├── .gitignore
├── LICENSE
├── README.md
├── once.go
└── once_test.go


/.gitignore:
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 1 | # Compiled Object files, Static and Dynamic libs (Shared Objects)
 2 | *.o
 3 | *.a
 4 | *.so
 5 | 
 6 | # Folders
 7 | _obj
 8 | _test
 9 | 
10 | # Architecture specific extensions/prefixes
11 | *.[568vq]
12 | [568vq].out
13 | 
14 | *.cgo1.go
15 | *.cgo2.c
16 | _cgo_defun.c
17 | _cgo_gotypes.go
18 | _cgo_export.*
19 | 
20 | _testmain.go
21 | 
22 | *.exe
23 | *.test
24 | *.prof
25 | 


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/LICENSE:
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 1 | The MIT License (MIT)
 2 | 
 3 | Copyright (c) 2016 Mat Ryer
 4 | 
 5 | Permission is hereby granted, free of charge, to any person obtaining a copy
 6 | of this software and associated documentation files (the "Software"), to deal
 7 | in the Software without restriction, including without limitation the rights
 8 | to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 9 | copies of the Software, and to permit persons to whom the Software is
10 | furnished to do so, 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,
17 | FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
18 | AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 | LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
20 | OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
21 | SOFTWARE.
22 | 


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/README.md:
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 1 | # resync
 2 | 
 3 | `sync.Once` with `Reset()`
 4 | 
 5 |   * See [sync.Once](http://golang.org/pkg/sync/#Once)
 6 | 
 7 | Rather than adding this project as a dependency, consider [dropping](https://github.com/matryer/drop) this file into your project.
 8 | 
 9 | ## Example
10 | 
11 | The following example examines how `resync.Once` could be used in a HTTP server situation.
12 | 
13 | ```go
14 | // use it just like sync.Once
15 | var once resync.Once
16 | 
17 | // handle a web request
18 | func handleRequest(w http.ResponseWriter, r *http.Request) {
19 | 	once.Do(func(){
20 | 		// load templates or something
21 | 	})
22 | 	// TODO: respond
23 | }
24 | 
25 | // handle some request that indicates things have changed
26 | func handleResetRequest(w http.ResponseWriter, r *http.Request) {
27 | 	once.Reset() // call Reset to cause initialisation to happen again above
28 | }
29 | ```
30 | 


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/once.go:
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 1 | package resync
 2 | 
 3 | import (
 4 | 	"sync"
 5 | 	"sync/atomic"
 6 | )
 7 | 
 8 | // Once is an object that will perform exactly one action
 9 | // until Reset is called.
10 | // See http://golang.org/pkg/sync/#Once
11 | type Once struct {
12 | 	m    sync.Mutex
13 | 	done uint32
14 | }
15 | 
16 | // Do simulates sync.Once.Do by executing the specified function
17 | // only once, until Reset is called.
18 | // See http://golang.org/pkg/sync/#Once
19 | func (o *Once) Do(f func()) {
20 | 	if atomic.LoadUint32(&o.done) == 1 {
21 | 		return
22 | 	}
23 | 	// Slow-path.
24 | 	o.m.Lock()
25 | 	defer o.m.Unlock()
26 | 	if o.done == 0 {
27 | 		defer atomic.StoreUint32(&o.done, 1)
28 | 		f()
29 | 	}
30 | }
31 | 
32 | // Reset indicates that the next call to Do should actually be called
33 | // once again.
34 | func (o *Once) Reset() {
35 | 	o.m.Lock()
36 | 	defer o.m.Unlock()
37 | 	atomic.StoreUint32(&o.done, 0)
38 | }
39 | 


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/once_test.go:
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 1 | package resync_test
 2 | 
 3 | import (
 4 | 	"testing"
 5 | 
 6 | 	"github.com/cheekybits/is"
 7 | 	"github.com/matryer/resync"
 8 | )
 9 | 
10 | func TestOnceReset(t *testing.T) {
11 | 	is := is.New(t)
12 | 	var calls int
13 | 	var c resync.Once
14 | 	c.Do(func() {
15 | 		calls++
16 | 	})
17 | 	c.Do(func() {
18 | 		calls++
19 | 	})
20 | 	c.Do(func() {
21 | 		calls++
22 | 	})
23 | 	is.Equal(calls, 1)
24 | 	c.Reset()
25 | 	c.Do(func() {
26 | 		calls++
27 | 	})
28 | 	c.Do(func() {
29 | 		calls++
30 | 	})
31 | 	c.Do(func() {
32 | 		calls++
33 | 	})
34 | 	is.Equal(calls, 2)
35 | }
36 | 


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