Crate aptos_jellyfish_merkle
source · [−]Expand description
This module implements JellyfishMerkleTree
backed by storage module. The tree itself doesn’t
persist anything, but realizes the logic of R/W only. The write path will produce all the
intermediate results in a batch for storage layer to commit and the read path will return
results directly. The public APIs are only new
, put_value_sets
, put_value_set
and
get_with_proof
. After each put with a value_set
based on a known version, the tree will
return a new root hash with a TreeUpdateBatch
containing all the new nodes and indices of
stale nodes.
A Jellyfish Merkle Tree itself logically is a 256-bit sparse Merkle tree with an optimization that any subtree containing 0 or 1 leaf node will be replaced by that leaf node or a placeholder node with default hash value. With this optimization we can save CPU by avoiding hashing on many sparse levels in the tree. Physically, the tree is structurally similar to the modified Patricia Merkle tree of Ethereum but with some modifications. A standard Jellyfish Merkle tree will look like the following figure:
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+──────────────────────────────────────────────────────────────────────────────────────────────+
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/ \/ \/ \/ \/ \/ \/ \/ \/ \/ \/ \/ \/ \/ \/ \/ \
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( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( (
) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) )
( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( (
) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) )
( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( (
) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) )
( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( ( (
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■: the [`Value`] type this tree stores.
A Jellyfish Merkle Tree consists of InternalNode
and LeafNode
. InternalNode
is like
branch node in ethereum patricia merkle with 16 children to represent a 4-level binary tree and
LeafNode
is similar to that in patricia merkle too. In the above figure, each bell
in the
jellyfish is an InternalNode
while each tentacle is a LeafNode
. It is noted that
Jellyfish merkle doesn’t have a counterpart for extension
node of ethereum patricia merkle.
Modules
This module implements JellyfishMerkleIterator
. Initialized with a version and a key, the
iterator generates all the key-value pairs in this version of the tree, starting from the
smallest key that is greater or equal to the given key, by performing a depth first traversal
on the tree.
Node types of JellyfishMerkleTree
This module implements the functionality to restore a JellyfishMerkleTree
from small chunks
of accounts.
Structs
The Jellyfish Merkle tree data structure. See crate
for description.
Indicates a node becomes stale since stale_since_version
.
This is a wrapper of NodeBatch
,
StaleNodeIndexBatch
and some stats of nodes that represents
the incremental updates of a tree and pruning indices after applying a write set,
which is a vector of hashed_account_address
and new_value
pairs.
Statics
Traits
Key
defines the types of data key that can be stored in a Jellyfish Merkle tree.
TreeReader
defines the interface between
JellyfishMerkleTree
and underlying storage holding nodes.
Value
defines the types of data that can be stored in a Jellyfish Merkle tree.
Type Definitions
Node batch that will be written into db atomically with other batches.
Key-Value batch that will be written into db atomically with other batches.