Implement basic queue, where is it impossible to run two identical job

in parallel

engine/queue.go

@@ -3,8 +3,33 @@ package engine
 import (
 	"crypto/sha256"
 	"fmt"
+	"strings"
 )
 
 func GenContainerPrefix(jobtype string) string {
 	return fmt.Sprintf("minifaas-%x-", sha256.Sum224([]byte(jobtype)))
 }
+
+func FilterRunningContainers(jobtype string, ctrs map[string]string) (ret []string) {
+	prefix := GenContainerPrefix(jobtype)
+
+	for cname, _ := range ctrs {
+		if jobtype == "" || strings.HasPrefix(cname, prefix) {
+			ret = append(ret, cname)
+		}
+	}
+
+	return
+}
+
+func CountRunningContainers(jobtype string, ctrs map[string]string) (n int) {
+	prefix := GenContainerPrefix(jobtype)
+
+	for cname, _ := range ctrs {
+		if jobtype == "" || strings.HasPrefix(strings.TrimPrefix(cname, "/"), prefix) {
+			n += 1
+		}
+	}
+
+	return
+}