Issue 1009 calculate diff software (#1305)

* First approach to diff

* Refactor things for better readability and testing

* Remove draft comment for algorithm

* Format things a bit better

* Remove unused and simplify code a bit

* Refactor for readability and testing

* Add changes file

* Implement new approach based on review comments

* Make sure to only delete from the current host

* Add single uninstall test and fix code

* Improve code based on review

changes/.keep

@@ -0,0 +1 @@
+IGNORE BUT DO NOT REMOVE. THIS IS HERE SO THAT THE DIRECTORY REMAINS

changes/issue-1009-inventory-software-reduce-inserts-deletes

@@ -0,0 +1,2 @@
+* Reduce the amount of inserts and deletes are done in the database when updating each host's
+software inventory. Fixes issue 1009

server/datastore/datastore_software.go

@@ -76,4 +76,21 @@ func testSaveHostSoftware(t *testing.T, ds fleet.Datastore) {
 	require.NoError(t, err)
 	assert.False(t, host2.HostSoftware.Modified)
 	test.ElementsMatchSkipID(t, soft2.Software, host2.HostSoftware.Software)
+
+	soft1 = fleet.HostSoftware{
+		Modified: true,
+		Software: []fleet.Software{
+			{Name: "foo", Version: "0.0.3", Source: "chrome_extensions"},
+			{Name: "towel", Version: "42.0.0", Source: "apps"},
+		},
+	}
+	host1.HostSoftware = soft1
+
+	err = ds.SaveHostSoftware(host1)
+	require.NoError(t, err)
+
+	err = ds.LoadHostSoftware(host1)
+	require.NoError(t, err)
+	assert.False(t, host1.HostSoftware.Modified)
+	test.ElementsMatchSkipID(t, soft1.Software, host1.HostSoftware.Software)
 }

server/datastore/mysql/software.go

@@ -22,49 +22,53 @@ func truncateString(str string, length int) string {
 	return str
 }
 
+func softwareToUniqueString(s fleet.Software) string {
+	return strings.Join([]string{s.Name, s.Version, s.Source}, "\u0000")
+}
+
+func uniqueStringToSoftware(s string) fleet.Software {
+	parts := strings.Split(s, "\u0000")
+	return fleet.Software{
+		Name:    truncateString(parts[0], maxSoftwareNameLen),
+		Version: truncateString(parts[1], maxSoftwareVersionLen),
+		Source:  truncateString(parts[2], maxSoftwareSourceLen),
+	}
+}
+
+func softwareSliceToSet(softwares []fleet.Software) map[string]bool {
+	result := make(map[string]bool)
+	for _, s := range softwares {
+		result[softwareToUniqueString(s)] = true
+	}
+	return result
+}
+
+func softwareSliceToIdMap(softwareSlice []fleet.Software) map[string]uint {
+	result := make(map[string]uint)
+	for _, s := range softwareSlice {
+		result[softwareToUniqueString(s)] = s.ID
+	}
+	return result
+}
+
 func (d *Datastore) SaveHostSoftware(host *fleet.Host) error {
 	if !host.HostSoftware.Modified {
 		return nil
 	}
 
 	if err := d.withRetryTxx(func(tx *sqlx.Tx) error {
-		// Clear join table for this host
-		sql := "DELETE FROM host_software WHERE host_id = ?"
-		if _, err := tx.Exec(sql, host.ID); err != nil {
-			return errors.Wrap(err, "clear join table entries")
-		}
-
 		if len(host.HostSoftware.Software) == 0 {
+			// Clear join table for this host
+			sql := "DELETE FROM host_software WHERE host_id = ?"
+			if _, err := tx.Exec(sql, host.ID); err != nil {
+				return errors.Wrap(err, "clear join table entries")
+			}
+
 			return nil
 		}
 
-		// Bulk insert software entries
-		var args []interface{}
-		for _, s := range host.HostSoftware.Software {
-			s.Name = truncateString(s.Name, maxSoftwareNameLen)
-			s.Version = truncateString(s.Version, maxSoftwareVersionLen)
-			s.Source = truncateString(s.Source, maxSoftwareSourceLen)
-			args = append(args, s.Name, s.Version, s.Source)
-		}
-		values := strings.TrimSuffix(strings.Repeat("(?,?,?),", len(host.HostSoftware.Software)), ",")
-		sql = fmt.Sprintf(`
-			INSERT INTO software (name, version, source)
-			VALUES %s
-			ON DUPLICATE KEY UPDATE name = name
-		`, values)
-		if _, err := tx.Exec(sql, args...); err != nil {
-			return errors.Wrap(err, "insert software")
-		}
-
-		// Bulk update join table
-		sql = fmt.Sprintf(`
-			INSERT INTO host_software (host_id, software_id)
-			SELECT ?, s.id as software_id
-			FROM software s
-			WHERE (name, version, source) IN (%s)
-		`, values)
-		if _, err := tx.Exec(sql, append([]interface{}{host.ID}, args...)...); err != nil {
-			return errors.Wrap(err, "insert join table entries")
+		if err := d.applyChangesForNewSoftware(tx, host); err != nil {
+			return err
 		}
 
 		return nil
@@ -76,16 +80,154 @@ func (d *Datastore) SaveHostSoftware(host *fleet.Host) error {
 	return nil
 }
 
-func (d *Datastore) LoadHostSoftware(host *fleet.Host) error {
-	host.HostSoftware = fleet.HostSoftware{Modified: false}
+func nothingChanged(current []fleet.Software, incoming []fleet.Software) bool {
+	if len(current) != len(incoming) {
+		return false
+	}
+
+	currentBitmap := make(map[string]bool)
+	for _, s := range current {
+		currentBitmap[softwareToUniqueString(s)] = true
+	}
+	for _, s := range incoming {
+		if _, ok := currentBitmap[softwareToUniqueString(s)]; !ok {
+			return false
+		}
+	}
+
+	return true
+}
+
+func (d *Datastore) applyChangesForNewSoftware(tx *sqlx.Tx, host *fleet.Host) error {
+	storedCurrentSoftware, err := d.hostSoftwareFromHostID(tx, host.ID)
+	if err != nil {
+		return errors.Wrap(err, "loading current software for host")
+	}
+
+	if nothingChanged(storedCurrentSoftware, host.Software) {
+		return nil
+	}
+
+	current := softwareSliceToIdMap(storedCurrentSoftware)
+	incoming := softwareSliceToSet(host.Software)
+
+	if err = d.deleteUninstalledHostSoftware(tx, host.ID, current, incoming); err != nil {
+		return err
+	}
+
+	if err = d.insertNewInstalledHostSoftware(tx, host.ID, current, incoming); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (d *Datastore) deleteUninstalledHostSoftware(
+	tx *sqlx.Tx,
+	hostID uint,
+	currentIdmap map[string]uint,
+	incomingBitmap map[string]bool,
+) error {
+	var deletesHostSoftware []interface{}
+	deletesHostSoftware = append(deletesHostSoftware, hostID)
+
+	for currentKey := range currentIdmap {
+		if _, ok := incomingBitmap[currentKey]; !ok {
+			deletesHostSoftware = append(deletesHostSoftware, currentIdmap[currentKey])
+			// TODO: delete from software if no host has it
+		}
+	}
+	if len(deletesHostSoftware) <= 1 {
+		return nil
+	}
+	sql := fmt.Sprintf(
+		`DELETE FROM host_software WHERE host_id = ? AND software_id IN (%s)`,
+		strings.TrimSuffix(strings.Repeat("?,", len(deletesHostSoftware)-1), ","),
+	)
+	if _, err := tx.Exec(sql, deletesHostSoftware...); err != nil {
+		return errors.Wrap(err, "delete host software")
+	}
+
+	return nil
+}
+
+func (d *Datastore) getOrGenerateSoftwareId(tx *sqlx.Tx, s fleet.Software) (uint, error) {
+	var existingId []int64
+	if err := tx.Select(
+		&existingId,
+		`SELECT id FROM software WHERE name = ? and version = ? and source = ?`,
+		s.Name, s.Version, s.Source,
+	); err != nil {
+		return 0, err
+	}
+	if len(existingId) > 0 {
+		return uint(existingId[0]), nil
+	}
+
+	result, err := tx.Exec(
+		`INSERT IGNORE INTO software (name, version, source) VALUES (?, ?, ?)`,
+		s.Name, s.Version, s.Source,
+	)
+	if err != nil {
+		return 0, errors.Wrap(err, "insert software")
+	}
+	id, err := result.LastInsertId()
+	if err != nil {
+		return 0, errors.Wrap(err, "last id from software")
+	}
+	return uint(id), nil
+}
+
+func (d *Datastore) insertNewInstalledHostSoftware(
+	tx *sqlx.Tx,
+	hostID uint,
+	currentIdmap map[string]uint,
+	incomingBitmap map[string]bool,
+) error {
+	var insertsHostSoftware []interface{}
+	for s := range incomingBitmap {
+		if _, ok := currentIdmap[s]; !ok {
+			id, err := d.getOrGenerateSoftwareId(tx, uniqueStringToSoftware(s))
+			if err != nil {
+				return err
+			}
+			insertsHostSoftware = append(insertsHostSoftware, hostID, id)
+		}
+	}
+	if len(insertsHostSoftware) > 0 {
+		values := strings.TrimSuffix(strings.Repeat("(?,?),", len(insertsHostSoftware)/2), ",")
+		sql := fmt.Sprintf(`INSERT INTO host_software (host_id, software_id) VALUES %s`, values)
+		if _, err := tx.Exec(sql, insertsHostSoftware...); err != nil {
+			return errors.Wrap(err, "insert host software")
+		}
+	}
+
+	return nil
+}
+
+func (d *Datastore) hostSoftwareFromHostID(tx *sqlx.Tx, id uint) ([]fleet.Software, error) {
+	selectFunc := d.db.Select
+	if tx != nil {
+		selectFunc = tx.Select
+	}
 	sql := `
 		SELECT * FROM software
 		WHERE id IN
 			(SELECT software_id FROM host_software WHERE host_id = ?)
 	`
-	if err := d.db.Select(&host.HostSoftware.Software, sql, host.ID); err != nil {
-		return errors.Wrap(err, "load host software")
+	var result []fleet.Software
+	if err := selectFunc(&result, sql, id); err != nil {
+		return nil, errors.Wrap(err, "load host software")
 	}
+	return result, nil
+}
 
+func (d *Datastore) LoadHostSoftware(host *fleet.Host) error {
+	host.HostSoftware = fleet.HostSoftware{Modified: false}
+	software, err := d.hostSoftwareFromHostID(nil, host.ID)
+	if err != nil {
+		return err
+	}
+	host.Software = software
 	return nil
 }