProducer::Ptr
• 199de23 LivestatusQuery#ExecuteCommandHelper(): take CheckResultProducer::Ptr
• 8991f33 ExternalCommandProcessor::ProcessFile(): take CheckResultProducer::Ptr
• 2c0b7cb ExternalCommandProcessor::ExecuteFromFile(): take CheckResultProducer::Ptr
• 8b6ee1c ExternalCommandProcessor::Execute(): take CheckResultProducer::Ptr
• f621b06 ExternalCommandProcessor::RegisterCommand(): allow callback to take a CheckResultProducer::Ptr
• ec00100 ExternalCommandProcessor::Process*CheckResult(): take CheckResultProducer::Ptr
• efce6ab ClusterEvents::ExecuteCheckFromQueue(): take ApiListener::Ptr
• 21846f8 Checkable#ExecuteCheck(): take CheckResultProducer::Ptr
• 3492279 CheckCommand#Execute(): take CheckResultProducer::Ptr
• c35f558 IcingadbCheck::ScriptFunc(): take CheckResultProducer::Ptr
• 5953a2a IdoCheckTask::ScriptFunc(): take CheckResultProducer::Ptr
• 9f1edd3 SleepCheckTask::ScriptFunc(): take CheckResultProducer::Ptr
• eb415bd RandomCheckTask::ScriptFunc(): take CheckResultProducer::Ptr
• 4976fe6 PluginCheckTask::ScriptFunc(): take CheckResultProducer::Ptr
• 2eb535c NullCheckTask::ScriptFunc(): take CheckResultProducer::Ptr
• 69bb267 IfwApiCheckTask::ScriptFunc(): take CheckResultProducer::Ptr
• eef64e2 IcingaCheckTask::ScriptFunc(): take CheckResultProducer::Ptr
• b3fcfb2 ExceptionCheckTask::ScriptFunc(): take CheckResultProducer::Ptr
• 9164858 DummyCheckTask::ScriptFunc(): take CheckResultProducer::Ptr
• 628353d ClusterZoneCheckTask::ScriptFunc(): take CheckResultProducer::Ptr
• 7016920 ClusterCheckTask::ScriptFunc(): take CheckResultProducer::Ptr

[julianbrost]

• TODO(@Al2Klimov): better PR description

Well, that's indeed necessary.

@julianbrost rather agreed with #10179 (comment), but said #10179 (comment) lacks some tracking.

Interesting that I've said something about a comment I haven't even seen until just now.

[Al2Klimov]

@julianbrost Very funny. Fact is, on Thursday you

1. agreed with me that components should stop/join their own checks along with themselves
2. said that will need some tracking

So I've done that. So far:

• 684ca7d Now Checkable#ProcessCheckResult() doesn't guess the CR origin, instead it demands a CheckResultProducer barely fitting into a std::shared_lock
• a8d011f CheckerComponent implements that CheckResultProducer (TODO(@Al2Klimov): more classes)

Finally, CheckResultProducer::Ptr just has to be passed through.