1 files changed, 47 insertions, 0 deletions
diff --git a/models/working_pool.go b/models/working_pool.go
new file mode 100644
index 0000000000..c522de56a0
--- /dev/null
+++ b/models/working_pool.go
@@ -0,0 +1,47 @@
+// Copyright 2015 The Gogs Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package models
+
+import (
+	"sync"
+)
+
+// workingPool represents a pool of working status which makes sure
+// that only one instance of same task is performing at a time.
+// However, different type of tasks can performing at the same time.
+type workingPool struct {
+	lock  sync.Mutex
+	pool  map[string]*sync.Mutex
+	count map[string]int
+}
+
+// CheckIn checks in a task and waits if others are running.
+func (p *workingPool) CheckIn(name string) {
+	p.lock.Lock()
+
+	lock, has := p.pool[name]
+	if !has {
+		lock = &sync.Mutex{}
+		p.pool[name] = lock
+	}
+	p.count[name]++
+
+	p.lock.Unlock()
+	lock.Lock()
+}
+
+// CheckOut checks out a task to let other tasks run.
+func (p *workingPool) CheckOut(name string) {
+	p.lock.Lock()
+	defer p.lock.Unlock()
+
+	p.pool[name].Unlock()
+	if p.count[name] == 1 {
+		delete(p.pool, name)
+		delete(p.count, name)
+	} else {
+		p.count[name]--
+	}
+}