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dirbuilder.go
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/
dirbuilder.go
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package io
import (
"context"
"fmt"
"os"
mdag "github.com/ipfs/go-ipfs/merkledag"
format "github.com/ipfs/go-ipfs/unixfs"
hamt "github.com/ipfs/go-ipfs/unixfs/hamt"
node "gx/ipfs/QmYDscK7dmdo2GZ9aumS8s5auUUAH5mR1jvj5pYhWusfK7/go-ipld-node"
)
// ShardSplitThreshold specifies how large of an unsharded directory
// the Directory code will generate. Adding entries over this value will
// result in the node being restructured into a sharded object.
var ShardSplitThreshold = 1000
// UseHAMTSharding is a global flag that signifies whether or not to use the
// HAMT sharding scheme for directory creation
var UseHAMTSharding = false
// DefaultShardWidth is the default value used for hamt sharding width.
var DefaultShardWidth = 256
type Directory struct {
dserv mdag.DAGService
dirnode *mdag.ProtoNode
shard *hamt.HamtShard
}
// NewDirectory returns a Directory. It needs a DAGService to add the Children
func NewDirectory(dserv mdag.DAGService) *Directory {
db := new(Directory)
db.dserv = dserv
if UseHAMTSharding {
s, err := hamt.NewHamtShard(dserv, DefaultShardWidth)
if err != nil {
panic(err) // will only panic if DefaultShardWidth is a bad value
}
db.shard = s
} else {
db.dirnode = format.EmptyDirNode()
}
return db
}
func NewDirectoryFromNode(dserv mdag.DAGService, nd node.Node) (*Directory, error) {
pbnd, ok := nd.(*mdag.ProtoNode)
if !ok {
return nil, mdag.ErrNotProtobuf
}
pbd, err := format.FromBytes(pbnd.Data())
if err != nil {
return nil, err
}
switch pbd.GetType() {
case format.TDirectory:
return &Directory{
dserv: dserv,
dirnode: pbnd.Copy().(*mdag.ProtoNode),
}, nil
case format.THAMTShard:
shard, err := hamt.NewHamtFromDag(dserv, nd)
if err != nil {
return nil, err
}
return &Directory{
dserv: dserv,
shard: shard,
}, nil
default:
return nil, fmt.Errorf("merkledag node was not a directory or shard")
}
}
// AddChild adds a (name, key)-pair to the root node.
func (d *Directory) AddChild(ctx context.Context, name string, nd node.Node) error {
if d.shard == nil {
if !UseHAMTSharding {
_ = d.dirnode.RemoveNodeLink(name)
return d.dirnode.AddNodeLinkClean(name, nd)
}
err := d.switchToSharding(ctx)
if err != nil {
return err
}
}
return d.shard.Set(ctx, name, nd)
}
func (d *Directory) switchToSharding(ctx context.Context) error {
s, err := hamt.NewHamtShard(d.dserv, DefaultShardWidth)
if err != nil {
return err
}
d.shard = s
for _, lnk := range d.dirnode.Links() {
cnd, err := d.dserv.Get(ctx, lnk.Cid)
if err != nil {
return err
}
err = d.shard.Set(ctx, lnk.Name, cnd)
if err != nil {
return err
}
}
d.dirnode = nil
return nil
}
func (d *Directory) ForEachLink(ctx context.Context, f func(*node.Link) error) error {
if d.shard == nil {
for _, l := range d.dirnode.Links() {
if err := f(l); err != nil {
return err
}
}
return nil
}
return d.shard.ForEachLink(ctx, f)
}
func (d *Directory) Links(ctx context.Context) ([]*node.Link, error) {
if d.shard == nil {
return d.dirnode.Links(), nil
}
return d.shard.EnumLinks(ctx)
}
func (d *Directory) Find(ctx context.Context, name string) (node.Node, error) {
if d.shard == nil {
lnk, err := d.dirnode.GetNodeLink(name)
switch err {
case mdag.ErrLinkNotFound:
return nil, os.ErrNotExist
default:
return nil, err
case nil:
}
return d.dserv.Get(ctx, lnk.Cid)
}
return d.shard.Find(ctx, name)
}
func (d *Directory) RemoveChild(ctx context.Context, name string) error {
if d.shard == nil {
return d.dirnode.RemoveNodeLink(name)
}
return d.shard.Remove(ctx, name)
}
// GetNode returns the root of this Directory
func (d *Directory) GetNode() (node.Node, error) {
if d.shard == nil {
return d.dirnode, nil
}
return d.shard.Node()
}