* Aristo/Kvt: Provide function hooks APIs
why:
These APIs can be used for installing tracers, profiling functoinality,
and other niceties on the databases.
* Aristo: Provide optional API profiling
details:
It basically is a re-implementation of the `CoreDb` profiling
implementation
* Kvt: Provide optional API profiling similar to `Aristo`
* CoreDb: Re-implementing profiling using `aristo_profile`
* Ledger: Re-implementing profiling using `aristo_profile`
* CoreDb: Update unit tests for maintainability
* update copyright dates
* 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 error return code
why:
Failing of `Aristo` function `delete()` might fail because there is
no such data item on the db. This must return a single error code
as is done with `fetch()`.
* Ledger: Better error handling
why:
The `expect()` clauses have been replaced by raising asserts indicating
the error from the database backend.
Also, `delete()` failures are legitimate if the item to delete does not
exist.
* Aristo: Delete function must always leave a label on DB for `hashify()`
why:
The `hashify()` uses the labels left bu `merge()` and `delete()` to
compile (and optimise) a scheduler for subsequent hashing.
Originally, the labels were not used for deleted entries and `delete()`
still had some edge case where the deletion label was not properly
handled.
* Aristo: Update `hashify()` scheduler, remove buggy optimisation
why:
Was left over from version without virtual state roots which did not
know about account payload leaf vertices referring to storage roots.
* Aristo: Label storage trie account in `delete()` similar to `merge()`
details;
The `delete()` 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 when runninh `hashify()`
* Aristo: Clean up and re-org recycled vertex IDs in `hashify()`
why:
Re-organising the recycled vertex IDs list intends to reduce the size of the
list.
This list is organised as a LIFO (or stack.) By reorganising it in a way
so that the least vertex ID numbers are on top, the list will be kept
smaller as observed on some examples (less than 30%.)
* CoreDb: Accept storage trie deletion requests in non-initialised state
why:
Due to lazy initialisation, the root vertex ID might not yet exist. So
the `Aristo` database handlers would reject this call with an error and
this condition needs to be handled by the API (which realises the lazy
feature.)
* Cosmetics & code massage, prettify logging
* fix missing import
* 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
* 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
* Explicitly use shared `Kvt` table on `Ledger` and `Clique` lookup.
why:
Speeds up lookup time with `Aristo` backend. For writing `Clique` data,
the `Companion` model allows to write `Clique` data past the database
locked by evm transactions.
* Implement `CoreDb` profiling with API tracking
why:
Chasing time spent per APT procs ...
* Implement `Ledger` profiling with API tracking
why:
Chasing time spent per APT procs ...
* Always hashify when commiting or storing
why:
A dirty cache makes no sense when committing
* Make sure that a zero key is created when adding/updating vertices
why:
This is an error fix mainly for edge cases. A typical error was
that the root key got deleted when there were only a few vertices
left on the DB.
* Need all created and changed vertices zero-keyed on the cache
why:
A zero key (i.e. empty Merkle hash) indicates that a vertex key
needs to be updated. This would not be needed immediately after
a merge as there is an actual leaf path on the cache layer. But
after subsequent merge and delete operations this information
might get blurred.
* Re-org hashing algorithm
why:
Apart from errors, the previous implementation was too slow for
two reasons:
+ some control hashes were calculated for debugging (now all
verification is done in `aristo_check` module)
+ the leaf paths stored on the cache are used to build the
labelling (aka hashing) schedule; there paths were accumulated
over successive hash sessions although it is clear that all
keys were generated, already
* Register paths for added leafs because of trie re-balancing
why:
While the payload would not change, the prefix in the leaf vertex
would. So it needs to be flagged for hash recompilation for the
`hashify()` module.
also:
Make sure that `Hike` paths which might have vertex links into the
backend filter are replaced by vertex copies before manipulating.
Otherwise the vertices on the immutable filter might be involuntarily
changed.
* Also check for paths where the leaf vertex is on the backend, already
why:
A a path can have dome vertices on the top layer cache with the
`Leaf` vertex on the backend.
* Re-define a void `HashLabel` type.
why:
A `HashLabel` type is a pair `(root-vertex-ID, Keccak-hash)`. Previously,
a valid `HashLabel` consisted of a non-empty hash and a non-zero vertex
ID. This definition leads to a non-unique representation of a void
`HashLabel` with either root-ID or has void. This has been changed to
the unique void `HashLabel` exactly if the hash entry is void.
* Update consistency checkers
* Re-org `hashify()` procedure
why:
Syncing against block chain showed serious deficiencies which produced
wrong hashes or simply bailed out with error.
So all fringe cases (mainly due to deleted entries) could be integrated
into the labelling schedule rather than handling separate fringe cases.
* Fix copyright year
* Show elapsed times with enabled `CoreDb` API tracking
* Show elapsed times with enabled `LedgerRef` API tracking
* Reorg `CoreDb` auto destructors for `Aristo` DB
why:
While `Aristo` supports some parallelism for concurrent database access,
this comes with a price of management overhead. With a naive approach,
the auto-destructor will slow down execution because the ledger and
evm treat the database in a shared mode where a DB descriptor is just
created and thrown away shortly after.
This is reflected in the `Coredb` abstraction layer above `Aristo`/`Kvt`
where a few `Shared` type descriptors are cached and a shared reference
is returned rather than a disposable new object.
* For `CoreDb` support transaction level tracking
details:
This is mainly an extra for the legacy DB as `Aristo` and `Kvt` support
this already.
Also return an error on the legacy DB backend when `persistent()` is
called while there are transactions pending (the `persistent()` call
does nothing otherwise on the legacy backend.)
* Clear compiler warnings (remove unused variables etc.)
* Disable `TransactionID` related functions from `state_db.nim`
why:
Functions `getCommittedStorage()` and `updateOriginalRoot()` from
the `state_db` module are nowhere used. The emulation of a legacy
`TransactionID` type functionality is administratively expensive to
provide by `Aristo` (the legacy DB version is only partially
implemented, anyway).
As there is no other place where `TransactionID`s are used, they will
not be provided by the `Aristo` variant of the `CoreDb`. For the
legacy DB API, nothing will change.
* Fix copyright headers in source code
* Get rid of compiler warning
* Update Aristo code, remove unused `merge()` variant, export `hashify()`
why:
Adapt to upcoming `CoreDb` wrapper
* Remove synced tx feature from `Aristo`
why:
+ This feature allowed to synchronise transaction methods like begin,
commit, and rollback for a group of descriptors.
+ The feature is over engineered and not needed for `CoreDb`, neither
is it complete (some convergence features missing.)
* Add debugging helpers to `Kvt`
also:
Update database iterator, add count variable yield argument similar
to `Aristo`.
* Provide optional destructors for `CoreDb` API
why;
For the upcoming Aristo wrapper, this allows to control when certain
smart destruction and update can take place. The auto destructor works
fine in general when the storage/cache strategy is known and acceptable
when creating descriptors.
* Add update option for `CoreDb` API function `hash()`
why;
The hash function is typically used to get the state root of the MPT.
Due to lazy hashing, this might be not available on the `Aristo` DB.
So the `update` function asks for re-hashing the gurrent state changes
if needed.
* Update API tracking log mode: `info` => `debug
* Use shared `Kvt` descriptor in new Ledger API
why:
No need to create a new descriptor all the time
* Fix debug noise in `hashify()` for perfectly normal situation
why:
Was previously considered a fixable error
* Fix test sample file names
why:
The larger test file `goerli68161.txt.gz` is already in the local
archive. So there is no need to use the smaller one from the external
repo.
* Activate `accounts_cache` module from `db/ledger`
why:
A copy of the original `accounts_cache.nim` source to be integrated
into the `Ledger` module wrapper which allows to switch between
different `accounts_cache` implementations unser tha same API.
details:
At a later state, the `db/accounts_cache.nim` wrapper will be
removed so that there is only one access to that module via
`db/ledger/accounts_cache.nim`.
* Fix copyright headers in source code
* Aristo: Provide key-value list signature calculator
detail:
Simple wrappers around `Aristo` core functionality
* Update new API for `CoreDb`
details:
+ Renamed new API functions `contains()` => `hasKey()` or `hasPath()`
which disables the `in` operator on non-boolean `contains()` functions
+ The functions `get()` and `fetch()` always return a not-found error if
there is no item, available. The new functions `getOrEmpty()` and
`mergeOrEmpty()` return an an empty `Blob` if there is no such key
found.
* Rewrite `core_apps.nim` using new API from `CoreDb`
* Use `Aristo` functionality for calculating Merkle signatures
details:
For debugging, the `VerifyAristoForMerkleRootCalc` can be set so
that `Aristo` results will be verified against the legacy versions.
* Provide general interface for Merkle signing key-value tables
details:
Export `Aristo` wrappers
* Activate `CoreDb` tests
why:
Now, API seems to be stable enough for general tests.
* Update `toHex()` usage
why:
Byteutils' `toHex()` is superior to `toSeq.mapIt(it.toHex(2)).join`
* Split `aristo_transcode` => `aristo_serialise` + `aristo_blobify`
why:
+ Different modules for different purposes
+ `aristo_serialise`: RLP encoding/decoding
+ `aristo_blobify`: Aristo database encoding/decoding
* Compacted representation of small nodes' links instead of Keccak hashes
why:
Ethereum MPTs use Keccak hashes as node links if the size of an RLP
encoded node is at least 32 bytes. Otherwise, the RLP encoded node
value is used as a pseudo node link (rather than a hash.) Such a node
is nor stored on key-value database. Rather the RLP encoded node value
is stored instead of a lode link in a parent node instead. Only for
the root hash, the top level node is always referred to by the hash.
This feature needed an abstraction of the `HashKey` object which is now
either a hash or a blob of length at most 31 bytes. This leaves two
ways of representing an empty/void `HashKey` type, either as an empty
blob of zero length, or the hash of an empty blob.
* Update `CoreDb` interface (mainly reducing logger noise)
* Fix copyright years (to make `Lint` happy)
* Aristo: Single `FetchPathNotFound` error in `fetchXxx()` and `hasPath()`
why:
Missing path hike returns too many detailed reasons why it failed
which becomes cumbersome to handle.
also:
Renamed `contains()` => `hasPath()` which disables the `in` operator on
non-boolean `contains()` functions
* Kvt: Renamed `contains()` => `hasKey()`
why:
which disables the `in` operator on non-boolean `contains()` functions
* Aristo: Generalising `HashID` by variable length `PathID`
why:
There are cases when the `Aristo` database is to be used with
shorter than 64 nibbles keys when handling transactions indexes
with sequence IDs.
caveat:
This patch only works reliable for full length `PathID` values. Tests
for shorter `PathID` values are currently missing.
* Aristo: remove obsolete functions
* Aristo: Fix error code for non-available hash keys
why:
Must not return `not-found` when the key is not available (i.e. the
current changes were not hashified, yet.)
* CoreDB: Provide TDD and test framework
* Kvt: Implemented multi-descriptor access on the same backend
why:
This behaviour mirrors the one of Aristo and can be used for
simultaneous transactions on Aristo + Kvt
* Kvt: Update database iterators
why:
Forgot to run on the top layer first
* Kvt: Misc fixes
* Aristo, use `openArray[byte]` rather than `Blob` in prototype
* Aristo, by default hashify right after cloning descriptor
why:
Typically, a completed descriptor is expected after cloning. Hashing
can be suppressed by argument flag.
* Aristo provides `replicate()` iterator, similar to legacy `replicate()`
* Aristo API fixes and updates
* CoreDB: Rename `legacy_persistent` => `legacy_rocksdb`
why:
More systematic, will be in line with Aristo DB which might have
more than one persistent backends
* CoreDB: Prettify API sources
why:
Better to read and maintain
details:
Annotating with custom pragmas which cleans up the prototypes
* CoreDB: Update MPT/put() prototype allowing `CatchableError`
why:
Will be needed for Aristo API (legacy is OK with `RlpError`)
* Update docu
* Update Aristo/Kvt constructor prototype
why:
Previous version used an `enum` value to indicate what backend is to
be used. This was replaced by using the backend object type.
* Rewrite `hikeUp()` return code into `Result[Hike,(Hike,AristoError)]`
why:
Better code maintenance. Previously, the `Hike` object was returned. It
had an internal error field so partial success was also available on
a failure. This error field has been removed.
* Use `openArray[byte]` rather than `Blob` in functions prototypes
* Provide synchronised multi instance transactions
why:
The `CoreDB` object was geared towards the legacy DB which used a single
transaction for the key-value backend DB. Different state roots are
provided by the backend database, so all instances work directly on the
same backend.
Aristo db instances have different in-memory mappings (aka different
state roots) and the transactions are on top of there mappings. So each
instance might run different transactions.
Multi instance transactions are a compromise to converge towards the
legacy behaviour. The synchronised transactions span over all instances
available at the time when base transaction was opened. Instances
created later are unaffected.
* Provide key-value pair database iterator
why:
Needed in `CoreDB` for `replicate()` emulation
also:
Some update of internal code
* Extend API (i.e. prototype variants)
why:
Needed for `CoreDB` geared towards the legacy backend which has a more
basic API than Aristo.
* Rewrite remaining `AristoError` return code into `Result[void,AristoError]`
why:
Better code maintenance
* Update import sections
* Update Aristo DB paths
why:
More systematic so directory can be shared with other DB types
* More cosmetcs
* Update unit tests runners
why:
Proper handling of persistent and mem-only DB. The latter can be
consistently triggered by an empty DB path.
* Renamed type `NoneBackendRef` => `VoidBackendRef`
* Clarify names: `BE=filter+backend` and `UBE=backend (unfiltered)`
why:
Most functions used full names as `getVtxUnfilteredBackend()` or
`getKeyBackend()`. After defining abbreviations (and its meaning) it
seems easier to use `getVtxUBE()` and `getKeyBE()`.
* Integrate `hashify()` process into transaction logic
why:
Is now transparent unless explicitly controlled.
details:
Cache changes imply setting a `dirty` flag which in turn triggers
`hashify()` processing in transaction and `pack()` directives.
* Removed `aristo_tx.exec()` directive
why:
Inconsistent implementation, functionality will be provided with a
different paradigm.
* Better error handling
why:
Bail out on some error as early as possible before any changes.
* Implement `fetch()` as opposite of `merge()`
rationale:
In the `Aristo` realm, the action named `fetch()` and `merge()` indicate
leaf value related actions on the MPT, while actions `get()` and `put()`
handle vertex or hash key related operations that constitute the MPT.
* Re-factor `merge()` prototypes
why:
The most used variant of `merge()` should have the simplest prototype.
* Persistent DB constructor needs to import `aristo/aristo_init/persistent`
why:
Most applications use memory DB anyway. This avoids linking `-lrocksdb`
or any other back end libraries by default.
* Re-factor transaction module
why:
Got the paradigm wrong. The transaction descriptor did replace the
database one but should be handled separately.
* Misc fixes
detail:
* Fix de-serialisation for account leafs
* Update node recovery from unit tests
* Remove `LegacyAccount` from `PayloadRef` object
why:
Legacy accounts use a hash key as storage root which is detrimental
to the working of the Aristo database which uses a vertex ID.
* Dissolve `hashify_helper` into `aristo_utils` and `aristo_transcode`
why:
Functions are of general interest so they should live in first level
code files.
* Added left/right iterators over leaf nodes
* Some helper/wrapper functions that might be useful
* Slightly tighten some self-check conditions
* Redefined the database descriptor object as reference (to the object)
why:
The upcoming transaction wrapper will work with a database reference
rather than the object itself
* Append state before `save()` to the Aristo descriptor
why:
This stae was previously returned by the function. Appending it to
a field of the Aristo descriptor seems easier to handle.
* Fix missing branch checks in transcoder
why:
Symmetry problem. `Blobify()` allowed for encoding degenerate branch
vertices while `Deblobify()` rejected decoding wrongly encoded data.
* Update memory backend so that it rejects storing bogus vertices.
why:
Error behaviour made similar to the rocks DB backend.
* Make sure that leaf vertex IDs are not repurposed
why:
This makes it easier to record leaf node changes
* Update error return code for next()/right() traversal
why:
Returning offending vertex ID (besides error code) helps debugging
* Update Merkle hasher for deleted nodes
why:
Not implemented, yet
also:
Provide cache & backend consistency check functions. This was
partly re-implemented from `hashifyCheck()`
* Simplify some unit tests
* Fix delete function
why:
Was conceptually wrong
* Added missing deferred cleanup directive to sub-test functions
why:
Rocksdb keeps the files locked for a short while leading to errors. This
was previously solved my using different db sub-directories
* Provide vertex deep-copy function globally.
why:
is just handy
* Avoid unnecessary vertex caching when merging proof nodes
also:
Run all merge tests on the rocksdb backend
Previously, proof node tests were run without backend
* Fix vertex ID generator state handling for rocksdb backend
why:
* Key error in walk iterator
* Needs to be loaded when opening the database
* Use non-zero sub-table prefixes for rocksdb
why:
Handy for debugging
* Fix error code for missing key on rocksdb backend
why:
Previously returned `VOID_HASH_KEY` rather than `GetKeyNotFound`
* Explicitly copy vertex data between internal table and function/result argument
why:
Function argument or return reference may still refer to the same data
object.
* Updated error symbols
why:
Error symbol names for the hike module now start with the prefix `Hike`.
* Write back modified branch node into local top layer cache
why:
With the backend available, the source of the branch node references
might not be the top layer cache. So any change must be explicitely
recorded.
* Generalised Aristo DB constructor for any type of backend
details:
* Records to be deleted are represented as key-void (rather than
key-value) pairs by the put-function arguments
* Allow direct driver access, iterators as example implementation and
for testing.
* Provide backend storage interface
details:
Stores the top layer onto backend tables
* Implemented Rocks DB backend
details:
Transaction based `put()` functionality
Iterators (based on direct RocksDB access)
* Fix include
why:
Eth67 not default yet so that got missed
* Rename `LeafKey` => `LeafTie`
why:
Name is a pen picture of what this object is for. Also, it avoids the
ubiquitous term `key`.
* Provided `getOrVoid()` wrapper for `getOrDefault()`
also:
Provide `isValid()` syntactic sugar for `.isNil.not`, `!= 0` etc.
Reorg descriptor source, split into sub-sources
* Bundled `NodeKey` objects with root ID and called it `HashLabel`
why:
`NodeKey` (aka repurposed Hash265) objects are unique only within a
particular sub-trie (e.g. storage slots) which are kept separated
(i.e non-interleaved) by design. This is not applied to the backend
as the map VertexID->NodeKey labelling the nodes needs not be injective.
For the in-memory database (transaction) layers, the injective map
VertexID->(VertexID,NodeKey) is used where the first field of the image
tuple is the root ID of the sub-trie the `NodeKey` object is valid. So
identical storage tries for different accounts can be represented.
* Exclude some storage tests
why:
These test running on external dumps slipped through. The particular
dumps were reported earlier as somehow dodgy.
This was changed in `#1457` but having a second look, the change on
hexary_interpolate.nim(350) might be incorrect.
* Redesign `Aristo DB` descriptor for transaction based layers
why:
Previous descriptor layout made it cumbersome to push/pop
database delta layers.
The new architecture keeps each layer with the full delta set
relative to the database backend.
* Keep root ID as part of the `Patricia Trie` leaf path
why;
That way, forests are supported
* Fix missing Merkle key removal in `merge()`
* Accept optional root hash argument in `hashify()`
why:
For importing a full database, there will be no proof data except the
root key. So this can be used to check and set the root key in the
database descriptor.
also:
Associate vertex ID to `hashify()` error return code
* Added Aristo Trie traversal function
why:
* step along leaf vertices in sorted order
* tree/trie consistency checks when debugging
* Enabled storage slots test data for Aristo DB
* Keep vertex ID generator state with each db-layer
why:
The vertex ID generator state is part of the difference to the below
layer
* Move otherwise unused source to test directory
* Add Merkle hash generator
also:
* Verification facility for debugging
* Empty Merkle key hashes encoded as `EMPTY_ROOT_HASH`
details:
1. Merging a leaf vertex merges a `Patricia Trie` path (while
adding/modiying vertices) and adds a leaf node with payload
2. Merging a Merkel node merges a single vertex to the `Patricia Trie`
and registers merkel hashes
3. Action 2 can be used before action 1 in order to construct a
Merkel proof as required for handling `snap/1` data.
4. Unit tests show that action 3 is benign for now :)
andri lim
Jordan Hrycaj