| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
Blockchain.Database.MerklePatricia
Description
This is an implementation of the modified Merkle Patricia database described in the Ethereum Yellowpaper (http://gavwood.com/paper.pdf). This modified version works like a canonical Merkle Patricia database, but includes certain optimizations. In particular, a new type of "shortcut node" has been added to represent multiple traditional nodes that fall in a linear string (ie- a stretch of parent child nodes where no branch choices exist).
A Merkle Patricia Database effeciently retains its full history, and a snapshot of all key-value pairs at a given time can be looked up using a "stateRoot" (a pointer to the root of the tree representing that data). Many of the functions in this module work by updating this object, so for anything more complicated than a single update, use of the state monad is recommended.
The underlying data is actually stored in LevelDB. This module provides the logic to organize the key-value pairs in the appropriate Patricia Merkle Tree.
- type Key = NibbleString
- type Val = RLPObject
- data MPDB = MPDB {}
- newtype StateRoot = StateRoot ByteString
- openMPDB :: String -> ResourceT IO MPDB
- emptyTriePtr :: StateRoot
- sha2StateRoot :: Digest Keccak_256 -> StateRoot
- unboxStateRoot :: StateRoot -> ByteString
- putKeyVal :: MonadResource m => MPDB -> Key -> Val -> m MPDB
- getKeyVal :: MonadResource m => MPDB -> Key -> m (Maybe Val)
- deleteKey :: MonadResource m => MPDB -> Key -> m MPDB
- keyExists :: MonadResource m => MPDB -> Key -> m Bool
- initializeBlank :: MonadResource m => MPDB -> m ()
Documentation
type Key = NibbleString Source #
The type of the database key
This is the database reference type, contianing both the handle to the underlying database, as well as the stateRoot to the current tree holding the data.
The MPDB acts a bit like a traditional database handle, although because it contains the stateRoot, many functions act by updating its value. Because of this, it is recommended that this item be stored and modified within the state monad.
Instances
| (Monad m, MonadBaseControl IO m, MonadThrow m, MonadIO m) => PointedKeyValDB (KeyValMPLevelDB m) Key Val MPDB String Source # | |
Internal nodes are indexed in the underlying database by their 256-bit SHA3 hash. This types represents said hash.
The stateRoot is of this type, (ie- the pointer to the full set of key/value pairs at a particular time in history), and will be of interest if you need to refer to older or parallel version of the data.
Constructors
| StateRoot ByteString |
This function is used to create an MPDB object corresponding to the blank database. After creation, the stateRoot can be changed to a previously saved version.
emptyTriePtr :: StateRoot Source #
The stateRoot of the empty database.
unboxStateRoot :: StateRoot -> ByteString Source #
Arguments
| :: MonadResource m | |
| => MPDB | The object containing the current stateRoot. |
| -> Key | Key of the data to be inserted. |
| -> Val | Value of the new data |
| -> m MPDB | The object containing the stateRoot to the data after the insert. |
Adds a new key/value pair.
Arguments
| :: MonadResource m | |
| => MPDB | Object containing the current stateRoot. |
| -> Key | Key of the data to be inserted. |
| -> m (Maybe Val) | The requested value. |
Retrieves all key/value pairs whose key starts with the given parameter.
Arguments
| :: MonadResource m | |
| => MPDB | The object containing the current stateRoot. |
| -> Key | The key to be deleted. |
| -> m MPDB | The object containing the stateRoot to the data after the delete. |
Deletes a key (and its corresponding data) from the database.
Note that the key/value pair will still be present in the history, and
can be accessed by using an older MPDB object.
Arguments
| :: MonadResource m | |
| => MPDB | The object containing the current stateRoot. |
| -> Key | The key to be deleted. |
| -> m Bool | True if the key exists |
Returns True is a key exists.
Arguments
| :: MonadResource m | |
| => MPDB | The object containing the current stateRoot. |
| -> m () |
Initialize the DB by adding a blank stateroot.