storj/satellite/metabase/segmentloop/service.go
Artur M. Wolff a5371353bf satellite/metabase/segmentloop: fix rate.NewLimiter call
This change fixes the call to rate.NewLimiter to account for the
"infinite" case.

Change-Id: Ib3f914ca33ad8b981157fd224f077e6ad8d8c644
2021-08-19 17:23:13 +00:00

530 lines
14 KiB
Go

// Copyright (C) 2021 Storj Labs, Inc.
// See LICENSE for copying information.
package segmentloop
import (
"context"
"errors"
"fmt"
"time"
"github.com/spacemonkeygo/monkit/v3"
"github.com/zeebo/errs"
"go.uber.org/zap"
"golang.org/x/time/rate"
"storj.io/common/errs2"
"storj.io/storj/satellite/metabase"
)
const batchsizeLimit = 2500
var (
mon = monkit.Package()
// Error is a standard error class for this component.
Error = errs.Class("segments loop")
// ErrClosed is a loop closed error.
ErrClosed = Error.New("loop closed")
)
// Segment contains information about segment metadata which will be received by observers.
type Segment metabase.LoopSegmentEntry
// Inline returns true if segment is inline.
func (s Segment) Inline() bool {
return s.Redundancy.IsZero() && len(s.Pieces) == 0
}
// Expired checks if segment expired relative to now.
func (s *Segment) Expired(now time.Time) bool {
return s.ExpiresAt != nil && s.ExpiresAt.Before(now)
}
// Observer is an interface defining an observer that can subscribe to the segments loop.
//
// architecture: Observer
type Observer interface {
LoopStarted(context.Context, LoopInfo) error
RemoteSegment(context.Context, *Segment) error
InlineSegment(context.Context, *Segment) error
}
// LoopInfo contains information about the current loop.
type LoopInfo struct {
Started time.Time
}
// NullObserver is an observer that does nothing. This is useful for joining
// and ensuring the segments loop runs once before you use a real observer.
type NullObserver struct{}
// LoopStarted is called at each loop start.
func (NullObserver) LoopStarted(context.Context, LoopInfo) error {
return nil
}
// RemoteSegment implements the Observer interface.
func (NullObserver) RemoteSegment(context.Context, *Segment) error {
return nil
}
// InlineSegment implements the Observer interface.
func (NullObserver) InlineSegment(context.Context, *Segment) error {
return nil
}
type observerContext struct {
trigger bool
observer Observer
ctx context.Context
done chan error
remote *monkit.DurationDist
inline *monkit.DurationDist
}
func newObserverContext(ctx context.Context, obs Observer) *observerContext {
name := fmt.Sprintf("%T", obs)
key := monkit.NewSeriesKey("observer").WithTag("name", name)
return &observerContext{
observer: obs,
ctx: ctx,
done: make(chan error),
inline: monkit.NewDurationDist(key.WithTag("pointer_type", "inline")),
remote: monkit.NewDurationDist(key.WithTag("pointer_type", "remote")),
}
}
func (observer *observerContext) RemoteSegment(ctx context.Context, segment *Segment) error {
start := time.Now()
defer func() { observer.remote.Insert(time.Since(start)) }()
return observer.observer.RemoteSegment(ctx, segment)
}
func (observer *observerContext) InlineSegment(ctx context.Context, segment *Segment) error {
start := time.Now()
defer func() { observer.inline.Insert(time.Since(start)) }()
return observer.observer.InlineSegment(ctx, segment)
}
func (observer *observerContext) HandleError(err error) bool {
if err != nil {
observer.done <- err
observer.Finish()
return true
}
return false
}
func (observer *observerContext) Finish() {
close(observer.done)
name := fmt.Sprintf("%T", observer.observer)
stats := allObserverStatsCollectors.GetStats(name)
stats.Observe(observer)
}
func (observer *observerContext) Wait() error {
return <-observer.done
}
// Config contains configurable values for the segments loop.
type Config struct {
CoalesceDuration time.Duration `help:"how long to wait for new observers before starting iteration" releaseDefault:"5s" devDefault:"5s" testDefault:"1s"`
RateLimit float64 `help:"rate limit (default is 0 which is unlimited segments per second)" default:"0"`
ListLimit int `help:"how many items to query in a batch" default:"2500"`
AsOfSystemInterval time.Duration `help:"as of system interval" releaseDefault:"-5m" devDefault:"-1us" testDefault:"-1us"`
SuspiciousProcessedRatio float64 `help:"ratio where to consider processed count as supicious" default:"0.03"`
}
// MetabaseDB contains iterators for the metabase data.
type MetabaseDB interface {
// Now returns the time on the database.
Now(ctx context.Context) (time.Time, error)
// IterateLoopStreams iterates through all streams passed in as arguments.
IterateLoopSegments(ctx context.Context, opts metabase.IterateLoopSegments, fn func(context.Context, metabase.LoopSegmentsIterator) error) (err error)
// GetTableStats gathers statistics about the tables.
GetTableStats(context.Context, metabase.GetTableStats) (metabase.TableStats, error)
}
// Service is a segments loop service.
//
// architecture: Service
type Service struct {
log *zap.Logger
config Config
metabaseDB MetabaseDB
join chan *observerContext
done chan struct{}
}
// New creates a new segments loop service.
func New(log *zap.Logger, config Config, metabaseDB MetabaseDB) *Service {
return &Service{
log: log,
metabaseDB: metabaseDB,
config: config,
join: make(chan *observerContext),
done: make(chan struct{}),
}
}
// Join will join the looper for one full cycle until completion and then returns.
// Joining will trigger a new iteration after coalesce duration.
// On ctx cancel the observer will return without completely finishing.
// Only on full complete iteration it will return nil.
// Safe to be called concurrently.
func (loop *Service) Join(ctx context.Context, observer Observer) (err error) {
return loop.joinObserver(ctx, true, observer)
}
// Monitor will join the looper for one full cycle until completion and then returns.
// Joining with monitoring won't trigger after coalesce duration.
// On ctx cancel the observer will return without completely finishing.
// Only on full complete iteration it will return nil.
// Safe to be called concurrently.
func (loop *Service) Monitor(ctx context.Context, observer Observer) (err error) {
return loop.joinObserver(ctx, false, observer)
}
// joinObserver will join the looper for one full cycle until completion and then returns.
// On ctx cancel the observer will return without completely finishing.
// Only on full complete iteration it will return nil.
// Safe to be called concurrently.
func (loop *Service) joinObserver(ctx context.Context, trigger bool, obs Observer) (err error) {
defer mon.Task()(&ctx)(&err)
obsctx := newObserverContext(ctx, obs)
obsctx.trigger = trigger
select {
case loop.join <- obsctx:
case <-ctx.Done():
return ctx.Err()
case <-loop.done:
return ErrClosed
}
return obsctx.Wait()
}
// Run starts the looping service.
// It can only be called once, otherwise a panic will occur.
func (loop *Service) Run(ctx context.Context) (err error) {
defer mon.Task()(&ctx)(&err)
for {
err := loop.RunOnce(ctx)
if err != nil {
loop.log.Error("segment loop failure", zap.Error(err))
if errs2.IsCanceled(err) {
return err
}
mon.Event("segmentloop_error") //mon:locked
}
}
}
// Close closes the looping services.
func (loop *Service) Close() (err error) {
close(loop.done)
return nil
}
// RunOnce goes through segments one time and sends information to observers.
//
// It is not safe to call this concurrently with Run.
func (loop *Service) RunOnce(ctx context.Context) (err error) {
defer mon.Task()(&ctx)(&err) //mon:locked
coalesceTimer := time.NewTimer(loop.config.CoalesceDuration)
defer coalesceTimer.Stop()
stopTimer(coalesceTimer)
earlyExit := make(chan *observerContext)
earlyExitDone := make(chan struct{})
monitorEarlyExit := func(obs *observerContext) {
select {
case <-obs.ctx.Done():
select {
case <-earlyExitDone:
case earlyExit <- obs:
}
case <-earlyExitDone:
}
}
timerStarted := false
observers := []*observerContext{}
waitformore:
for {
select {
// when the coalesce timer hits, we have waited enough for observers to join.
case <-coalesceTimer.C:
break waitformore
// wait for a new observer to join.
case obsctx := <-loop.join:
// when the observer triggers the loop and it's the first one,
// then start the coalescing timer.
if obsctx.trigger {
if !timerStarted {
coalesceTimer.Reset(loop.config.CoalesceDuration)
timerStarted = true
}
}
observers = append(observers, obsctx)
go monitorEarlyExit(obsctx)
// remove an observer from waiting when it's canceled before the loop starts.
case obsctx := <-earlyExit:
for i, obs := range observers {
if obs == obsctx {
observers = append(observers[:i], observers[i+1:]...)
break
}
}
obsctx.HandleError(obsctx.ctx.Err())
// reevalute, whether we acually need to start the loop.
timerShouldRun := false
for _, obs := range observers {
timerShouldRun = timerShouldRun || obs.trigger
}
if !timerShouldRun && timerStarted {
stopTimer(coalesceTimer)
}
// when ctx done happens we can finish all the waiting observers.
case <-ctx.Done():
close(earlyExitDone)
errorObservers(observers, ctx.Err())
return ctx.Err()
}
}
close(earlyExitDone)
return loop.iterateDatabase(ctx, observers)
}
func stopTimer(t *time.Timer) {
t.Stop()
// drain if it contains something
select {
case <-t.C:
default:
}
}
// Wait waits for run to be finished.
// Safe to be called concurrently.
func (loop *Service) Wait() {
<-loop.done
}
var errNoObservers = errs.New("no observers")
func (loop *Service) iterateDatabase(ctx context.Context, observers []*observerContext) (err error) {
defer func() {
if err != nil {
errorObservers(observers, err)
return
}
finishObservers(observers)
}()
before, err := loop.metabaseDB.GetTableStats(ctx, metabase.GetTableStats{
AsOfSystemInterval: loop.config.AsOfSystemInterval,
})
if err != nil {
return Error.Wrap(err)
}
var processed processedStats
processed, observers, err = loop.iterateSegments(ctx, observers)
if errors.Is(err, errNoObservers) {
return nil
}
if err != nil {
return Error.Wrap(err)
}
after, err := loop.metabaseDB.GetTableStats(ctx, metabase.GetTableStats{
AsOfSystemInterval: loop.config.AsOfSystemInterval,
})
if err != nil {
return Error.Wrap(err)
}
if err := loop.verifyCount(before.SegmentCount, after.SegmentCount, processed.segments); err != nil {
return Error.Wrap(err)
}
return err
}
func (loop *Service) verifyCount(before, after, processed int64) error {
low, high := before, after
if low > high {
low, high = high, low
}
var deltaFromBounds int64
var ratio float64
if processed < low {
deltaFromBounds = low - processed
// +1 to avoid division by zero
ratio = float64(deltaFromBounds) / float64(low+1)
} else if processed > high {
deltaFromBounds = processed - high
// +1 to avoid division by zero
ratio = float64(deltaFromBounds) / float64(high+1)
}
mon.IntVal("segmentloop_verify_before").Observe(before)
mon.IntVal("segmentloop_verify_after").Observe(after)
mon.IntVal("segmentloop_verify_processed").Observe(processed)
mon.IntVal("segmentloop_verify_outside").Observe(deltaFromBounds)
mon.FloatVal("segmentloop_verify_outside_ratio").Observe(ratio)
// If we have very few items from the bounds, then it's expected and the ratio does not capture it well.
const minimumDeltaThreshold = 100
if deltaFromBounds < minimumDeltaThreshold {
return nil
}
if ratio > loop.config.SuspiciousProcessedRatio {
return Error.New("processed count looks suspicious: before:%v after:%v processed:%v ratio:%v threshold:%v", before, after, processed, ratio, loop.config.SuspiciousProcessedRatio)
}
return nil
}
type processedStats struct {
segments int64
}
func (loop *Service) iterateSegments(ctx context.Context, observers []*observerContext) (processed processedStats, _ []*observerContext, err error) {
defer mon.Task()(&ctx)(&err)
rateLimiter := rate.NewLimiter(rate.Limit(loop.config.RateLimit), 1)
if loop.config.RateLimit == 0 {
rateLimiter = rate.NewLimiter(rate.Inf, 1)
}
limit := loop.config.ListLimit
if limit <= 0 || limit > batchsizeLimit {
limit = batchsizeLimit
}
startingTime, err := loop.metabaseDB.Now(ctx)
if err != nil {
return processed, observers, Error.Wrap(err)
}
observers = withObservers(ctx, observers, func(ctx context.Context, observer *observerContext) bool {
err := observer.observer.LoopStarted(ctx, LoopInfo{Started: startingTime})
return !observer.HandleError(err)
})
if len(observers) == 0 {
return processed, observers, errNoObservers
}
err = loop.metabaseDB.IterateLoopSegments(ctx, metabase.IterateLoopSegments{
BatchSize: limit,
AsOfSystemTime: startingTime,
AsOfSystemInterval: loop.config.AsOfSystemInterval,
}, func(ctx context.Context, iterator metabase.LoopSegmentsIterator) error {
defer mon.TaskNamed("iterateLoopSegmentsCB")(&ctx)(&err)
var entry metabase.LoopSegmentEntry
for iterator.Next(ctx, &entry) {
if err := ctx.Err(); err != nil {
return err
}
timer := mon.Timer("iterateLoopSegmentsRateLimit").Start()
if err := rateLimiter.Wait(ctx); err != nil {
// We don't really execute concurrent batches so we should never
// exceed the burst size of 1 and this should never happen.
// We can also enter here if the context is cancelled.
timer.Stop()
return err
}
timer.Stop()
observers = withObservers(ctx, observers, func(ctx context.Context, observer *observerContext) bool {
segment := Segment(entry)
return !observer.HandleError(handleSegment(ctx, observer, &segment))
})
if len(observers) == 0 {
return errNoObservers
}
processed.segments++
mon.IntVal("segmentsProcessed").Observe(processed.segments) //mon:locked
}
return nil
})
return processed, observers, err
}
func withObservers(ctx context.Context, observers []*observerContext, handleObserver func(ctx context.Context, observer *observerContext) bool) []*observerContext {
defer mon.Task()(&ctx)(nil)
nextObservers := observers[:0]
for _, observer := range observers {
keepObserver := handleObserver(ctx, observer)
if keepObserver {
nextObservers = append(nextObservers, observer)
}
}
return nextObservers
}
func handleSegment(ctx context.Context, observer *observerContext, segment *Segment) (err error) {
defer mon.Task()(&ctx)(&err)
if segment.Inline() {
if err := observer.InlineSegment(ctx, segment); err != nil {
return err
}
} else {
if err := observer.RemoteSegment(ctx, segment); err != nil {
return err
}
}
return observer.ctx.Err()
}
func finishObservers(observers []*observerContext) {
for _, observer := range observers {
observer.Finish()
}
}
func errorObservers(observers []*observerContext, err error) {
for _, observer := range observers {
observer.HandleError(err)
}
}