IsSnapshotActive() method is only called one place outside of tests and asserts, and is confusing because it returns true even after the snapshot is fully validated. The documentation which said this "implies that a background validation chainstate is also in use" is also incorrect, because after the snapshot is validated, the background chainstate gets disabled and IsUsable() would return false.
Internal c++ interfaces
The following interfaces are defined here:
-
Chain— used by wallet to access blockchain and mempool state. Added in #14437, #14711, #15288, and #10973. -
ChainClient— used by node to start & stopChainclients. Added in #14437. -
Node— used by GUI to start & stop bitcoin node. Added in #10244. -
Handler— returned byhandleEventmethods on interfaces above and used to manage lifetimes of event handlers. -
Init— used by multiprocess code to access interfaces above on startup. Added in #19160. -
Ipc— used by multiprocess code to accessInitinterface across processes. Added in #19160.
The interfaces above define boundaries between major components of bitcoin code (node, wallet, and gui), making it possible for them to run in different processes, and be tested, developed, and understood independently. These interfaces are not currently designed to be stable or to be used externally.