searcher.go

/*
 *     Copyright 2020 The Dragonfly 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.
 */

//go:generate mockgen -destination mocks/searcher_mock.go -source searcher.go -package mocks

package searcher

import (
	"context"
	"errors"
	"fmt"
	"sort"
	"strings"

	"github.com/mitchellh/mapstructure"

	logger "d7y.io/dragonfly/v2/internal/dflog"
	"d7y.io/dragonfly/v2/manager/model"
	"d7y.io/dragonfly/v2/pkg/math"
	"d7y.io/dragonfly/v2/pkg/rpc/manager"
)

const (
	// Condition security domain key
	ConditionSecurityDomain = "security_domain"

	// Condition IDC key
	ConditionIDC = "idc"

	// Condition netTopology key
	ConditionNetTopology = "net_topology"

	// Condition location key
	ConditionLocation = "location"
)

const (
	// SecurityDomain affinity weight
	securityDomainAffinityWeight float64 = 0.4

	// IDC affinity weight
	idcAffinityWeight float64 = 0.3

	// NetTopology affinity weight
	netTopologyAffinityWeight = 0.2

	// Location affinity weight
	locationAffinityWeight = 0.1
)

const (
	// Maximum score
	maxScore float64 = 1.0

	// Minimum score
	minScore = 0
)

const (
	// Maximum number of elements
	maxElementLen = 5
)

// Scheduler cluster scopes
type Scopes struct {
	IDC         string `mapstructure:"idc"`
	Location    string `mapstructure:"location"`
	NetTopology string `mapstructure:"net_topology"`
}

type Searcher interface {
	// FindSchedulerClusters finds scheduler clusters that best matches the evaluation
	FindSchedulerClusters(context.Context, []model.SchedulerCluster, *manager.ListSchedulersRequest) ([]model.SchedulerCluster, error)
}

type searcher struct{}

func New(pluginDir string) Searcher {
	s, err := LoadPlugin(pluginDir)
	if err != nil {
		logger.Info("use default searcher")
		return &searcher{}
	}

	logger.Info("use searcher plugin")
	return s
}

// FindSchedulerClusters finds scheduler clusters that best matches the evaluation
func (s *searcher) FindSchedulerClusters(ctx context.Context, schedulerClusters []model.SchedulerCluster, client *manager.ListSchedulersRequest) ([]model.SchedulerCluster, error) {
	conditions := client.HostInfo
	if len(conditions) <= 0 {
		return nil, errors.New("empty conditions")
	}

	if len(schedulerClusters) <= 0 {
		return nil, errors.New("empty scheduler clusters")
	}

	clusters := FilterSchedulerClusters(conditions, schedulerClusters)
	if len(clusters) == 0 {
		return nil, fmt.Errorf("conditions %#v does not match any scheduler cluster", conditions)
	}

	sort.Slice(
		clusters,
		func(i, j int) bool {
			var si, sj Scopes
			if err := mapstructure.Decode(clusters[i].Scopes, &si); err != nil {
				logger.Errorf("cluster %s decode scopes failed: %v", clusters[i].Name, err)
				return false
			}

			if err := mapstructure.Decode(clusters[j].Scopes, &sj); err != nil {
				logger.Errorf("cluster %s decode scopes failed: %v", clusters[i].Name, err)
				return false
			}

			return Evaluate(conditions, si, clusters[i].SecurityGroup.SecurityRules) > Evaluate(conditions, sj, clusters[j].SecurityGroup.SecurityRules)
		},
	)

	return clusters, nil
}

// Filter the scheduler clusters that dfdaemon can be used
func FilterSchedulerClusters(conditions map[string]string, schedulerClusters []model.SchedulerCluster) []model.SchedulerCluster {
	var clusters []model.SchedulerCluster
	securityDomain := conditions[ConditionSecurityDomain]
	for _, schedulerCluster := range schedulerClusters {
		// There are no active schedulers in the scheduler cluster
		if len(schedulerCluster.Schedulers) == 0 {
			continue
		}

		// Dfdaemon security_domain does not exist, matching all scheduler clusters
		if securityDomain == "" {
			clusters = append(clusters, schedulerCluster)
			continue
		}

		// Scheduler cluster is default, matching all dfdaemons
		if schedulerCluster.IsDefault {
			clusters = append(clusters, schedulerCluster)
			continue
		}

		// Scheduler cluster SecurityRules does not exist, matching all dfdaemons
		if len(schedulerCluster.SecurityGroup.SecurityRules) == 0 {
			clusters = append(clusters, schedulerCluster)
			continue
		}

		// If security_domain exists for dfdaemon and
		// scheduler cluster SecurityRules also exists,
		// then security_domain and SecurityRules are equal to match.
		for _, securityRule := range schedulerCluster.SecurityGroup.SecurityRules {
			if strings.EqualFold(securityRule.Domain, securityDomain) {
				clusters = append(clusters, schedulerCluster)
			}
		}
	}

	return clusters
}

// Evaluate the degree of matching between scheduler cluster and dfdaemon
func Evaluate(conditions map[string]string, scopes Scopes, securityRules []model.SecurityRule) float64 {
	return securityDomainAffinityWeight*calculateSecurityDomainAffinityScore(conditions[ConditionSecurityDomain], securityRules) +
		idcAffinityWeight*calculateIDCAffinityScore(conditions[ConditionIDC], scopes.IDC) +
		locationAffinityWeight*calculateMultiElementAffinityScore(conditions[ConditionLocation], scopes.Location) +
		netTopologyAffinityWeight*calculateMultiElementAffinityScore(conditions[ConditionNetTopology], scopes.NetTopology)
}

// calculateSecurityDomainAffinityScore 0.0~1.0 larger and better
func calculateSecurityDomainAffinityScore(securityDomain string, securityRules []model.SecurityRule) float64 {
	if securityDomain == "" {
		return minScore
	}

	if len(securityRules) == 0 {
		return minScore

	}

	return maxScore
}

// calculateIDCAffinityScore 0.0~1.0 larger and better
func calculateIDCAffinityScore(dst, src string) float64 {
	if dst == "" || src == "" {
		return minScore
	}

	if strings.EqualFold(dst, src) {
		return maxScore
	}

	// Dst has only one element, src has multiple elements separated by "|".
	// When dst element matches one of the multiple elements of src,
	// it gets the max score of idc.
	srcElements := strings.Split(src, "|")
	for _, srcElement := range srcElements {
		if strings.EqualFold(dst, srcElement) {
			return maxScore
		}
	}

	return minScore
}

// calculateMultiElementAffinityScore 0.0~1.0 larger and better
func calculateMultiElementAffinityScore(dst, src string) float64 {
	if dst == "" || src == "" {
		return minScore
	}

	if strings.EqualFold(dst, src) {
		return maxScore
	}

	// Calculate the number of multi-element matches divided by "|"
	var score, elementLen int
	dstElements := strings.Split(dst, "|")
	srcElements := strings.Split(src, "|")
	elementLen = math.Min(len(dstElements), len(srcElements))

	// Maximum element length is 5
	if elementLen > maxElementLen {
		elementLen = maxElementLen
	}

	for i := 0; i < elementLen; i++ {
		if !strings.EqualFold(dstElements[i], srcElements[i]) {
			break
		}
		score++
	}

	return float64(score) / float64(maxElementLen)
}