ChainStore

/// All chain-related database operations
pub struct ChainStore {
    db: store::Store,
}

主要对和“链”相关的元素进行增、删、查。

相关元素：

const BLOCK_HEADER_PREFIX: u8 = 'h' as u8;
const BLOCK_PREFIX: u8 = 'b' as u8;
const HEAD_PREFIX: u8 = 'H' as u8;
const HEADER_HEAD_PREFIX: u8 = 'I' as u8;
const SYNC_HEAD_PREFIX: u8 = 's' as u8;
const HEADER_HEIGHT_PREFIX: u8 = '8' as u8;
const COMMIT_POS_PREFIX: u8 = 'c' as u8;
const BLOCK_INPUT_BITMAP_PREFIX: u8 = 'B' as u8;
const BLOCK_SUMS_PREFIX: u8 = 'M' as u8;

Batch

/// An atomic batch in which all changes can be committed all at once or
/// discarded on error.
pub struct Batch<'a> {
    store: &'a ChainStore,
    db: store::Batch<'a>,
}

DifficultyIter

/// An iterator on blocks, from latest to earliest, specialized to return
/// information pertaining to block difficulty calculation (timestamp and
/// previous difficulties). Mostly used by the consensus next difficulty
/// calculation.
pub struct DifficultyIter<'a> {
    start: Hash,
    store: Option<Arc<ChainStore>>,
    batch: Option<Batch<'a>>,

    // maintain state for both the "next" header in this iteration
    // and its previous header in the chain ("next next" in the iteration)
    // so we effectively read-ahead as we iterate through the chain back
    // toward the genesis block (while maintaining current state)
    header: Option<BlockHeader>,
    prev_header: Option<BlockHeader>,
}