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points_writer.go
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points_writer.go
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package coordinator
import (
"errors"
"fmt"
"sort"
"sync"
"sync/atomic"
"time"
"github.com/influxdata/influxdb"
"github.com/influxdata/influxdb/models"
"github.com/influxdata/influxdb/services/meta"
"github.com/influxdata/influxdb/tsdb"
"github.com/uber-go/zap"
)
// The keys for statistics generated by the "write" module.
const (
statWriteReq = "req"
statPointWriteReq = "pointReq"
statPointWriteReqLocal = "pointReqLocal"
statWriteOK = "writeOk"
statWriteDrop = "writeDrop"
statWriteTimeout = "writeTimeout"
statWriteErr = "writeError"
statSubWriteOK = "subWriteOk"
statSubWriteDrop = "subWriteDrop"
)
var (
// ErrTimeout is returned when a write times out.
ErrTimeout = errors.New("timeout")
// ErrPartialWrite is returned when a write partially succeeds but does
// not meet the requested consistency level.
ErrPartialWrite = errors.New("partial write")
// ErrWriteFailed is returned when no writes succeeded.
ErrWriteFailed = errors.New("write failed")
)
// PointsWriter handles writes across multiple local and remote data nodes.
type PointsWriter struct {
mu sync.RWMutex
closing chan struct{}
WriteTimeout time.Duration
Logger zap.Logger
Node *influxdb.Node
MetaClient interface {
Database(name string) (di *meta.DatabaseInfo)
RetentionPolicy(database, policy string) (*meta.RetentionPolicyInfo, error)
CreateShardGroup(database, policy string, timestamp time.Time) (*meta.ShardGroupInfo, error)
}
TSDBStore interface {
CreateShard(database, retentionPolicy string, shardID uint64, enabled bool) error
WriteToShard(shardID uint64, points []models.Point) error
}
Subscriber interface {
Points() chan<- *WritePointsRequest
}
subPoints chan<- *WritePointsRequest
stats *WriteStatistics
}
// WritePointsRequest represents a request to write point data to the cluster.
type WritePointsRequest struct {
Database string
RetentionPolicy string
Points []models.Point
}
// AddPoint adds a point to the WritePointRequest with field key 'value'
func (w *WritePointsRequest) AddPoint(name string, value interface{}, timestamp time.Time, tags map[string]string) {
pt, err := models.NewPoint(
name, models.NewTags(tags), map[string]interface{}{"value": value}, timestamp,
)
if err != nil {
return
}
w.Points = append(w.Points, pt)
}
// NewPointsWriter returns a new instance of PointsWriter for a node.
func NewPointsWriter() *PointsWriter {
return &PointsWriter{
closing: make(chan struct{}),
WriteTimeout: DefaultWriteTimeout,
Logger: zap.New(zap.NullEncoder()),
stats: &WriteStatistics{},
}
}
// ShardMapping contains a mapping of shards to points.
type ShardMapping struct {
n int
Points map[uint64][]models.Point // The points associated with a shard ID
Shards map[uint64]*meta.ShardInfo // The shards that have been mapped, keyed by shard ID
Dropped []models.Point // Points that were dropped
}
// NewShardMapping creates an empty ShardMapping.
func NewShardMapping(n int) *ShardMapping {
return &ShardMapping{
n: n,
Points: map[uint64][]models.Point{},
Shards: map[uint64]*meta.ShardInfo{},
}
}
// MapPoint adds the point to the ShardMapping, associated with the given shardInfo.
func (s *ShardMapping) MapPoint(shardInfo *meta.ShardInfo, p models.Point) {
if cap(s.Points[shardInfo.ID]) < s.n {
s.Points[shardInfo.ID] = make([]models.Point, 0, s.n)
}
s.Points[shardInfo.ID] = append(s.Points[shardInfo.ID], p)
s.Shards[shardInfo.ID] = shardInfo
}
// Open opens the communication channel with the point writer.
func (w *PointsWriter) Open() error {
w.mu.Lock()
defer w.mu.Unlock()
w.closing = make(chan struct{})
if w.Subscriber != nil {
w.subPoints = w.Subscriber.Points()
}
return nil
}
// Close closes the communication channel with the point writer.
func (w *PointsWriter) Close() error {
w.mu.Lock()
defer w.mu.Unlock()
if w.closing != nil {
close(w.closing)
}
if w.subPoints != nil {
// 'nil' channels always block so this makes the
// select statement in WritePoints hit its default case
// dropping any in-flight writes.
w.subPoints = nil
}
return nil
}
// WithLogger sets the Logger on w.
func (w *PointsWriter) WithLogger(log zap.Logger) {
w.Logger = log.With(zap.String("service", "write"))
}
// WriteStatistics keeps statistics related to the PointsWriter.
type WriteStatistics struct {
WriteReq int64
PointWriteReq int64
PointWriteReqLocal int64
WriteOK int64
WriteDropped int64
WriteTimeout int64
WriteErr int64
SubWriteOK int64
SubWriteDrop int64
}
// Statistics returns statistics for periodic monitoring.
func (w *PointsWriter) Statistics(tags map[string]string) []models.Statistic {
return []models.Statistic{{
Name: "write",
Tags: tags,
Values: map[string]interface{}{
statWriteReq: atomic.LoadInt64(&w.stats.WriteReq),
statPointWriteReq: atomic.LoadInt64(&w.stats.PointWriteReq),
statPointWriteReqLocal: atomic.LoadInt64(&w.stats.PointWriteReqLocal),
statWriteOK: atomic.LoadInt64(&w.stats.WriteOK),
statWriteDrop: atomic.LoadInt64(&w.stats.WriteDropped),
statWriteTimeout: atomic.LoadInt64(&w.stats.WriteTimeout),
statWriteErr: atomic.LoadInt64(&w.stats.WriteErr),
statSubWriteOK: atomic.LoadInt64(&w.stats.SubWriteOK),
statSubWriteDrop: atomic.LoadInt64(&w.stats.SubWriteDrop),
},
}}
}
// MapShards maps the points contained in wp to a ShardMapping. If a point
// maps to a shard group or shard that does not currently exist, it will be
// created before returning the mapping.
func (w *PointsWriter) MapShards(wp *WritePointsRequest) (*ShardMapping, error) {
rp, err := w.MetaClient.RetentionPolicy(wp.Database, wp.RetentionPolicy)
if err != nil {
return nil, err
} else if rp == nil {
return nil, influxdb.ErrRetentionPolicyNotFound(wp.RetentionPolicy)
}
// Holds all the shard groups and shards that are required for writes.
list := make(sgList, 0, 8)
min := time.Unix(0, models.MinNanoTime)
if rp.Duration > 0 {
min = time.Now().Add(-rp.Duration)
}
for _, p := range wp.Points {
// Either the point is outside the scope of the RP, or we already have
// a suitable shard group for the point.
if p.Time().Before(min) || list.Covers(p.Time()) {
continue
}
// No shard groups overlap with the point's time, so we will create
// a new shard group for this point.
sg, err := w.MetaClient.CreateShardGroup(wp.Database, wp.RetentionPolicy, p.Time())
if err != nil {
return nil, err
}
if sg == nil {
return nil, errors.New("nil shard group")
}
list = list.Append(*sg)
}
mapping := NewShardMapping(len(wp.Points))
for _, p := range wp.Points {
sg := list.ShardGroupAt(p.Time())
if sg == nil {
// We didn't create a shard group because the point was outside the
// scope of the RP.
mapping.Dropped = append(mapping.Dropped, p)
atomic.AddInt64(&w.stats.WriteDropped, 1)
continue
}
sh := sg.ShardFor(p.HashID())
mapping.MapPoint(&sh, p)
}
return mapping, nil
}
// sgList is a wrapper around a meta.ShardGroupInfos where we can also check
// if a given time is covered by any of the shard groups in the list.
type sgList meta.ShardGroupInfos
func (l sgList) Covers(t time.Time) bool {
if len(l) == 0 {
return false
}
return l.ShardGroupAt(t) != nil
}
// ShardGroupAt attempts to find a shard group that could contain a point
// at the given time.
//
// Shard groups are sorted first according to end time, and then according
// to start time. Therefore, if there are multiple shard groups that match
// this point's time they will be preferred in this order:
//
// - a shard group with the earliest end time;
// - (assuming identical end times) the shard group with the earliest start time.
func (l sgList) ShardGroupAt(t time.Time) *meta.ShardGroupInfo {
idx := sort.Search(len(l), func(i int) bool { return l[i].EndTime.After(t) })
// We couldn't find a shard group the point falls into.
if idx == len(l) || t.Before(l[idx].StartTime) {
return nil
}
return &l[idx]
}
// Append appends a shard group to the list, and returns a sorted list.
func (l sgList) Append(sgi meta.ShardGroupInfo) sgList {
next := append(l, sgi)
sort.Sort(meta.ShardGroupInfos(next))
return next
}
// WritePointsInto is a copy of WritePoints that uses a tsdb structure instead of
// a cluster structure for information. This is to avoid a circular dependency.
func (w *PointsWriter) WritePointsInto(p *IntoWriteRequest) error {
return w.WritePointsPrivileged(p.Database, p.RetentionPolicy, models.ConsistencyLevelOne, p.Points)
}
// WritePoints writes the data to the underlying storage. consitencyLevel and user are only used for clustered scenarios
func (w *PointsWriter) WritePoints(database, retentionPolicy string, consistencyLevel models.ConsistencyLevel, user meta.User, points []models.Point) error {
return w.WritePointsPrivileged(database, retentionPolicy, consistencyLevel, points)
}
// WritePointsPrivileged writes the data to the underlying storage, consitencyLevel is only used for clustered scenarios
func (w *PointsWriter) WritePointsPrivileged(database, retentionPolicy string, consistencyLevel models.ConsistencyLevel, points []models.Point) error {
atomic.AddInt64(&w.stats.WriteReq, 1)
atomic.AddInt64(&w.stats.PointWriteReq, int64(len(points)))
if retentionPolicy == "" {
db := w.MetaClient.Database(database)
if db == nil {
return influxdb.ErrDatabaseNotFound(database)
}
retentionPolicy = db.DefaultRetentionPolicy
}
shardMappings, err := w.MapShards(&WritePointsRequest{Database: database, RetentionPolicy: retentionPolicy, Points: points})
if err != nil {
return err
}
// Write each shard in it's own goroutine and return as soon as one fails.
ch := make(chan error, len(shardMappings.Points))
for shardID, points := range shardMappings.Points {
go func(shard *meta.ShardInfo, database, retentionPolicy string, points []models.Point) {
ch <- w.writeToShard(shard, database, retentionPolicy, points)
}(shardMappings.Shards[shardID], database, retentionPolicy, points)
}
// Send points to subscriptions if possible.
ok := false
// We need to lock just in case the channel is about to be nil'ed
w.mu.RLock()
select {
case w.subPoints <- &WritePointsRequest{Database: database, RetentionPolicy: retentionPolicy, Points: points}:
ok = true
default:
}
w.mu.RUnlock()
if ok {
atomic.AddInt64(&w.stats.SubWriteOK, 1)
} else {
atomic.AddInt64(&w.stats.SubWriteDrop, 1)
}
if err == nil && len(shardMappings.Dropped) > 0 {
err = tsdb.PartialWriteError{Reason: "points beyond retention policy", Dropped: len(shardMappings.Dropped)}
}
timeout := time.NewTimer(w.WriteTimeout)
defer timeout.Stop()
for range shardMappings.Points {
select {
case <-w.closing:
return ErrWriteFailed
case <-timeout.C:
atomic.AddInt64(&w.stats.WriteTimeout, 1)
// return timeout error to caller
return ErrTimeout
case err := <-ch:
if err != nil {
return err
}
}
}
return err
}
// writeToShards writes points to a shard.
func (w *PointsWriter) writeToShard(shard *meta.ShardInfo, database, retentionPolicy string, points []models.Point) error {
atomic.AddInt64(&w.stats.PointWriteReqLocal, int64(len(points)))
err := w.TSDBStore.WriteToShard(shard.ID, points)
if err == nil {
atomic.AddInt64(&w.stats.WriteOK, 1)
return nil
}
// If this is a partial write error, that is also ok.
if _, ok := err.(tsdb.PartialWriteError); ok {
atomic.AddInt64(&w.stats.WriteErr, 1)
return err
}
// If we've written to shard that should exist on the current node, but the store has
// not actually created this shard, tell it to create it and retry the write
if err == tsdb.ErrShardNotFound {
err = w.TSDBStore.CreateShard(database, retentionPolicy, shard.ID, true)
if err != nil {
w.Logger.Info(fmt.Sprintf("write failed for shard %d: %v", shard.ID, err))
atomic.AddInt64(&w.stats.WriteErr, 1)
return err
}
}
err = w.TSDBStore.WriteToShard(shard.ID, points)
if err != nil {
w.Logger.Info(fmt.Sprintf("write failed for shard %d: %v", shard.ID, err))
atomic.AddInt64(&w.stats.WriteErr, 1)
return err
}
atomic.AddInt64(&w.stats.WriteOK, 1)
return nil
}