Trait grin_core::core::pmmr::Backend

pub trait Backend<T: PMMRable> {
    // Required methods
    fn append(&mut self, data: &T, hashes: &[Hash]) -> Result<(), String>;
    fn append_pruned_subtree(
        &mut self,
        hash: Hash,
        pos0: u64
    ) -> Result<(), String>;
    fn append_hash(&mut self, hash: Hash) -> Result<(), String>;
    fn rewind(
        &mut self,
        pos1: u64,
        rewind_rm_pos: &Bitmap
    ) -> Result<(), String>;
    fn get_hash(&self, pos0: u64) -> Option<Hash>;
    fn get_data(&self, pos0: u64) -> Option<T::E>;
    fn get_from_file(&self, pos0: u64) -> Option<Hash>;
    fn get_peak_from_file(&self, pos0: u64) -> Option<Hash>;
    fn get_data_from_file(&self, pos0: u64) -> Option<T::E>;
    fn leaf_pos_iter(&self) -> Box<dyn Iterator<Item = u64> + '_>;
    fn n_unpruned_leaves(&self) -> u64;
    fn n_unpruned_leaves_to_index(&self, to_index: u64) -> u64;
    fn leaf_idx_iter(&self, from_idx: u64) -> Box<dyn Iterator<Item = u64> + '_>;
    fn remove(&mut self, position: u64) -> Result<(), String>;
    fn remove_from_leaf_set(&mut self, pos0: u64);
    fn release_files(&mut self);
    fn reset_prune_list(&mut self);
    fn snapshot(&self, header: &BlockHeader) -> Result<(), String>;
    fn dump_stats(&self);
}

Storage backend for the MMR, just needs to be indexed by order of insertion. The PMMR itself does not need the Backend to be accurate on the existence of an element (i.e. remove could be a no-op) but layers above can depend on an accurate Backend to check existence.

Required Methods

fn append(&mut self, data: &T, hashes: &[Hash]) -> Result<(), String>

Append the provided Hashes to the backend storage, and optionally an associated data element to flatfile storage (for leaf nodes only). The position of the first element of the Vec in the MMR is provided to help the implementation.

fn append_pruned_subtree(&mut self, hash: Hash, pos0: u64) -> Result<(), String>

Rebuilding a PMMR locally from PIBD segments requires pruned subtree support. This allows us to append an existing pruned subtree directly without the underlying leaf nodes.

fn append_hash(&mut self, hash: Hash) -> Result<(), String>

Append a single hash to the pmmr

fn rewind(&mut self, pos1: u64, rewind_rm_pos: &Bitmap) -> Result<(), String>

Rewind the backend state to a previous position, as if all append operations after that had been canceled. Expects a position in the PMMR to rewind to as well as bitmaps representing the positions added and removed since the rewind position. These are what we will “undo” during the rewind.

fn get_hash(&self, pos0: u64) -> Option<Hash>

Get a Hash by insertion position.

fn get_data(&self, pos0: u64) -> Option<T::E>

Get underlying data by insertion position.

fn get_from_file(&self, pos0: u64) -> Option<Hash>

Get a Hash by original insertion position (ignoring the remove log).

fn get_peak_from_file(&self, pos0: u64) -> Option<Hash>

Get hash for peak pos. Optimized for reading peak hashes rather than arbitrary pos hashes. Peaks can be assumed to not be compacted.

fn get_data_from_file(&self, pos0: u64) -> Option<T::E>

Get a Data Element by original insertion position (ignoring the remove log).

fn leaf_pos_iter(&self) -> Box<dyn Iterator<Item = u64> + '_>

Iterator over current (unpruned, unremoved) leaf positions.

fn n_unpruned_leaves(&self) -> u64

Number of leaves

fn n_unpruned_leaves_to_index(&self, to_index: u64) -> u64

Number of leaves up to the given leaf index

fn leaf_idx_iter(&self, from_idx: u64) -> Box<dyn Iterator<Item = u64> + '_>

Iterator over current (unpruned, unremoved) leaf insertion index. Note: This differs from underlying MMR pos - [0, 1, 2, 3, 4] vs. [1, 2, 4, 5, 8].

fn remove(&mut self, position: u64) -> Result<(), String>

Remove Hash by insertion position. An index is also provided so the underlying backend can implement some rollback of positions up to a given index (practically the index is the height of a block that triggered removal).

fn remove_from_leaf_set(&mut self, pos0: u64)

Remove a leaf from the leaf set

fn release_files(&mut self)

Release underlying datafiles and locks

fn reset_prune_list(&mut self)

Reset prune list, used when PIBD is reset

fn snapshot(&self, header: &BlockHeader) -> Result<(), String>

Saves a snapshot of the rewound utxo file with the block hash as filename suffix. We need this when sending a txhashset zip file to a node for fast sync.

fn dump_stats(&self)

For debugging purposes so we can see how compaction is doing.

Implementors

impl<T: PMMRable> Backend<T> for VecBackend<T>