以太坊源码分析-同步之Syncing接口

// Syncing returns false in case the node is currently not syncing with the network. It can be up to date or has not
// yet received the latest block headers from its pears. In case it is synchronizing:
// - startingBlock: block number this node started to synchronise from
// - currentBlock:  block number this node is currently importing
// - highestBlock:  block number of the highest block header this node has received from peers
// - pulledStates:  number of state entries processed until now
// - knownStates:   number of known state entries that still need to be pulled
func (s *PublicEthereumAPI) Syncing() (interface{}, error) {
    progress := s.b.Downloader().Progress()

    // Return not syncing if the synchronisation already completed
    if progress.CurrentBlock >= progress.HighestBlock {
        return false, nil
    }
    // Otherwise gather the block sync stats
    return map[string]interface{}{
        "startingBlock": hexutil.Uint64(progress.StartingBlock),
        "currentBlock":  hexutil.Uint64(progress.CurrentBlock),
        "highestBlock":  hexutil.Uint64(progress.HighestBlock),
        "pulledStates":  hexutil.Uint64(progress.PulledStates),
        "knownStates":   hexutil.Uint64(progress.KnownStates),
    }, nil
}

// SyncProgress gives progress indications when the node is synchronising with
// the Ethereum network.
type SyncProgress struct {
    StartingBlock uint64 // Block number where sync began
    CurrentBlock  uint64 // Current block number where sync is at
    HighestBlock  uint64 // Highest alleged block number in the chain
    PulledStates  uint64 // Number of state trie entries already downloaded
    KnownStates   uint64 // Total number of state trie entries known about
}

progress := s.b.Downloader().Progress()

// Progress retrieves the synchronisation boundaries, specifically the origin
// block where synchronisation started at (may have failed/suspended); the block
// or header sync is currently at; and the latest known block which the sync targets.
//
// In addition, during the state download phase of fast synchronisation the number
// of processed and the total number of known states are also returned. Otherwise
// these are zero.
func (d *Downloader) Progress() ethereum.SyncProgress {
    // Lock the current stats and return the progress
    d.syncStatsLock.RLock()
    defer d.syncStatsLock.RUnlock()

    current := uint64(0)
    switch d.mode {
    case FullSync:
        current = d.blockchain.CurrentBlock().NumberU64()
    case FastSync:
        current = d.blockchain.CurrentFastBlock().NumberU64()
    case LightSync:
        current = d.lightchain.CurrentHeader().Number.Uint64()
    }
    return ethereum.SyncProgress{
        StartingBlock: d.syncStatsChainOrigin,
        CurrentBlock:  current,
        HighestBlock:  d.syncStatsChainHeight,
        PulledStates:  d.syncStatsState.processed,
        KnownStates:   d.syncStatsState.processed + d.syncStatsState.pending,
    }
}