Crate sc_statement_store 

Disk-backed statement store.

This module contains an implementation of sp_statement_store::StatementStore which is backed by a database.

Constraint management.

The statement store validates statements using node-side signature verification and static runtime allowance limits. The following constraints are then checked:

• For a given account id, there may be at most max_count statements with max_size total data size. To satisfy this, statements for this account ID are removed from the store starting with the lowest priority until a constraint is satisfied.
• There may not be more than MAX_TOTAL_STATEMENTS total statements with MAX_TOTAL_SIZE size. To satisfy this, statements are removed from the store starting with the lowest global_priority until a constraint is satisfied.

When a new statement is inserted that would not satisfy constraints in the first place, no statements are deleted and Ignored result is returned. The order in which statements with the same priority are deleted is unspecified.

Statement expiration.

Each time a statement is removed from the store (Either evicted by higher priority statement or explicitly with the remove function) the statement is marked as expired. Expired statements can’t be added to the store for Options::purge_after_sec seconds. This is to prevent old statements from being propagated on the network.

Modules

subxt_client

Custom subxt configuration for runtimes interacting with statement-store, used only for tests

test_utils

Test utilities for the statement store

Structs

Config

Statement store and network handler configuration.

Store

Statement store.

Enums

Error

Statement store error.

Constants

DEFAULT_MAX_TOTAL_SIZE

The maximum amount of data the statement store can hold, regardless of the number of statements from which the data originates.

DEFAULT_MAX_TOTAL_STATEMENTS

The maximum number of statements the statement store can hold.

DEFAULT_NETWORK_WORKERS

Default number of concurrent workers for statement validation.

DEFAULT_PURGE_AFTER_SEC

The amount of time an expired statement is kept before it is removed from the store entirely.

DEFAULT_RATE_LIMIT

Default maximum statements per second per peer before rate limiting kicks in. Default maximum statements per second before rate limiting kicks in.

MAX_STATEMENT_SIZE

The maximum size of a single statement in bytes. Accounts for the 1-byte vector length prefix when statements are gossiped as Vec<Statement>.

MAX_TOPICS

Total number of topic fields allowed in a statement and in MatchAll filters.

Traits

StatementStore

Statement store API.

StatementStoreSubscriptionApi

Trait for initiating statement store subscriptions from the RPC module.