srvtopo

package
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 Go to latest Published: Mar 26, 2020 License: Apache-2.0 Imports: 20 Imported by: 0

Documentation

Overview

Package srvtopo contains a set of helper methods and classes to use the topology service in a serving environment.

Index

Constants

View Source 
const (

	// TopoTemplate is the HTML to use to display the
	// ResilientServerCacheStatus object
	TopoTemplate = `` /* 1447-byte string literal not displayed */

)

Variables

View Source 
var StatusFuncs = template.FuncMap{
	"github_com_vitessio_vitess_srvtopo_ttl_time":   ttlTime,
	"github_com_vitessio_vitess_srvtopo_time_since": timeSince,
}

StatusFuncs is required for CacheStatus) to work properly. We don't register them inside servenv directly so we don't introduce a dependency here.

Functions

func FindAllTargets 

func FindAllTargets(ctx context.Context, ts Server, cell string, tabletTypes []topodatapb.TabletType) ([]*querypb.Target, error)

FindAllTargets goes through all serving shards in the topology for the provided tablet types. It returns one Target object per keyspace / shard / matching TabletType.

func ResolvedShardEqual 

func ResolvedShardEqual(rs1, rs2 *ResolvedShard) bool

ResolvedShardEqual is an equality check on *ResolvedShard.

func ResolvedShardsEqual 

func ResolvedShardsEqual(rss1, rss2 []*ResolvedShard) bool

ResolvedShardsEqual is an equality check on []*ResolvedShard.

func ValuesEqual 

func ValuesEqual(vss1, vss2 [][]*querypb.Value) bool

ValuesEqual is a helper method to compare arrays of values.

Types

type ResilientServer 

type ResilientServer struct {
	// contains filtered or unexported fields
}

ResilientServer is an implementation of srvtopo.Server based on a topo.Server that uses a cache for two purposes: - limit the QPS to the underlying topo.Server - return the last known value of the data if there is an error

func NewResilientServer 

func NewResilientServer(base *topo.Server, counterPrefix string) *ResilientServer

NewResilientServer creates a new ResilientServer based on the provided topo.Server.

func (*ResilientServer) CacheStatus 

func (server *ResilientServer) CacheStatus() *ResilientServerCacheStatus

CacheStatus returns a displayable version of the cache

func (*ResilientServer) GetSrvKeyspace 

func (server *ResilientServer) GetSrvKeyspace(ctx context.Context, cell, keyspace string) (*topodatapb.SrvKeyspace, error)

GetSrvKeyspace returns SrvKeyspace object for the given cell and keyspace.

func (*ResilientServer) GetSrvKeyspaceNames 

func (server *ResilientServer) GetSrvKeyspaceNames(ctx context.Context, cell string) ([]string, error)

GetSrvKeyspaceNames returns all keyspace names for the given cell.

func (*ResilientServer) GetTopoServer 

func (server *ResilientServer) GetTopoServer() *topo.Server

GetTopoServer returns the topo.Server that backs the resilient server.

func (*ResilientServer) WatchSrvVSchema 

func (server *ResilientServer) WatchSrvVSchema(ctx context.Context, cell string, callback func(*vschemapb.SrvVSchema, error))

WatchSrvVSchema is part of the srvtopo.Server interface.

type ResilientServerCacheStatus 

type ResilientServerCacheStatus struct {
	SrvKeyspaceNames SrvKeyspaceNamesCacheStatusList
	SrvKeyspaces     SrvKeyspaceCacheStatusList
}

ResilientServerCacheStatus has the full status of the cache

type ResolvedShard 

type ResolvedShard struct {
	// Target describes the target shard.
	Target *querypb.Target

	// QueryService is the actual way to execute the query.
	QueryService queryservice.QueryService
}

ResolvedShard contains everything we need to send a query to a shard.

type Resolver 

type Resolver struct {
	// contains filtered or unexported fields
}

A Resolver can resolve keyspace ids and key ranges into ResolvedShard* objects. It uses an underlying srvtopo.Server to find the topology, and a TargetStats object to find the healthy destinations.

func NewResolver 

func NewResolver(topoServ Server, stats TargetStats, localCell string) *Resolver

NewResolver creates a new Resolver.

func (*Resolver) GetAllKeyspaces 

func (r *Resolver) GetAllKeyspaces(ctx context.Context) ([]string, error)

GetAllKeyspaces returns all the known keyspaces in the local cell.

func (*Resolver) GetAllShards 

func (r *Resolver) GetAllShards(ctx context.Context, keyspace string, tabletType topodatapb.TabletType) ([]*ResolvedShard, *topodatapb.SrvKeyspace, error)

GetAllShards returns the list of ResolvedShards associated with all the shards in a keyspace. FIXME(alainjobart) callers should convert to ResolveDestination(), and GetSrvKeyspace.

func (*Resolver) GetKeyspaceShards 

func (r *Resolver) GetKeyspaceShards(ctx context.Context, keyspace string, tabletType topodatapb.TabletType) (string, *topodatapb.SrvKeyspace, []*topodatapb.ShardReference, error)

GetKeyspaceShards return all the shards in a keyspace. It follows redirection if ServedFrom is set. It is only valid for the local cell. Do not use it to further resolve shards, instead use the Resolve* methods.

func (*Resolver) ResolveDestination 

func (r *Resolver) ResolveDestination(ctx context.Context, keyspace string, tabletType topodatapb.TabletType, destination key.Destination) ([]*ResolvedShard, error)

ResolveDestination is a shortcut to ResolveDestinations with only one Destination, and no ids.

func (*Resolver) ResolveDestinations 

func (r *Resolver) ResolveDestinations(ctx context.Context, keyspace string, tabletType topodatapb.TabletType, ids []*querypb.Value, destinations []key.Destination) ([]*ResolvedShard, [][]*querypb.Value, error)

ResolveDestinations resolves values and their destinations into their respective shards.

If ids is nil, the returned [][]*querypb.Value is also nil. Otherwise, len(ids) has to match len(destinations), and then the returned [][]*querypb.Value is populated with all the values that go in each shard, and len([]*ResolvedShard) matches len([][]*querypb.Value).

Sample input / output: - destinations: dst1, dst2, dst3 - ids: id1, id2, id3 If dst1 is in shard1, and dst2 and dst3 are in shard2, the output will be: - []*ResolvedShard: shard1, shard2 - [][]*querypb.Value: [id1], [id2, id3]

type Server 

type Server interface {
	// GetTopoServer returns the full topo.Server instance
	GetTopoServer() *topo.Server

	// GetSrvKeyspaceNames returns the list of keyspaces served in
	// the provided cell.
	GetSrvKeyspaceNames(ctx context.Context, cell string) ([]string, error)

	// GetSrvKeyspace returns the SrvKeyspace for a cell/keyspace.
	GetSrvKeyspace(ctx context.Context, cell, keyspace string) (*topodatapb.SrvKeyspace, error)

	// WatchSrvVSchema starts watching the SrvVSchema object for
	// the provided cell.  It will call the callback when
	// a new value or an error occurs.
	WatchSrvVSchema(ctx context.Context, cell string, callback func(*vschemapb.SrvVSchema, error))
}

Server is a subset of the topo.Server API that only contains the serving graph read-only calls used by clients to resolve serving addresses, and to get VSchema.

type SrvKeyspaceCacheStatus 

type SrvKeyspaceCacheStatus struct {
	Cell           string
	Keyspace       string
	Value          *topodatapb.SrvKeyspace
	ExpirationTime time.Time
	LastErrorTime  time.Time
	LastError      error
	LastErrorCtx   context.Context
}

SrvKeyspaceCacheStatus is the current value for a SrvKeyspace object

func (*SrvKeyspaceCacheStatus) StatusAsHTML 

func (st *SrvKeyspaceCacheStatus) StatusAsHTML() template.HTML

StatusAsHTML returns an HTML version of our status. It works best if there is data in the cache.

type SrvKeyspaceCacheStatusList 

type SrvKeyspaceCacheStatusList []*SrvKeyspaceCacheStatus

SrvKeyspaceCacheStatusList is used for sorting

func (SrvKeyspaceCacheStatusList) Len 

func (skcsl SrvKeyspaceCacheStatusList) Len() int

Len is part of sort.Interface

func (SrvKeyspaceCacheStatusList) Less 

func (skcsl SrvKeyspaceCacheStatusList) Less(i, j int) bool

Less is part of sort.Interface

func (SrvKeyspaceCacheStatusList) Swap 

func (skcsl SrvKeyspaceCacheStatusList) Swap(i, j int)

Swap is part of sort.Interface

type SrvKeyspaceNamesCacheStatus 

type SrvKeyspaceNamesCacheStatus struct {
	Cell           string
	Value          []string
	ExpirationTime time.Time
	LastQueryTime  time.Time
	LastError      error
	LastErrorCtx   context.Context
}

SrvKeyspaceNamesCacheStatus is the current value for SrvKeyspaceNames

type SrvKeyspaceNamesCacheStatusList 

type SrvKeyspaceNamesCacheStatusList []*SrvKeyspaceNamesCacheStatus

SrvKeyspaceNamesCacheStatusList is used for sorting

func (SrvKeyspaceNamesCacheStatusList) Len 

func (skncsl SrvKeyspaceNamesCacheStatusList) Len() int

Len is part of sort.Interface

func (SrvKeyspaceNamesCacheStatusList) Less 

func (skncsl SrvKeyspaceNamesCacheStatusList) Less(i, j int) bool

Less is part of sort.Interface

func (SrvKeyspaceNamesCacheStatusList) Swap 

func (skncsl SrvKeyspaceNamesCacheStatusList) Swap(i, j int)

Swap is part of sort.Interface

type TargetStats 

type TargetStats interface {
	// GetAggregateStats returns the aggregate stats for the given Target.
	// The srvtopo module will use that information to route queries
	// to the right cell. Also returns the QueryService to use to
	// reach that target.
	// Can return topo.ErrNoNode if the target has no stats.
	GetAggregateStats(target *querypb.Target) (*querypb.AggregateStats, queryservice.QueryService, error)

	// GetMasterCell returns the master location for a keyspace/shard.
	// Since there is only one master for a shard, we only need to
	// know its cell to complete the Target. Also returns the QueryService
	// to use to reach that target.
	GetMasterCell(keyspace, shard string) (cell string, qs queryservice.QueryService, err error)
}

TargetStats is an interface that the srvtopo module uses to handle routing of queries.

  • discovery.TabletStatsCache will implement the discovery part of the interface, and discoverygateway will have the QueryService.
  • hybridgateway will also implement this interface: for each l2vtgate pool, it will establish a StreamHealth connection, and store the returned health stats.

type TargetStatsEntry 

type TargetStatsEntry struct {
	// Target is what this entry applies to.
	Target *querypb.Target

	// Stats is the aggregate stats for this entry.
	Stats *querypb.AggregateStats

	// TabletExternallyReparentedTimestamp is the latest timestamp
	// that was reported for this entry. It applies to masters only.
	TabletExternallyReparentedTimestamp int64
}

TargetStatsEntry has the updated information for a Target.

type TargetStatsListener 

type TargetStatsListener interface {
	// Subscribe will return the current full state of the TargetStats,
	// and a channel that will receive subsequent updates. The int returned
	// is the channel id, and can be sent to unsubscribe to stop
	// notifications.
	Subscribe() (int, []TargetStatsEntry, <-chan (*TargetStatsEntry), error)

	// Unsubscribe stops sending updates to the channel returned
	// by Subscribe. The channel still needs to be drained to
	// avoid deadlocks.
	Unsubscribe(int) error
}

TargetStatsListener is an interface used to propagate TargetStats changes.

  • discovery.TabletStatsCache will implement this interface.
  • the StreamHealth method in l2vtgate will use this interface to surface the health of its targets.

type TargetStatsMultiplexer 

type TargetStatsMultiplexer struct {
	// contains filtered or unexported fields
}

TargetStatsMultiplexer is a helper class to help broadcast stats updates. It doesn't have any synchronization, as the container class will already have some and this can just use it.

func NewTargetStatsMultiplexer 

func NewTargetStatsMultiplexer() TargetStatsMultiplexer

NewTargetStatsMultiplexer returns an initialized TargetStatsMultiplexer.

func (*TargetStatsMultiplexer) Broadcast 

func (tsm *TargetStatsMultiplexer) Broadcast(tse *TargetStatsEntry)

Broadcast sends an update to the list. Will read the list.

func (*TargetStatsMultiplexer) HasSubscribers 

func (tsm *TargetStatsMultiplexer) HasSubscribers() bool

HasSubscribers returns true if we have registered subscribers. Will read the list.

func (*TargetStatsMultiplexer) Subscribe 

func (tsm *TargetStatsMultiplexer) Subscribe() (int, <-chan (*TargetStatsEntry))

Subscribe adds a channel to the list. Will change the list.

func (*TargetStatsMultiplexer) Unsubscribe 

func (tsm *TargetStatsMultiplexer) Unsubscribe(i int) error

Unsubscribe removes a channel from the list. Will change the list.

Source Files

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