Add Pagination to Listing Projects for Housekeeping

cmd/yorkie/server.go

@@ -227,6 +227,12 @@ func init() {
 		server.DefaultHousekeepingCandidatesLimitPerProject,
 		"candidates limit per project for a single housekeeping run",
 	)
+	cmd.Flags().IntVar(
+		&conf.Housekeeping.ProjectFetchSize,
+		"housekeeping-project-fetch-size",
+		server.DefaultHousekeepingProjectFetchSize,
+		"housekeeping project fetch size for a single housekeeping run",
+	)
 	cmd.Flags().StringVar(
 		&mongoConnectionURI,
 		"mongo-connection-uri",

server/backend/database/database.go

@@ -138,7 +138,9 @@ type Database interface {
 	FindDeactivateCandidates(
 		ctx context.Context,
 		candidatesLimitPerProject int,
-	) ([]*ClientInfo, error)
+		projectFetchSize int,
+		lastProjectID types.ID,
+	) (types.ID, []*ClientInfo, error)
 
 	// FindDocInfoByKey finds the document of the given key.
 	FindDocInfoByKey(

server/backend/database/memory/database.go

@@ -224,27 +224,38 @@ func (d *DB) CreateProjectInfo(
 	return info, nil
 }
 
-// ListAllProjectInfos returns all project infos.
-func (d *DB) listAllProjectInfos(
+// listProjectInfos returns all project infos rotationally.
+func (d *DB) listProjectInfos(
 	ctx context.Context,
+	pageSize int,
+	housekeepingLastProjectID types.ID,
 ) ([]*database.ProjectInfo, error) {
 	txn := d.db.Txn(false)
 	defer txn.Abort()
 
-	// TODO(krapie): txn.Get() loads all projects in memory,
-	// which will cause performance issue as number of projects in DB grows.
-	// Therefore, pagination of projects is needed to avoid this issue.
-	iter, err := txn.Get(
+	iter, err := txn.LowerBound(
 		tblProjects,
 		"id",
+		housekeepingLastProjectID.String(),
 	)
 	if err != nil {
-		return nil, fmt.Errorf("fetch all projects: %w", err)
+		return nil, fmt.Errorf("fetch projects: %w", err)
 	}
 
 	var infos []*database.ProjectInfo
-	for raw := iter.Next(); raw != nil; raw = iter.Next() {
+
+	for i := 0; i < pageSize; i++ {
+		raw := iter.Next()
+		if raw == nil {
+			break
+		}
 		info := raw.(*database.ProjectInfo).DeepCopy()
+
+		if i == 0 && info.ID == housekeepingLastProjectID {
+			pageSize++
+			continue
+		}
+
 		infos = append(infos, info)
 	}
 
@@ -599,23 +610,32 @@ func (d *DB) findDeactivateCandidatesPerProject(
 func (d *DB) FindDeactivateCandidates(
 	ctx context.Context,
 	candidatesLimitPerProject int,
-) ([]*database.ClientInfo, error) {
-	projects, err := d.listAllProjectInfos(ctx)
+	projectFetchSize int,
+	lastProjectID types.ID,
+) (types.ID, []*database.ClientInfo, error) {
+	projects, err := d.listProjectInfos(ctx, projectFetchSize, lastProjectID)
 	if err != nil {
-		return nil, err
+		return database.DefaultProjectID, nil, err
 	}
 
 	var candidates []*database.ClientInfo
 	for _, project := range projects {
 		infos, err := d.findDeactivateCandidatesPerProject(ctx, project, candidatesLimitPerProject)
 		if err != nil {
-			return nil, err
+			return database.DefaultProjectID, nil, err
 		}
 
 		candidates = append(candidates, infos...)
 	}
 
-	return candidates, nil
+	var topProjectID types.ID
+	if len(projects) < projectFetchSize {
+		topProjectID = database.DefaultProjectID
+	} else {
+		topProjectID = projects[len(projects)-1].ID
+	}
+
+	return topProjectID, candidates, nil
 }
 
 // FindDocInfoByKeyAndOwner finds the document of the given key. If the

server/backend/database/memory/housekeeping_test.go

@@ -28,6 +28,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	monkey "github.com/undefinedlabs/go-mpatch"
 
+	"github.com/yorkie-team/yorkie/server/backend/database"
 	"github.com/yorkie-team/yorkie/server/backend/database/memory"
 )
 
@@ -39,7 +40,10 @@ func TestHousekeeping(t *testing.T) {
 		ctx := context.Background()
 
 		clientDeactivateThreshold := "23h"
-		_, project, err := memdb.EnsureDefaultUserAndProject(ctx, "test", "test", clientDeactivateThreshold)
+
+		userInfo, err := memdb.CreateUserInfo(ctx, "test", "test")
+		assert.NoError(t, err)
+		project, err := memdb.CreateProjectInfo(ctx, database.DefaultProjectName, userInfo.ID, clientDeactivateThreshold)
 		assert.NoError(t, err)
 
 		yesterday := gotime.Now().Add(-24 * gotime.Hour)
@@ -59,14 +63,71 @@ func TestHousekeeping(t *testing.T) {
 		clientC, err := memdb.ActivateClient(ctx, project.ID, fmt.Sprintf("%s-C", t.Name()))
 		assert.NoError(t, err)
 
-		candidates, err := memdb.FindDeactivateCandidates(
+		_, candidates, err := memdb.FindDeactivateCandidates(
 			ctx,
 			10,
+			10,
+			database.DefaultProjectID,
 		)
 		assert.NoError(t, err)
 		assert.Len(t, candidates, 2)
 		assert.Contains(t, candidates, clientA)
 		assert.Contains(t, candidates, clientB)
 		assert.NotContains(t, candidates, clientC)
 	})
+
+	t.Run("housekeeping pagination test", func(t *testing.T) {
+		ctx := context.Background()
+		memdb, projects := createDBandProjects(t)
+
+		fetchSize := 4
+		lastProjectID, _, err := memdb.FindDeactivateCandidates(
+			ctx,
+			0,
+			fetchSize,
+			database.DefaultProjectID,
+		)
+		assert.NoError(t, err)
+		assert.Equal(t, projects[fetchSize-1].ID, lastProjectID)
+
+		lastProjectID, _, err = memdb.FindDeactivateCandidates(
+			ctx,
+			0,
+			fetchSize,
+			lastProjectID,
+		)
+		assert.NoError(t, err)
+		assert.Equal(t, projects[fetchSize*2-1].ID, lastProjectID)
+
+		lastProjectID, _, err = memdb.FindDeactivateCandidates(
+			ctx,
+			0,
+			fetchSize,
+			lastProjectID,
+		)
+		assert.NoError(t, err)
+		assert.Equal(t, database.DefaultProjectID, lastProjectID)
+	})
+}
+
+func createDBandProjects(t *testing.T) (*memory.DB, []*database.ProjectInfo) {
+	t.Helper()
+
+	ctx := context.Background()
+	memdb, err := memory.New()
+	assert.NoError(t, err)
+
+	clientDeactivateThreshold := "23h"
+	userInfo, err := memdb.CreateUserInfo(ctx, "test", "test")
+	assert.NoError(t, err)
+
+	projects := make([]*database.ProjectInfo, 0)
+	for i := 0; i < 10; i++ {
+		p, err := memdb.CreateProjectInfo(ctx, fmt.Sprintf("%d project", i), userInfo.ID, clientDeactivateThreshold)
+		assert.NoError(t, err)
+
+		projects = append(projects, p)
+	}
+
+	return memdb, projects
 }

server/backend/database/mongo/client.go

@@ -235,21 +235,32 @@ func (c *Client) CreateProjectInfo(
 	return info, nil
 }
 
-// ListAllProjectInfos returns all project infos.
-func (c *Client) listAllProjectInfos(
+// listProjectInfos returns all project infos rotationally.
+func (c *Client) listProjectInfos(
 	ctx context.Context,
+	pageSize int,
+	housekeepingLastProjectID types.ID,
 ) ([]*database.ProjectInfo, error) {
-	// TODO(krapie): Find(ctx, bson.D{{}}) loads all projects in memory,
-	// which will cause performance issue as number of projects in DB grows.
-	// Therefore, pagination of projects is needed to avoid this issue.
-	cursor, err := c.collection(colProjects).Find(ctx, bson.D{{}})
+	encodedID, err := encodeID(housekeepingLastProjectID)
+	if err != nil {
+		return nil, err
+	}
+
+	opts := options.Find()
+	opts.SetLimit(int64(pageSize))
+
+	cursor, err := c.collection(colProjects).Find(ctx, bson.M{
+		"_id": bson.M{
+			"$gt": encodedID,
+		},
+	}, opts)
 	if err != nil {
-		return nil, fmt.Errorf("fetch all project infos: %w", err)
+		return nil, fmt.Errorf("find project infos: %w", err)
 	}
 
 	var infos []*database.ProjectInfo
 	if err := cursor.All(ctx, &infos); err != nil {
-		return nil, fmt.Errorf("fetch all project infos: %w", err)
+		return nil, fmt.Errorf("fetch project infos: %w", err)
 	}
 
 	return infos, nil
@@ -657,23 +668,31 @@ func (c *Client) findDeactivateCandidatesPerProject(
 func (c *Client) FindDeactivateCandidates(
 	ctx context.Context,
 	candidatesLimitPerProject int,
-) ([]*database.ClientInfo, error) {
-	projects, err := c.listAllProjectInfos(ctx)
+	projectFetchSize int,
+	lastProjectID types.ID,
+) (types.ID, []*database.ClientInfo, error) {
+	projects, err := c.listProjectInfos(ctx, projectFetchSize, lastProjectID)
 	if err != nil {
-		return nil, err
+		return database.DefaultProjectID, nil, err
 	}
 
 	var candidates []*database.ClientInfo
 	for _, project := range projects {
 		clientInfos, err := c.findDeactivateCandidatesPerProject(ctx, project, candidatesLimitPerProject)
 		if err != nil {
-			return nil, err
+			return database.DefaultProjectID, nil, err
 		}
 
 		candidates = append(candidates, clientInfos...)
 	}
 
-	return candidates, nil
+	var topProjectID types.ID
+	if len(projects) < projectFetchSize {
+		topProjectID = database.DefaultProjectID
+	} else {
+		topProjectID = projects[len(projects)-1].ID
+	}
+	return topProjectID, candidates, nil
 }
 
 // FindDocInfoByKeyAndOwner finds the document of the given key. If the

server/backend/database/mongo/client_test.go

@@ -100,4 +100,8 @@ func TestClient(t *testing.T) {
 	t.Run("IsDocumentAttached test", func(t *testing.T) {
 		testcases.RunIsDocumentAttachedTest(t, cli, dummyProjectID)
 	})
+
+	t.Run("FindDeactivateCandidates test", func(t *testing.T) {
+		testcases.RunFindDeactivateCandidates(t, cli)
+	})
 }

server/backend/database/testcases/testcases.go

@@ -19,8 +19,10 @@
 package testcases
 
 import (
+	"bytes"
 	"context"
 	"fmt"
+	"sort"
 	"strconv"
 	"testing"
 	gotime "time"
@@ -622,6 +624,52 @@ func RunFindDocInfosByPagingTest(t *testing.T, db database.Database, projectID t
 	})
 }
 
+// RunFindDeactivateCandidates runs the FindDeactivateCandidates tests for the given db.
+func RunFindDeactivateCandidates(t *testing.T, db database.Database) {
+	t.Run("housekeeping pagination test", func(t *testing.T) {
+		ctx := context.Background()
+
+		// Lists all projects of the dummyOwnerID and otherOwnerID.
+		projects, err := db.ListProjectInfos(ctx, dummyOwnerID)
+		assert.NoError(t, err)
+		otherProjects, err := db.ListProjectInfos(ctx, otherOwnerID)
+		assert.NoError(t, err)
+
+		projects = append(projects, otherProjects...)
+
+		sort.Slice(projects, func(i, j int) bool {
+			iBytes, err := projects[i].ID.Bytes()
+			assert.NoError(t, err)
+			jBytes, err := projects[j].ID.Bytes()
+			assert.NoError(t, err)
+			return bytes.Compare(iBytes, jBytes) < 0
+		})
+
+		fetchSize := 3
+		lastProjectID := database.DefaultProjectID
+
+		for i := 0; i < len(projects)/fetchSize; i++ {
+			lastProjectID, _, err = db.FindDeactivateCandidates(
+				ctx,
+				0,
+				fetchSize,
+				lastProjectID,
+			)
+			assert.NoError(t, err)
+			assert.Equal(t, projects[((i+1)*fetchSize)-1].ID, lastProjectID)
+		}
+
+		lastProjectID, _, err = db.FindDeactivateCandidates(
+			ctx,
+			0,
+			fetchSize,
+			lastProjectID,
+		)
+		assert.NoError(t, err)
+		assert.Equal(t, database.DefaultProjectID, lastProjectID)
+	})
+}
+
 // RunCreateChangeInfosTest runs the CreateChangeInfos tests for the given db.
 func RunCreateChangeInfosTest(t *testing.T, db database.Database, projectID types.ID) {
 	t.Run("set RemovedAt in docInfo test", func(t *testing.T) {