Move boltdb implementation to storage package
Removes storage interface and replaces with storage functions. Signed-off-by: Derek McGowan <derek@mcgstyle.net>
This commit is contained in:
Derek McGowan
parent
8affca40bb
commit
b319ba7c5a
12 changed files with 373 additions and 404 deletions
380
snapshot/storage/bolt.go
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380
snapshot/storage/bolt.go
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@ -0,0 +1,380 @@
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package storage
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import (
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"context"
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"encoding/binary"
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"fmt"
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"github.com/boltdb/bolt"
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"github.com/containerd/containerd/snapshot"
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db "github.com/containerd/containerd/snapshot/storage/proto"
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"github.com/gogo/protobuf/proto"
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"github.com/pkg/errors"
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)
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var (
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bucketKeyStorageVersion = []byte("v1")
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bucketKeySnapshot = []byte("snapshots")
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bucketKeyParents = []byte("parents")
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)
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type boltFileTransactor struct {
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db *bolt.DB
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tx *bolt.Tx
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}
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func (bft *boltFileTransactor) Rollback() error {
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defer bft.db.Close()
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return bft.tx.Rollback()
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}
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func (bft *boltFileTransactor) Commit() error {
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defer bft.db.Close()
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return bft.tx.Commit()
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}
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// parentKey returns a composite key of the parent and child identifiers. The
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// parts of the key are separated by a zero byte.
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func parentKey(parent, child uint64) []byte {
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b := make([]byte, binary.Size([]uint64{parent, child})+1)
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i := binary.PutUvarint(b, parent)
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j := binary.PutUvarint(b[i+1:], child)
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return b[0 : i+j+1]
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}
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// parentPrefixKey returns the parent part of the composite key with the
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// zero byte separator.
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func parentPrefixKey(parent uint64) []byte {
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b := make([]byte, binary.Size(parent)+1)
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i := binary.PutUvarint(b, parent)
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return b[0 : i+1]
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}
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// getParentPrefix returns the first part of the composite key which
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// represents the parent identifier.
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func getParentPrefix(b []byte) uint64 {
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parent, _ := binary.Uvarint(b)
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return parent
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}
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// GetInfo returns the snapshot Info directly from the metadata. Requires a
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// context with a storage transaction.
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func GetInfo(ctx context.Context, key string) (snapshot.Info, error) {
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var ss db.Snapshot
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err := withBucket(ctx, func(ctx context.Context, bkt, pbkt *bolt.Bucket) error {
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return getSnapshot(bkt, key, &ss)
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})
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if err != nil {
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return snapshot.Info{}, err
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}
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return snapshot.Info{
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Name: key,
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Parent: ss.Parent,
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Kind: fromProtoKind(ss.Kind),
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Readonly: ss.Readonly,
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}, nil
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}
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// WalkInfo iterates through all metadata Info for the stored snapshots and
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// calls the provided function for each. Requires a context with a storage
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// transaction.
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func WalkInfo(ctx context.Context, fn func(context.Context, snapshot.Info) error) error {
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return withBucket(ctx, func(ctx context.Context, bkt, pbkt *bolt.Bucket) error {
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return bkt.ForEach(func(k, v []byte) error {
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// skip nested buckets
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if v == nil {
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return nil
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}
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var ss db.Snapshot
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if err := proto.Unmarshal(v, &ss); err != nil {
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return errors.Wrap(err, "failed to unmarshal snapshot")
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}
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info := snapshot.Info{
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Name: string(k),
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Parent: ss.Parent,
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Kind: fromProtoKind(ss.Kind),
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Readonly: ss.Readonly,
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}
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return fn(ctx, info)
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})
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})
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}
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// CreateActive creates a new active snapshot transaction referenced by
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// the provided key. The new active snapshot will have the provided
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// parent. If the readonly option is given, the active snapshot will be
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// marked as readonly and can only be removed, and not committed. The
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// provided context must contain a writable transaction.
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func CreateActive(ctx context.Context, key, parent string, readonly bool) (a Active, err error) {
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err = createBucketIfNotExists(ctx, func(ctx context.Context, bkt, pbkt *bolt.Bucket) error {
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var (
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parentS *db.Snapshot
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)
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if parent != "" {
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parentS = new(db.Snapshot)
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if err := getSnapshot(bkt, parent, parentS); err != nil {
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return errors.Wrap(err, "failed to get parent snapshot")
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}
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if parentS.Kind != db.KindCommitted {
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return errors.Wrap(snapshot.ErrSnapshotNotCommitted, "parent is not committed snapshot")
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}
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}
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b := bkt.Get([]byte(key))
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if len(b) != 0 {
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return snapshot.ErrSnapshotExist
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}
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id, err := bkt.NextSequence()
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if err != nil {
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return errors.Wrap(err, "unable to get identifier")
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}
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ss := db.Snapshot{
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ID: id,
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Parent: parent,
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Kind: db.KindActive,
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Readonly: readonly,
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}
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if err := putSnapshot(bkt, key, &ss); err != nil {
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return err
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}
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if parentS != nil {
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// Store a backlink from the key to the parent. Store the snapshot name
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// as the value to allow following the backlink to the snapshot value.
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if err := pbkt.Put(parentKey(parentS.ID, ss.ID), []byte(key)); err != nil {
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return errors.Wrap(err, "failed to write parent link")
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}
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a.ParentIDs, err = parents(bkt, parentS)
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if err != nil {
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return errors.Wrap(err, "failed to get parent chain")
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}
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}
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a.ID = fmt.Sprintf("%d", id)
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a.Readonly = readonly
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return nil
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})
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if err != nil {
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return Active{}, err
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}
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return
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}
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// GetActive returns the metadata for the active snapshot transaction referenced
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// by the given key. Requires a context with a storage transaction.
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func GetActive(ctx context.Context, key string) (a Active, err error) {
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err = withBucket(ctx, func(ctx context.Context, bkt, pbkt *bolt.Bucket) error {
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b := bkt.Get([]byte(key))
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if len(b) == 0 {
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return snapshot.ErrSnapshotNotExist
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}
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var ss db.Snapshot
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if err := proto.Unmarshal(b, &ss); err != nil {
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return errors.Wrap(err, "failed to unmarshal snapshot")
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}
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if ss.Kind != db.KindActive {
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return snapshot.ErrSnapshotNotActive
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}
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a.ID = fmt.Sprintf("%d", ss.ID)
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a.Readonly = ss.Readonly
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if ss.Parent != "" {
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var parent db.Snapshot
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if err := getSnapshot(bkt, ss.Parent, &parent); err != nil {
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return errors.Wrap(err, "failed to get parent snapshot")
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}
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a.ParentIDs, err = parents(bkt, &parent)
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if err != nil {
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return errors.Wrap(err, "failed to get parent chain")
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}
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}
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return nil
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})
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if err != nil {
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return Active{}, err
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}
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return
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}
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// Remove removes a snapshot from the metastore. The string identifier for the
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// snapshot is returned as well as the kind. The provided context must contain a
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// writable transaction.
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func Remove(ctx context.Context, key string) (id string, k snapshot.Kind, err error) {
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err = withBucket(ctx, func(ctx context.Context, bkt, pbkt *bolt.Bucket) error {
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var ss db.Snapshot
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b := bkt.Get([]byte(key))
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if len(b) == 0 {
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return snapshot.ErrSnapshotNotExist
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}
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if err := proto.Unmarshal(b, &ss); err != nil {
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return errors.Wrap(err, "failed to unmarshal snapshot")
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}
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if pbkt != nil {
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k, _ := pbkt.Cursor().Seek(parentPrefixKey(ss.ID))
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if getParentPrefix(k) == ss.ID {
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return errors.Errorf("cannot remove snapshot with child")
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}
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if ss.Parent != "" {
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var ps db.Snapshot
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if err := getSnapshot(bkt, ss.Parent, &ps); err != nil {
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return errors.Wrap(err, "failed to get parent snapshot")
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}
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if err := pbkt.Delete(parentKey(ps.ID, ss.ID)); err != nil {
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return errors.Wrap(err, "failed to delte parent link")
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}
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}
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}
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if err := bkt.Delete([]byte(key)); err != nil {
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return errors.Wrap(err, "failed to delete snapshot")
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}
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id = fmt.Sprintf("%d", ss.ID)
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k = fromProtoKind(ss.Kind)
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return nil
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})
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return
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}
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// CommitActive renames the active snapshot transaction referenced by `key`
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// as a committed snapshot referenced by `Name`. The resulting snapshot will be
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// committed and readonly. The `key` reference will no longer be available for
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// lookup or removal. The returned string identifier for the committed snapshot
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// is the same identifier of the original active snapshot. The provided context
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// must contain a writable transaction.
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func CommitActive(ctx context.Context, key, name string) (id string, err error) {
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err = withBucket(ctx, func(ctx context.Context, bkt, pbkt *bolt.Bucket) error {
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b := bkt.Get([]byte(name))
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if len(b) != 0 {
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return errors.Wrap(snapshot.ErrSnapshotExist, "committed name already exists")
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}
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var ss db.Snapshot
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if err := getSnapshot(bkt, key, &ss); err != nil {
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return errors.Wrap(err, "failed to get active snapshot")
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}
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if ss.Kind != db.KindActive {
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return snapshot.ErrSnapshotNotActive
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}
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if ss.Readonly {
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return errors.Errorf("active snapshot is readonly")
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}
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ss.Kind = db.KindCommitted
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ss.Readonly = true
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if err := putSnapshot(bkt, name, &ss); err != nil {
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return err
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}
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if err := bkt.Delete([]byte(key)); err != nil {
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return errors.Wrap(err, "failed to delete active")
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}
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id = fmt.Sprintf("%d", ss.ID)
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return nil
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})
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if err != nil {
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return "", err
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}
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return
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}
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func withBucket(ctx context.Context, fn func(context.Context, *bolt.Bucket, *bolt.Bucket) error) error {
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t, ok := ctx.Value(transactionKey{}).(*boltFileTransactor)
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if !ok {
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return errors.Errorf("no transaction in context")
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}
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bkt := t.tx.Bucket(bucketKeyStorageVersion)
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if bkt == nil {
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return errors.Wrap(snapshot.ErrSnapshotNotExist, "bucket does not exist")
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}
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return fn(ctx, bkt.Bucket(bucketKeySnapshot), bkt.Bucket(bucketKeyParents))
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}
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func createBucketIfNotExists(ctx context.Context, fn func(context.Context, *bolt.Bucket, *bolt.Bucket) error) error {
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t, ok := ctx.Value(transactionKey{}).(*boltFileTransactor)
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if !ok {
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return errors.Errorf("no transaction in context")
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}
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bkt, err := t.tx.CreateBucketIfNotExists(bucketKeyStorageVersion)
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if err != nil {
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return errors.Wrap(err, "failed to create version bucket")
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}
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sbkt, err := bkt.CreateBucketIfNotExists(bucketKeySnapshot)
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if err != nil {
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return errors.Wrap(err, "failed to create snapshots bucket")
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}
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pbkt, err := bkt.CreateBucketIfNotExists(bucketKeyParents)
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if err != nil {
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return errors.Wrap(err, "failed to create snapshots bucket")
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}
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return fn(ctx, sbkt, pbkt)
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}
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func fromProtoKind(k db.Kind) snapshot.Kind {
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if k == db.KindActive {
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return snapshot.KindActive
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}
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return snapshot.KindCommitted
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}
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func parents(bkt *bolt.Bucket, parent *db.Snapshot) (parents []string, err error) {
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for {
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parents = append(parents, fmt.Sprintf("%d", parent.ID))
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if parent.Parent == "" {
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return
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}
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var ps db.Snapshot
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if err := getSnapshot(bkt, parent.Parent, &ps); err != nil {
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return nil, errors.Wrap(err, "failed to get parent snapshot")
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}
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parent = &ps
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}
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return
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}
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func getSnapshot(bkt *bolt.Bucket, key string, ss *db.Snapshot) error {
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b := bkt.Get([]byte(key))
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if len(b) == 0 {
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return snapshot.ErrSnapshotNotExist
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}
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if err := proto.Unmarshal(b, ss); err != nil {
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return errors.Wrap(err, "failed to unmarshal snapshot")
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}
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return nil
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}
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func putSnapshot(bkt *bolt.Bucket, key string, ss *db.Snapshot) error {
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b, err := proto.Marshal(ss)
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if err != nil {
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return errors.Wrap(err, "failed to marshal snapshot")
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}
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if err := bkt.Put([]byte(key), b); err != nil {
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return errors.Wrap(err, "failed to save snapshot")
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}
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return nil
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}
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