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gc.go
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gc.go
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// Package gc provides garbage collection for go-ipfs.
package gc
import (
"context"
"errors"
"fmt"
"strings"
pin "github.com/TRON-US/go-btfs-pinner"
bserv "github.com/ipfs/go-blockservice"
cid "github.com/ipfs/go-cid"
dstore "github.com/ipfs/go-datastore"
bstore "github.com/ipfs/go-ipfs-blockstore"
offline "github.com/ipfs/go-ipfs-exchange-offline"
ipld "github.com/ipfs/go-ipld-format"
logging "github.com/ipfs/go-log"
dag "github.com/ipfs/go-merkledag"
"github.com/ipfs/go-verifcid"
)
const (
Eagar = iota + 1 // This may cause a deadlock when multiple GC's are running
Lazy
)
var cleanMode = Eagar
var log = logging.Logger("gc")
// Result represents an incremental output from a garbage collection
// run. It contains either an error, or the cid of a removed object.
type Result struct {
KeyRemoved cid.Cid
Error error
}
// GC performs a mark and sweep garbage collection of the blocks in the blockstore
// first, it creates a 'marked' set and adds to it the following:
// - all recursively pinned blocks, plus all of their descendants (recursively)
// - bestEffortRoots, plus all of its descendants (recursively)
// - all directly pinned blocks
// - all blocks utilized internally by the pinner
//
// The routine then iterates over every block in the blockstore and
// deletes any block that is not found in the marked set.
func GC(ctx context.Context, bs bstore.GCBlockstore, dstor dstore.Datastore, pn pin.Pinner, bestEffortRoots []cid.Cid) <-chan Result {
ctx, cancel := context.WithCancel(ctx)
unlocker := bs.GCLock()
bsrv := bserv.New(bs, offline.Exchange(bs))
ds := dag.NewDAGService(bsrv)
output := make(chan Result, 128)
go func() {
defer cancel()
defer close(output)
defer unlocker.Unlock()
gcs, err := ColoredSet(ctx, pn, ds, bestEffortRoots, output)
if err != nil {
select {
case output <- Result{Error: err}:
case <-ctx.Done():
}
return
}
keychan, err := bs.AllKeysChan(ctx)
if err != nil {
select {
case output <- Result{Error: err}:
case <-ctx.Done():
}
return
}
errors := false
var removed uint64
loop:
for ctx.Err() == nil { // select may not notice that we're "done".
select {
case k, ok := <-keychan:
if !ok {
break loop
}
if !gcs.Has(k) {
err := bs.DeleteBlock(k)
removed++
if err != nil {
errors = true
select {
case output <- Result{Error: &CannotDeleteBlockError{k, err}}:
case <-ctx.Done():
break loop
}
// continue as error is non-fatal
continue loop
}
select {
case output <- Result{KeyRemoved: k}:
case <-ctx.Done():
break loop
}
}
case <-ctx.Done():
break loop
}
}
if errors {
select {
case output <- Result{Error: ErrCannotDeleteSomeBlocks}:
case <-ctx.Done():
return
}
}
gds, ok := dstor.(dstore.GCDatastore)
if !ok {
return
}
err = gds.CollectGarbage()
if err != nil {
select {
case output <- Result{Error: err}:
case <-ctx.Done():
}
return
}
}()
return output
}
// Descendants recursively finds all the descendants of the given roots and
// adds them to the given cid.Set, using the provided dag.GetLinks function
// to walk the tree.
func Descendants(ctx context.Context, pn pin.Pinner, getLinks dag.GetLinks,
set *cid.Set, pinMap *cid.Map, pinMap2 *cid.Map, roots []cid.Cid) error {
verifyGetLinks := func(ctx context.Context, c cid.Cid) ([]*ipld.Link, error) {
err := verifcid.ValidateCid(c)
if err != nil {
return nil, err
}
if pn.IsExpiredPin(ctx, c) {
return nil, nil
}
return getLinks(ctx, c)
}
verboseCidError := func(err error) error {
if strings.Contains(err.Error(), verifcid.ErrBelowMinimumHashLength.Error()) ||
strings.Contains(err.Error(), verifcid.ErrPossiblyInsecureHashFunction.Error()) {
err = fmt.Errorf("\"%s\"\nPlease run 'btfs pin verify'"+
" to list insecure hashes. If you want to read them,"+
" please downgrade your go-btfs to 0.0.1\n", err)
log.Error(err)
}
return err
}
for _, c := range roots {
if pn.IsExpiredPin(ctx, c) {
if cleanMode == Eagar {
pn.Unpin(ctx, c, true)
pn.Flush(ctx)
}
continue
}
// Walk recursively walks the dag and adds the keys to the given set
err := dag.Walk(ctx, verifyGetLinks, c, set.Visit, dag.Concurrent())
if err != nil {
err = verboseCidError(err)
return err
}
}
return nil
}
// ColoredSet computes the set of nodes in the graph that are pinned by the
// pins in the given pinner.
func ColoredSet(ctx context.Context, pn pin.Pinner, ng ipld.NodeGetter, bestEffortRoots []cid.Cid, output chan<- Result) (*cid.Set, error) {
// KeySet currently implemented in memory, in the future, may be bloom filter or
// disk backed to conserve memory.
errors := false
gcs := cid.NewSet()
getLinks := func(ctx context.Context, cid cid.Cid) ([]*ipld.Link, error) {
links, err := ipld.GetLinks(ctx, ng, cid)
if err != nil {
errors = true
select {
case output <- Result{Error: &CannotFetchLinksError{cid, err}}:
case <-ctx.Done():
return nil, ctx.Err()
}
}
return links, nil
}
rmap, err := pn.RecursiveMap(ctx)
if err != nil {
return nil, err
}
dmap, err := pn.DirectMap(ctx)
if err != nil {
return nil, err
}
rkeys, err := pn.RecursiveKeys(ctx)
if err != nil {
return nil, err
}
err = Descendants(ctx, pn, getLinks, gcs, rmap, dmap, rkeys)
if err != nil {
errors = true
select {
case output <- Result{Error: err}:
case <-ctx.Done():
return nil, ctx.Err()
}
}
bestEffortGetLinks := func(ctx context.Context, cid cid.Cid) ([]*ipld.Link, error) {
links, err := ipld.GetLinks(ctx, ng, cid)
if err != nil && err != ipld.ErrNotFound {
errors = true
select {
case output <- Result{Error: &CannotFetchLinksError{cid, err}}:
case <-ctx.Done():
return nil, ctx.Err()
}
}
return links, nil
}
err = Descendants(ctx, pn, bestEffortGetLinks, gcs, rmap, dmap, bestEffortRoots)
if err != nil {
errors = true
select {
case output <- Result{Error: err}:
case <-ctx.Done():
return nil, ctx.Err()
}
}
dkeys, err := pn.DirectKeys(ctx)
if err != nil {
return nil, err
}
for _, k := range dkeys {
// Skip expired pins
if pn.IsExpiredPin(ctx, k) {
if cleanMode == Eagar {
pn.Unpin(ctx, k, false)
pn.Flush(ctx)
}
continue
}
gcs.Add(k)
}
ikeys, err := pn.InternalPins(ctx)
if err != nil {
return nil, err
}
err = Descendants(ctx, pn, getLinks, gcs, rmap, dmap, ikeys)
if err != nil {
errors = true
select {
case output <- Result{Error: err}:
case <-ctx.Done():
return nil, ctx.Err()
}
}
if errors {
return nil, ErrCannotFetchAllLinks
}
return gcs, nil
}
// ErrCannotFetchAllLinks is returned as the last Result in the GC output
// channel when there was an error creating the marked set because of a
// problem when finding descendants.
var ErrCannotFetchAllLinks = errors.New("garbage collection aborted: could not retrieve some links")
// ErrCannotDeleteSomeBlocks is returned when removing blocks marked for
// deletion fails as the last Result in GC output channel.
var ErrCannotDeleteSomeBlocks = errors.New("garbage collection incomplete: could not delete some blocks")
// CannotFetchLinksError provides detailed information about which links
// could not be fetched and can appear as a Result in the GC output channel.
type CannotFetchLinksError struct {
Key cid.Cid
Err error
}
// Error implements the error interface for this type with a useful
// message.
func (e *CannotFetchLinksError) Error() string {
return fmt.Sprintf("could not retrieve links for %s: %s", e.Key, e.Err)
}
// CannotDeleteBlockError provides detailed information about which
// blocks could not be deleted and can appear as a Result in the GC output
// channel.
type CannotDeleteBlockError struct {
Key cid.Cid
Err error
}
// Error implements the error interface for this type with a
// useful message.
func (e *CannotDeleteBlockError) Error() string {
return fmt.Sprintf("could not remove %s: %s", e.Key, e.Err)
}