Struct SystemDataContracts 

pub struct SystemDataContracts { /* private fields */ }

Memoized materializations of the compiled-in system data contracts.

load_system_data_contract(variant, platform_version) is a deterministic pure function of the variant and the protocol version, and its result changes across protocol versions (the DPNS domain document type gains its history flags at protocol version 13, for instance). This cache only avoids repeating that work — schema compilation and validation — so it holds no authoritative state: any entry may be dropped and rebuilt with a bit-identical result.

There is no “current” contract. Every read is pinned to the protocol version the caller is executing under, which it already carries in its [PlatformVersion]. That matters because materializations are loaded speculatively: the first block of a protocol change is executed for a candidate block that may be rejected, and the in-memory cache has no part in the grovedb rollback that follows. Keying every entry by its protocol version keeps the candidate’s materializations on keys no committed-version read can reach, so a rejected candidate is inert rather than something that has to be undone.

Reads are lock-free and writes replace the whole map. The set of materializations only changes when a protocol version is first read from — a handful of times per protocol upgrade — while reads happen on every block and every contract fetch, so cloning a map of at most a dozen Arc pointers on that rare path is cheaper than making every reader contend on a lock word.

Implementations

impl SystemDataContracts

pub fn new() -> Self

Creates an empty cache. Contracts are materialized on first use.

pub fn load( &self, system_contract: SystemDataContract, platform_version: &PlatformVersion, ) -> Result<Arc<DataContract>, Error>

Returns system_contract materialized for platform_version, reusing the memoized materialization when one is present.

The contract is materialized at the protocol version the caller is executing at, which is what the state holds: whenever a system contract’s materialization changes at a protocol version, the first block of that change rewrites the persisted contract (see perform_events_on_first_block_of_protocol_change).

Errors

Propagates any error from load_system_data_contract, notably when a contract’s schema is not expressible under platform_version — which is the case for contracts asked for below their activation version.

pub fn load_withdrawals( &self, platform_version: &PlatformVersion, ) -> Result<Arc<DataContract>, Error>

Returns the withdrawals contract materialized for platform_version.

pub fn load_token_history( &self, platform_version: &PlatformVersion, ) -> Result<Arc<DataContract>, Error>

Returns the token history contract materialized for platform_version.

pub fn load_dpns( &self, platform_version: &PlatformVersion, ) -> Result<Arc<DataContract>, Error>

Returns the DPNS contract materialized for platform_version.

pub fn load_dashpay( &self, platform_version: &PlatformVersion, ) -> Result<Arc<DataContract>, Error>

Returns the Dashpay contract materialized for platform_version.

pub fn load_masternode_reward_shares( &self, platform_version: &PlatformVersion, ) -> Result<Arc<DataContract>, Error>

Returns the masternode reward shares contract materialized for platform_version.

pub fn load_keyword_search( &self, platform_version: &PlatformVersion, ) -> Result<Arc<DataContract>, Error>

Returns the keyword search contract materialized for platform_version.

pub fn load_document_history( &self, platform_version: &PlatformVersion, ) -> Result<Arc<DataContract>, Error>

Returns the document history contract materialized for platform_version.

pub fn find_by_id( &self, id: Identifier, platform_version: &PlatformVersion, ) -> Result<Option<Arc<DataContract>>, Error>

Returns the system contract whose deterministic identifier matches id, materialized for platform_version.

Returns None for user contracts, for system contracts this cache does not materialize (WalletUtils, which lives only in grovedb), and for system contracts that are not yet active at platform_version: before activation the contract does not exist in the state, so the lookup must fall through to the billed grovedb fetch and report it absent exactly like a non-upgraded node would.

pub fn drop_versions_below(&self, protocol_version: ProtocolVersion)

Drops materializations for protocol versions below protocol_version.

Call this when a block commits, passing the committed protocol version: from that point every live read asks for it or higher — check_tx validates against the committed state, and the next block executes at the committed version until another upgrade proposes a candidate — so everything below is garbage. Materializations above it are kept: those belong to an upgrade candidate that was proposed and will be proposed again.

Nothing depends on this being called. Entries are reproducible, so skipping it costs memory bounded by [MAX_MEMOIZED_PROTOCOL_VERSIONS], never correctness.

Trait Implementations

impl Default for SystemDataContracts

fn default() -> Self

Returns the “default value” for a type.