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app/service/main/upcredit/mathutil/BUILD

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+package(default_visibility = ["//visibility:public"])
+
+load(
+    "@io_bazel_rules_go//go:def.bzl",
+    "go_library",
+    "go_test",
+)
+
+go_library(
+    name = "go_default_library",
+    srcs = [
+        "base_utils.go",
+        "limiter.go",
+    ],
+    importmap = "go-common/app/service/main/upcredit/mathutil",
+    importpath = "go-common/app/service/main/upcredit/mathutil",
+    tags = ["automanaged"],
+    visibility = ["//visibility:public"],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+    visibility = ["//visibility:public"],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["limiter_test.go"],
+    embed = [":go_default_library"],
+    rundir = ".",
+    tags = ["automanaged"],
+    deps = ["//vendor/github.com/smartystreets/goconvey/convey:go_default_library"],
+)

app/service/main/upcredit/mathutil/base_utils.go

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+package mathutil
+
+//EPSILON very small
+var EPSILON float32 = 0.00000001
+
+//FloatEquals float equal
+func FloatEquals(a, b float32) bool {
+	if (a-b) < EPSILON && (b-a) < EPSILON {
+		return true
+	}
+	return false
+}
+
+//EPSILON64 very small
+var EPSILON64 = 0.00000001
+
+//Float64Equals  float equal
+func Float64Equals(a, b float64) bool {
+	if (a-b) < EPSILON64 && (b-a) < EPSILON64 {
+		return true
+	}
+	return false
+}
+
+//Min min
+func Min(a, b int) int {
+	if a < b {
+		return a
+	}
+	if b < a {
+		return b
+	}
+	return a
+}
+
+//Max max
+func Max(a, b int) int {
+	if a > b {
+		return a
+	}
+	if b > a {
+		return b
+	}
+	return a
+}

app/service/main/upcredit/mathutil/limiter.go

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+package mathutil
+
+import "time"
+
+//Limiter speed limiter
+type Limiter struct {
+	Rate  float64 // 每秒多少个
+	token chan time.Time
+	timer *time.Ticker
+}
+
+//Token get token
+func (l *Limiter) Token() (c <-chan time.Time) {
+	return l.token
+}
+
+func (l *Limiter) putToken() {
+	for t := range l.timer.C {
+		l.token <- t
+	}
+}
+
+//NewLimiter create new limiter
+func NewLimiter(rate float64) *Limiter {
+	var l = &Limiter{
+		Rate:  rate,
+		token: make(chan time.Time, 1),
+		timer: time.NewTicker(time.Duration(1.0 / rate * float64(time.Second))),
+	}
+	go l.putToken()
+	return l
+}

app/service/main/upcredit/mathutil/limiter_test.go

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+package mathutil
+
+import (
+	. "github.com/smartystreets/goconvey/convey"
+	"math"
+	"testing"
+	"time"
+)
+
+func Test_limiter(t *testing.T) {
+	Convey("limit interval", t, func() {
+		var rate = 100.0
+		var limit = NewLimiter(rate)
+		var interval = 1.0 / rate
+		var last time.Time
+
+		for i := 0; i < 100; i++ {
+			var t = <-limit.Token()
+			if !last.IsZero() {
+				var diff = t.Sub(last)
+				So(math.Abs(diff.Seconds()-interval), ShouldBeLessThanOrEqualTo, 0.002)
+			}
+			last = t
+		}
+	})
+
+	Convey("limit count", t, func() {
+		var rate = 100.0
+		var seconds = 10.0
+		var limit = NewLimiter(rate)
+		var expect = rate * seconds
+		var timer = time.NewTimer(time.Duration(float64(time.Second) * seconds))
+		var total = 0
+		var run = true
+		for run {
+			select {
+			case <-timer.C:
+				run = false
+			default:
+				<-limit.Token()
+				total++
+			}
+		}
+		So(math.Abs(float64(total)-expect), ShouldBeLessThanOrEqualTo, rate*0.01)
+	})
+}