From 47367cdcb7572d49f43a4c0c184b5f676c9adffe Mon Sep 17 00:00:00 2001
From: eric <1048315650@qq.com>
Date: Fri, 20 May 2022 14:44:19 +0800
Subject: [PATCH] =?UTF-8?q?feat(=E4=BA=92=E6=96=A5=E9=94=81[mutex]):=20?=
 =?UTF-8?q?=E4=BA=92=E6=96=A5=E9=94=81=20=E6=94=AF=E6=8C=81?=
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---
 sync/try_lock/try_lock.distributed.go | 77 +++++++++++++++++++++++++++
 sync/try_lock/try_locker.go           | 45 ++++++++++++++++
 2 files changed, 122 insertions(+)
 create mode 100644 sync/try_lock/try_lock.distributed.go
 create mode 100644 sync/try_lock/try_locker.go

diff --git a/sync/try_lock/try_lock.distributed.go b/sync/try_lock/try_lock.distributed.go
new file mode 100644
index 0000000..33f8771
--- /dev/null
+++ b/sync/try_lock/try_lock.distributed.go
@@ -0,0 +1,77 @@
+package try_lock
+
+import (
+	"fmt"
+	"math/rand"
+	"runtime"
+	"time"
+)
+
+type distributedTryLocker struct {
+	cmd CASCommand
+
+	key   string
+	value string
+
+	option *options
+}
+
+type CASCommand interface {
+	CAS(key, src, dst string) bool
+}
+
+type Option func(*options)
+
+func WithScheduleFunc(f func()) Option {
+	return func(o *options) {
+		o.schedule = f
+	}
+}
+
+type options struct {
+	schedule Schedule
+}
+
+type Schedule func()
+
+func defaultSchedule() {
+	time.Sleep(time.Millisecond * time.Duration((rand.Intn(20)+1)*10))
+	runtime.Gosched()
+}
+
+func NewDistributedTryLocker(cmd CASCommand, key, value string, opts ...Option) TryMutexLocker {
+	option := &options{
+		schedule: defaultSchedule,
+	}
+	for _, opt := range opts {
+		opt(option)
+	}
+	return &distributedTryLocker{cmd: cmd, key: key, value: value, option: option}
+
+}
+
+func (r *distributedTryLocker) Unlock() {
+	r.cmd.CAS(r.key, r.value, "")
+}
+
+func (r *distributedTryLocker) TryLock(duration time.Duration) error {
+	if r.cmd.CAS(r.key, "", r.value) {
+		return nil
+	}
+	if duration > 0 {
+		timeoutChan := time.After(duration)
+		for {
+			select {
+			case <-timeoutChan:
+				return fmt.Errorf("%w: key=%s value=%s", errGetLockTimeOut, r.key, r.value)
+			default:
+				if r.cmd.CAS(r.key, "", r.value) {
+					return nil
+				}
+				// 执行一次切换调度
+				r.option.schedule()
+			}
+		}
+	}
+	return fmt.Errorf("%w: key=%s value=%s", errGetLockTimeOut, r.key, r.value)
+}
diff --git a/sync/try_lock/try_locker.go b/sync/try_lock/try_locker.go
new file mode 100644
index 0000000..be1682d
--- /dev/null
+++ b/sync/try_lock/try_locker.go
@@ -0,0 +1,45 @@
+package try_lock
+
+import (
+	"errors"
+	"time"
+)
+
+type TryMutexLocker interface {
+	Unlock()
+	TryLock(duration time.Duration) error
+}
+
+type chMutex struct {
+	ch chan struct{}
+}
+
+func NewChMutex() TryMutexLocker {
+	return &chMutex{ch: make(chan struct{}, 1)}
+}
+
+var (
+	errGetLockTimeOut = errors.New("get lock timeout")
+)
+
+func (c *chMutex) TryLock(duration time.Duration) error {
+	if duration > 0 {
+		timeoutChan := time.After(duration)
+		select {
+		case <-timeoutChan:
+			return errGetLockTimeOut
+		case c.ch <- struct{}{}:
+		}
+	} else {
+		select {
+		case c.ch <- struct{}{}:
+		default:
+			return errGetLockTimeOut
+		}
+	}
+	return nil
+}
+
+func (c *chMutex) Unlock() {
+	<-c.ch
+}