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metadb.go
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metadb.go
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package renterutil
import (
"encoding/binary"
"errors"
"sort"
"sync"
"time"
"gitlab.com/NebulousLabs/Sia/crypto"
"gitlab.com/NebulousLabs/Sia/encoding"
"gitlab.com/NebulousLabs/bolt"
"golang.org/x/crypto/blake2b"
"lukechampine.com/us/hostdb"
"lukechampine.com/us/renter"
)
// ErrKeyNotFound is returned when a key is not found in a MetaDB.
var ErrKeyNotFound = errors.New("key not found")
// A DBBlob is the concatenation of one or more chunks.
type DBBlob struct {
Key []byte
Chunks []uint64
Seed [32]byte
}
// DeriveKey derives an encryption key from a seed and a chunk ID.
func (b *DBBlob) DeriveKey(chunk uint64) (key renter.KeySeed) {
buf := make([]byte, 7+32+8)
n := copy(buf, "keyseed")
n += copy(buf[n:], b.Seed[:])
binary.LittleEndian.PutUint64(buf[n:], chunk)
h := blake2b.Sum256(buf)
copy(key[:], h[:])
return
}
// DeriveNonce derives a nonce from a seed and shard index.
func DeriveNonce(seed renter.KeySeed, shard int) (nonce [24]byte) {
buf := make([]byte, 5+32+8)
n := copy(buf, "nonce")
n += copy(buf[n:], seed[:])
binary.LittleEndian.PutUint64(buf[n:], uint64(shard))
h := blake2b.Sum256(buf)
copy(nonce[:], h[:])
return
}
// A DBChunk is a set of erasure-encoded shards.
type DBChunk struct {
ID uint64
Shards []uint64
MinShards uint8
Len uint64 // of chunk, before erasure encoding
}
// A DBShard is a piece of data stored on a Sia host.
type DBShard struct {
HostKey hostdb.HostPublicKey
SectorRoot crypto.Hash
Offset uint32
// NOTE: Length is not stored, as it can be derived from the DBChunk.Len
}
// A MetaDB stores the metadata of blobs stored on Sia hosts.
type MetaDB interface {
AddBlob(b DBBlob) error
Blob(key []byte) (DBBlob, error)
DeleteBlob(key []byte) error
ForEachBlob(func(key []byte) error) error
AddChunk(m, n int, length uint64) (DBChunk, error)
Chunk(id uint64) (DBChunk, error)
SetChunkShard(id uint64, i int, s uint64) error
AddShard(s DBShard) (uint64, error)
Shard(id uint64) (DBShard, error)
UnreferencedSectors() (map[hostdb.HostPublicKey][]crypto.Hash, error)
AddMetadata(key, val []byte) error
Metadata(key []byte) ([]byte, error)
Close() error
}
// EphemeralMetaDB implements MetaDB in memory.
type EphemeralMetaDB struct {
shards []DBShard
chunks []DBChunk
blobs map[string]DBBlob
refs map[uint64]int
meta map[string]string
mu sync.Mutex
}
// AddShard implements MetaDB.
func (db *EphemeralMetaDB) AddShard(s DBShard) (uint64, error) {
db.mu.Lock()
defer db.mu.Unlock()
db.shards = append(db.shards, s)
return uint64(len(db.shards)), nil
}
// Shard implements MetaDB.
func (db *EphemeralMetaDB) Shard(id uint64) (DBShard, error) {
db.mu.Lock()
defer db.mu.Unlock()
return db.shards[id-1], nil
}
// AddChunk implements MetaDB.
func (db *EphemeralMetaDB) AddChunk(m, n int, length uint64) (DBChunk, error) {
db.mu.Lock()
defer db.mu.Unlock()
c := DBChunk{
ID: uint64(len(db.chunks)) + 1,
Shards: make([]uint64, n),
MinShards: uint8(m),
Len: length,
}
db.chunks = append(db.chunks, c)
return c, nil
}
// SetChunkShard implements MetaDB.
func (db *EphemeralMetaDB) SetChunkShard(id uint64, i int, s uint64) error {
db.mu.Lock()
defer db.mu.Unlock()
db.refs[db.chunks[id-1].Shards[i]]--
db.chunks[id-1].Shards[i] = s
db.refs[s]++
return nil
}
// Chunk implements MetaDB.
func (db *EphemeralMetaDB) Chunk(id uint64) (DBChunk, error) {
if id == 0 {
panic("GetChunk: unset id")
}
db.mu.Lock()
defer db.mu.Unlock()
return db.chunks[id-1], nil
}
// AddBlob implements MetaDB.
func (db *EphemeralMetaDB) AddBlob(b DBBlob) error {
db.mu.Lock()
defer db.mu.Unlock()
db.blobs[string(b.Key)] = b
return nil
}
// Blob implements MetaDB.
func (db *EphemeralMetaDB) Blob(key []byte) (DBBlob, error) {
db.mu.Lock()
defer db.mu.Unlock()
b, ok := db.blobs[string(key)]
if !ok {
return DBBlob{}, ErrKeyNotFound
}
return b, nil
}
// DeleteBlob implements MetaDB.
func (db *EphemeralMetaDB) DeleteBlob(key []byte) error {
db.mu.Lock()
defer db.mu.Unlock()
b, ok := db.blobs[string(key)]
if !ok {
return nil
}
for _, cid := range b.Chunks {
for _, sid := range db.chunks[cid-1].Shards {
db.refs[sid]--
}
}
delete(db.blobs, string(key))
return nil
}
// ForEachBlob implements MetaDB.
func (db *EphemeralMetaDB) ForEachBlob(fn func(key []byte) error) error {
db.mu.Lock()
var keys []string
for key := range db.blobs {
keys = append(keys, key)
}
db.mu.Unlock()
sort.Strings(keys)
for _, key := range keys {
if err := fn([]byte(key)); err != nil {
return err
}
}
return nil
}
// UnreferencedSectors returns all sectors that are not referenced by any blob
// in the db.
func (db *EphemeralMetaDB) UnreferencedSectors() (map[hostdb.HostPublicKey][]crypto.Hash, error) {
db.mu.Lock()
defer db.mu.Unlock()
m := make(map[hostdb.HostPublicKey][]crypto.Hash)
for sid, n := range db.refs {
if n == 0 {
s := db.shards[sid-1]
m[s.HostKey] = append(m[s.HostKey], s.SectorRoot)
}
}
return m, nil
}
// AddMetadata implements MetaDB.
func (db *EphemeralMetaDB) AddMetadata(key, val []byte) error {
db.mu.Lock()
defer db.mu.Unlock()
db.meta[string(key)] = string(val)
return nil
}
// Metadata implements MetaDB.
func (db *EphemeralMetaDB) Metadata(key []byte) ([]byte, error) {
db.mu.Lock()
defer db.mu.Unlock()
md, ok := db.meta[string(key)]
if !ok {
return nil, ErrKeyNotFound
}
return []byte(md), nil
}
// Close implements MetaDB.
func (db *EphemeralMetaDB) Close() error {
return nil
}
// NewEphemeralMetaDB initializes an EphemeralMetaDB.
func NewEphemeralMetaDB() *EphemeralMetaDB {
db := &EphemeralMetaDB{
refs: make(map[uint64]int),
blobs: make(map[string]DBBlob),
}
return db
}
// BoltMetaDB implements MetaDB with a Bolt database.
type BoltMetaDB struct {
bdb *bolt.DB
}
var (
bucketBlobs = []byte("blobs")
bucketChunks = []byte("chunks")
bucketShards = []byte("shards")
bucketMeta = []byte("meta")
)
// AddShard implements MetaDB.
func (db *BoltMetaDB) AddShard(s DBShard) (id uint64, err error) {
err = db.bdb.Update(func(tx *bolt.Tx) error {
id, err = tx.Bucket(bucketChunks).NextSequence()
if err != nil {
return err
}
key := make([]byte, 8)
binary.LittleEndian.PutUint64(key, id)
return tx.Bucket(bucketShards).Put(key, encoding.Marshal(s))
})
return
}
// Shard implements MetaDB.
func (db *BoltMetaDB) Shard(id uint64) (s DBShard, err error) {
key := make([]byte, 8)
binary.LittleEndian.PutUint64(key, id)
err = db.bdb.View(func(tx *bolt.Tx) error {
return encoding.Unmarshal(tx.Bucket(bucketShards).Get(key), &s)
})
return
}
// AddChunk implements MetaDB.
func (db *BoltMetaDB) AddChunk(m, n int, length uint64) (c DBChunk, err error) {
err = db.bdb.Update(func(tx *bolt.Tx) error {
id, err := tx.Bucket(bucketChunks).NextSequence()
if err != nil {
return err
}
c = DBChunk{
ID: id,
Shards: make([]uint64, n),
MinShards: uint8(m),
Len: length,
}
key := make([]byte, 8)
binary.LittleEndian.PutUint64(key, id)
return tx.Bucket(bucketChunks).Put(key, encoding.Marshal(c))
})
return
}
// SetChunkShard implements MetaDB.
func (db *BoltMetaDB) SetChunkShard(id uint64, i int, s uint64) error {
return db.bdb.Update(func(tx *bolt.Tx) error {
key := make([]byte, 8)
binary.LittleEndian.PutUint64(key, id)
var c DBChunk
if err := encoding.Unmarshal(tx.Bucket(bucketChunks).Get(key), &c); err != nil {
return err
}
c.Shards[i] = s
return tx.Bucket(bucketChunks).Put(key, encoding.Marshal(c))
})
}
// Chunk implements MetaDB.
func (db *BoltMetaDB) Chunk(id uint64) (c DBChunk, err error) {
key := make([]byte, 8)
binary.LittleEndian.PutUint64(key, id)
err = db.bdb.View(func(tx *bolt.Tx) error {
return encoding.Unmarshal(tx.Bucket(bucketChunks).Get(key), &c)
})
return
}
// AddBlob implements MetaDB.
func (db *BoltMetaDB) AddBlob(b DBBlob) error {
return db.bdb.Update(func(tx *bolt.Tx) error {
return tx.Bucket(bucketBlobs).Put(b.Key, encoding.MarshalAll(b.Chunks, b.Seed))
})
}
// Blob implements MetaDB.
func (db *BoltMetaDB) Blob(key []byte) (b DBBlob, err error) {
err = db.bdb.View(func(tx *bolt.Tx) error {
blobBytes := tx.Bucket(bucketBlobs).Get(key)
if len(blobBytes) == 0 {
return ErrKeyNotFound
}
return encoding.UnmarshalAll(blobBytes, &b.Chunks, &b.Seed)
})
b.Key = key
return
}
// DeleteBlob implements MetaDB.
func (db *BoltMetaDB) DeleteBlob(key []byte) error {
return db.bdb.Update(func(tx *bolt.Tx) error {
// TODO: refcounts
return tx.Bucket(bucketBlobs).Delete(key)
})
}
// ForEachBlob implements MetaDB.
func (db *BoltMetaDB) ForEachBlob(fn func(key []byte) error) error {
return db.bdb.View(func(tx *bolt.Tx) error {
return tx.Bucket(bucketBlobs).ForEach(func(k, _ []byte) error {
return fn(k)
})
})
}
// UnreferencedSectors returns all sectors that are not referenced by any blob
// in the db.
func (db *BoltMetaDB) UnreferencedSectors() (map[hostdb.HostPublicKey][]crypto.Hash, error) {
return nil, nil // TODO
}
// AddMetadata implements MetaDB.
func (db *BoltMetaDB) AddMetadata(key, val []byte) error {
return db.bdb.Update(func(tx *bolt.Tx) error {
return tx.Bucket(bucketMeta).Put(key, val)
})
}
// Metadata implements MetaDB.
func (db *BoltMetaDB) Metadata(key []byte) (val []byte, err error) {
err = db.bdb.View(func(tx *bolt.Tx) error {
val = append(val, tx.Bucket(bucketMeta).Get(key)...)
return nil
})
if err == nil && val == nil {
err = ErrKeyNotFound
}
return
}
// Close implements MetaDB.
func (db *BoltMetaDB) Close() error {
return db.bdb.Close()
}
// NewBoltMetaDB initializes a MetaDB backed by a Bolt database.
func NewBoltMetaDB(path string) (*BoltMetaDB, error) {
bdb, err := bolt.Open(path, 0660, &bolt.Options{
Timeout: 3 * time.Second,
})
if err != nil {
return nil, err
}
db := &BoltMetaDB{
bdb: bdb,
}
// initialize
err = bdb.Update(func(tx *bolt.Tx) error {
for _, bucket := range [][]byte{
bucketBlobs,
bucketChunks,
bucketShards,
bucketMeta,
} {
if _, err := tx.CreateBucketIfNotExists(bucket); err != nil {
return err
}
}
return nil
})
if err != nil {
return nil, err
}
return db, nil
}