This is preparation for the simulation fuzz test added in a later commit. Since
AddChildrenToWorkSet consumes randomness, there is no way for the simulator to
exactly predict its behavior. By returning the set of made-reconsiderable announcements
instead, the simulator can instead test that it is *a* valid choice, and then
apply it to its own data structures.
This is largely a reimplementation using boost::multi_index_container.
All the same public methods are available. It has an index by outpoint,
per-peer tracking, peer worksets, etc.
A few differences:
- Limits have changed: instead of a global limit of 100 unique orphans,
we have a maximum number of announcements (which can include duplicate
orphans) and a global memory limit which scales with the number of
peers.
- The maximum announcements limit is 100 to match the original limit,
but this is actually a stricter limit because the announcement count
is not de-duplicated.
- Eviction strategy: when global limits are reached, a per-peer limit
comes into play. While limits are exceeded, we choose the peer whose
“DoS score” (max usage / limit ratio for announcements and memory
limits) is highest and evict announcements by entry time, sorting
non-reconsiderable ones before reconsiderable ones. Since announcements
are unique by (wtxid, peer), as long as 1 announcement remains for a
transaction, it remains in the orphanage.
- This eviction strategy means no peer can influence the eviction of
another peer’s orphans.
- Also, since global limits are a multiple of per-peer limits, as long
as a peer does not exceed its limits, its orphans are protected from
eviction.
- Orphans no longer expire, since older announcements are generally
removed before newer ones.
- GetChildrenFromSamePeer returns the transactions from newest to
oldest.
Co-authored-by: Pieter Wuille <pieter@wuille.net>
Move towards a model where TxOrphanage is initialized with limits that
it remembers throughout its lifetime.
Remove the param. Limiting by number of unique orphans will be removed
in a later commit.
Now that -maxorphantx is gone, this does not change the node behavior.
The parameter is only used in tests.
Expiry is going away in a later commit.
This is only an RPC change. Behavior of the orphanage does not change.
Note that getorphantxs is marked experimental.
