refactor: split flat internal/ module into modules-per-cmd (#64)

internal/cmd/write/throttler.go

@@ -0,0 +1,89 @@
+package write
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"regexp"
+	"strconv"
+	"strings"
+
+	"github.com/fujiwara/shapeio"
+	"github.com/influxdata/influx-cli/v2/pkg/csv2lp"
+)
+
+type Throttler struct {
+	bytesPerSecond float64
+}
+
+func NewThrottler(bytesPerSec BytesPerSec) *Throttler {
+	return &Throttler{bytesPerSecond: float64(bytesPerSec)}
+}
+
+func (t *Throttler) Throttle(ctx context.Context, in io.Reader) io.Reader {
+	if t.bytesPerSecond == 0.0 {
+		return in
+	}
+
+	// LineReader ensures that original reader is consumed in the smallest possible
+	// units (at most one protocol line) to avoid bigger pauses in throttling
+	throttledReader := shapeio.NewReaderWithContext(csv2lp.NewLineReader(in), ctx)
+	throttledReader.SetRateLimit(t.bytesPerSecond)
+
+	return throttledReader
+}
+
+var rateLimitRegexp = regexp.MustCompile(`^(\d*\.?\d*)(B|kB|MB)/?(\d*)?(s|sec|m|min)$`)
+var bytesUnitMultiplier = map[string]float64{"B": 1, "kB": 1024, "MB": 1_048_576}
+var timeUnitMultiplier = map[string]float64{"s": 1, "sec": 1, "m": 60, "min": 60}
+
+type BytesPerSec float64
+
+func (b *BytesPerSec) Set(v string) (err error) {
+	bps, err := ToBytesPerSecond(v)
+	if err != nil {
+		return err
+	}
+	*b = BytesPerSec(bps)
+	return nil
+}
+
+func (b BytesPerSec) String() string {
+	return strconv.FormatFloat(float64(b), 'E', -1, 64)
+}
+
+// ToBytesPerSecond converts rate from string to number. The supplied string
+// value format must be COUNT(B|kB|MB)/TIME(s|sec|m|min) with / and TIME being optional.
+// All spaces are ignored, they can help with formatting. Examples: "5 MB / 5 min", 17kbs. 5.1MB5m.
+func ToBytesPerSecond(rateLimit string) (BytesPerSec, error) {
+	// ignore all spaces
+	strVal := strings.ReplaceAll(rateLimit, " ", "")
+	if len(strVal) == 0 {
+		return 0, nil
+	}
+
+	matches := rateLimitRegexp.FindStringSubmatch(strVal)
+	if matches == nil {
+		return 0, fmt.Errorf("invalid rate limit %q: it does not match format COUNT(B|kB|MB)/TIME(s|sec|m|min) with / and TIME being optional, rexpexp: %v", strVal, rateLimitRegexp)
+	}
+	bytes, err := strconv.ParseFloat(matches[1], 64)
+	if err != nil {
+		return 0, fmt.Errorf("invalid rate limit %q: '%v' is not count of bytes: %v", strVal, matches[1], err)
+	}
+	bytes = bytes * bytesUnitMultiplier[matches[2]]
+	var time float64
+	if len(matches[3]) == 0 {
+		time = 1 // number is not specified, for example 5kbs or 1Mb/s
+	} else {
+		int64Val, err := strconv.ParseUint(matches[3], 10, 32)
+		if err != nil {
+			return 0, fmt.Errorf("invalid rate limit %q: time is out of range: %v", strVal, err)
+		}
+		if int64Val <= 0 {
+			return 0, fmt.Errorf("invalid rate limit %q: positive time expected but %v supplied", strVal, matches[3])
+		}
+		time = float64(int64Val)
+	}
+	time = time * timeUnitMultiplier[matches[4]]
+	return BytesPerSec(bytes / time), nil
+}