forked from TrueCloudLab/frostfs-node
cf73feb3f8
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>
114 lines
2.8 KiB
Go
114 lines
2.8 KiB
Go
package pilorama
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import (
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cidSDK "github.com/nspcc-dev/neofs-sdk-go/container/id"
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)
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// memoryForest represents multiple replicating trees sharing a single storage.
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type memoryForest struct {
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// treeMap maps tree identifier (container ID + name) to the replicated log.
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treeMap map[string]*state
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}
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var _ Forest = (*memoryForest)(nil)
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// NewMemoryForest creates new empty forest.
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// TODO: this function will eventually be removed and is here for debugging.
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func NewMemoryForest() ForestStorage {
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return &memoryForest{
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treeMap: make(map[string]*state),
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}
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}
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// TreeMove implements the Forest interface.
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func (f *memoryForest) TreeMove(cid cidSDK.ID, treeID string, op *Move) (*LogMove, error) {
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fullID := cid.String() + "/" + treeID
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s, ok := f.treeMap[fullID]
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if !ok {
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s = newState()
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f.treeMap[fullID] = s
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}
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op.Time = s.timestamp()
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if op.Child == RootID {
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op.Child = s.findSpareID()
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}
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lm := s.do(op)
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s.operations = append(s.operations, lm)
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return &lm, nil
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}
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// TreeAddByPath implements the Forest interface.
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func (f *memoryForest) TreeAddByPath(cid cidSDK.ID, treeID string, attr string, path []string, m []KeyValue) ([]LogMove, error) {
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fullID := cid.String() + "/" + treeID
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s, ok := f.treeMap[fullID]
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if !ok {
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s = newState()
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f.treeMap[fullID] = s
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}
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i, node := s.getPathPrefix(attr, path)
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lm := make([]LogMove, len(path)-i+1)
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for j := i; j < len(path); j++ {
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lm[j-i] = s.do(&Move{
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Parent: node,
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Meta: Meta{Time: s.timestamp(), Items: []KeyValue{{Key: attr, Value: []byte(path[j])}}},
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Child: s.findSpareID(),
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})
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node = lm[j-i].Child
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s.operations = append(s.operations, lm[j-i])
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}
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lm[len(lm)-1] = s.do(&Move{
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Parent: node,
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Meta: Meta{Time: s.timestamp(), Items: m},
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Child: s.findSpareID(),
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})
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return lm, nil
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}
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// TreeApply implements the Forest interface.
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func (f *memoryForest) TreeApply(cid cidSDK.ID, treeID string, op *Move) error {
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fullID := cid.String() + "/" + treeID
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s, ok := f.treeMap[fullID]
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if !ok {
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s = newState()
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f.treeMap[fullID] = s
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}
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return s.Apply(op)
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}
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func (f *memoryForest) Init() error {
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return nil
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}
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func (f *memoryForest) Open() error {
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return nil
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}
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func (f *memoryForest) Close() error {
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return nil
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}
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// TreeGetByPath implements the Forest interface.
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func (f *memoryForest) TreeGetByPath(cid cidSDK.ID, treeID string, attr string, path []string, latest bool) ([]Node, error) {
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fullID := cid.String() + "/" + treeID
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s, ok := f.treeMap[fullID]
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if !ok {
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return nil, ErrTreeNotFound
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}
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return s.get(attr, path, latest), nil
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}
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// TreeGetMeta implements the Forest interface.
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func (f *memoryForest) TreeGetMeta(cid cidSDK.ID, treeID string, nodeID Node) (Meta, error) {
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fullID := cid.String() + "/" + treeID
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s, ok := f.treeMap[fullID]
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if !ok {
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return Meta{}, ErrTreeNotFound
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}
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return s.getMeta(nodeID), nil
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}
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