When lazily verifying state roots, we may end up with an entire state
without roots that gets computed for the whole database - in the current
design, that would result in hashes for the entire trie being held in
memory.
Since the hash depends only on the data in the vertex, we can store it
directly at the top-most level derived from the verticies it depends on
- be that memory or database - this makes the memory usage broadly
linear with respect to the already-existing in-memory change set stored
in the layers.
It also ensures that if we have multiple forks in memory, hashes get
cached in the correct layer maximising reuse between forks.
The same layer numbering scheme as elsewhere is reused, where -2 is the
backend, -1 is the balancer, then 0+ is the top of the stack and stack.
A downside of this approach is that we create many small batches - a
future improvement could be to collect all such writes in a single
batch, though the memory profile of this approach should be examined
first (where is the batch kept, exactly?).
This PR adds a storage hike cache similar to the account hike cache
already present - this cache is less efficient because account storage
is already partically cached in the account ledger but nonetheless helps
keep hiking down.
Notably, there's an opportunity to optimise this cache and the others so
that they cooperate better insteado of overlapping, which is left for a
future PR.
This PR also fixes an O(N) memory usage for storage slots where the
delete would keep the full storage in a work list which on mainnet can
grow very large - the work list is replaced with a more conventional
recursive `O(log N)` approach.
The Vertex type unifies branches, extensions and leaves into a single
memory area where the larges member is the branch (128 bytes + overhead) -
the payloads we have are all smaller than 128 thus wrapping them in an
extra layer of `ref` is wasteful from a memory usage perspective.
Further, the ref:s must be visited during the M&S phase of garbage
collection - since we keep millions of these, many of them
short-lived, this takes up significant CPU time.
```
Function CPU Time: Total CPU Time: Self Module Function (Full) Source File Start Address
system::markStackAndRegisters 10.0% 4.922s nimbus system::markStackAndRegisters(var<system::GcHeap>).constprop.0 gc.nim 0x701230`
```
The state and account MPT:s currenty share key space in the database
based on that vertex id:s are assigned essentially randomly, which means
that when two adjacent slot values from the same contract are accessed,
they might reside at large distance from each other.
Here, we prefix each vertex id by its root causing them to be sorted
together thus bringing all data belonging to a particular contract
closer together - the same effect also happens for the main state MPT
whose nodes now end up clustered together more tightly.
In the future, the prefix given to the storage keys can also be used to
perform range operations such as reading all the storage at once and/or
deleting an account with a batch operation.
Notably, parts of the API already supported this rooting concept while
parts didn't - this PR makes the API consistent by always working with a
root+vid.
The storage id is frequently accessed when executing contract code and
finding the path via the database requires several hops making the
process slow - here, we add a cache to keep the most recently used
account storage id:s in memory.
A possible future improvement would be to cache all account accesses so
that for example updating the balance doesn't cause several hikes.
* Remove `dirty` set from structural objects
why:
Not used anymore, the tree is dirty by default.
* Rename `aristo_hashify` -> `aristo_compute`
* Remove cruft, update comments, cosmetics, etc.
* Simplify `SavedState` object
why:
The key chaining have become obsolete after extra lazy hashing. There
is some available space for a state hash to be maintained in future.
details:
Accept the legacy `SavedState` object serialisation format for a
while (which will be overwritten by new format.)
* rebased from `github/on-demand-mpt`
ackn:
wip: on-demand mpt construction
Given that actual data is stored in the `Vertex` structure, it's useful
to think of the MPT as a cache for computing roots rather than being a
functional requirement on its own.
This PR engenders this line of thinking by incrementally computing the
MPT only when it's needed, ie when a state (or similar) root is needed.
This has the effect of siginficantly reducing memory usage as well as
improving performance:
* no need for dirty-mpt-node book-keeping
* no need to build complex forest of upcoming hashing work
* only hashes that are functionally needed are ever computed -
intermediate nodes whose MTP root is not observed are never computed /
processed
* Unit test hot fixes
* Unit test hot fixes cont.
(somehow lost that part)
---------
Co-authored-by: Jacek Sieka <jacek@status.im>
* Provide dedicated functions for fetching accounts and storage trees
why:
Different prototypes for each class `account`, `generic` and
`storage`.
* Remove `fetchPayload()` and other cruft from API, `aristo_fetch`, etc.
* Fix typos, debugging left overs, comments
* Remove all journal related stuff
* Refactor function names journal*() => delta*(), filter*() => delta*()
* remove `trg` fileld from `FilterRef`
why:
Same as `kMap[$1]`
* Re-type FilterRef.src as `HashKey`
why:
So it is directly comparable to `kMap[$1]`
* Moved `vGen[]` field from `LayerFinalRef` to `LayerDeltaRef`
why:
Then a separate `FilterRef` type is not needed, anymore
* Rename `roFilter` field in `AristoDbRef` => `balancer`
why:
New name more appropriate.
* Replace `FilterRef` by `LayerDeltaRef` type
why:
This allows to avoid copying into the `balancer` (see next patch set)
most of the time. Typically, only one instance is running on the backend
and the `balancer` is only used as a stage before saving data.
* Refactor way how to store data persistently
why:
Avoid useless copy when staging `top` layer for persistently saving to
backend.
* Fix copyright header?
* Aristo: Reorg `hashify()` using different schedule algorithm
why:
Directly calculating the search tree top down from the roots turns
out to be faster than using the cached structures left over by `merge()`
and `delete()`.
Time gains is short of 20%
* Aristo: Remove `lTab[]` leaf entry object type
why:
Not used anymore. It was previously needed to build the schedule for
`hashify()`.
* Aristo: Avoid unnecessary re-org of the vertex ID recycling list
why:
This list can become quite large so a heuristic is employed whether
it makes sense to re-org.
Also, re-org check is only done by `delete()` functions.
* Aristo: Remove key/reverse lookup table from tx layers
why:
It is ignored except for handling proof nodes and costs unnecessary
run time resources.
This feature was originally needed to accommodate the mental transition
from the legacy MPT to the `Aristo` trie :).
* Fix copyright year
* CoreDb: update test suite
* Aristo: Simplify reverse key map
why:
The reverse key map `pAmk: (root,key) -> {vid,..}` as been simplified to
`pAmk: key -> {vid,..}` as the state `root` domain argument is not used,
anymore
* Aristo: Remove `HashLabel` object type and replace it by `HashKey`
why:
The `HashLabel` object attaches a root hash to a hash key. This is
nowhere used, anymore.
* Fix copyright
* Aristo: Update unit test suite
* Aristo/Kvt: Fix iterators
why:
Generic iterators were not properly updated after backend change
* Aristo: Add sub-trie deletion functionality
why:
For storage tries linked to an account payload vertex ID, a the
whole storage trie needs to be deleted with the account.
* Aristo: Reserve vertex ID numbers for static custom state roots
why:
Static custom state roots may be controlled by an application,
e.g. for a receipt or a transaction root. The `Aristo` functions
are agnostic of what the static state roots are when different
from the internal tree vertex ID 1.
details;
The `merge()` function applied to a non-static state root (assumed
to be a storage root) will check the payload of an accounts leaf
and mark its Merkle keys to be re-checked.
* Aristo: Correct error code symbol
* Aristo: Update error code symbols
* Aristo: Code cosmetics/comments
* Aristo: Fix hashify schedule calculator
why:
Had a tendency to stop early leaving an incomplete job
* Aristo: Re-phrase `LayerDelta` and `LayerFinal` as object references
why:
Avoids copying in some cases
* Fix copyright header
* Aristo: Verify `leafTie.root` function argument for `merge()` proc
why:
Zero root will lead to inconsistent DB entry
* Aristo: Update failure condition for hash labels compiler `hashify()`
why:
Node need not be rejected as long as links are on the schedule. In
that case, `redo[]` is to become `wff.base[]` at a later stage.
This amends an earlier fix, part of #1952 by also testing against
the target nodes of the `wff.base[]` sets.
* Aristo: Add storage root glue record to `hashify()` schedule
why:
An account leaf node might refer to a non-resolvable storage root ID.
Storage root node chains will end up at the storage root. So the link
`storage-root->account-leaf` needs an extra item in the schedule.
* Aristo: fix error code returned by `fetchPayload()`
details:
Final error code is implied by the error code form the `hikeUp()`
function.
* CoreDb: Discard `createOk` argument in API `getRoot()` function
why:
Not needed for the legacy DB. For the `Arsto` DB, a lazy approach is
implemented where a stprage root node is created on-the-fly.
* CoreDb: Prevent `$$` logging in some cases
why:
Logging the function `$$` is not useful when it is used for internal
use, i.e. retrieving an an error text for logging.
* CoreDb: Add `tryHashFn()` to API for pretty printing
why:
Pretty printing must not change the hashification status for the
`Aristo` DB. So there is an independent API wrapper for getting the
node hash which never updated the hashes.
* CoreDb: Discard `update` argument in API `hash()` function
why:
When calling the API function `hash()`, the latest state is always
wanted. For a version that uses the current state as-is without checking,
the function `tryHash()` was added to the backend.
* CoreDb: Update opaque vertex ID objects for the `Aristo` backend
why:
For `Aristo`, vID objects encapsulate a numeric `VertexID`
referencing a vertex (rather than a node hash as used on the
legacy backend.) For storage sub-tries, there might be no initial
vertex known when the descriptor is created. So opaque vertex ID
objects are supported without a valid `VertexID` which will be
initalised on-the-fly when the first item is merged.
* CoreDb: Add pretty printer for opaque vertex ID objects
* Cosmetics, printing profiling data
* CoreDb: Fix segfault in `Aristo` backend when creating MPT descriptor
why:
Missing initialisation error
* CoreDb: Allow MPT to inherit shared context on `Aristo` backend
why:
Creates descriptors with different storage roots for the same
shared `Aristo` DB descriptor.
* Cosmetics, update diagnostic message items for `Aristo` backend
* Fix Copyright year
* Update KVT layers abstraction
details:
modelled after Aristo layers
* Simplified KVT database iterators (removed item counters)
why:
Not needed for production functions
* Simplify KVT merge function `layersCc()`
* Simplified Aristo database iterators (removed item counters)
why:
Not needed for production functions
* Update failure condition for hash labels compiler `hashify()`
why:
Node need not be rejected as long as links are on the schedule. In
that case, `redo[]` is to become `wff.base[]` at a later stage.
* Update merging layers and label update functions
why:
+ Merging a stack of layers with `layersCc()` could be simplified
+ Merging layers will optimise the reverse `kMap[]` table maps
`pAmk: label->{vid, ..}` by deleting empty mappings `label->{}` where
they are redundant.
+ Updated `layersPutLabel()` for optimising `pAmk[]` tables
* Fix kvt headers
* Provide differential layers for KVT transaction stack
why:
Significant performance improvement
* Provide abstraction layer for database top cache layer
why:
This will eventually implemented as a differential database layers
or transaction layers. The latter is needed to improve performance.
behavioural changes:
Zero vertex and keys (i.e. delete requests) are not optimised out
until the last layer is written to the database.
* Provide differential layers for Aristo transaction stack
why:
Significant performance improvement
Jacek Sieka
Jordan Hrycaj
tersec