first commit

cli/main.go

@@ -0,0 +1,71 @@
+package main
+
+import (
+	"backoff/fibonacci"
+	"context"
+	"flag"
+	"fmt"
+	"math"
+	"os"
+	"strconv"
+	"time"
+)
+
+func FormatOutput(pause time.Duration, ns bool) string {
+	switch ns {
+	case true:
+		return strconv.FormatInt(pause.Nanoseconds(), 10)
+	default:
+		return pause.String()
+	}
+}
+
+func main() {
+	start := time.Now()
+	var (
+		doPanic           bool
+		doSleep           bool
+		multiplier        time.Duration
+		jitter            time.Duration
+		iteration         int64
+		nanosecondsOutput bool
+	)
+	flag.BoolVar(&doPanic, "panic", false, "panic instead of overflowing values (default returns the max value instead of overflowing).")
+	flag.BoolVar(&doSleep, "sleep", false, "sleep for the resulting duration after calculating it. prints the run duration of the program instead of the calculated pause duration.")
+	flag.DurationVar(&multiplier, "multiplier", time.Millisecond, "pause multiplier.")
+	flag.DurationVar(&jitter, "jitter", 0, "jitter boundary. pause duration is randomly selected in the range of resultDuration+-jitter.")
+	flag.Int64Var(&iteration, "iteration", 1, "iteration to use for calculating pause time.")
+	flag.BoolVar(&nanosecondsOutput, "ns", false, "outputs int64 nanoseconds instead of string.")
+	flag.Parse()
+
+	if jitter < 0 {
+		jitter = time.Duration(int(math.Abs(float64(jitter.Nanoseconds()))))
+	}
+	if iteration >= int64(len(fibonacci.TheFibonacciSequence)) {
+		switch doPanic {
+		case true:
+			panic(fmt.Sprintf("error: input %d would overflow int64\n", iteration))
+		default:
+			maxIteration := int64(len(fibonacci.TheFibonacciSequence) - 1)
+			fmt.Fprintf(os.Stderr, "iteration %d would overflow int64 - using %d\n", iteration, maxIteration)
+			iteration = maxIteration
+		}
+	}
+
+	backoff := &fibonacci.FibonacciBackoff{
+		Iteration:       iteration,
+		PauseMultiplier: multiplier,
+		Jitter:          jitter,
+	}
+
+	var response string
+	switch doSleep {
+	case true:
+		<-backoff.After(context.Background())
+		response = FormatOutput(time.Since(start), nanosecondsOutput)
+	default:
+		response = FormatOutput(backoff.Next(), nanosecondsOutput)
+	}
+	fmt.Println(response)
+
+}