36 lines
840 B
Go
36 lines
840 B
Go
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package goroutine
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import (
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"database/sql"
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"fmt"
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"math/rand"
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"time"
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)
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func Dataread(db *sql.DB, donetitle chan struct{}) {
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// 启动一个长事务（整个循环在一个事务内，而非每次查询一个事务）
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tx, err := db.Begin()
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if err != nil {
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panic(err)
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}
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defer tx.Rollback() // 确保退出时回滚（仅为测试）
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// 随机种子（保持不变）
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rand.Seed(time.Now().UnixNano())
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// 只执行两次查询，方便观察结果
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for i := 0; i < 2; i++ {
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select {
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case <-time.After(2 * time.Second): // 第一次查询后等待2秒，给Datawrite插入时间
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var count int
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err = tx.QueryRow("SELECT count(*) FROM article WHERE age > 50 FOR UPDATE ").Scan(&count)
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if err != nil {
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panic(err)
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}
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fmt.Printf("第%d次查询 count: %d\n", i+1, count)
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case <-donetitle:
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return
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}
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}
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}
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