├── README.md
├── locker.go
├── LICENSE
└── locker_test.go


/README.md:
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 1 | # spinlock
 2 | 
 3 | [![GoDoc](https://img.shields.io/badge/api-reference-blue.svg?style=flat-square)](https://godoc.org/github.com/tidwall/spinlock)
 4 | 
 5 | 
 6 | A [spinlock](https://en.wikipedia.org/wiki/Spinlock) implementation for Go.
 7 | 
 8 | It shares the same interface as [sync.Mutex](https://golang.org/pkg/sync/#Mutex), and is intended to be used to synchronize exceptionally short lived operations.
 9 | 
10 | ## Install
11 | 
12 | ```
13 | go get -u github.com/tidwall/spinlock
14 | ```
15 | 
16 | ## Contact
17 | 
18 | Josh Baker [@tidwall](http://twitter.com/tidwall)
19 | 
20 | ## License
21 | 
22 | spinlock source code is available under the MIT [License](/LICENSE).
23 | 


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/locker.go:
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 1 | package spinlock
 2 | 
 3 | import (
 4 | 	"runtime"
 5 | 	"sync"
 6 | 	"sync/atomic"
 7 | )
 8 | 
 9 | // Locker is a spinlock implementation.
10 | //
11 | // A Locker must not be copied after first use.
12 | type Locker struct {
13 | 	_    sync.Mutex // for copy protection compiler warning
14 | 	lock uintptr
15 | }
16 | 
17 | // Lock locks l.
18 | // If the lock is already in use, the calling goroutine
19 | // blocks until the locker is available.
20 | func (l *Locker) Lock() {
21 | loop:
22 | 	if !atomic.CompareAndSwapUintptr(&l.lock, 0, 1) {
23 | 		runtime.Gosched()
24 | 		goto loop
25 | 	}
26 | }
27 | 
28 | // Unlock unlocks l.
29 | func (l *Locker) Unlock() {
30 | 	atomic.StoreUintptr(&l.lock, 0)
31 | }
32 | 


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/LICENSE:
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 1 | The MIT License (MIT)
 2 | 
 3 | Copyright (c) 2018 Josh Baker
 4 | 
 5 | Permission is hereby granted, free of charge, to any person obtaining a copy of
 6 | this software and associated documentation files (the "Software"), to deal in
 7 | the Software without restriction, including without limitation the rights to
 8 | use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 9 | the Software, and to permit persons to whom the Software is furnished to do so,
10 | subject to the following conditions:
11 | 
12 | The above copyright notice and this permission notice shall be included in all
13 | copies or substantial portions of the Software.
14 | 
15 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 | IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
17 | FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
18 | COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
19 | IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
20 | CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.


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/locker_test.go:
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 1 | package spinlock
 2 | 
 3 | import (
 4 | 	"fmt"
 5 | 	"sync"
 6 | 	"testing"
 7 | 	"time"
 8 | )
 9 | 
10 | func testLock(threads, n int, l sync.Locker) time.Duration {
11 | 	var wg sync.WaitGroup
12 | 	wg.Add(threads)
13 | 
14 | 	var count1 int
15 | 	var count2 int
16 | 
17 | 	start := time.Now()
18 | 	for i := 0; i < threads; i++ {
19 | 		go func() {
20 | 			for i := 0; i < n; i++ {
21 | 				l.Lock()
22 | 				count1++
23 | 				count2 += 2
24 | 				l.Unlock()
25 | 			}
26 | 			wg.Done()
27 | 		}()
28 | 	}
29 | 	wg.Wait()
30 | 	dur := time.Since(start)
31 | 	if count1 != threads*n {
32 | 		panic("mismatch")
33 | 	}
34 | 	if count2 != threads*n*2 {
35 | 		panic("mismatch")
36 | 	}
37 | 	return dur
38 | }
39 | 
40 | func TestSpinLock(t *testing.T) {
41 | 	fmt.Printf("[1] spinlock %4.0fms\n", testLock(1, 1000000, &Locker{}).Seconds()*1000)
42 | 	fmt.Printf("[1] mutex    %4.0fms\n", testLock(1, 1000000, &sync.Mutex{}).Seconds()*1000)
43 | 	fmt.Printf("[4] spinlock %4.0fms\n", testLock(4, 1000000, &Locker{}).Seconds()*1000)
44 | 	fmt.Printf("[4] mutex    %4.0fms\n", testLock(4, 1000000, &sync.Mutex{}).Seconds()*1000)
45 | 	fmt.Printf("[8] spinlock %4.0fms\n", testLock(8, 1000000, &Locker{}).Seconds()*1000)
46 | 	fmt.Printf("[8] mutex    %4.0fms\n", testLock(8, 1000000, &sync.Mutex{}).Seconds()*1000)
47 | }
48 | 


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