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loop.go
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loop.go
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// Copyright (C) 2019 Storj Labs, Inc.
// See LICENSE for copying information.
package metainfo
import (
"context"
"errors"
"fmt"
"time"
"github.com/spacemonkeygo/monkit/v3"
"github.com/zeebo/errs"
"golang.org/x/time/rate"
"storj.io/common/uuid"
"storj.io/storj/satellite/metainfo/metabase"
)
const batchsizeLimit = 2500
var (
// LoopError is a standard error class for this component.
LoopError = errs.Class("metainfo loop error")
// LoopClosedError is a loop closed error.
LoopClosedError = LoopError.New("loop closed")
)
// Object is the object info passed to Observer by metainfo loop.
type Object metabase.LoopObjectEntry
// Expired checks if object expired relative to now.
func (object *Object) Expired(now time.Time) bool {
return object.ExpiresAt != nil && object.ExpiresAt.Before(now)
}
// Segment is the segment info passed to Observer by metainfo loop.
type Segment struct {
Location metabase.SegmentLocation // tally, repair, graceful exit, audit
CreationDate time.Time // repair
ExpirationDate time.Time // tally, repair
LastRepaired time.Time // repair
metabase.LoopSegmentEntry
}
// Expired checks if segment is expired relative to now.
func (segment *Segment) Expired(now time.Time) bool {
return !segment.ExpirationDate.IsZero() && segment.ExpirationDate.Before(now)
}
// Observer is an interface defining an observer that can subscribe to the metainfo loop.
//
// architecture: Observer
type Observer interface {
Object(context.Context, *Object) error
RemoteSegment(context.Context, *Segment) error
InlineSegment(context.Context, *Segment) error
}
// NullObserver is an observer that does nothing. This is useful for joining
// and ensuring the metainfo loop runs once before you use a real observer.
type NullObserver struct{}
// Object implements the Observer interface.
func (NullObserver) Object(context.Context, *Object) 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 {
observer Observer
ctx context.Context
done chan error
object *monkit.DurationDist
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),
object: monkit.NewDurationDist(key.WithTag("pointer_type", "object")),
inline: monkit.NewDurationDist(key.WithTag("pointer_type", "inline")),
remote: monkit.NewDurationDist(key.WithTag("pointer_type", "remote")),
}
}
func (observer *observerContext) Object(ctx context.Context, object *Object) error {
start := time.Now()
defer func() { observer.object.Insert(time.Since(start)) }()
return observer.observer.Object(ctx, object)
}
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
}
// LoopConfig contains configurable values for the metainfo loop.
type LoopConfig struct {
CoalesceDuration time.Duration `help:"how long to wait for new observers before starting iteration" releaseDefault:"5s" devDefault:"5s"`
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"`
}
// Loop is a metainfo loop service.
//
// architecture: Service
type Loop struct {
config LoopConfig
metabaseDB MetabaseDB
join chan []*observerContext
done chan struct{}
}
// NewLoop creates a new metainfo loop service.
func NewLoop(config LoopConfig, metabaseDB MetabaseDB) *Loop {
return &Loop{
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.
// 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 *Loop) Join(ctx context.Context, observers ...Observer) (err error) {
defer mon.Task()(&ctx)(&err)
obsContexts := make([]*observerContext, len(observers))
for i, obs := range observers {
obsContexts[i] = newObserverContext(ctx, obs)
}
select {
case loop.join <- obsContexts:
case <-ctx.Done():
return ctx.Err()
case <-loop.done:
return LoopClosedError
}
var errList errs.Group
for _, ctx := range obsContexts {
errList.Add(ctx.Wait())
}
return errList.Err()
}
// Run starts the looping service.
// It can only be called once, otherwise a panic will occur.
func (loop *Loop) Run(ctx context.Context) (err error) {
defer mon.Task()(&ctx)(&err)
for {
err := loop.RunOnce(ctx)
if err != nil {
return err
}
}
}
// Close closes the looping services.
func (loop *Loop) Close() (err error) {
close(loop.done)
return nil
}
// RunOnce goes through metainfo one time and sends information to observers.
//
// It is not safe to call this concurrently with Run.
func (loop *Loop) RunOnce(ctx context.Context) (err error) {
defer mon.Task()(&ctx)(&err)
var observers []*observerContext
// wait for the first observer, or exit because context is canceled
select {
case list := <-loop.join:
observers = append(observers, list...)
case <-ctx.Done():
return ctx.Err()
}
// after the first observer is found, set timer for CoalesceDuration and add any observers that try to join before the timer is up
timer := time.NewTimer(loop.config.CoalesceDuration)
waitformore:
for {
select {
case list := <-loop.join:
observers = append(observers, list...)
case <-timer.C:
break waitformore
case <-ctx.Done():
finishObservers(observers)
return ctx.Err()
}
}
return iterateDatabase(ctx, loop.metabaseDB, observers, loop.config.ListLimit, rate.NewLimiter(rate.Limit(loop.config.RateLimit), 1))
}
// Wait waits for run to be finished.
// Safe to be called concurrently.
func (loop *Loop) Wait() {
<-loop.done
}
func iterateDatabase(ctx context.Context, metabaseDB MetabaseDB, observers []*observerContext, limit int, rateLimiter *rate.Limiter) (err error) {
defer func() {
if err != nil {
for _, observer := range observers {
observer.HandleError(err)
}
return
}
finishObservers(observers)
}()
observers, err = iterateObjects(ctx, metabaseDB, observers, limit, rateLimiter)
if err != nil {
return LoopError.Wrap(err)
}
return err
}
func iterateObjects(ctx context.Context, metabaseDB MetabaseDB, observers []*observerContext, limit int, rateLimiter *rate.Limiter) (_ []*observerContext, err error) {
defer mon.Task()(&ctx)(&err)
if limit <= 0 || limit > batchsizeLimit {
limit = batchsizeLimit
}
startingTime := time.Now()
noObserversErr := errs.New("no observers")
// TODO we may consider keeping only expiration time as its
// only thing we need to handle segments
objectsMap := make(map[uuid.UUID]metabase.LoopObjectEntry)
ids := make([]uuid.UUID, 0, limit)
processBatch := func() error {
if len(objectsMap) == 0 {
return nil
}
err := metabaseDB.IterateLoopStreams(ctx, metabase.IterateLoopStreams{
StreamIDs: ids,
AsOfSystemTime: startingTime,
}, func(ctx context.Context, streamID uuid.UUID, next metabase.SegmentIterator) error {
if err := ctx.Err(); err != nil {
return err
}
obj, ok := objectsMap[streamID]
if !ok {
return Error.New("unable to find corresponding object: %v", streamID)
}
delete(objectsMap, streamID)
observers = withObservers(observers, func(observer *observerContext) bool {
object := Object(obj)
return handleObject(ctx, observer, &object)
})
if len(observers) == 0 {
return noObserversErr
}
for {
// if context has been canceled exit. Otherwise, continue
if err := ctx.Err(); err != nil {
return err
}
var segment metabase.LoopSegmentEntry
if !next(&segment) {
break
}
location := metabase.SegmentLocation{
ProjectID: obj.ProjectID,
BucketName: obj.BucketName,
ObjectKey: obj.ObjectKey,
Position: segment.Position,
}
observers = withObservers(observers, func(observer *observerContext) bool {
return handleSegment(ctx, observer, location, segment, obj.ExpiresAt)
})
if len(observers) == 0 {
return noObserversErr
}
}
return nil
})
if err != nil {
return Error.Wrap(err)
}
if len(objectsMap) > 0 {
return Error.New("unhandled objects %#v", objectsMap)
}
return nil
}
segmentsInBatch := int32(0)
err = metabaseDB.IterateLoopObjects(ctx, metabase.IterateLoopObjects{
BatchSize: limit,
AsOfSystemTime: startingTime,
}, func(ctx context.Context, it metabase.LoopObjectsIterator) error {
var entry metabase.LoopObjectEntry
for it.Next(ctx, &entry) {
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.
return err
}
objectsMap[entry.StreamID] = entry
ids = append(ids, entry.StreamID)
// add +1 to reduce risk of crossing limit
segmentsInBatch += entry.SegmentCount + 1
if segmentsInBatch >= int32(limit) {
err := processBatch()
if err != nil {
if errors.Is(err, noObserversErr) {
return nil
}
return err
}
if len(objectsMap) > 0 {
return errs.New("objects map is not empty")
}
ids = ids[:0]
segmentsInBatch = 0
}
}
err = processBatch()
if errors.Is(err, noObserversErr) {
return nil
}
return err
})
return observers, err
}
func withObservers(observers []*observerContext, handleObserver func(observer *observerContext) bool) []*observerContext {
nextObservers := observers[:0]
for _, observer := range observers {
keepObserver := handleObserver(observer)
if keepObserver {
nextObservers = append(nextObservers, observer)
}
}
return nextObservers
}
func handleObject(ctx context.Context, observer *observerContext, object *Object) bool {
if observer.HandleError(observer.Object(ctx, object)) {
return false
}
select {
case <-observer.ctx.Done():
observer.HandleError(observer.ctx.Err())
return false
default:
}
return true
}
func handleSegment(ctx context.Context, observer *observerContext, location metabase.SegmentLocation, segment metabase.LoopSegmentEntry, expirationDate *time.Time) bool {
loopSegment := &Segment{
Location: location,
// TODO we are not setting this since multipart-upload branch, we need to
// check if thats affecting anything and if we need to set it correctly
// or just replace it with something else
CreationDate: time.Time{},
// TODO we are not setting this and we need to decide what to do with this
LastRepaired: time.Time{},
LoopSegmentEntry: segment,
}
if expirationDate != nil {
loopSegment.ExpirationDate = *expirationDate
}
if loopSegment.Inline() {
if observer.HandleError(observer.InlineSegment(ctx, loopSegment)) {
return false
}
} else {
if observer.HandleError(observer.RemoteSegment(ctx, loopSegment)) {
return false
}
}
select {
case <-observer.ctx.Done():
observer.HandleError(observer.ctx.Err())
return false
default:
}
return true
}
func finishObservers(observers []*observerContext) {
for _, observer := range observers {
observer.Finish()
}
}