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tablet.go
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tablet.go
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// Copyright 2013, Google Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package topo
import (
"fmt"
"sync"
"golang.org/x/net/context"
log "github.com/golang/glog"
"github.com/youtube/vitess/go/event"
"github.com/youtube/vitess/go/netutil"
"github.com/youtube/vitess/go/trace"
topodatapb "github.com/youtube/vitess/go/vt/proto/topodata"
"github.com/youtube/vitess/go/vt/topo/events"
"github.com/youtube/vitess/go/vt/topo/topoproto"
)
// IsTrivialTypeChange returns if this db type be trivially reassigned
// without changes to the replication graph
func IsTrivialTypeChange(oldTabletType, newTabletType topodatapb.TabletType) bool {
switch oldTabletType {
case topodatapb.TabletType_REPLICA, topodatapb.TabletType_RDONLY, topodatapb.TabletType_SPARE, topodatapb.TabletType_BACKUP, topodatapb.TabletType_EXPERIMENTAL, topodatapb.TabletType_DRAINED:
switch newTabletType {
case topodatapb.TabletType_REPLICA, topodatapb.TabletType_RDONLY, topodatapb.TabletType_SPARE, topodatapb.TabletType_BACKUP, topodatapb.TabletType_EXPERIMENTAL, topodatapb.TabletType_DRAINED:
return true
}
case topodatapb.TabletType_RESTORE:
switch newTabletType {
case topodatapb.TabletType_SPARE:
return true
}
}
return false
}
// IsInServingGraph returns if a tablet appears in the serving graph
func IsInServingGraph(tt topodatapb.TabletType) bool {
switch tt {
case topodatapb.TabletType_MASTER, topodatapb.TabletType_REPLICA, topodatapb.TabletType_RDONLY:
return true
}
return false
}
// IsRunningQueryService returns if a tablet is running the query service
func IsRunningQueryService(tt topodatapb.TabletType) bool {
switch tt {
case topodatapb.TabletType_MASTER, topodatapb.TabletType_REPLICA, topodatapb.TabletType_RDONLY, topodatapb.TabletType_EXPERIMENTAL, topodatapb.TabletType_DRAINED:
return true
}
return false
}
// IsSubjectToLameduck returns if a tablet is subject to being
// lameduck. Lameduck is a transition period where we are still
// allowed to serve, but we tell the clients we are going away
// soon. Typically, a vttablet will still serve, but broadcast a
// non-serving state through its health check. then vtgate will ctahc
// that non-serving state, and stop sending queries.
//
// Masters are not subject to lameduck, as we usually want to transition
// them as fast as possible.
//
// Replica and rdonly will use lameduck when going from healthy to
// unhealhty (either because health check fails, or they're shutting down).
//
// Other types are probably not serving user visible traffic, so they
// need to transition as fast as possible too.
func IsSubjectToLameduck(tt topodatapb.TabletType) bool {
switch tt {
case topodatapb.TabletType_REPLICA, topodatapb.TabletType_RDONLY:
return true
}
return false
}
// IsRunningUpdateStream returns if a tablet is running the update stream
// RPC service.
func IsRunningUpdateStream(tt topodatapb.TabletType) bool {
switch tt {
case topodatapb.TabletType_MASTER, topodatapb.TabletType_REPLICA, topodatapb.TabletType_RDONLY:
return true
}
return false
}
// IsSlaveType returns if this type should be connected to a master db
// and actively replicating?
// MASTER is not obviously (only support one level replication graph)
// BACKUP, RESTORE, DRAINED may or may not be, but we don't know for sure
func IsSlaveType(tt topodatapb.TabletType) bool {
switch tt {
case topodatapb.TabletType_MASTER, topodatapb.TabletType_BACKUP, topodatapb.TabletType_RESTORE, topodatapb.TabletType_DRAINED:
return false
}
return true
}
// TabletComplete validates and normalizes the tablet. If the shard name
// contains a '-' it is going to try to infer the keyrange from it.
func TabletComplete(tablet *topodatapb.Tablet) error {
shard, kr, err := ValidateShardName(tablet.Shard)
if err != nil {
return err
}
tablet.Shard = shard
tablet.KeyRange = kr
return nil
}
// NewTablet create a new Tablet record with the given id, cell, and hostname.
func NewTablet(uid uint32, cell, host string) *topodatapb.Tablet {
return &topodatapb.Tablet{
Alias: &topodatapb.TabletAlias{
Cell: cell,
Uid: uid,
},
Hostname: host,
PortMap: make(map[string]int32),
}
}
// TabletEquality returns true iff two Tablet are representing the same tablet
// process: same uid/cell, running on the same host / ports.
func TabletEquality(left, right *topodatapb.Tablet) bool {
if !topoproto.TabletAliasEqual(left.Alias, right.Alias) {
return false
}
if left.Hostname != right.Hostname {
return false
}
if len(left.PortMap) != len(right.PortMap) {
return false
}
for key, lvalue := range left.PortMap {
rvalue, ok := right.PortMap[key]
if !ok {
return false
}
if lvalue != rvalue {
return false
}
}
return true
}
// TabletInfo is the container for a Tablet, read from the topology server.
type TabletInfo struct {
version int64 // node version - used to prevent stomping concurrent writes
*topodatapb.Tablet
}
// String returns a string describing the tablet.
func (ti *TabletInfo) String() string {
return fmt.Sprintf("Tablet{%v}", topoproto.TabletAliasString(ti.Alias))
}
// AliasString returns the string representation of the tablet alias
func (ti *TabletInfo) AliasString() string {
return topoproto.TabletAliasString(ti.Alias)
}
// Addr returns hostname:vt port.
func (ti *TabletInfo) Addr() string {
return netutil.JoinHostPort(ti.Hostname, int32(ti.PortMap["vt"]))
}
// MysqlAddr returns hostname:mysql port.
func (ti *TabletInfo) MysqlAddr() string {
return netutil.JoinHostPort(ti.Hostname, int32(ti.PortMap["mysql"]))
}
// DbName is usually implied by keyspace. Having the shard information in the
// database name complicates mysql replication.
func (ti *TabletInfo) DbName() string {
return topoproto.TabletDbName(ti.Tablet)
}
// Version returns the version of this tablet from last time it was read or
// updated.
func (ti *TabletInfo) Version() int64 {
return ti.version
}
// IsInServingGraph returns if this tablet is in the serving graph
func (ti *TabletInfo) IsInServingGraph() bool {
return IsInServingGraph(ti.Type)
}
// IsSlaveType returns if this tablet's type is a slave
func (ti *TabletInfo) IsSlaveType() bool {
return IsSlaveType(ti.Type)
}
// NewTabletInfo returns a TabletInfo basing on tablet with the
// version set. This function should be only used by Server
// implementations.
func NewTabletInfo(tablet *topodatapb.Tablet, version int64) *TabletInfo {
return &TabletInfo{version: version, Tablet: tablet}
}
// GetTablet is a high level function to read tablet data.
// It generates trace spans.
func (ts Server) GetTablet(ctx context.Context, alias *topodatapb.TabletAlias) (*TabletInfo, error) {
span := trace.NewSpanFromContext(ctx)
span.StartClient("TopoServer.GetTablet")
span.Annotate("tablet", topoproto.TabletAliasString(alias))
defer span.Finish()
value, version, err := ts.Impl.GetTablet(ctx, alias)
if err != nil {
return nil, err
}
return &TabletInfo{
version: version,
Tablet: value,
}, nil
}
// UpdateTablet updates the tablet data only - not associated replication paths.
// It also uses a span, and sends the event.
func (ts Server) UpdateTablet(ctx context.Context, tablet *TabletInfo) error {
span := trace.NewSpanFromContext(ctx)
span.StartClient("TopoServer.UpdateTablet")
span.Annotate("tablet", topoproto.TabletAliasString(tablet.Alias))
defer span.Finish()
var version int64 = -1
if tablet.version != 0 {
version = tablet.version
}
newVersion, err := ts.Impl.UpdateTablet(ctx, tablet.Tablet, version)
if err != nil {
return err
}
tablet.version = newVersion
event.Dispatch(&events.TabletChange{
Tablet: *tablet.Tablet,
Status: "updated",
})
return nil
}
// UpdateTabletFields is a high level helper to read a tablet record, call an
// update function on it, and then write it back. If the write fails due to
// a version mismatch, it will re-read the record and retry the update.
// If the update succeeds, it returns the updated tablet.
// If the update method returns ErrNoUpdateNeeded, nothing is written,
// and nil,nil is returned.
func (ts Server) UpdateTabletFields(ctx context.Context, alias *topodatapb.TabletAlias, update func(*topodatapb.Tablet) error) (*topodatapb.Tablet, error) {
span := trace.NewSpanFromContext(ctx)
span.StartClient("TopoServer.UpdateTabletFields")
span.Annotate("tablet", topoproto.TabletAliasString(alias))
defer span.Finish()
for {
ti, err := ts.GetTablet(ctx, alias)
if err != nil {
return nil, err
}
if err = update(ti.Tablet); err != nil {
if err == ErrNoUpdateNeeded {
return nil, nil
}
return nil, err
}
if err = ts.UpdateTablet(ctx, ti); err != ErrBadVersion {
return ti.Tablet, err
}
}
}
// Validate makes sure a tablet is represented correctly in the topology server.
func Validate(ctx context.Context, ts Server, tabletAlias *topodatapb.TabletAlias) error {
// read the tablet record, make sure it parses
tablet, err := ts.GetTablet(ctx, tabletAlias)
if err != nil {
return err
}
if !topoproto.TabletAliasEqual(tablet.Alias, tabletAlias) {
return fmt.Errorf("bad tablet alias data for tablet %v: %#v", topoproto.TabletAliasString(tabletAlias), tablet.Alias)
}
// Validate the entry in the shard replication nodes
si, err := ts.GetShardReplication(ctx, tablet.Alias.Cell, tablet.Keyspace, tablet.Shard)
if err != nil {
return err
}
if _, err = si.GetShardReplicationNode(tabletAlias); err != nil {
return fmt.Errorf("tablet %v not found in cell %v shard replication: %v", tabletAlias, tablet.Alias.Cell, err)
}
return nil
}
// CreateTablet creates a new tablet and all associated paths for the
// replication graph.
func (ts Server) CreateTablet(ctx context.Context, tablet *topodatapb.Tablet) error {
// Have the Server create the tablet
err := ts.Impl.CreateTablet(ctx, tablet)
if err != nil && err != ErrNodeExists {
return err
}
// Update ShardReplication in any case, to be sure. This is
// meant to fix the case when a Tablet record was created, but
// then the ShardReplication record was not (because for
// instance of a startup timeout). Upon running this code
// again, we want to fix ShardReplication.
if updateErr := UpdateTabletReplicationData(ctx, ts, tablet); updateErr != nil {
return updateErr
}
if err == nil {
event.Dispatch(&events.TabletChange{
Tablet: *tablet,
Status: "created",
})
}
return err
}
// DeleteTablet wraps the underlying Impl.DeleteTablet
// and dispatches the event.
func (ts Server) DeleteTablet(ctx context.Context, tabletAlias *topodatapb.TabletAlias) error {
// get the current tablet record, if any, to log the deletion
tablet, _, tErr := ts.Impl.GetTablet(ctx, tabletAlias)
if err := ts.Impl.DeleteTablet(ctx, tabletAlias); err != nil {
return err
}
// Only try to log if we have the required info.
if tErr == nil {
// Only copy the identity info for the tablet. The rest has been deleted.
event.Dispatch(&events.TabletChange{
Tablet: topodatapb.Tablet{
Alias: tabletAlias,
Keyspace: tablet.Keyspace,
Shard: tablet.Shard,
},
Status: "deleted",
})
}
return nil
}
// UpdateTabletReplicationData creates or updates the replication
// graph data for a tablet
func UpdateTabletReplicationData(ctx context.Context, ts Server, tablet *topodatapb.Tablet) error {
return UpdateShardReplicationRecord(ctx, ts, tablet.Keyspace, tablet.Shard, tablet.Alias)
}
// DeleteTabletReplicationData deletes replication data.
func DeleteTabletReplicationData(ctx context.Context, ts Server, tablet *topodatapb.Tablet) error {
return RemoveShardReplicationRecord(ctx, ts, tablet.Alias.Cell, tablet.Keyspace, tablet.Shard, tablet.Alias)
}
// GetTabletMap tries to read all the tablets in the provided list,
// and returns them all in a map.
// If error is ErrPartialResult, the results in the dictionary are
// incomplete, meaning some tablets couldn't be read.
func (ts Server) GetTabletMap(ctx context.Context, tabletAliases []*topodatapb.TabletAlias) (map[topodatapb.TabletAlias]*TabletInfo, error) {
span := trace.NewSpanFromContext(ctx)
span.StartLocal("topo.GetTabletMap")
span.Annotate("num_tablets", len(tabletAliases))
defer span.Finish()
wg := sync.WaitGroup{}
mutex := sync.Mutex{}
tabletMap := make(map[topodatapb.TabletAlias]*TabletInfo)
var someError error
for _, tabletAlias := range tabletAliases {
wg.Add(1)
go func(tabletAlias *topodatapb.TabletAlias) {
defer wg.Done()
tabletInfo, err := ts.GetTablet(ctx, tabletAlias)
mutex.Lock()
if err != nil {
log.Warningf("%v: %v", tabletAlias, err)
// There can be data races removing nodes - ignore them for now.
if err != ErrNoNode {
someError = ErrPartialResult
}
} else {
tabletMap[*tabletAlias] = tabletInfo
}
mutex.Unlock()
}(tabletAlias)
}
wg.Wait()
return tabletMap, someError
}