The bitmap is used in compact-encoded trie nodes to indicate which elements
have been modified. The bitmap format has been updated to use big-endian
encoding.
Bit positions are numbered from 0 to 15, where position 0 corresponds to
the most significant bit of b[0], and position 15 corresponds to the least
significant bit of b[1].
This pull request introduces a mechanism to compress trienode history by
storing only the node diffs between consecutive versions.
- For full nodes, only the modified children are recorded in the history;
- For short nodes, only the modified value is stored;
If the node type has changed, or if the node is newly created or
deleted, the entire node value is stored instead.
To mitigate the overhead of reassembling nodes from diffs during history
reads, checkpoints are introduced by periodically storing full node values.
The current checkpoint interval is set to every 16 mutations, though
this parameter may be made configurable in the future.
This PR is the first step in the trienode history series.
It introduces the `nodeWithOrigin` struct in the path database, which tracks
the original values of dirty nodes to support trienode history construction.
Note, the original value is always empty in this PR, so it won't break the
existing journal for encoding and decoding. The compatibility of journal
should be handled in the following PR.
This PR refactors the `nodeSet` structure in the path database to use
separate maps for account and storage trie nodes, resulting in
performance improvements. The change maintains the same API while
optimizing the internal data structure.
This pull request ports some changes from the main state snapshot
integration one, specifically introducing the flat state tracking in
pathdb.
Note, the tracked flat state changes are only held in memory and won't
be persisted in the disk. Meanwhile, the correspoding state retrieval in
persistent state is also not supported yet. The states management in
disk is more complicated and will be implemented in a separate pull
request.
Part 1: https://github.com/ethereum/go-ethereum/pull/30752
