retry: 增加闭包 Retry 方法，避免用户重复写类似的垃圾代码

internal/errs/error.go

@@ -36,3 +36,7 @@ func NewErrInvalidIntervalValue(interval time.Duration) error {
 func NewErrInvalidMaxIntervalValue(maxInterval, initialInterval time.Duration) error {
 	return fmt.Errorf("ekit: 最大重试间隔的时间 [%d] 应大于等于初始重试的间隔时间 [%d] ", maxInterval, initialInterval)
 }
+
+func NewErrRetryExhausted(lastErr error) error {
+	return fmt.Errorf("ekit: 超过最大重试次数，业务返回的最后一个 error %w", lastErr)
+}

retry/retry.go

@@ -0,0 +1,60 @@
+// Copyright 2021 ecodeclub
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package retry
+
+import (
+	"context"
+	"time"
+
+	"github.com/ecodeclub/ekit/internal/errs"
+)
+
+// Retry 会在以下条件满足的情况下返回：
+// 1. 重试达到了最大次数，而后返回重试耗尽的错误
+// 2. ctx 被取消或者超时
+// 3. bizFunc 没有返回 error
+// 而只要 bizFunc 返回 error，就会尝试重试
+func Retry(ctx context.Context,
+	s Strategy,
+	bizFunc func() error) error {
+	var ticker *time.Ticker
+	defer func() {
+		if ticker != nil {
+			ticker.Stop()
+		}
+	}()
+	for {
+		err := bizFunc()
+		// 直接退出
+		if err == nil {
+			return nil
+		}
+		duration, ok := s.Next()
+		if !ok {
+			return errs.NewErrRetryExhausted(err)
+		}
+		if ticker == nil {
+			ticker = time.NewTicker(duration)
+		} else {
+			ticker.Reset(duration)
+		}
+		select {
+		case <-ctx.Done():
+			// 超时或者被取消了，直接返回
+			return ctx.Err()
+		case <-ticker.C:
+		}
+	}
+}

retry/retry_test.go

@@ -0,0 +1,84 @@
+// Copyright 2021 ecodeclub
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package retry
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRetry(t *testing.T) {
+	bizErr := errors.New("biz error")
+	testCases := []struct {
+		name      string
+		biz       func() error
+		strategy  Strategy
+		wantError error
+	}{
+		{
+			name: "第一次就成功",
+			biz: func() error {
+				t.Log("模拟业务")
+				return nil
+			},
+			strategy: func() Strategy {
+				res, _ := NewFixedIntervalRetryStrategy(time.Second, 3)
+				return res
+			}(),
+		},
+		{
+			name: "重试最终失败",
+			biz: func() error {
+				return bizErr
+			},
+			strategy: func() Strategy {
+				res, _ := NewFixedIntervalRetryStrategy(time.Second, 3)
+				return res
+			}(),
+			wantError: bizErr,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
+			defer cancel()
+			err := Retry(ctx, tc.strategy, tc.biz)
+			assert.ErrorIs(t, err, tc.wantError)
+		})
+	}
+}
+
+func ExampleRetry() {
+	// 这是你的业务
+	bizFunc := func() error {
+		fmt.Print("hello, world")
+		return nil
+	}
+	strategy, _ := NewFixedIntervalRetryStrategy(time.Millisecond*100, 3)
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
+	defer cancel()
+	err := Retry(ctx, strategy, bizFunc)
+	if err != nil {
+		fmt.Println("error:", err)
+	}
+	// Output:
+	// hello, world
+}