* Relocated mothballing (i.e. swap-in preparation) logic
details:
Mothballing was previously tested & started after downloading
account ranges in `range_fetch_accounts`.
Whenever current download or healing stops because of a pivot change,
swap-in preparation is needed (otherwise some storage slots may get
lost when swap-in takes place.)
Also, `execSnapSyncAction()` has been moved back to `pivot_helper`.
* Reorganised source file directories
details:
Grouped pivot focused modules into `pivot` directory
* Renamed `checkNodes`, `sickSubTries` as `nodes.check`, `nodes.missing`
why:
Both lists are typically used together as pair. Renaming `sickSubTries`
reflects moving away from a healing centric view towards a swap-in
attitude.
* Multi times coverage recording
details:
Per pivot account ranges are accumulated into coverage range set. This
set fill eventually contain a singe range of account hashes [0..2^256]
which amounts to 100% capacity.
A counter has been added that is incremented whenever max capacity is
reached. The accumulated range is then reset to empty.
The effect of this setting is that the coverage can be evenly duplicated.
So 200% would not accumulate on a particular region.
* Update range length comparisons (mod 2^256)
why:
A range interval can have sizes 1..2^256 as it cannot be empty by
definition. The number of points in a range intervals set can have
0..2^256 points. As the scalar range is a residue class modulo 2^256,
the residue class 0 means length 2^256 for a range interval, but can
be 0 or 2^256 for the number of points in a range intervals set.
* Generalised `hexaryEnvelopeDecompose()`
details:
Compile the complement of the union of some (processed) intervals and
express this complement as a list of envelopes of sub-tries.
This facility is directly applicable to swap-in book-keeping.
* Re-factor `swapIn()`
why:
Good idea but baloney implementation. The main algorithm is based on
the generalised version of `hexaryEnvelopeDecompose()` which has been
derived from this implementation.
* Refactor `healAccounts()` using `hexaryEnvelopeDecompose()` as main driver
why:
Previously, the hexary trie was searched recursively for dangling nodes
which has a poor worst case performance already when the trie is
reasonably populated.
The function `hexaryEnvelopeDecompose()` is a magnitude faster because
it does not peruse existing sub-tries in order to find missing nodes
although result is not fully compatible with the previous function.
So recursive search is used in a limited mode only when the decomposer
will not deliver a useful result.
* Logging & maintenance fixes
details:
Preparation for abandoning buddy-global healing variables `node`,
`resumeCtx`, and `lockTriePerusal`. These variable are trie-perusal
centric which will be run on the back burner in favour of
`hexaryEnvelopeDecompose()` which is used for accounts healing already.
* Provide index to reconstruct missing storage slots
why;
Pivots will be changed anymore once they are officially archived. The
account of the archived pivots are ready to be swapped into the active
pivot. This leaves open how to treat storage slots not fetched yet.
Solution: when mothballing, an `account->storage-root` index is
compiled that can be used when swapping in accounts.
* Implement swap-in from earlier pivots
details;
When most accounts are covered by the current and previous pivot
sessions, swapping inthe accounts and storage slots (i.e. registering
account ranges done) from earlier pivots takes place if there is a
common sub-trie.
* Throttle pivot change when healing state has bean reached
why:
There is a hope to complete the current pivot, so pivot update can be
throttled. This is achieved by setting another minimum block number
distance for the pivot headers. This feature is still experimental
* Add quick hexary trie inspector, called `dismantle()`
why:
+ Full hexary trie perusal is slow if running down leaf nodes
+ For known range of leaf nodes, work out the UInt126-complement of
partial sub-trie paths (for existing nodes). The result should cover
no (or only a few) sub-tries with leaf nodes.
* Extract common healing methods => `sub_tries_helper.nim`
details:
Also apply quick hexary trie inspection tool `dismantle()`
Replace `inspectAccountsTrie()` wrapper by `hexaryInspectTrie()`
* Re-arrange task dispatching in main peer worker
* Refactor accounts and storage slots downloaders
* Rename `HexaryDbError` => `HexaryError`
* Stop negotiating pivot if peer repeatedly replies w/usesless answers
why:
There is some fringe condition where a peer replies with legit but
useless empty headers repetely. This goes on until somebody stops.
We stop now.
* Rename `missingNodes` => `sickSubTries`
why:
These (probably missing) nodes represent in reality fully or partially
missing sub-tries. The top nodes may even exist, e.g. as a shallow
sub-trie.
also:
Keep track of account healing on/of by bool variable `accountsHealing`
controlled in `pivot_helper.execSnapSyncAction()`
* Add `nimbus` option argument `snapCtx` for starting snap recovery (if any)
also:
+ Trigger the recovery (or similar) process from inside the global peer
worker initialisation `worker.setup()` and not by the `snap.start()`
function.
+ Have `runPool()` returned a `bool` code to indicate early stop to
scheduler.
* Can import partial snap sync checkpoint at start
details:
+ Modified what is stored with the checkpoint in `snapdb_pivot.nim`
+ Will be loaded within `runDaemon()` if activated
* Forgot to import total coverage range
why:
Only the top (or latest) pivot needs coverage but the total coverage
is the list of all ranges for all pivots -- simply forgotten.
* Piecemeal trie inspection
details:
Trie inspection will stop after maximum number of nodes visited.
The inspection can be resumed using the returned state from the
last session.
why:
This feature allows for task switch between `piecemeal` sessions.
* Extract pivot helper code from `worker.nim` => `pivot_helper.nim`
* Accounts import will now return dangling paths from `proof` nodes
why:
With proper bookkeeping, this can be used to start healing without
analysing the the probably full trie.
* Update `unprocessed` account range handling
why:
More generally, the API of a pairs of unprocessed intervals favours
the first set and not before that is exhausted the second set comes
into play.
This was unfortunately implemented which caused the ranges to be
unnecessarily fractioned. Now the number of range interval typically
remains in the lower single digit numbers.
* Save sync state after end of downloading some accounts
details:
restore/resume to be implemented later
* Update log ticker, using time interval rather than ticker count
why:
Counting and logging ticker occurrences is inherently imprecise. So
time intervals are used.
* Use separate storage tables for snap sync data
* Left boundary proof update
why:
Was not properly implemented, yet.
* Capture pivot in peer worker (aka buddy) tasks
why:
The pivot environment is linked to the `buddy` descriptor. While
there is a task switch, the pivot may change. So it is passed on as
function argument `env` rather than retrieved from the buddy at
the start of a sub-function.
* Split queues `fetchStorage` into `fetchStorageFull` and `fetchStoragePart`
* Remove obsolete account range returned from `GetAccountRange` message
why:
Handler returned the wrong right value of the range. This range was
for convenience, only.
* Prioritise storage slots if the queue becomes large
why:
Currently, accounts processing is prioritised up until all accounts
are downloaded. The new prioritisation has two thresholds for
+ start processing storage slots with a new worker
+ stop account processing and switch to storage processing
also:
Provide api for `SnapTodoRanges` pair of range sets in `worker_desc.nim`
* Generalise left boundary proof for accounts or storage slots.
why:
Detailed explanation how this works is documented with
`snapdb_accounts.importAccounts()`.
Instead of enforcing a left boundary proof (which is still the default),
the importer functions return a list of `holes` (aka node paths) found in
the argument ranges of leaf nodes. This in turn is used by the book
keeping software for data download.
* Forgot to pass on variable in function wrapper
also:
+ Start healing not before 99% accounts covered (previously 95%)
+ Logging updated/prettified
* Update docu and logging
* Extracted and updated constants from `worker_desc` into separate file
* Update and re-calibrate communication error handling
* Allow simplified pivot negotiation
why:
This feature allows to turn off pivot negotiation so that peers agree
on a a pivot header.
For snap sync with fast changing pivots this only throttles the sync
process. The finally downloaded DB snapshot is typically a merged
version of different pivot states augmented by a healing process.
* Re-model worker queues for accounts download & healing
why:
Currently there is only one data fetch per download or healing task.
This task is then repeated by the scheduler after a short time. In
many cases, this short time seems enough for some peers to decide to
terminate connection.
* Update main task batch `runMulti()`
details:
The function `runMulti()` is activated in quasi-parallel mode by the
scheduler. This function calls the download, healing and fast-sync
functions.
While in debug mode, after each set of jobs run by this function the
database is analysed (by the `snapdb_check` module) and the result
printed.
Jordan Hrycaj