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Update documentation to storage package

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Signed-off-by: Derek McGowan <derek@mcgstyle.net>
This commit is contained in:
Derek McGowan 2017-04-04 13:31:38 -07:00
parent 9ffbfccdaf
commit 1c2f5fe203
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2 changed files with 20 additions and 5 deletions
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8
snapshot/storage/bolt.go
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@ -16,6 +16,10 @@ var (
bucketKeyStorageVersion = []byte("v1")
bucketKeySnapshot = []byte("snapshots")
bucketKeyParents = []byte("parents")
// ErrNoTransaction is returned when an operation is attempted with
// a context which is not inside of a transaction.
ErrNoTransaction = errors.New("no transaction in context")
)
type boltFileTransactor struct {
@ -301,7 +305,7 @@ func CommitActive(ctx context.Context, key, name string) (id string, err error)
func withBucket(ctx context.Context, fn func(context.Context, *bolt.Bucket, *bolt.Bucket) error) error {
t, ok := ctx.Value(transactionKey{}).(*boltFileTransactor)
if !ok {
return errors.Errorf("no transaction in context")
return ErrNoTransaction
}
bkt := t.tx.Bucket(bucketKeyStorageVersion)
if bkt == nil {
@ -313,7 +317,7 @@ func withBucket(ctx context.Context, fn func(context.Context, *bolt.Bucket, *bol
func createBucketIfNotExists(ctx context.Context, fn func(context.Context, *bolt.Bucket, *bolt.Bucket) error) error {
t, ok := ctx.Value(transactionKey{}).(*boltFileTransactor)
if !ok {
return errors.Errorf("no transaction in context")
return ErrNoTransaction
}
bkt, err := t.tx.CreateBucketIfNotExists(bucketKeyStorageVersion)

17
snapshot/storage/metastore.go
View file

@ -1,3 +1,8 @@
// Package storage provides a metadata storage implementation for snapshot
// drivers. Drive implementations are responsible for starting and managing
// transactions using the defined context creator. This storage package uses
// BoltDB for storing metadata. Access to the raw boltdb transaction is not
// provided, but the stored object is provided by the proto subpackage.
package storage
import (
@ -9,10 +14,15 @@ import (
// Transactor is used to finalize an active transaction.
type Transactor interface {
// Commit commits any changes made during the transaction.
// Commit commits any changes made during the transaction. On error a
// caller is expected to clean up any resources which would have relied
// on data mutated as part of this transaction. Only writable
// transactions can commit, non-writable must call Rollback.
Commit() error
// Rollback rolls back any changes made during the transaction.
// Rollback rolls back any changes made during the transaction. This
// must be called on all non-writable transactions and aborted writable
// transaction.
Rollback() error
}
@ -48,7 +58,8 @@ func NewMetaStore(dbfile string) (*MetaStore, error) {
type transactionKey struct{}
// TransactionContext creates a new transaction context.
// TransactionContext creates a new transaction context. The writable value
// should be set to true for transactions which are expected to mutate data.
func (ms *MetaStore) TransactionContext(ctx context.Context, writable bool) (context.Context, Transactor, error) {
db, err := bolt.Open(ms.dbfile, 0600, nil)
if err != nil {