storj/satellite/metainfo/loop.go

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// Copyright (C) 2019 Storj Labs, Inc.
// See LICENSE for copying information.
package metainfo
import (
"context"
"fmt"
"time"
"github.com/spacemonkeygo/monkit/v3"
"github.com/zeebo/errs"
"golang.org/x/time/rate"
"storj.io/common/pb"
"storj.io/common/storj"
"storj.io/common/uuid"
"storj.io/storj/storage"
)
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")
)
// Observer is an interface defining an observer that can subscribe to the metainfo loop.
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//
// architecture: Observer
type Observer interface {
Object(context.Context, ScopedPath, *pb.Pointer) error
RemoteSegment(context.Context, ScopedPath, *pb.Pointer) error
InlineSegment(context.Context, ScopedPath, *pb.Pointer) 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, ScopedPath, *pb.Pointer) error {
return nil
}
// RemoteSegment implements the Observer interface
func (NullObserver) RemoteSegment(context.Context, ScopedPath, *pb.Pointer) error {
return nil
}
// InlineSegment implements the Observer interface
func (NullObserver) InlineSegment(context.Context, ScopedPath, *pb.Pointer) error {
return nil
}
// ScopedPath contains full expanded information about the path.
type ScopedPath struct {
ProjectID uuid.UUID
ProjectIDString string
Segment string
BucketName string
EncryptedObjectPath string
// TODO: should these be a []byte?
// Raw is the same path as pointerDB is using.
Raw storj.Path
}
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, path ScopedPath, pointer *pb.Pointer) error {
start := time.Now()
defer func() { observer.object.Insert(time.Since(start)) }()
return observer.observer.Object(ctx, path, pointer)
}
func (observer *observerContext) RemoteSegment(ctx context.Context, path ScopedPath, pointer *pb.Pointer) error {
start := time.Now()
defer func() { observer.remote.Insert(time.Since(start)) }()
return observer.observer.RemoteSegment(ctx, path, pointer)
}
func (observer *observerContext) InlineSegment(ctx context.Context, path ScopedPath, pointer *pb.Pointer) error {
start := time.Now()
defer func() { observer.inline.Insert(time.Since(start)) }()
return observer.observer.InlineSegment(ctx, path, pointer)
}
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:"10000"`
}
// Loop is a metainfo loop service.
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//
// architecture: Service
type Loop struct {
config LoopConfig
db PointerDB
join chan []*observerContext
done chan struct{}
}
// NewLoop creates a new metainfo loop service.
func NewLoop(config LoopConfig, db PointerDB) *Loop {
return &Loop{
db: db,
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.
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.db, observers, loop.config.ListLimit, rate.NewLimiter(rate.Limit(loop.config.RateLimit), 1))
}
// IterateDatabase iterates over PointerDB and notifies specified observers about results.
//
// It uses 10000 as the lookup limit for iterating.
func IterateDatabase(ctx context.Context, rateLimit float64, db PointerDB, observers ...Observer) error {
obsContexts := make([]*observerContext, len(observers))
for i, observer := range observers {
obsContexts[i] = newObserverContext(ctx, observer)
}
return iterateDatabase(ctx, db, obsContexts, 10000, rate.NewLimiter(rate.Limit(rateLimit), 1))
}
// handlePointer deals with a pointer for a single observer
// if there is some error on the observer, handles the error and returns false. Otherwise, returns true.
func handlePointer(ctx context.Context, observer *observerContext, path ScopedPath, isLastSegment bool, pointer *pb.Pointer) bool {
switch pointer.GetType() {
case pb.Pointer_REMOTE:
if observer.HandleError(observer.RemoteSegment(ctx, path, pointer)) {
return false
}
case pb.Pointer_INLINE:
if observer.HandleError(observer.InlineSegment(ctx, path, pointer)) {
return false
}
default:
return false
}
if isLastSegment {
if observer.HandleError(observer.Object(ctx, path, pointer)) {
return false
}
}
select {
case <-observer.ctx.Done():
observer.HandleError(observer.ctx.Err())
return false
default:
}
return true
}
// Wait waits for run to be finished.
// Safe to be called concurrently.
func (loop *Loop) Wait() {
<-loop.done
}
func iterateDatabase(ctx context.Context, db PointerDB, observers []*observerContext, limit int, rateLimiter *rate.Limiter) (err error) {
defer func() {
if err != nil {
for _, observer := range observers {
observer.HandleError(err)
}
return
}
finishObservers(observers)
}()
err = db.IterateWithoutLookupLimit(ctx, storage.IterateOptions{
Recurse: true,
Limit: limit,
}, func(ctx context.Context, it storage.Iterator) error {
var item storage.ListItem
// iterate over every segment in metainfo
nextSegment:
for it.Next(ctx, &item) {
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 LoopError.Wrap(err)
}
rawPath := item.Key.String()
pointer := &pb.Pointer{}
err := pb.Unmarshal(item.Value, pointer)
if err != nil {
return LoopError.New("unexpected error unmarshalling pointer %s", err)
}
pathElements := storj.SplitPath(rawPath)
if len(pathElements) < 4 {
// We skip this path because it belongs to bucket metadata, not to an
// actual object
continue nextSegment
}
isLastSegment := pathElements[1] == "l"
path := ScopedPath{
Raw: rawPath,
ProjectIDString: pathElements[0],
Segment: pathElements[1],
BucketName: pathElements[2],
EncryptedObjectPath: storj.JoinPaths(pathElements[3:]...),
}
path.ProjectID, err = uuid.FromString(path.ProjectIDString)
if err != nil {
return LoopError.Wrap(err)
}
nextObservers := observers[:0]
for _, observer := range observers {
keepObserver := handlePointer(ctx, observer, path, isLastSegment, pointer)
if keepObserver {
nextObservers = append(nextObservers, observer)
}
}
observers = nextObservers
if len(observers) == 0 {
return nil
}
// if context has been canceled exit. Otherwise, continue
select {
case <-ctx.Done():
return ctx.Err()
default:
}
}
return nil
})
return err
}
func finishObservers(observers []*observerContext) {
for _, observer := range observers {
observer.Finish()
}
}