/
db.go
214 lines (185 loc) · 4.6 KB
/
db.go
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package hashdb
import (
"bytes"
"compress/zlib"
"context"
"crypto/sha256"
"io"
"github.com/zeebo/errs"
"github.com/jtolio/jam/backends"
"github.com/jtolio/jam/manifest"
"github.com/jtolio/jam/streams"
"github.com/jtolio/jam/utils"
)
const versionHeader = "jam-v0\n"
const HashPrefix = "hash/"
const SmallHashsetSuffix = ".hs"
const SmallHashsetThreshold = 64 * 1024
type DB struct {
backend backends.Backend
// TODO: do an LSM tree instead of putting all of this in RAM
existing map[string]*manifest.Stream
new map[string]*manifest.Stream
source map[string]string
paths []string
}
func Open(ctx context.Context, backend backends.Backend) (*DB, error) {
db := New(backend)
return db, db.load(ctx)
}
func New(backend backends.Backend) *DB {
return &DB{
backend: backend,
existing: map[string]*manifest.Stream{},
new: map[string]*manifest.Stream{},
source: map[string]string{},
}
}
func (d *DB) load(ctx context.Context) error {
var paths []string
err := d.backend.List(ctx, HashPrefix,
func(ctx context.Context, path string) error {
r, err := d.backend.Get(ctx, path, 0, -1)
if err != nil {
return err
}
defer r.Close()
paths = append(paths, path)
return d.loadStream(ctx, r, path)
})
if err != nil {
return err
}
d.paths = paths
return nil
}
func (d *DB) loadStream(ctx context.Context, stream io.Reader, path string) error {
// TODO: reduce code duplication with pathdb.load
v := make([]byte, len([]byte(versionHeader)))
_, err := io.ReadFull(stream, v)
if err != nil {
if err == io.EOF {
err = errs.New("unexpected EOF for hashset %q", path)
}
return err
}
if versionHeader != string(v) {
return errs.New("invalid hashset version for hashset %q", path)
}
r, err := zlib.NewReader(utils.NewUnframingReader(stream))
if err != nil {
return errs.New("error for hashset %q: %+v", path, err)
}
defer func() {
err = errs.Combine(err, r.Close())
}()
for {
var set manifest.HashSet
err := utils.UnmarshalSized(r, &set)
if err != nil {
if err == io.EOF {
break
}
return errs.New("error for hashset %q: %+v", path, err)
}
for _, entry := range set.Hashes {
hashBytes := entry.Hash
if len(hashBytes) != sha256.Size {
if len(hashBytes) != sha256.Size*2 {
return errs.New("unknown hash length for hashset %q", path)
}
// TODO: sadlol, remove after everything is migrated
hashBytes = hashBytes[len(hashBytes)-sha256.Size:]
}
hash := string(hashBytes)
// TODO: log on overwrites?
d.existing[hash] = entry.Data
d.source[hash] = path
}
}
return nil
}
func (d *DB) Has(ctx context.Context, hash string) (exists bool, err error) {
stream, err := d.Lookup(ctx, hash)
return stream != nil, err
}
func (d *DB) Lookup(ctx context.Context, hash string) (*manifest.Stream, error) {
rv := d.existing[hash]
if rv != nil {
return rv, nil
}
return d.new[hash], nil
}
func (d *DB) Put(ctx context.Context, hash string, data *manifest.Stream) error {
d.new[hash] = data
return nil
}
func (d *DB) flush(ctx context.Context, hashes map[string]*manifest.Stream) (string, error) {
if len(hashes) == 0 {
return "", nil
}
// TODO: LSM tree instead of this
var set manifest.HashSet
for hash, data := range hashes {
set.Hashes = append(set.Hashes, &manifest.HashedData{
Hash: []byte(hash),
Data: data,
})
}
// TODO: reduce code duplication with pathdb.Serialize
data, err := utils.MarshalSized(&set)
if err != nil {
return "", err
}
var out bytes.Buffer
compressor := zlib.NewWriter(&out)
_, err = compressor.Write(data)
if err != nil {
return "", err
}
err = compressor.Close()
if err != nil {
return "", err
}
path := HashPrefix + streams.IdPathComponent(utils.IdGen())
if out.Len() <= SmallHashsetThreshold {
path += SmallHashsetSuffix
}
err = d.backend.Put(ctx, path, io.MultiReader(
bytes.NewReader([]byte(versionHeader)),
utils.NewFramingReader(&out)))
if err != nil {
return "", err
}
return path, nil
}
func (d *DB) Flush(ctx context.Context) error {
path, err := d.flush(ctx, d.new)
if err != nil {
return err
}
for hash, data := range d.new {
d.existing[hash] = data
d.source[hash] = path
}
d.new = map[string]*manifest.Stream{}
return nil
}
func (d *DB) Close() error {
return nil
}
func (d *DB) Iterate(ctx context.Context, cb func(ctx context.Context, hash, hashset string, data *manifest.Stream) error) error {
for hash, data := range d.existing {
err := cb(ctx, hash, d.source[hash], data)
if err != nil {
return err
}
}
for hash, data := range d.new {
err := cb(ctx, hash, "", data)
if err != nil {
return err
}
}
return nil
}