This is a new implementation of the incremental merkle tree used by our
scheme to witness commitments to spendable value. It serves as a fixed-sized
accumulator.
This new construction has a much simpler API surface area, avoids memory
safety issues, remains pruned at all times, avoids serialization edge cases,
has more efficient insertion, and is abstract over the depth and hash
function used at the type level.
Further, it lays the groundwork for efficient "fast-forwarding" of witnesses
into the tree as the treestate is updated.
Some specifics on consensus changes:
* Transactions must be anchored to a real anchor in the chain.
* Anchors are pushed and popped during ConnectBlock/DisconnectBlock as appropriate.
* DisconnectTip triggers evictions, under some circumstances, of transactions in the
mempool which are anchored to roots that are no longer valid.
* Commitments append to the tree at the current best root during ConnectBlock.
It is easily confused with CCoinsViewCache(CCoinsView*), which creates a sub-cache, but instead of creating a sub-cache, the copy constructor would copy the original and use that original's base, defeating the intended isolation.
- Update comments in checkpoints to be doxygen compatible
- Update comments in checkqueue to be doxygen compatible
- Update coins to be doxygen compatible
- Fix comment typo in crypter.h
- Update licenses/copyright dates
Closes#5325#5184#5183#5182
Instead of storing CCoins entries directly in CCoinsMap, store a CCoinsCacheEntry
which additionally keeps track of whether a particular entry is:
* dirty: potentially different from its parent view.
* fresh: the parent view is known to not have a non-pruned version.
This allows us to skip non-dirty cache entries when pushing batches of changes up,
and to remove CCoins entries about transactions that are fully spent before the
parent cache learns about them.
All direct modifications are now done through ModifyCoins, and BatchWrite is
used for pushing batches of queued modifications up, so we don't need the
low-level SetCoins and SetBestBlock anymore in the top-level CCoinsView class.
Replace the mutable non-copying GetCoins method with a ModifyCoins, which
returns an encapsulated iterator, so we can keep track of concurrent
modifications (as iterators can be invalidated by those) and run cleanup
code after a modification is finished.
This also removes the overloading of the 'GetCoins' name.
The efficient version of CCoinsViewCache::GetCoins only works for known-to-exist
cache entries, requiring a separate HaveCoins call beforehand. This is
inefficient as both perform a hashtable lookup.
Replace the non-mutable GetCoins with AccessCoins, which returns a potentially-NULL
pointer. This also decreases the overloading of GetCoins.
Also replace some copying (inefficient) GetCoins calls with equivalent AccessCoins,
decreasing the copying.
- ensures a consistent usage in header files
- also add a blank line after the copyright header where missing
- also remove orphan new-lines at the end of some files
It currently returns uint64_t, which on older boost (at least 1.46) causes
test failures on 32-bit systems.
This problem was introduced in bc42503.
Fixes#4634.
Pieter Wuille