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Commit 155c2a7

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slightly adjust mutexes examples
1 parent 3efdd92 commit 155c2a7

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36 files changed

+412
-245
lines changed

36 files changed

+412
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‎README.md‎

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@@ -63,7 +63,6 @@
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- [Map - sync.Map](https://github.com/golang-basics/concurrency/tree/master/mutexes/syncmap)
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- [Cond - sync.Cond](https://github.com/golang-basics/concurrency/tree/master/mutexes/cond)
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- [Once - sync.Once](https://github.com/golang-basics/concurrency/tree/master/mutexes/once)
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- [Locker - sync.Locker](https://github.com/golang-basics/concurrency/tree/master/mutexes/synclocker)
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- [Race Conditions](https://github.com/golang-basics/concurrency/tree/master/go-routines/race-condition)
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- [Threads](https://github.com/golang-basics/concurrency/tree/master/threads)
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- [GOMAXPROCS](https://github.com/golang-basics/concurrency/tree/master/gomaxprocs)

‎mutexes/README.md‎

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@@ -60,7 +60,7 @@ the database consistency which otherwise is not possible for a non-serial schedu
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### Presentations
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- [Concurrency in Go #6 - Mutexes](https://github.com/golang-basics/concurrency/raw/master/presentations/6_mutexes)
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- [Concurrency in Go #7 - Mutexes](https://github.com/golang-basics/concurrency/raw/master/presentations/7_mutexes)
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### Examples
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‎mutexes/atomic-waitgroup/main.go‎

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This file was deleted.

‎mutexes/basic-mutex/main.go‎

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package main
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import (
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"fmt"
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"sync"
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"time"
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)
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// to check for race conditions use the -race flag
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// go run -race main.go
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func main() {
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var count int
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var mu sync.Mutex
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go func() {
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mu.Lock()
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count = 10
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mu.Unlock()
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}()
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// remember: the main function is also running as a go routine
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// a good rule of thumb is to avoid RW conflicts in the main
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// and keep all the concurrent operations in their own go routines
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mu.Lock()
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count = 15
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mu.Unlock()
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// to avoid using WaitGroup
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time.Sleep(time.Second)
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mu.Lock()
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fmt.Println("count", count)
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mu.Unlock()
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}

‎mutexes/context/coarse-grained-context/main.go‎ renamed to ‎mutexes/contexts/coarse-grained-context/main.go‎

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@@ -16,7 +16,7 @@ func main() {
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defer wg.Done()
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var localCount int
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mu.Lock()
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localCount = count+1
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localCount = count+1
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count = localCount
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mu.Unlock()
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}()

‎mutexes/context/fine-grained-context/main.go‎ renamed to ‎mutexes/contexts/fine-grained-context/main.go‎

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@@ -16,7 +16,7 @@ func main() {
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defer wg.Done()
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var localCount int
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mu.Lock()
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localCount = count+1
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localCount = count+1
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mu.Unlock()
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mu.Lock()
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count = localCount

‎mutexes/context/multiple-gouroutines/main.go‎ renamed to ‎mutexes/contexts/multiple-gouroutines-readonly/main.go‎

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@@ -16,7 +16,7 @@ func main() {
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defer wg.Done()
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// Each go routine only reads the count data and does not expose its data outside
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var localCount int
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localCount += count+i+1
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localCount += count+i+1
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fmt.Println("local count", localCount)
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}(i)
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}

‎mutexes/context/single-gouroutine/main.go‎ renamed to ‎mutexes/contexts/single-gouroutine/main.go‎

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// Only the G1 go routine will do the write operation, thus it's safe
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count++
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}()
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// Main G does not read or write while G1 is running
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// So this will not run in a race condition
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// Main G does not read or write while G1 is running,
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// so this will not run in a race condition.
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// Or we could just move count++ inside main, which will execute in its own go routine
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wg.Wait()
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fmt.Println("count", count)
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package main
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import (
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"fmt"
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"sync"
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)
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// to check for race conditions use the -race flag
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// go run -race main.go
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func main() {
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d := newDB()
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var wg sync.WaitGroup
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wg.Add(2)
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go func() {
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// setting k1 here
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d.set("k1", "v1")
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wg.Done()
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}()
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go func() {
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// setting k1 as well here
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d.set("k1", "v2")
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wg.Done()
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}()
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// trying to get a value while it's being set by the go routines
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fmt.Println(d.get("k1"))
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wg.Wait()
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}
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func newDB() db {
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return db{values: map[string]string{}}
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}
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type db struct {
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values map[string]string
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mu sync.Mutex
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}
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func (d *db) set(key, value string) {
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d.mu.Lock()
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defer d.mu.Unlock()
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d.values[key] = value
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}
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func (d *db) get(key string) string {
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d.mu.Lock()
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defer d.mu.Unlock()
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return d.values[key]
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}

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