69 lines
2.8 KiB
Go
69 lines
2.8 KiB
Go
package storage
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import (
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"context"
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"github.com/docker/containerd/snapshot"
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)
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// MetaStore is used to store metadata related to a snapshot driver. The
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// MetaStore is intended to store metadata related to name, state and
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// parentage. Using the MetaStore is not required to implement a snapshot
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// driver but can be used to handle the persistence and transactional
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// complexities of a driver implementation.
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type MetaStore interface {
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// TransactionContext creates a new transaction context.
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TransactionContext(ctx context.Context, writable bool) (context.Context, Transactor, error)
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// Stat returns the snapshot stat Info directly from
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// the metadata.
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Stat(ctx context.Context, key string) (snapshot.Info, error)
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// Walk iterates through all metadata for the stored
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// snapshots and calls the provided function for each.
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Walk(ctx context.Context, fn func(context.Context, snapshot.Info) error) error
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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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CreateActive(ctx context.Context, key, parent string, readonly bool) (Active, error)
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// GetActive returns the metadata for the active snapshot transaction
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// referenced by the given key.
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GetActive(ctx context.Context, key string) (Active, error)
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// Remove removes a snapshot from the metastore. The provided context
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// must contain a writable transaction. The string identifier for the
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// snapshot is returned.
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Remove(ctx context.Context, key string) (string, error)
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// Commit renames the active snapshot transaction referenced by `key`
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// as a committed snapshot referenced by `Name`. The resulting snapshot
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// will be committed and readonly. The `key` reference will no longer
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// be available for lookup or removal. The returned string identifier
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// for the committed snapshot is the same identifier of the original
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// active snapshot.
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Commit(ctx context.Context, key, name string) (string, error)
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}
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// Transactor is used to finalize an active transaction.
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type Transactor interface {
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// Commit commits any changes made during the transaction.
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Commit() error
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// Rollback rolls back any changes made during the transaction.
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Rollback() error
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}
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// Active hold the metadata for an active snapshot transaction. The ParentIDs
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// hold the snapshot identifiers for the committed snapshots this active is
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// based on. The ParentIDs are ordered from the lowest base to highest, meaning
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// they should be applied in order from the first index to the last index. The
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// last index should always be considered the active snapshots immediate parent.
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type Active struct {
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ID string
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ParentIDs []string
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Readonly bool
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}
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