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including arbo as key-value database to be used with updater filter t…
…o avoid reprocessing transactions
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,128 @@ | ||
| package treedb | ||
|
|
||
| // The treedb package provides a wrapper of key-value database that uses a | ||
| // merkle tree under the hood. Every tree is stored in the same database, but | ||
| // with a different prefix. | ||
|
|
||
| import ( | ||
| "fmt" | ||
|
|
||
| "go.vocdoni.io/dvote/db" | ||
| "go.vocdoni.io/dvote/db/prefixeddb" | ||
| "go.vocdoni.io/dvote/log" | ||
| "go.vocdoni.io/dvote/tree" | ||
| "go.vocdoni.io/dvote/tree/arbo" | ||
| ) | ||
|
|
||
| // filterTreeLevels is the number of levels of the tree used to store the | ||
| // filter. It is a constant to avoid re-creating the tree with a different | ||
| // number of levels. The available number of leaves is 2^filterTreeLevels. | ||
| // It also limits the size of the key to filterTreeLevels/8 bytes. | ||
| const filterTreeLevels = 64 | ||
|
|
||
| // ErrNotInitialized is returned when no tree is initialized in a TreeDB | ||
| // instance, which means that LoadTree has not been called and the tree is | ||
| // not ready to be used. | ||
| var ErrNotInitialized = fmt.Errorf("tree not initialized, call Load first") | ||
|
|
||
| // TokenFilter is a filter associated with a token. | ||
| type TreeDB struct { | ||
| prefix string | ||
| parentDB db.Database | ||
| tree *tree.Tree | ||
| } | ||
|
|
||
| // LoadTree loads a tree from the database identified by the given prefix. If it | ||
| // does not exist, it creates a new tree with the given prefix. It also creates | ||
| // the index if it does not exist. It returns an error if the tree cannot be | ||
| // loaded or created. | ||
| func LoadTree(db db.Database, prefix string) (*TreeDB, error) { | ||
| treeDB := prefixeddb.NewPrefixedDatabase(db, []byte(prefix)) | ||
| tree, err := tree.New(nil, tree.Options{ | ||
| DB: treeDB, | ||
| MaxLevels: filterTreeLevels, | ||
| HashFunc: arbo.HashFunctionBlake2b, | ||
| }) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| // ensure index is created | ||
| wTx := tree.DB().WriteTx() | ||
| defer wTx.Discard() | ||
| return &TreeDB{ | ||
| prefix: prefix, | ||
| parentDB: db, | ||
| tree: tree, | ||
| }, wTx.Commit() | ||
| } | ||
|
|
||
| func (tdb *TreeDB) Close() error { | ||
| if tdb.tree != nil { | ||
| if err := tdb.tree.DB().Close(); err != nil { | ||
| return err | ||
| } | ||
| } | ||
| if tdb.parentDB != nil { | ||
| return tdb.parentDB.Close() | ||
| } | ||
| return nil | ||
| } | ||
|
|
||
| // DeleteTree deletes a tree from the database identified by current prefix. | ||
| // It iterates over all the keys in the tree and deletes them. If some key | ||
| // cannot be deleted, it logs a warning and continues with the next key. It | ||
| // commits the transaction at the end. | ||
| func (tdb *TreeDB) Delete() error { | ||
| treeDB := prefixeddb.NewPrefixedDatabase(tdb.parentDB, []byte(tdb.prefix)) | ||
| wTx := treeDB.WriteTx() | ||
| if err := treeDB.Iterate(nil, func(k, _ []byte) bool { | ||
| if err := wTx.Delete(k); err != nil { | ||
| log.Warnw("error deleting key", "key", k, "err", err) | ||
| } | ||
| return true | ||
| }); err != nil { | ||
| return err | ||
| } | ||
| return wTx.Commit() | ||
| } | ||
|
|
||
| // Add adds a key to the tree. | ||
| func (tdb *TreeDB) Add(key, value []byte) error { | ||
| if tdb.tree == nil { | ||
| return ErrNotInitialized | ||
| } | ||
| wTx := tdb.tree.DB().WriteTx() | ||
| defer wTx.Discard() | ||
| if err := tdb.tree.Add(wTx, key, value); err != nil { | ||
| return err | ||
| } | ||
| return wTx.Commit() | ||
| } | ||
|
|
||
| // Test checks if a key is in the tree. | ||
| func (tdb *TreeDB) Test(key []byte) (bool, error) { | ||
| if tdb.tree == nil { | ||
| return false, ErrNotInitialized | ||
| } | ||
| _, err := tdb.tree.Get(nil, key) | ||
| if err != nil { | ||
| if err == arbo.ErrKeyNotFound { | ||
| return false, nil | ||
| } | ||
| return false, err | ||
| } | ||
| return true, nil | ||
| } | ||
|
|
||
| // TestAndAdd checks if a key is in the tree, if not, add it to the tree. It | ||
| // is the combination of Test and conditional Add. | ||
| func (tdb *TreeDB) TestAndAdd(key, value []byte) (bool, error) { | ||
| exists, err := tdb.Test(key) | ||
| if err != nil { | ||
| return false, err | ||
| } | ||
| if exists { | ||
| return true, nil | ||
| } | ||
| return false, tdb.Add(key, value) | ||
| } |
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