From 3c356f488ae469bf492234bc1738289daac957f2 Mon Sep 17 00:00:00 2001
From: Your Name <you@example.com>
Date: Tue, 9 Jul 2024 00:38:00 +0800
Subject: [PATCH] rwmutex finished

---
 .idea/vcs.xml   |  1 -
 sync/mutex.go   |  1 +
 sync/rwmutex.go | 53 +++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 54 insertions(+), 1 deletion(-)
 create mode 100644 sync/rwmutex.go

diff --git a/.idea/vcs.xml b/.idea/vcs.xml
index a9aa77a..94a25f7 100644
--- a/.idea/vcs.xml
+++ b/.idea/vcs.xml
@@ -2,6 +2,5 @@
 <project version="4">
   <component name="VcsDirectoryMappings">
     <mapping directory="$PROJECT_DIR$" vcs="Git" />
-    <mapping directory="$PROJECT_DIR$/logging" vcs="Git" />
   </component>
 </project>
\ No newline at end of file
diff --git a/sync/mutex.go b/sync/mutex.go
index a5c2295..ef262e6 100644
--- a/sync/mutex.go
+++ b/sync/mutex.go
@@ -6,6 +6,7 @@ import (
 )
 
 // 互斥锁
+// 保证同一时间只有一个goroutine进入临界区，其他的goroutine在等待锁的释放，多个goroutine等待同一个锁的时候，唤醒的策略是随机的
 var x = 0
 
 var wg sync.WaitGroup
diff --git a/sync/rwmutex.go b/sync/rwmutex.go
new file mode 100644
index 0000000..234a941
--- /dev/null
+++ b/sync/rwmutex.go
@@ -0,0 +1,53 @@
+package main
+
+import (
+	"fmt"
+	"sync"
+	"time"
+)
+
+// 读写互斥锁，读的时候远远大于写的场景
+// rwlock
+// 当读的时候加读锁，写的时候加写锁。和互斥锁相比性能差很多
+// 当持有写锁，所有的goroutine都需要等待写锁解锁不能读也不能写，当持有读锁，所有goroutine仍然能够读访问共享资源，但不允许写
+var (
+	v        = 0
+	locker   sync.Mutex
+	w        sync.WaitGroup
+	rwlocker sync.RWMutex
+)
+
+func read() {
+	defer w.Done()
+	locker.Lock()
+	//rwlocker.RLock()
+	fmt.Println(v)
+	time.Sleep(time.Millisecond * 1)
+	locker.Unlock()
+	//rwlocker.RUnlock()
+}
+
+func write() {
+	defer w.Done()
+	locker.Lock()
+	//rwlocker.Lock()
+	v += 1
+	time.Sleep(time.Millisecond * 5)
+	locker.Unlock()
+	//rwlocker.Unlock()
+}
+
+func main() {
+	start := time.Now()
+	for i := 0; i < 10; i++ {
+		w.Add(1)
+		go write()
+	}
+	time.Sleep(time.Second)
+	for i := 0; i < 1000; i++ {
+		w.Add(1)
+		go read()
+	}
+	w.Wait()
+	fmt.Println(time.Now().Sub(start))
+}