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service.go
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service.go
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package continuous_querier
import (
"errors"
"fmt"
"log"
"os"
"strings"
"sync"
"time"
"github.com/influxdb/influxdb/cluster"
"github.com/influxdb/influxdb/influxql"
"github.com/influxdb/influxdb/meta"
"github.com/influxdb/influxdb/tsdb"
)
const (
// When planning a select statement, passing zero tells it not to chunk results. Only applies to raw queries
NoChunkingSize = 0
)
// ContinuousQuerier represents a service that executes continuous queries.
type ContinuousQuerier interface {
// Run executes the named query in the named database. Blank database or name matches all.
Run(database, name string, t time.Time) error
}
// queryExecutor is an internal interface to make testing easier.
type queryExecutor interface {
ExecuteQuery(query *influxql.Query, database string, chunkSize int) (<-chan *influxql.Result, error)
}
// metaStore is an internal interface to make testing easier.
type metaStore interface {
IsLeader() bool
Databases() ([]meta.DatabaseInfo, error)
Database(name string) (*meta.DatabaseInfo, error)
}
// pointsWriter is an internal interface to make testing easier.
type pointsWriter interface {
WritePoints(p *cluster.WritePointsRequest) error
}
// RunRequest is a request to run one or more CQs.
type RunRequest struct {
// Now tells the CQ serivce what the current time is.
Now time.Time
// CQs tells the CQ service which queries to run.
// If nil, all queries will be run.
CQs []string
}
// matches returns true if the CQ matches one of the requested CQs.
func (rr *RunRequest) matches(cq *meta.ContinuousQueryInfo) bool {
if rr.CQs == nil {
return true
}
for _, q := range rr.CQs {
if q == cq.Name {
return true
}
}
return false
}
// Service manages continuous query execution.
type Service struct {
MetaStore metaStore
QueryExecutor queryExecutor
PointsWriter pointsWriter
Config *Config
RunInterval time.Duration
// RunCh can be used by clients to signal service to run CQs.
RunCh chan *RunRequest
Logger *log.Logger
loggingEnabled bool
// lastRuns maps CQ name to last time it was run.
mu sync.RWMutex
lastRuns map[string]time.Time
stop chan struct{}
wg *sync.WaitGroup
}
// NewService returns a new instance of Service.
func NewService(c Config) *Service {
s := &Service{
Config: &c,
RunInterval: time.Second,
RunCh: make(chan *RunRequest),
loggingEnabled: c.LogEnabled,
Logger: log.New(os.Stderr, "[continuous_querier] ", log.LstdFlags),
lastRuns: map[string]time.Time{},
}
return s
}
// Open starts the service.
func (s *Service) Open() error {
s.Logger.Println("Starting continuous query service")
if s.stop != nil {
return nil
}
assert(s.MetaStore != nil, "MetaStore is nil")
assert(s.QueryExecutor != nil, "QueryExecutor is nil")
assert(s.PointsWriter != nil, "PointsWriter is nil")
s.stop = make(chan struct{})
s.wg = &sync.WaitGroup{}
s.wg.Add(1)
go s.backgroundLoop()
return nil
}
// Close stops the service.
func (s *Service) Close() error {
if s.stop == nil {
return nil
}
close(s.stop)
s.wg.Wait()
s.wg = nil
s.stop = nil
return nil
}
// SetLogger sets the internal logger to the logger passed in.
func (s *Service) SetLogger(l *log.Logger) {
s.Logger = l
}
// Run runs the specified continuous query, or all CQs if none is specified.
func (s *Service) Run(database, name string, t time.Time) error {
var dbs []meta.DatabaseInfo
if database != "" {
// Find the requested database.
db, err := s.MetaStore.Database(database)
if err != nil {
return err
} else if db == nil {
return tsdb.ErrDatabaseNotFound(database)
}
dbs = append(dbs, *db)
} else {
// Get all databases.
var err error
dbs, err = s.MetaStore.Databases()
if err != nil {
return err
}
}
// Loop through databases.
s.mu.Lock()
defer s.mu.Unlock()
for _, db := range dbs {
// Loop through CQs in each DB executing the ones that match name.
for _, cq := range db.ContinuousQueries {
if name == "" || cq.Name == name {
// Reset the last run time for the CQ.
s.lastRuns[cq.Name] = time.Time{}
}
}
}
// Signal the background routine to run CQs.
s.RunCh <- &RunRequest{Now: t}
return nil
}
// backgroundLoop runs on a go routine and periodically executes CQs.
func (s *Service) backgroundLoop() {
defer s.wg.Done()
for {
select {
case <-s.stop:
s.Logger.Println("continuous query service terminating")
return
case req := <-s.RunCh:
if s.MetaStore.IsLeader() {
s.Logger.Printf("running continuous queries by request for time: %v", req.Now.UnixNano())
s.runContinuousQueries(req)
}
case <-time.After(s.RunInterval):
if s.MetaStore.IsLeader() {
s.runContinuousQueries(&RunRequest{Now: time.Now()})
}
}
}
}
// runContinuousQueries gets CQs from the meta store and runs them.
func (s *Service) runContinuousQueries(req *RunRequest) {
// Get list of all databases.
dbs, err := s.MetaStore.Databases()
if err != nil {
s.Logger.Println("error getting databases")
return
}
// Loop through all databases executing CQs.
for _, db := range dbs {
// TODO: distribute across nodes
for _, cq := range db.ContinuousQueries {
if !req.matches(&cq) {
continue
}
if err := s.ExecuteContinuousQuery(&db, &cq, req.Now); err != nil {
s.Logger.Printf("error executing query: %s: err = %s", cq.Query, err)
}
}
}
}
// ExecuteContinuousQuery executes a single CQ.
func (s *Service) ExecuteContinuousQuery(dbi *meta.DatabaseInfo, cqi *meta.ContinuousQueryInfo, now time.Time) error {
// TODO: re-enable stats
//s.stats.Inc("continuousQueryExecuted")
// Local wrapper / helper.
cq, err := NewContinuousQuery(dbi.Name, cqi)
if err != nil {
return err
}
// Get the last time this CQ was run from the service's cache.
s.mu.Lock()
defer s.mu.Unlock()
cq.LastRun = s.lastRuns[cqi.Name]
// Set the retention policy to default if it wasn't specified in the query.
if cq.intoRP() == "" {
cq.setIntoRP(dbi.DefaultRetentionPolicy)
}
// See if this query needs to be run.
computeNoMoreThan := time.Duration(s.Config.ComputeNoMoreThan)
run, err := cq.shouldRunContinuousQuery(s.Config.ComputeRunsPerInterval, computeNoMoreThan)
if err != nil {
return err
} else if !run {
return nil
}
// We're about to run the query so store the time.
lastRun := time.Now()
cq.LastRun = lastRun
s.lastRuns[cqi.Name] = lastRun
// Get the group by interval.
interval, err := cq.q.GroupByInterval()
if err != nil {
return err
} else if interval == 0 {
return nil
}
// Calculate and set the time range for the query.
startTime := now.Round(interval)
if startTime.UnixNano() > now.UnixNano() {
startTime = startTime.Add(-interval)
}
if err := cq.q.SetTimeRange(startTime, startTime.Add(interval)); err != nil {
s.Logger.Printf("error setting time range: %s\n", err)
}
if s.loggingEnabled {
s.Logger.Printf("executing continuous query %s", cq.Info.Name)
}
// Do the actual processing of the query & writing of results.
if err := s.runContinuousQueryAndWriteResult(cq); err != nil {
s.Logger.Printf("error: %s. running: %s\n", err, cq.q.String())
return err
}
recomputeNoOlderThan := time.Duration(s.Config.RecomputeNoOlderThan)
for i := 0; i < s.Config.RecomputePreviousN; i++ {
// if we're already more time past the previous window than we're going to look back, stop
if now.Sub(startTime) > recomputeNoOlderThan {
return nil
}
newStartTime := startTime.Add(-interval)
if err := cq.q.SetTimeRange(newStartTime, startTime); err != nil {
s.Logger.Printf("error setting time range: %s\n", err)
return err
}
if err := s.runContinuousQueryAndWriteResult(cq); err != nil {
s.Logger.Printf("error during recompute previous: %s. running: %s\n", err, cq.q.String())
return err
}
startTime = newStartTime
}
return nil
}
// runContinuousQueryAndWriteResult will run the query against the cluster and write the results back in
func (s *Service) runContinuousQueryAndWriteResult(cq *ContinuousQuery) error {
// Wrap the CQ's inner SELECT statement in a Query for the QueryExecutor.
q := &influxql.Query{
Statements: influxql.Statements{cq.q},
}
// Execute the SELECT.
ch, err := s.QueryExecutor.ExecuteQuery(q, cq.Database, NoChunkingSize)
if err != nil {
return err
}
// Read all rows from the result channel.
points := make([]tsdb.Point, 0, 100)
for result := range ch {
if result.Err != nil {
return result.Err
}
for _, row := range result.Series {
// Get the measurement name for the result.
measurement := cq.intoMeasurement()
if measurement == "" {
measurement = row.Name
}
// Convert the result row to points.
part, err := s.convertRowToPoints(measurement, row)
if err != nil {
log.Println(err)
continue
}
if len(part) == 0 {
continue
}
// If the points have any nil values, can't write.
// This happens if the CQ is created and running before data is written to the measurement.
for _, p := range part {
fields := p.Fields()
for _, v := range fields {
if v == nil {
return nil
}
}
}
points = append(points, part...)
}
}
if len(points) == 0 {
return nil
}
// Create a write request for the points.
req := &cluster.WritePointsRequest{
Database: cq.intoDB(),
RetentionPolicy: cq.intoRP(),
ConsistencyLevel: cluster.ConsistencyLevelAny,
Points: points,
}
// Write the request.
if err := s.PointsWriter.WritePoints(req); err != nil {
s.Logger.Println(err)
return err
}
if s.loggingEnabled {
s.Logger.Printf("wrote %d point(s) to %s.%s", len(points), cq.intoDB(), cq.intoRP())
}
return nil
}
// convertRowToPoints will convert a query result Row into Points that can be written back in.
// Used for continuous and INTO queries
func (s *Service) convertRowToPoints(measurementName string, row *influxql.Row) ([]tsdb.Point, error) {
// figure out which parts of the result are the time and which are the fields
timeIndex := -1
fieldIndexes := make(map[string]int)
for i, c := range row.Columns {
if c == "time" {
timeIndex = i
} else {
fieldIndexes[c] = i
}
}
if timeIndex == -1 {
return nil, errors.New("error finding time index in result")
}
points := make([]tsdb.Point, 0, len(row.Values))
for _, v := range row.Values {
vals := make(map[string]interface{})
for fieldName, fieldIndex := range fieldIndexes {
vals[fieldName] = v[fieldIndex]
}
p := tsdb.NewPoint(measurementName, row.Tags, vals, v[timeIndex].(time.Time))
points = append(points, p)
}
return points, nil
}
// ContinuousQuery is a local wrapper / helper around continuous queries.
type ContinuousQuery struct {
Database string
Info *meta.ContinuousQueryInfo
LastRun time.Time
q *influxql.SelectStatement
}
func (cq *ContinuousQuery) intoDB() string {
if cq.q.Target.Measurement.Database != "" {
return cq.q.Target.Measurement.Database
}
return cq.Database
}
func (cq *ContinuousQuery) intoRP() string { return cq.q.Target.Measurement.RetentionPolicy }
func (cq *ContinuousQuery) setIntoRP(rp string) { cq.q.Target.Measurement.RetentionPolicy = rp }
func (cq *ContinuousQuery) intoMeasurement() string { return cq.q.Target.Measurement.Name }
// NewContinuousQuery returns a ContinuousQuery object with a parsed influxql.CreateContinuousQueryStatement
func NewContinuousQuery(database string, cqi *meta.ContinuousQueryInfo) (*ContinuousQuery, error) {
stmt, err := influxql.NewParser(strings.NewReader(cqi.Query)).ParseStatement()
if err != nil {
return nil, err
}
q, ok := stmt.(*influxql.CreateContinuousQueryStatement)
if !ok || q.Source.Target == nil || q.Source.Target.Measurement == nil {
return nil, errors.New("query isn't a valid continuous query")
}
cquery := &ContinuousQuery{
Database: database,
Info: cqi,
q: q.Source,
}
return cquery, nil
}
// shouldRunContinuousQuery returns true if the CQ should be schedule to run. It will use the
// lastRunTime of the CQ and the rules for when to run set through the config to determine
// if this CQ should be run
func (cq *ContinuousQuery) shouldRunContinuousQuery(runsPerInterval int, noMoreThan time.Duration) (bool, error) {
// if it's not aggregated we don't run it
if cq.q.IsRawQuery {
return false, errors.New("continuous queries must be aggregate queries")
}
// since it's aggregated we need to figure how often it should be run
interval, err := cq.q.GroupByInterval()
if err != nil {
return false, err
}
// determine how often we should run this continuous query.
// group by time / the number of times to compute
computeEvery := time.Duration(interval.Nanoseconds()/int64(runsPerInterval)) * time.Nanosecond
// make sure we're running no more frequently than the setting in the config
if computeEvery < noMoreThan {
computeEvery = noMoreThan
}
// if we've passed the amount of time since the last run, do it up
if cq.LastRun.Add(computeEvery).UnixNano() <= time.Now().UnixNano() {
return true, nil
}
return false, nil
}
// assert will panic with a given formatted message if the given condition is false.
func assert(condition bool, msg string, v ...interface{}) {
if !condition {
panic(fmt.Sprintf("assert failed: "+msg, v...))
}
}