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// Copyright 2017 The LUCI 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 model
import (
"context"
"go.chromium.org/luci/common/errors"
"go.chromium.org/luci/common/logging"
"go.chromium.org/luci/machine-db/api/config/v1"
"go.chromium.org/luci/machine-db/appengine/database"
)
// Switch represents a row in the switches table.
type Switch struct {
config.Switch
RackId int64
Id int64
}
// SwitchesTable represents the table of switches in the database.
type SwitchesTable struct {
// racks is a map of rack name to ID in the database.
racks map[string]int64
// current is the slice of switches in the database.
current []*Switch
// additions is a slice of switches pending addition to the database.
additions []*Switch
// removals is a slice of switches pending removal from the database.
removals []*Switch
// updates is a slice of switches pending update in the database.
updates []*Switch
}
// fetch fetches the switches from the database.
func (t *SwitchesTable) fetch(c context.Context) error {
db := database.Get(c)
rows, err := db.QueryContext(c, `
SELECT id, name, description, ports, state, rack_id
FROM switches
`)
if err != nil {
return errors.Annotate(err, "failed to select switches").Err()
}
defer rows.Close()
for rows.Next() {
s := &Switch{}
if err := rows.Scan(&s.Id, &s.Name, &s.Description, &s.Ports, &s.State, &s.RackId); err != nil {
return errors.Annotate(err, "failed to scan switch").Err()
}
t.current = append(t.current, s)
}
return nil
}
// needsUpdate returns true if the given row needs to be updated to match the given config.
func (*SwitchesTable) needsUpdate(row, cfg *Switch) bool {
return row.Ports != cfg.Ports || row.Description != cfg.Description || row.State != cfg.State || row.RackId != cfg.RackId
}
// computeChanges computes the changes that need to be made to the switches in the database.
func (t *SwitchesTable) computeChanges(c context.Context, datacenters []*config.Datacenter) error {
cfgs := make(map[string]*Switch, len(datacenters))
for _, dc := range datacenters {
for _, rack := range dc.Rack {
for _, cfg := range rack.Switch {
id, ok := t.racks[rack.Name]
if !ok {
return errors.Reason("failed to determine rack ID for switch %q: rack %q does not exist", cfg.Name, rack.Name).Err()
}
cfgs[cfg.Name] = &Switch{
Switch: config.Switch{
Name: cfg.Name,
Description: cfg.Description,
Ports: cfg.Ports,
State: cfg.State,
},
RackId: id,
}
}
}
}
for _, s := range t.current {
if cfg, ok := cfgs[s.Name]; ok {
// Switch found in the config.
if t.needsUpdate(s, cfg) {
// Switch doesn't match the config.
cfg.Id = s.Id
t.updates = append(t.updates, cfg)
}
// Record that the switch config has been seen.
delete(cfgs, cfg.Name)
} else {
// Switch not found in the config.
t.removals = append(t.removals, s)
}
}
// Switches remaining in the map are present in the config but not the database.
// Iterate deterministically over the slices to determine which switches need to be added.
for _, dc := range datacenters {
for _, rack := range dc.Rack {
for _, cfg := range rack.Switch {
if s, ok := cfgs[cfg.Name]; ok {
t.additions = append(t.additions, s)
}
}
}
}
return nil
}
// add adds all switches pending addition to the database, clearing pending additions.
// No-op unless computeChanges was called first. Idempotent until computeChanges is called again.
func (t *SwitchesTable) add(c context.Context) error {
// Avoid using the database connection to prepare unnecessary statements.
if len(t.additions) == 0 {
return nil
}
db := database.Get(c)
stmt, err := db.PrepareContext(c, `
INSERT INTO switches (name, description, ports, state, rack_id)
VALUES (?, ?, ?, ?, ?)
`)
if err != nil {
return errors.Annotate(err, "failed to prepare statement").Err()
}
defer stmt.Close()
// Add each switch to the database, and update the slice of switches with each addition.
for len(t.additions) > 0 {
s := t.additions[0]
result, err := stmt.ExecContext(c, s.Name, s.Description, s.Ports, s.State, s.RackId)
if err != nil {
return errors.Annotate(err, "failed to add switch %q", s.Name).Err()
}
t.current = append(t.current, s)
t.additions = t.additions[1:]
logging.Infof(c, "Added switch %q", s.Name)
s.Id, err = result.LastInsertId()
if err != nil {
return errors.Annotate(err, "failed to get switch ID %q", s.Name).Err()
}
}
return nil
}
// remove removes all switches pending removal from the database, clearing pending removals.
// No-op unless computeChanges was called first. Idempotent until computeChanges is called again.
func (t *SwitchesTable) remove(c context.Context) error {
// Avoid using the database connection to prepare unnecessary statements.
if len(t.removals) == 0 {
return nil
}
db := database.Get(c)
stmt, err := db.PrepareContext(c, `
DELETE FROM switches
WHERE id = ?
`)
if err != nil {
return errors.Annotate(err, "failed to prepare statement").Err()
}
defer stmt.Close()
// Remove each switch from the table. It's more efficient to update the slice of
// switches once at the end rather than for each removal, so use a defer.
removed := make(map[int64]struct{}, len(t.removals))
defer func() {
var switches []*Switch
for _, s := range t.current {
if _, ok := removed[s.Id]; !ok {
switches = append(switches, s)
}
}
t.current = switches
}()
for len(t.removals) > 0 {
s := t.removals[0]
if _, err := stmt.ExecContext(c, s.Id); err != nil {
// Defer ensures the slice of switches is updated even if we exit early.
return errors.Annotate(err, "failed to remove switch %q", s.Name).Err()
}
removed[s.Id] = struct{}{}
t.removals = t.removals[1:]
logging.Infof(c, "Removed switch %q", s.Name)
}
return nil
}
// update updates all switches pending update in the database, clearing pending updates.
// No-op unless computeChanges was called first. Idempotent until computeChanges is called again.
func (t *SwitchesTable) update(c context.Context) error {
// Avoid using the database connection to prepare unnecessary statements.
if len(t.updates) == 0 {
return nil
}
db := database.Get(c)
stmt, err := db.PrepareContext(c, `
UPDATE switches
SET description = ?, ports = ?, state = ?, rack_id = ?
WHERE id = ?
`)
if err != nil {
return errors.Annotate(err, "failed to prepare statement").Err()
}
defer stmt.Close()
// Update each switch in the table. It's more efficient to update the slice of
// switches once at the end rather than for each update, so use a defer.
updated := make(map[int64]*Switch, len(t.updates))
defer func() {
for _, s := range t.current {
if u, ok := updated[s.Id]; ok {
s.Description = u.Description
s.Ports = u.Ports
s.State = u.State
s.RackId = u.RackId
}
}
}()
for len(t.updates) > 0 {
s := t.updates[0]
if _, err := stmt.ExecContext(c, s.Description, s.Ports, s.State, s.RackId, s.Id); err != nil {
return errors.Annotate(err, "failed to update switch %q", s.Name).Err()
}
updated[s.Id] = s
t.updates = t.updates[1:]
logging.Infof(c, "Updated switch %q", s.Name)
}
return nil
}
// ids returns a map of switch names to IDs.
func (t *SwitchesTable) ids(c context.Context) map[string]int64 {
switches := make(map[string]int64, len(t.current))
for _, s := range t.current {
switches[s.Name] = s.Id
}
return switches
}
// EnsureSwitches ensures the database contains exactly the given switches.
func EnsureSwitches(c context.Context, cfgs []*config.Datacenter, rackIds map[string]int64) error {
t := &SwitchesTable{}
t.racks = rackIds
if err := t.fetch(c); err != nil {
return errors.Annotate(err, "failed to fetch switches").Err()
}
if err := t.computeChanges(c, cfgs); err != nil {
return errors.Annotate(err, "failed to compute changes").Err()
}
if err := t.add(c); err != nil {
return errors.Annotate(err, "failed to add switches").Err()
}
if err := t.remove(c); err != nil {
return errors.Annotate(err, "failed to remove switches").Err()
}
if err := t.update(c); err != nil {
return errors.Annotate(err, "failed to update switches").Err()
}
return nil
}