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I'm trying to code a notification struct in Go, that will hold a series of keys and their respective values, and will fire a notification if a value falls below a threshold.

the notification should fire only once, when the first sample falls below the threshold, and further samples below that should not fire again, UNTIL the value rises above the threshold.

for example, say my threshold is 10, and I send samples of 15, 14, 11, 10, ... 9. once 9 is sent, a notification should be fired. further samples of 8, 7, 4, should not cause any effect. following samples like 5, 6, 7, 9, 10, 11, 14, 30, should do nothing to. once a sample falls again below 10: 30, 20, 15, 10, 7... another notification must be sent.

I'm having a problem when multiple goroutines are manipulating my struct.

I tried syncrhonizing with a sync.Mutex, and ALSO use a sync.Map, but no luck. I'm feeling there is a reference copy or caching somewhere, but I'm too new in Go to find the problem.

for this, I created a struct like this: