Implement random reassign and add test case (#5474)

Signed-off-by: Congqi Xia <congqi.xia@zilliz.com>

internal/dataservice/policy.go

@@ -84,35 +84,43 @@ type randomAssignUnregisterPolicy struct{}
 
 func (p *randomAssignUnregisterPolicy) apply(cluster map[string]*datapb.DataNodeInfo, session *datapb.DataNodeInfo) []*datapb.DataNodeInfo {
 	if len(cluster) == 0 || // no available node
+		session == nil ||
 		len(session.Channels) == 0 { // lost node not watching any channels
 		return []*datapb.DataNodeInfo{}
 	}
 
-	mChan := make(map[string]struct{}, len(session.Channels))
+	appliedNodes := make([]*datapb.DataNodeInfo, 0, len(session.Channels))
+	raResult := make(map[int][]*datapb.ChannelStatus)
 	for _, chanSt := range session.Channels {
-		mChan[chanSt.Name] = struct{}{}
+		bIdx, err := rand.Int(rand.Reader, big.NewInt(int64(len(cluster))))
+		if err != nil {
+			log.Error("error generated rand idx", zap.Error(err))
+			return []*datapb.DataNodeInfo{}
+		}
+		idx := bIdx.Int64()
+		if int(idx) >= len(cluster) {
+			continue
+		}
+		cs, ok := raResult[int(idx)]
+		if !ok {
+			cs = make([]*datapb.ChannelStatus, 0, 10)
+		}
+		chanSt.State = datapb.ChannelWatchState_Uncomplete
+		cs = append(cs, chanSt)
+		raResult[int(idx)] = cs
 	}
 
-	bIdx, err := rand.Int(rand.Reader, big.NewInt(int64(len(cluster))))
-	if err != nil {
-		log.Error("error generated rand idx", zap.Error(err))
-		return []*datapb.DataNodeInfo{}
-	}
-	idx := bIdx.Int64()
-	if int(idx) >= len(cluster) {
-		return []*datapb.DataNodeInfo{}
-	}
 	i := 0
 	for _, node := range cluster {
-		if i == int(idx) {
-			//TODO add channel to node
-			return []*datapb.DataNodeInfo{
-				node,
-			}
-		}
+		cs, ok := raResult[i]
 		i++
+		if ok {
+			node.Channels = append(node.Channels, cs...)
+			appliedNodes = append(appliedNodes, node)
+		}
 	}
-	return []*datapb.DataNodeInfo{}
+
+	return appliedNodes
 }
 
 type channelAssignPolicy interface {

internal/dataservice/policy_test.go

@@ -1,3 +1,14 @@
+// Copyright (C) 2019-2020 Zilliz. All rights reserved.
+//
+// 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 dataservice
 
 import (
@@ -44,3 +55,62 @@ func TestWatchRestartsPolicy(t *testing.T) {
 	assert.EqualValues(t, 1, len(nodes))
 	assert.EqualValues(t, datapb.ChannelWatchState_Uncomplete, nodes[0].Channels[0].State)
 }
+
+func TestRandomReassign(t *testing.T) {
+	p := randomAssignUnregisterPolicy{}
+
+	clusters := make(map[string]*datapb.DataNodeInfo)
+	clusters["addr1"] = &datapb.DataNodeInfo{
+		Address:  "addr1",
+		Channels: make([]*datapb.ChannelStatus, 0, 10),
+	}
+	clusters["addr2"] = &datapb.DataNodeInfo{
+		Address:  "addr2",
+		Channels: make([]*datapb.ChannelStatus, 0, 10),
+	}
+	clusters["addr3"] = &datapb.DataNodeInfo{
+		Address:  "addr3",
+		Channels: make([]*datapb.ChannelStatus, 0, 10),
+	}
+
+	cases := []*datapb.DataNodeInfo{
+		{
+			Channels: []*datapb.ChannelStatus{},
+		},
+		{
+			Channels: []*datapb.ChannelStatus{
+				{Name: "VChan1", CollectionID: 1},
+				{Name: "VChan2", CollectionID: 2},
+			},
+		},
+		{
+			Channels: []*datapb.ChannelStatus{
+				{Name: "VChan3", CollectionID: 1},
+				{Name: "VChan4", CollectionID: 2},
+			},
+		},
+		nil,
+	}
+
+	for _, ca := range cases {
+		nodes := p.apply(clusters, ca)
+		if ca == nil || len(ca.Channels) == 0 {
+			assert.Equal(t, 0, len(nodes))
+		} else {
+			for _, ch := range ca.Channels {
+				found := false
+			loop:
+				for _, node := range nodes {
+					for _, nch := range node.Channels {
+						if nch.Name == ch.Name {
+							found = true
+							assert.EqualValues(t, datapb.ChannelWatchState_Uncomplete, nch.State)
+							break loop
+						}
+					}
+				}
+				assert.Equal(t, true, found)
+			}
+		}
+	}
+}