add vendor

vendor/github.com/jtolds/gls/id_pool.go

@@ -0,0 +1,34 @@
+package gls
+
+// though this could probably be better at keeping ids smaller, the goal of
+// this class is to keep a registry of the smallest unique integer ids
+// per-process possible
+
+import (
+	"sync"
+)
+
+type idPool struct {
+	mtx      sync.Mutex
+	released []uint
+	max_id   uint
+}
+
+func (p *idPool) Acquire() (id uint) {
+	p.mtx.Lock()
+	defer p.mtx.Unlock()
+	if len(p.released) > 0 {
+		id = p.released[len(p.released)-1]
+		p.released = p.released[:len(p.released)-1]
+		return id
+	}
+	id = p.max_id
+	p.max_id++
+	return id
+}
+
+func (p *idPool) Release(id uint) {
+	p.mtx.Lock()
+	defer p.mtx.Unlock()
+	p.released = append(p.released, id)
+}