go_rate_01.go

package main

import (
        "context"
        "log"
        "os"
        "time"

        "golang.org/x/time/rate"
)

func main() {
        log.SetOutput(os.Stdout)
        log.SetFlags(log.Lmicroseconds)

        // 1秒間に実行する回数
        ntimes := 5

        n := rate.Every(time.Second / time.Duration(ntimes))
        // バッファーは1
        limiter := rate.NewLimiter(n, 1)

        ctx := context.Background()

        log.Println("--- Start ---")
        for i := 0; i < 20 ; i ++ {
                if err := limiter.Wait(ctx); err != nil {
                        log.Fatalln(err)
                }
                log.Printf("Do work %02d", i+1)
        }
}

go_rate_01_result

17:29:32.839459 --- Start ---
17:29:32.839559 Do work 01
17:29:33.039795 Do work 02
17:29:33.239790 Do work 03
17:29:33.439756 Do work 04
17:29:33.639779 Do work 05
17:29:33.839807 Do work 06
17:29:34.039784 Do work 07
17:29:34.239764 Do work 08
17:29:34.439718 Do work 09
17:29:34.639772 Do work 10
17:29:34.839776 Do work 11
17:29:35.039786 Do work 12
17:29:35.239792 Do work 13
17:29:35.439847 Do work 14
17:29:35.639805 Do work 15
17:29:35.839770 Do work 16
17:29:36.039750 Do work 17
17:29:36.239730 Do work 18
17:29:36.439778 Do work 19
17:29:36.639786 Do work 20

go_rate_02.go

package main

import (
        "context"
        "log"
        "os"
        "time"

        "golang.org/x/time/rate"
)

func main() {
        log.SetOutput(os.Stdout)
        log.SetFlags(log.Lmicroseconds)

        // 1秒間に実行する回数
        ntimes := 5

        n := rate.Every(time.Second / time.Duration(ntimes))
        // バッファーを10にする
        limiter := rate.NewLimiter(n, 10)

        ctx := context.Background()

        log.Println("--- Start ---")
        for i := 0; i < 20 ; i ++ {
                if err := limiter.Wait(ctx); err != nil {
                        log.Fatalln(err)
                }
                log.Printf("Do work %02d", i+1)
        }
}

go_rate_02_result

17:31:15.981971 --- Start ---
17:31:15.982024 Do work 01
17:31:15.982027 Do work 02
17:31:15.982029 Do work 03
17:31:15.982031 Do work 04
17:31:15.982033 Do work 05
17:31:15.982035 Do work 06
17:31:15.982036 Do work 07
17:31:15.982038 Do work 08
17:31:15.982040 Do work 09
17:31:15.982042 Do work 10
17:31:16.182243 Do work 11
17:31:16.382219 Do work 12
17:31:16.582234 Do work 13
17:31:16.782242 Do work 14
17:31:16.982248 Do work 15
17:31:17.182247 Do work 16
17:31:17.382214 Do work 17
17:31:17.582262 Do work 18
17:31:17.782244 Do work 19
17:31:17.982247 Do work 20

go_rate_03

package main

import (
        "context"
        "log"
        "os"

        "golang.org/x/time/rate"
)

func main() {
        log.SetOutput(os.Stdout)
        log.SetFlags(log.Lmicroseconds)

        // Limit を rate.Limit(n) にすると1秒間にn回
        limiter := rate.NewLimiter(rate.Limit(1), 1)

        ctx := context.Background()

        log.Println("--- Start ---")
        for i := 0; i < 20 ; i ++ {
                if err := limiter.Wait(ctx); err != nil {
                        log.Fatalln(err)
                }
                log.Printf("Do work %02d", i+1)
        }
}

go_rate_03‗result

17:43:46.807694 --- Start ---
17:43:46.807780 Do work 01
17:43:47.808017 Do work 02
17:43:48.808015 Do work 03
17:43:49.807991 Do work 04
17:43:50.807969 Do work 05
17:43:51.807975 Do work 06
17:43:52.807996 Do work 07
17:43:53.807986 Do work 08
17:43:54.808001 Do work 09
17:43:55.807990 Do work 10
17:43:56.808000 Do work 11
17:43:57.808031 Do work 12
17:43:58.808018 Do work 13
17:43:59.808008 Do work 14
17:44:00.808003 Do work 15
17:44:01.807958 Do work 16
17:44:02.807953 Do work 17
17:44:03.807984 Do work 18
17:44:04.807985 Do work 19
17:44:05.807995 Do work 20

go_rate_04.go

package main

import (
        "context"
        "log"
        "os"
        "time"

        "golang.org/x/time/rate"
)

func main() {
        log.SetOutput(os.Stdout)
        log.SetFlags(log.Lmicroseconds)

        // 1秒間に実行する回数
        ntimes := 5

        n := rate.Every(time.Second / time.Duration(ntimes))
        limiter := rate.NewLimiter(n, 10)

        ctx := context.Background()

        log.Println("--- Start ---")
        for i := 0; i < 20 ; i ++ {
                // 1秒間に5コトークンが溜まるが、5トークン溜まったごとに1回実行
                // →すなわち1秒に一回実行になる
                if err := limiter.WaitN(ctx, 5); err != nil {
                        log.Fatalln(err)
                }
                log.Printf("Do work %02d", i+1)
        }
}

go_rate_04‗result

17:55:20.033969 --- Start ---
17:55:20.034020 Do work 01
17:55:20.034023 Do work 02
17:55:21.034249 Do work 03
17:55:22.034229 Do work 04
17:55:23.034255 Do work 05
17:55:24.034258 Do work 06
17:55:25.034214 Do work 07
17:55:26.034269 Do work 08
17:55:27.034190 Do work 09
17:55:28.034225 Do work 10
17:55:29.034215 Do work 11
17:55:30.034232 Do work 12
17:55:31.034231 Do work 13
17:55:32.034242 Do work 14
17:55:33.034237 Do work 15
17:55:34.034243 Do work 16
17:55:35.034243 Do work 17
17:55:36.034278 Do work 18
17:55:37.034257 Do work 19
17:55:38.034246 Do work 20

go_rate_05.go

package main

import (
        "context"
        "log"
        "os"
        "time"

        "golang.org/x/time/rate"
)

func main() {
        log.SetOutput(os.Stdout)
        log.SetFlags(log.Lmicroseconds)

        // 1秒間に実行する回数
        ntimes := 5

        n := rate.Every(time.Second / time.Duration(ntimes))
        limiter := rate.NewLimiter(n, 1)

        ctx := context.Background()

        log.Println("--- Start ---")
        for i := 0; i < 20 ; i ++ {
                if err := limiter.Wait(ctx); err != nil {
                        log.Fatalln(err)
                }

                // 10回目から1秒間に２回実行に変更する
                if (i + 1) == 10 {
                        limiter.SetLimit(rate.Every(time.Second / time.Duration(2)))
                }

                log.Printf("Do work %02d", i+1)
        }
}

go_rate_05_result

18:04:21.237587 --- Start ---
18:04:21.237637 Do work 01
18:04:21.437903 Do work 02
18:04:21.637820 Do work 03
18:04:21.837844 Do work 04
18:04:22.037846 Do work 05
18:04:22.237880 Do work 06
18:04:22.437871 Do work 07
18:04:22.637830 Do work 08
18:04:22.837845 Do work 09
18:04:23.037851 Do work 10
18:04:23.537504 Do work 11
18:04:24.037544 Do work 12
18:04:24.537508 Do work 13
18:04:25.037518 Do work 14
18:04:25.537554 Do work 15
18:04:26.037556 Do work 16
18:04:26.537548 Do work 17
18:04:27.037534 Do work 18
18:04:27.537534 Do work 19
18:04:28.037544 Do work 20

go_rate_06.go

package main

import (
        "context"
        "log"
        "os"
        "time"

        "golang.org/x/time/rate"
)

func main() {
        log.SetOutput(os.Stdout)
        log.SetFlags(log.Lmicroseconds)

        // 1秒間に実行する回数
        ntimes := 5

        n := rate.Every(time.Second / time.Duration(ntimes))
        limiter := rate.NewLimiter(n, 1)

        ctx := context.Background()

        var rsv *rate.Reservation

        log.Println("--- Start ---")
        for i := 0; i < 20 ; i ++ {
                if err := limiter.Wait(ctx); err != nil {
                        log.Fatalln(err)
                }

                log.Printf("Do work %02d", i+1)

                if (i + 1) == 10 {
                        rsv = limiter.Reserve()
                }

                if rsv != nil {
                        log.Printf(rsv.Delay().String())
                }
        }
}

go_rate_06_result

18:52:56.763809 --- Start ---
18:52:56.763858 Do work 01
18:52:56.964062 Do work 02
18:52:57.164063 Do work 03
18:52:57.364088 Do work 04
18:52:57.564032 Do work 05
18:52:57.764060 Do work 06
18:52:57.964093 Do work 07
18:52:58.164063 Do work 08
18:52:58.364081 Do work 09
18:52:58.564029 Do work 10
18:52:58.564063 199.79173ms
18:52:58.964117 Do work 11
18:52:58.964133 0s
18:52:59.164076 Do work 12
18:52:59.164093 0s
18:52:59.364049 Do work 13
18:52:59.364077 0s
18:52:59.564050 Do work 14
18:52:59.564068 0s
18:52:59.764130 Do work 15
18:52:59.764148 0s
18:52:59.964103 Do work 16
18:52:59.964120 0s
18:53:00.164049 Do work 17
18:53:00.164077 0s
18:53:00.364126 Do work 18
18:53:00.364142 0s
18:53:00.564072 Do work 19
18:53:00.564089 0s
18:53:00.764112 Do work 20
18:53:00.764131 0s

go_rate_07.go

package main

import (
        "context"
        "log"
        "os"
        "time"

        "golang.org/x/time/rate"
)

func main() {
        log.SetOutput(os.Stdout)
        log.SetFlags(log.Lmicroseconds)

        // 1秒間に実行する回数
        ntimes := 5

        n := rate.Every(time.Second / time.Duration(ntimes))
        limiter := rate.NewLimiter(n, 1)

        ctx := context.Background()

        log.Println("--- Start ---")
        for i := 0; i < 20 ; i ++ {
                if err := limiter.Wait(ctx); err != nil {
                        log.Fatalln(err)
                }

                log.Printf("Do work %02d", i+1)

                if 10 <= (i + 1) {
                        time.Sleep(200 * time.Millisecond)
                }

                if limiter.Allow() {
                        log.Println("Allow() true")
                } else {
                        log.Println("Allow() false")
                }
        }
}

go_rate_07_result

19:01:50.117299 --- Start ---
19:01:50.117350 Do work 01
19:01:50.117353 Allow() false
19:01:50.317610 Do work 02
19:01:50.317629 Allow() false
19:01:50.517559 Do work 03
19:01:50.517576 Allow() false
19:01:50.717573 Do work 04
19:01:50.717592 Allow() false
19:01:50.917506 Do work 05
19:01:50.917524 Allow() false
19:01:51.117570 Do work 06
19:01:51.117588 Allow() false
19:01:51.317564 Do work 07
19:01:51.317586 Allow() false
19:01:51.517576 Do work 08
19:01:51.517595 Allow() false
19:01:51.717560 Do work 09
19:01:51.717578 Allow() false
19:01:51.917548 Do work 10
19:01:52.117767 Allow() true
19:01:52.317993 Do work 11
19:01:52.518254 Allow() true
19:01:52.718454 Do work 12
19:01:52.918698 Allow() true
19:01:53.118913 Do work 13
19:01:53.319110 Allow() true
19:01:53.519305 Do work 14
19:01:53.719535 Allow() true
19:01:53.919728 Do work 15
19:01:54.119973 Allow() true
19:01:54.320157 Do work 16
19:01:54.520363 Allow() true
19:01:54.720583 Do work 17
19:01:54.920774 Allow() true
19:01:55.120989 Do work 18
19:01:55.321212 Allow() true
19:01:55.521434 Do work 19
19:01:55.721667 Allow() true
19:01:55.921878 Do work 20
19:01:56.122113 Allow() true