windows: Refactor whole code

Signed-off-by: Kenfe-Mickael Laventure <mickael.laventure@gmail.com>

windows/pid_pool.go

@@ -0,0 +1,47 @@
+// +build windows
+
+package windows
+
+import (
+	"errors"
+	"sync"
+)
+
+type pidPool struct {
+	sync.Mutex
+	pool map[uint32]struct{}
+	cur  uint32
+}
+
+func newPidPool() *pidPool {
+	return &pidPool{
+		pool: make(map[uint32]struct{}),
+	}
+}
+
+func (p *pidPool) Get() (uint32, error) {
+	p.Lock()
+	defer p.Unlock()
+
+	pid := p.cur + 1
+	for pid != p.cur {
+		// 0 is reserved and invalid
+		if pid == 0 {
+			pid = 1
+		}
+		if _, ok := p.pool[pid]; !ok {
+			p.cur = pid
+			p.pool[pid] = struct{}{}
+			return pid, nil
+		}
+		pid++
+	}
+
+	return 0, errors.New("pid pool exhausted")
+}
+
+func (p *pidPool) Put(pid uint32) {
+	p.Lock()
+	delete(p.pool, pid)
+	p.Unlock()
+}