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Practice code for alerting with varying intervals for different severity levels
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| package main | |
| import ( | |
| "crypto/rand" | |
| "fmt" | |
| "math/big" | |
| "strings" | |
| "time" | |
| ) | |
| type level int | |
| const ( | |
| NULL level = iota | |
| SAFE // ALERT ONCE | |
| WARN | |
| CRITICAL | |
| CATASTROPHE | |
| ) | |
| var ( | |
| updateInterval = time.Duration(time.Second * 1) | |
| // Alert interval in seconds | |
| intervals = map[level]time.Duration{ | |
| SAFE: time.Second * time.Duration(20), | |
| WARN: time.Second * time.Duration(10), | |
| CRITICAL: time.Second * time.Duration(5), | |
| CATASTROPHE: time.Second * time.Duration(2), | |
| } | |
| treshold = big.NewInt(25) | |
| tresholdx2 = new(big.Int).Mul(treshold, big.NewInt(2)) | |
| tresholdx4 = new(big.Int).Mul(treshold, big.NewInt(4)) | |
| ) | |
| type alert struct { | |
| level level | |
| balance *big.Int | |
| } | |
| func main() { | |
| c := make(chan alert) | |
| go notifyAlert(c) // notifyAlert randomizes alerts | |
| // go notifyAlertMock(c) // notifyAlert mocks alerts | |
| // go notifySafe(c) // notifySafe only pushes SAFE alert into c | |
| alertFunc(c) | |
| } | |
| // event generator | |
| func notifyAlert(c chan<- alert) { | |
| for { | |
| balance, err := rand.Int(rand.Reader, big.NewInt(300)) | |
| if err != nil { | |
| panic(err.Error()) | |
| } | |
| var mostRecent alert | |
| if cmp := balance.Cmp(tresholdx4); cmp == 1 { | |
| mostRecent.level = SAFE | |
| } else if cmp := balance.Cmp(tresholdx2); cmp == 1 { | |
| mostRecent.level = WARN | |
| } else if cmp := balance.Cmp(treshold); cmp == 1 { | |
| mostRecent.level = CRITICAL | |
| } else { | |
| mostRecent.level = CATASTROPHE | |
| } | |
| c <- mostRecent | |
| time.Sleep(updateInterval) | |
| } | |
| } | |
| // event consumer | |
| func alertFunc(c <-chan alert) { | |
| var prevLevel level = NULL | |
| var prevTime time.Time | |
| for a := range c { | |
| interval := intervals[a.level] | |
| thisTime := time.Now() | |
| if a.level != prevLevel { | |
| printAlert(a) | |
| // Alert right away if level changes | |
| prevTime = thisTime | |
| } else { | |
| // If level stays the same, only alert if time has elasped past the interval | |
| if elapsed := time.Since(prevTime); elapsed >= interval && a.level != SAFE { | |
| printAlert(a) | |
| prevTime = thisTime | |
| } | |
| printBail(a) | |
| } | |
| prevLevel = a.level | |
| } | |
| } | |
| func notifySafe(c chan<- alert) { | |
| for i := 0; i < 30; i++ { | |
| c <- alert{level: SAFE} | |
| time.Sleep(updateInterval) | |
| } | |
| close(c) | |
| } | |
| func notifyAlertMock(c chan<- alert) { | |
| l1 := alert{level: SAFE} | |
| l2 := alert{level: WARN} | |
| l3 := alert{level: CRITICAL} | |
| l4 := alert{level: CATASTROPHE} | |
| mock := []alert{l1, l1, l1, l1, l1, l1, l2, l2, l3, l2, l3, l4, l4, l4} | |
| for _, a := range mock { | |
| c <- a | |
| time.Sleep(updateInterval) | |
| } | |
| close(c) | |
| } | |
| func pront(s string, alert alert) { | |
| fmt.Printf("%s!\t%d %v\t%s\n", s, alert.level, alert.balance, strings.Split(time.Now().String(), " ")[1]) | |
| } | |
| func printAlert(alert alert) { | |
| pront("ALERT", alert) | |
| } | |
| func printBail(alert alert) { | |
| pront("BAIL", alert) | |
| } |
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