关于福大大架构师每日一题:20210220手写代码读写锁

福哥答案2021-02-20：

四大办法：读加锁，读解锁，写加锁，写解锁。读加锁里有写加锁，读解锁里有写解锁。代码有写线程饥饿景象，但实现简略。

代码用golang编写，代码如下：

package mainimport (    "fmt"    "sync"    "time")func main() {    fdd := FddRWMutex{}    go func() {        i := 0        for k := 0; k < 5; k++ {            go func() {                j := i                i++                fdd.RLock()                fmt.Println("读操作", j)                time.Sleep(5 * time.Second)                fdd.RUnlock()            }()            time.Sleep(3 * time.Second)        }    }()    time.Sleep(1000)    fdd.Lock()    fmt.Println("写操作------------------------------------------")    fdd.Unlock()    fmt.Println("有写线程饥饿景象")}type FddRWMutex struct {    w           sync.Mutex    r           sync.Mutex    readerCount int}func (rw *FddRWMutex) RLock() {    rw.r.Lock()    rw.readerCount++    if rw.readerCount == 1 {        rw.w.Lock()    }    rw.r.Unlock()}func (rw *FddRWMutex) RUnlock() {    rw.r.Lock()    rw.readerCount--    if rw.readerCount == 0 {        rw.w.Unlock()    }    rw.r.Unlock()}func (rw *FddRWMutex) Lock() {    rw.w.Lock()}func (rw *FddRWMutex) Unlock() {    rw.w.Unlock()}

执行后果如下：

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