factory: add direct and cache factory

direct factory just creates the vm directly.
cache factory uses the base factory (either direct or template) to
create the vm.

Fixes: #52

Signed-off-by: Peng Tao <[email protected]>

virtcontainers/factory/cache/cache.go

@@ -7,27 +7,80 @@
 package cache
 
 import (
+	"fmt"
+	"sync"
+
 	vc "github.com/kata-containers/runtime/virtcontainers"
 	"github.com/kata-containers/runtime/virtcontainers/factory/base"
 )
 
 type cache struct {
-	count uint
-
 	base base.FactoryBase
+
+	cachech   chan *vc.VM
+	closed    chan<- int
+	wg        sync.WaitGroup
+	closeOnce sync.Once
 }
 
 func New(count uint, b base.FactoryBase) base.FactoryBase {
-	return &cache{count, b}
+	if count < 1 {
+		return b
+	}
+
+	cachech := make(chan *vc.VM)
+	closed := make(chan int, count)
+	c := cache{base: b, cachech: cachech, closed: closed}
+	for i := 0; i < int(count); i++ {
+		c.wg.Add(1)
+		go func() {
+			for {
+				vm, err := b.GetBaseVM()
+				if err != nil {
+					//glog.Errorf("cache factory get error when allocate vm: %v", err)
+					c.wg.Done()
+					c.CloseFactory()
+					return
+				}
+				//glog.V(3).Infof("cache factory get vm from lower layer: %s", vm.Id)
+
+				select {
+				case cachech <- vm:
+					//glog.V(3).Infof("cache factory sent one vm: %s", vm.Id)
+				case _ = <-closed:
+					//glog.V(3).Infof("cache factory is going to close")
+					vm.Kill()
+					c.wg.Done()
+					return
+				}
+			}
+		}()
+	}
+	return &c
 }
 
 func (c *cache) Config() (vc.HypervisorType, *vc.HypervisorConfig) {
 	return c.base.Config()
 }
 
 func (c *cache) GetBaseVM() (*vc.VM, error) {
-	return c.base.GetBaseVM()
+	vm, ok := <-c.cachech
+	if ok {
+		//glog.V(3).Infof("cache factory get vm from cache: %s", vm.Id)
+		return vm, nil
+	}
+	return nil, fmt.Errorf("cache factory is closed")
 }
 
 func (c *cache) CloseFactory() {
+	c.closeOnce.Do(func() {
+		//glog.V(3).Infof("CloseFactory() close cache factory")
+		for len(c.closed) < cap(c.closed) { // send sufficient closed signal
+			c.closed <- 0
+		}
+		//glog.V(3).Infof("CloseFactory() sent close signal")
+		c.wg.Wait()
+		close(c.cachech)
+		c.base.CloseFactory()
+	})
 }

virtcontainers/factory/direct/direct.go

@@ -25,7 +25,7 @@ func (d *direct) Config() (vc.HypervisorType, *vc.HypervisorConfig) {
 }
 
 func (d *direct) GetBaseVM() (*vc.VM, error) {
-	return nil, nil
+	return vc.NewVM(d.hypervisorType, d.hypervisorConfig)
 }
 
 func (d *direct) CloseFactory() {