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[#1324] local_object_storage: Implement tree service backend

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In this commit we implement algorithm for CRDT trees from
https://martin.klepmann.com/papers/move-op.pdf

Each tree is identified by the ID of a container it belongs to
and the tree name itself. Essentially, it is a sequence of operations
which should be applied in chronological order to get a usual tree
representation.

There are 2 backends for now: bbolt database and in-memory.
In-memory backend is here for debugging and will eventually act
as a memory-cache for the on-disk database.

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>
This commit is contained in:
Evgenii Stratonikov 2022-04-22 16:22:40 +03:00 • committed by fyrchik
parent 198beae703
commit 8cf71b7f1c
8 changed files with 1499 additions and 0 deletions
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35
pkg/local_object_storage/pilorama/interface.go Normal file
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package pilorama
import cidSDK "github.com/nspcc-dev/neofs-sdk-go/container/id"
// Forest represents CRDT tree.
type Forest interface {
// TreeMove moves node in the tree.
// If the parent of the move operation is TrashID, the node is removed.
// If the child of the move operation is RootID, new ID is generated and added to a tree.
TreeMove(cid cidSDK.ID, treeID string, m *Move) (*LogMove, error)
// TreeAddByPath adds new node in the tree using provided path.
// The path is constructed by descending from the root using the values of the attr in meta.
TreeAddByPath(cid cidSDK.ID, treeID string, attr string, path []string, meta []KeyValue) ([]LogMove, error)
// TreeApply applies replicated operation from another node.
TreeApply(cid cidSDK.ID, treeID string, m *Move) error
// TreeGetByPath returns all nodes corresponding to the path.
// The path is constructed by descending from the root using the values of the
// AttributeFilename in meta.
// The last argument determines whether only the node with the latest timestamp is returned.
TreeGetByPath(cid cidSDK.ID, treeID string, attr string, path []string, latest bool) ([]Node, error)
// TreeGetMeta returns meta information of the node with the specified ID.
TreeGetMeta(cid cidSDK.ID, treeID string, nodeID Node) (Meta, error)
}
type ForestStorage interface {
Init() error
Open() error
Close() error
Forest
}
const (
AttributeFilename = "FileName"
AttributeVersion = "Version"
)