vitess.io/vitess@v0.16.2/go/vt/wrangler/cleaner.go

/*
Copyright 2019 The Vitess 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 wrangler

import (
	"fmt"
	"sync"
	"time"

	"context"

	"vitess.io/vitess/go/vt/concurrency"
	"vitess.io/vitess/go/vt/topo"
	"vitess.io/vitess/go/vt/topo/topoproto"

	topodatapb "vitess.io/vitess/go/vt/proto/topodata"
)

const (
	// ChangeTabletTypeActionName is the name of the action to change a tablet type
	// (can be used to find such an action by name)
	ChangeTabletTypeActionName = "ChangeTabletTypeAction"

	// TabletTagActionName is the name of the Tag action
	TabletTagActionName = "TabletTagAction"

	// StartReplicationActionName is the name of the start replication action
	StartReplicationActionName = "StartReplicationAction"

	// VReplicationActionName is the name of the action to execute VReplication commands
	VReplicationActionName = "VReplicationAction"
)

// Cleaner remembers a list of cleanup steps to perform.  Just record
// action cleanup steps, and execute them at the end in reverse
// order, with various guarantees.
type Cleaner struct {
	// mu protects the following members
	mu      sync.Mutex
	actions []cleanerActionReference
}

// cleanerActionReference is the node used by Cleaner
type cleanerActionReference struct {
	name   string
	target string
	action CleanerFunction
}

// CleanerFunction is the interface that clean-up actions need to implement
type CleanerFunction func(context.Context, *Wrangler) error

// Record will add a cleaning action to the list
func (cleaner *Cleaner) Record(name, target string, action CleanerFunction) {
	cleaner.mu.Lock()
	cleaner.actions = append(cleaner.actions, cleanerActionReference{
		name:   name,
		target: target,
		action: action,
	})
	cleaner.mu.Unlock()
}

type cleanUpHelper struct {
	err error
}

// CleanUp will run the recorded actions.
// If an action on a target fails, it will not run the next action on
// the same target.
// We return the aggregate errors for all cleanups.
// CleanUp uses its own context, with a timeout of 5 minutes, so that clean up action will run even if the original context times out.
// TODO(alainjobart) Actions should run concurrently on a per target
// basis. They are then serialized on each target.
func (cleaner *Cleaner) CleanUp(wr *Wrangler) error {
	// we use a background context so we're not dependent on the original context timeout
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Minute)
	actionMap := make(map[string]*cleanUpHelper)
	rec := concurrency.AllErrorRecorder{}
	cleaner.mu.Lock()
	for i := len(cleaner.actions) - 1; i >= 0; i-- {
		actionReference := cleaner.actions[i]
		helper, ok := actionMap[actionReference.target]
		if !ok {
			helper = &cleanUpHelper{
				err: nil,
			}
			actionMap[actionReference.target] = helper
		}
		if helper.err != nil {
			wr.Logger().Warningf("previous action failed on target %v, not running %v", actionReference.target, actionReference.name)
			continue
		}
		err := actionReference.action(ctx, wr)
		if err != nil {
			helper.err = err
			rec.RecordError(err)
			wr.Logger().Errorf2(err, "action %v failed on %v", actionReference.name, actionReference.target)
		} else {
			wr.Logger().Infof("action %v successful on %v", actionReference.name, actionReference.target)
		}
	}
	cleaner.mu.Unlock()
	cancel()
	return rec.Error()
}

// RecordChangeTabletTypeAction records a new ChangeTabletTypeAction
// into the specified Cleaner
func RecordChangeTabletTypeAction(cleaner *Cleaner, tabletAlias *topodatapb.TabletAlias, from topodatapb.TabletType, to topodatapb.TabletType) {
	cleaner.Record(ChangeTabletTypeActionName, topoproto.TabletAliasString(tabletAlias), func(ctx context.Context, wr *Wrangler) error {
		ti, err := wr.ts.GetTablet(ctx, tabletAlias)
		if err != nil {
			return err
		}
		if ti.Type != from {
			return fmt.Errorf("tablet %v is not of the right type (got %v expected %v), not changing it to %v", topoproto.TabletAliasString(tabletAlias), ti.Type, from, to)
		}
		if !topo.IsTrivialTypeChange(ti.Type, to) {
			return fmt.Errorf("tablet %v type change %v -> %v is not an allowed transition for ChangeTabletType", topoproto.TabletAliasString(tabletAlias), ti.Type, to)
		}

		// ask the tablet to make the change
		return wr.ChangeTabletType(ctx, ti.Tablet.Alias, to)
	})
}

// RecordStartReplicationAction records a new action to restart binlog replication on a server
// into the specified Cleaner
func RecordStartReplicationAction(cleaner *Cleaner, tablet *topodatapb.Tablet) {
	cleaner.Record(StartReplicationActionName, topoproto.TabletAliasString(tablet.Alias), func(ctx context.Context, wr *Wrangler) error {
		return wr.StartReplication(ctx, tablet)
	})
}

// RecordVReplicationAction records an action to restart binlog replication on a server
// into the specified Cleaner
func RecordVReplicationAction(cleaner *Cleaner, tablet *topodatapb.Tablet, query string) {
	cleaner.Record(VReplicationActionName, topoproto.TabletAliasString(tablet.Alias), func(ctx context.Context, wr *Wrangler) error {
		_, err := wr.TabletManagerClient().VReplicationExec(ctx, tablet, query)
		return err
	})
}