Crate pallet_stateful_storage

Stateful Storage Pallet

The Stateful Storage pallet provides functionality for reading and writing stateful data representing stateful data for which we are only ever interested in the latest state.

• Configuration: Config
• Extrinsics: Call
• Runtime API: StatefulStorageRuntimeApi
• Custom RPC API: StatefulStorageApiServer
• Event Enum: Event
• Error Enum: Error

Overview

For state transitions for which we only care about the latest state, Stateful Storage provides a way to store and retrieve such data outside of the existing Announcement mechanism, which would require the latest state to be tracked using some kind of 3rd-party indexer.

This pallet supports two models for storing stateful data:

1. Itemized: Data is stored in a single page (max size: Config::MaxItemizedPageSizeBytes) containing multiple items (max item size MaxItemizedBlobSizeBytes) of the associated schema. Useful for schemas with a relative small item size and higher potential item count. The read and write complexity is O(n) when n is the number of bytes for all items.
2. Paginated: Data is stored in multiple pages of size Config::MaxPaginatedPageSizeBytes, each containing a single item of the associated schema. Page IDs range from 0 .. MaxPaginatedPageId (implying there may be at most MaxPaginatedPageId + 1 pages per MSA+Schema at any given time, though there may be holes in that range). Useful for schemas with a larger item size and smaller potential item count.

Features

• Provide for storage of stateful data with flexible schemas on-chain.
• Data stored for one MSA does not have impact read/write access times or storage costs for any data stored for another MSA.
• High write throughput.
• High read throughput.
• Data race condition protection

The Stateful Storage pallet provides functions for:

• Appending items in an itemized model
• Removing items in an itemized model
• Upserting items in a paginated model
• Removing pages in a paginated model

Terminology

• Page: Block of on-chain data of a fixed size, which is the underlying type for Itemized and Paginated storage.
• ItemizedPage: A page containing itemized data
• PaginatedPage: A page containing paginated data

Re-exports

• pub use pallet::*;
• pub use weights::*;

Modules

• pallet
  The pallet module in each FRAME pallet hosts the most important items needed to construct this pallet.
• types
  Types for the Stateful Storage Pallet
• weights
  Autogenerated weights for pallet_stateful_storage