Loadpoint: fix reentrant locks #2

[andig]

Fix reentrant locks in #18603 (comment). Follow-up to #18650.

[jeffborg]

@andig server doesn't startup even to port 7070 had to make some changes below is here is the pprof

1 @ 0x85de8 0x62418 0x623f5 0x8771c 0x9d3c4 0xd77eb8 0x8e604
#	0x8771b		sync.runtime_Semacquire+0x2b					runtime/sema.go:71
#	0x9d3c3		sync.(*WaitGroup).Wait+0x73					sync/waitgroup.go:118
#	0xd77eb7	github.com/eclipse/paho%2emqtt%2egolang.startComms.func3+0x27	github.com/eclipse/[email protected]/net.go:438

1 @ 0x85de8 0x62418 0x623f5 0x87868 0x1ed38d8 0x1ed3885 0x1ed3b4c 0x1ed3a58 0x1ec0e24 0x1ee107c 0x20cfbb0 0x5b76ec 0x5b7ec4 0x20ce014 0x20ce009 0x20e2a94 0x4de58 0x8e604
#	0x87867		sync.runtime_SemacquireRWMutexR+0x27					runtime/sema.go:100
#	0x1ed38d7	sync.(*RWMutex).RLock+0x77						sync/rwmutex.go:72
>>> #	0x1ed3884	github.com/evcc-io/evcc/core.(*Loadpoint).getMeasuredPhases+0x24	github.com/evcc-io/evcc/core/loadpoint_phases.go:45
#	0x1ed3b4b	github.com/evcc-io/evcc/core.(*Loadpoint).activePhases+0x3b		github.com/evcc-io/evcc/core/loadpoint_phases.go:73
>>> #	0x1ed3a57	github.com/evcc-io/evcc/core.(*Loadpoint).ActivePhases+0x67		github.com/evcc-io/evcc/core/loadpoint_phases.go:65
#	0x1ec0e23	github.com/evcc-io/evcc/core.(*Loadpoint).Prepare+0x963			github.com/evcc-io/evcc/core/loadpoint.go:664
#	0x1ee107b	github.com/evcc-io/evcc/core.(*Site).Prepare+0x15b			github.com/evcc-io/evcc/core/site.go:992
#	0x20cfbaf	github.com/evcc-io/evcc/cmd.runRoot+0x1b3f				github.com/evcc-io/evcc/cmd/root.go:307
#	0x5b76eb	github.com/spf13/cobra.(*Command).execute+0x81b				github.com/spf13/[email protected]/command.go:989
#	0x5b7ec3	github.com/spf13/cobra.(*Command).ExecuteC+0x343			github.com/spf13/[email protected]/command.go:1117
#	0x20ce013	github.com/spf13/cobra.(*Command).Execute+0x23				github.com/spf13/[email protected]/command.go:1041
#	0x20ce008	github.com/evcc-io/evcc/cmd.Execute+0x18				github.com/evcc-io/evcc/cmd/root.go:118
#	0x20e2a93	main.main+0x43								github.com/evcc-io/evcc/main.go:53
#	0x4de57		runtime.main+0x287							runtime/proc.go:272

I removed lock in getMeasuredPhases just to get evcc to start, so far it seems ok. I'm writing values into most writeable values. So far seems ok.

If RLock/RUnlock can be mocked/intercepted in tests then would be easy to count and ensure via tests never called in a way to cause this issue in future.

[andig]

@jeffborg great idea. Fixed bug and added test support. Should catch this type of error immediately without waiting for test timeout.