Add queuing system

queue.go

@@ -1,6 +1,12 @@
 package main
 
 import (
+	"fmt"
+	"log"
+	"time"
+
+	"github.com/docker/docker/api/types"
+
 	"github.com/nemunaire/minifaas/engine"
 	"github.com/nemunaire/minifaas/engine/docker"
 )
@@ -22,3 +28,50 @@ func CountRunningContainers(jobtype string) (n int, err error) {
 
 	return engine.CountRunningContainers(jobtype, ctrs), nil
 }
+
+func GetJobTypeFromNames(names []string) (jobtype string, err error) {
+	for _, name := range names {
+		if jobtype, _, err = engine.ParseContainerName(name); err == nil {
+			// We found it, jobtype is already defined, just return
+			return
+		}
+	}
+
+	// Not returned before == not found
+	return "", fmt.Errorf("This is not a minifass job")
+}
+
+func runQueue() {
+	for {
+		time.Sleep(time.Second)
+		//log.Println("queue: tick")
+
+		ctrs, err := docker.Ps(types.ContainerListOptions{All: true})
+		if err != nil {
+			log.Println("queue: run:", err.Error())
+			continue
+		}
+
+		for _, ctr := range ctrs {
+			if ctr.State == "created" {
+				jobtype, err := GetJobTypeFromNames(ctr.Names)
+				if err != nil {
+					log.Println(err.Error())
+					continue
+				}
+
+				n, err := CountRunningContainers(jobtype)
+				if err != nil {
+					continue
+				}
+				if n > 0 {
+					log.Printf("Waiting slot for container %s (jobtype=%s)", ctr.ID, jobtype)
+					continue
+				}
+
+				log.Printf("Starting container %s (jobtype=%s) on available slot", ctr.ID, jobtype)
+				docker.Start(ctr.ID)
+			}
+		}
+	}
+}