From ae078ebcf71697658e201dba34dd5d6bd7598695 Mon Sep 17 00:00:00 2001
From: barryz <barryzxb@gmail.com>
Date: Fri, 7 Sep 2018 22:17:26 +0800
Subject: [PATCH] Add Flip method to flip boolean value

---
 README.md    |  5 +++++
 bool.go      |  5 +++++
 bool_test.go | 40 +++++++++++++++++++++++++++++++++++++++-
 3 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 042d1ca..1542a83 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,7 @@ cond.IsSet()               // Returns true
 cond.UnSet()               // Set to false
 cond.SetTo(true)           // Set to whatever you want
 cond.SetToIf(false, true)  // Set to true if it is false, returns false(not set)
+cond.Flip()                // Flip the boolean value, true to false, or false to ture
 
 
 // embedding
@@ -45,5 +46,9 @@ BenchmarkAtomicBoolWrite-4 	200000000	         9.87 ns/op  # <--- This package
 # CAS
 BenchmarkMutexCAS-4        	 30000000	        44.9 ns/op
 BenchmarkAtomicBoolCAS-4   	100000000	        11.7 ns/op   # <--- This package
+
+# Flip
+BenchmarkMutexFlip-4            50000000           29.7 ns/op
+BenchmarkAtomicBoolFlip-4      200000000           8.65 ns/op   # <--- This package
 ```
 
diff --git a/bool.go b/bool.go
index fdda210..7c8d194 100644
--- a/bool.go
+++ b/bool.go
@@ -49,6 +49,11 @@ func (ab *AtomicBool) SetTo(yes bool) {
 	}
 }
 
+// Flip flips the boolean value whether the value is set or not
+func (ab *AtomicBool) Flip() {
+	atomic.StoreInt32((*int32)(ab), atomic.LoadInt32((*int32)(ab))^1)
+}
+
 // SetToIf sets the Boolean to new only if the Boolean matches the old
 // Returns whether the set was done
 func (ab *AtomicBool) SetToIf(old, new bool) (set bool) {
diff --git a/bool_test.go b/bool_test.go
index d63517f..6d83431 100644
--- a/bool_test.go
+++ b/bool_test.go
@@ -49,12 +49,18 @@ func TestBool(t *testing.T) {
 	if set := v.SetToIf(false, true); !set || !v.IsSet() {
 		t.Fatal("AtomicBool.SetTo(false, true) failed")
 	}
+
+	v.Flip() // expected false
+	if v.IsSet() {
+		t.Fatal("AtomicBool.Flip() failed")
+	}
+
 }
 
 func TestRace(t *testing.T) {
 	repeat := 10000
 	var wg sync.WaitGroup
-	wg.Add(repeat * 3)
+	wg.Add(repeat * 4)
 	v := New()
 
 	// Writer
@@ -80,6 +86,15 @@ func TestRace(t *testing.T) {
 			wg.Done()
 		}
 	}()
+
+	// Reader And Writer
+	go func() {
+		for i := 0; i < repeat; i++ {
+			v.Flip()
+			wg.Done()
+		}
+	}()
+
 	wg.Wait()
 }
 
@@ -89,6 +104,7 @@ func ExampleAtomicBool() {
 	cond.IsSet()     // returns true
 	cond.UnSet()     // set to false
 	cond.SetTo(true) // set to whatever you want
+	cond.Flip()      // flips the boolean value
 }
 
 // Benchmark Read
@@ -174,3 +190,25 @@ func BenchmarkAtomicBoolCAS(b *testing.B) {
 		v.SetToIf(false, true)
 	}
 }
+
+// Benchmark flip boolean value
+
+func BenchmarkMutexFlip(b *testing.B) {
+	var m sync.RWMutex
+	var v bool
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		m.Lock()
+		v = !v
+		m.Unlock()
+	}
+	b.StopTimer()
+}
+
+func BenchmarkAtomicBoolFlip(b *testing.B) {
+	v := New()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		v.Flip()
+	}
+}