更新ID生成器

idGenerator/buffer.go

@@ -0,0 +1,72 @@
+package idgenerator
+
+import (
+	"sync"
+	"time"
+
+	"github.com/charlienet/go-mixed/idGenerator/store"
+)
+
+type obtainFunc func() (*store.Segment, error)
+
+type doubleBuffer struct {
+	current  *store.Segment // 当前
+	backup   *store.Segment // 备用
+	obtain   obtainFunc     // 数据段获取函数
+	inFill   bool           // 备用缓冲填充中
+	isReadly bool           // 备用缓冲区填充完成
+	mu       sync.Mutex
+}
+
+func newDoubleBuffer(obtainFunc obtainFunc) *doubleBuffer {
+	b := &doubleBuffer{obtain: obtainFunc}
+	b.current, _ = b.obtain()
+
+	return b
+}
+
+func (b *doubleBuffer) allot() (int64, bool) {
+	if !b.inFill && b.current.IsEnding() {
+		go b.full() // 填充备用缓冲
+	}
+
+	// 缓冲区耗尽时切换
+	if b.current.IsEmpty() {
+		// 检查备用缓冲是否已经填充完成，已完成时切换，否则等待
+		for !b.isReadly {
+			time.Sleep(time.Microsecond * 100)
+		}
+
+		b.switchBuf()
+	}
+
+	return b.current.Allot(), b.current.Reback()
+}
+
+func (b *doubleBuffer) full() {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	if !b.inFill {
+		var err error
+		b.inFill = true
+
+		b.backup, err = b.obtain()
+		if err != nil {
+			println("填充失败:", err.Error())
+			panic(err)
+		}
+		b.isReadly = true
+	}
+}
+
+func (b *doubleBuffer) switchBuf() {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	if b.isReadly {
+		b.current, b.backup = b.backup, b.current
+		b.inFill = false
+		b.isReadly = false
+	}
+}