State jump should be an atomic operation, we can't modify contract
storage items state on-the-fly. Thus, store fresh items under temp
prefix and replase the outdated ones after state sync is completed.
Related
https://github.com/nspcc-dev/neo-go/pull/2019#discussion_r693350460.
In this commit:
1. Request unknown MPT nodes from peers. Note, that StateSync module itself
shouldn't be responsible for nodes requests, that's a server duty.
2. Do not request the same node twice, check if it is in storage
already. If so, then the only thing remaining is to update refcounter.
MPT restore process is much simpler then regular MPT maintaining: trie
has a fixed structure, we don't need to remove or rebuild MPT nodes. The
only thing we should do is to replace Hash nodes to their unhashed
counterparts and increment refcount. It's better not to touch the
regular MPT code and create a separate structure for this.
C# node does not return empty proof enymore in case if path is bad. C#
node also throws an exception on bad Put.
Our node does not return an error on delete if the key is empty.
Allow it for (*Trie).Put. And distinguish empty value and nil value for
(*Trie).PutBatch, because batch is already capable of handling both nil
and empty value. For (*Trie).PutBatch putting nil value means deletion,
while putting empty value means just putting LeafNode with an empty
value.
We use them quite frequently (consider children for a new branch
node) and it is better to get rid of unneeded allocations.
Signed-off-by: Evgeniy Stratonikov <evgeniy@nspcc.ru>
This is not a problem in practice, as all keys are prefixed
by a contract ID. However in theory it can lead to a different
state root after new portion of changes thus this fix.
This reverts commit 168ba7960c.
It seems, there are some problems with it:
`2020-12-25T18:13:07.476+0300 WARN blockQueue: failed adding block into the blockchain {"error": "error while trying to apply MPT changes: unexpected EOF", "blockHeight": 9729, "nextIndex": 9730}`
Running time becomes faster under high load while staying the same in
the average case.
Memory allocation done in `Trie` goes down by about ~10% (even more,
actually).
Because trie size is rather big, it can't be stored in memory.
Thus some form of caching should also be implemented. To avoid
marshaling/unmarshaling of items which are close to root and are used
very frequenly we can save them across the persists.
This commit implements pruning items at the specified depth,
replacing them by hash nodes.
Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>
Because there is no distinct type field in JSONized nodes, distinction
is made via payload itself, thus all unmarshaling is done via
NodeObject.
Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>
MPT is a trie with a branching factor = 16, i.e. it consists of sequences in
16-element alphabet.
Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>
