chore(refactor): refactor scheduler for ZFS-LocalPV

Signed-off-by: Pawan <pawan@mayadata.io>

pkg/driver/schd_helper.go

@@ -0,0 +1,67 @@
+/*
+Copyright 2020 The OpenEBS Authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package driver
+
+import (
+	"github.com/openebs/zfs-localpv/pkg/builder/volbuilder"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+
+	zfs "github.com/openebs/zfs-localpv/pkg/zfs"
+)
+
+// scheduling algorithm constants
+const (
+	// pick the node where less volumes are provisioned for the given pool
+	// this will be the default scheduler when none provided
+	VolumeWeighted = "VolumeWeighted"
+)
+
+// getVolumeWeightedMap goes through all the pools on all the nodes
+// and creats the node mapping of the volume for all the nodes.
+// It returns a map which has nodes as key and volumes present
+// on the nodes as corresponding value.
+func getVolumeWeightedMap(pool string) (map[string]int64, error) {
+	nmap := map[string]int64{}
+
+	zvlist, err := volbuilder.NewKubeclient().
+		WithNamespace(zfs.OpenEBSNamespace).
+		List(metav1.ListOptions{})
+
+	if err != nil {
+		return nmap, err
+	}
+
+	// create the map of the volume count
+	// for the given pool
+	for _, zv := range zvlist.Items {
+		if zv.Spec.PoolName == pool {
+			nmap[zv.Spec.OwnerNodeID]++
+		}
+	}
+
+	return nmap, nil
+}
+
+// getNodeMap returns the node mapping for the given scheduling algorithm
+func getNodeMap(schd string, pool string) (map[string]int64, error) {
+	switch schd {
+	case VolumeWeighted:
+		return getVolumeWeightedMap(pool)
+	}
+	// return VolumeWeighted(default) if not specified
+	return getVolumeWeightedMap(pool)
+}