Documentation

Overview

    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.

    Index

    Constants

    This section is empty.

    Variables

    View Source
    var (
    
    	// 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")
    )

    Functions

    func CommitActive

    func CommitActive(ctx context.Context, key, name string, usage snapshots.Usage, opts ...snapshots.Opt) (string, error)

      CommitActive renames the active snapshot transaction referenced by `key` as a committed snapshot referenced by `Name`. The resulting snapshot will be committed and readonly. The `key` reference will no longer be available for lookup or removal. The returned string identifier for the committed snapshot is the same identifier of the original active snapshot. The provided context must contain a writable transaction.

      func GetInfo

        GetInfo returns the snapshot Info directly from the metadata. Requires a context with a storage transaction.

        func IDMap

        func IDMap(ctx context.Context) (map[string]string, error)

          IDMap returns all the IDs mapped to their key

          func Remove

          func Remove(ctx context.Context, key string) (string, snapshots.Kind, error)

            Remove removes a snapshot from the metastore. The string identifier for the snapshot is returned as well as the kind. The provided context must contain a writable transaction.

            func UpdateInfo

            func UpdateInfo(ctx context.Context, info snapshots.Info, fieldpaths ...string) (snapshots.Info, error)

              UpdateInfo updates an existing snapshot info's data

              func WalkInfo

              func WalkInfo(ctx context.Context, fn snapshots.WalkFunc, fs ...string) error

                WalkInfo iterates through all metadata Info for the stored snapshots and calls the provided function for each. Requires a context with a storage transaction.

                Types

                type MetaStore

                type MetaStore struct {
                	// contains filtered or unexported fields
                }

                  MetaStore is used to store metadata related to a snapshot driver. The MetaStore is intended to store metadata related to name, state and parentage. Using the MetaStore is not required to implement a snapshot driver but can be used to handle the persistence and transactional complexities of a driver implementation.

                  func NewMetaStore

                  func NewMetaStore(dbfile string) (*MetaStore, error)

                    NewMetaStore returns a snapshot MetaStore for storage of metadata related to a snapshot driver backed by a bolt file database. This implementation is strongly consistent and does all metadata changes in a transaction to prevent against process crashes causing inconsistent metadata state.

                    func (*MetaStore) Close

                    func (ms *MetaStore) Close() error

                      Close closes the metastore and any underlying database connections

                      func (*MetaStore) TransactionContext

                      func (ms *MetaStore) TransactionContext(ctx context.Context, writable bool) (context.Context, Transactor, error)

                        TransactionContext creates a new transaction context. The writable value should be set to true for transactions which are expected to mutate data.

                        type Snapshot

                        type Snapshot struct {
                        	Kind      snapshots.Kind
                        	ID        string
                        	ParentIDs []string
                        }

                          Snapshot hold the metadata for an active or view snapshot transaction. The ParentIDs hold the snapshot identifiers for the committed snapshots this active or view is based on. The ParentIDs are ordered from the lowest base to highest, meaning they should be applied in order from the first index to the last index. The last index should always be considered the active snapshots immediate parent.

                          func CreateSnapshot

                          func CreateSnapshot(ctx context.Context, kind snapshots.Kind, key, parent string, opts ...snapshots.Opt) (s Snapshot, err error)

                            CreateSnapshot inserts a record for an active or view snapshot with the provided parent.

                            func GetSnapshot

                            func GetSnapshot(ctx context.Context, key string) (s Snapshot, err error)

                              GetSnapshot returns the metadata for the active or view snapshot transaction referenced by the given key. Requires a context with a storage transaction.

                              type Transactor

                              type Transactor interface {
                              	// 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. This
                              	// must be called on all non-writable transactions and aborted writable
                              	// transaction.
                              	Rollback() error
                              }

                                Transactor is used to finalize an active transaction.