// findCandidates searches the chain backwards for checkpoint candidates and
// returns a slice of found candidates, if any. It also stops searching for
// candidates at the last checkpoint that is already hard coded into btcchain
// since there is no point in finding candidates before already existing
// checkpoints.
func findCandidates(chain *blockchain.BlockChain, latestHash *chainhash.Hash) ([]*chaincfg.Checkpoint, error) {
// Start with the latest block of the main chain.
block, err := chain.BlockByHash(latestHash)
if err != nil {
return nil, err
}
// Get the latest known checkpoint.
latestCheckpoint := chain.LatestCheckpoint()
if latestCheckpoint == nil {
// Set the latest checkpoint to the genesis block if there isn't
// already one.
latestCheckpoint = &chaincfg.Checkpoint{
Hash: activeNetParams.GenesisHash,
Height: 0,
}
}
// The latest known block must be at least the last known checkpoint
// plus required checkpoint confirmations.
checkpointConfirmations := int32(blockchain.CheckpointConfirmations)
requiredHeight := latestCheckpoint.Height + checkpointConfirmations
if block.Height() < requiredHeight {
return nil, fmt.Errorf("the block database is only at height "+
"%d which is less than the latest checkpoint height "+
"of %d plus required confirmations of %d",
block.Height(), latestCheckpoint.Height,
checkpointConfirmations)
}
// For the first checkpoint, the required height is any block after the
// genesis block, so long as the chain has at least the required number
// of confirmations (which is enforced above).
if len(activeNetParams.Checkpoints) == 0 {
requiredHeight = 1
}
// Indeterminate progress setup.
numBlocksToTest := block.Height() - requiredHeight
progressInterval := (numBlocksToTest / 100) + 1 // min 1
fmt.Print("Searching for candidates")
defer fmt.Println()
// Loop backwards through the chain to find checkpoint candidates.
candidates := make([]*chaincfg.Checkpoint, 0, cfg.NumCandidates)
numTested := int32(0)
for len(candidates) < cfg.NumCandidates && block.Height() > requiredHeight {
// Display progress.
if numTested%progressInterval == 0 {
fmt.Print(".")
}
// Determine if this block is a checkpoint candidate.
isCandidate, err := chain.IsCheckpointCandidate(block)
if err != nil {
return nil, err
}
// All checks passed, so this node seems like a reasonable
// checkpoint candidate.
if isCandidate {
checkpoint := chaincfg.Checkpoint{
Height: block.Height(),
Hash: block.Hash(),
}
candidates = append(candidates, &checkpoint)
}
prevHash := &block.MsgBlock().Header.PrevBlock
block, err = chain.BlockByHash(prevHash)
if err != nil {
return nil, err
}
numTested++
}
return candidates, nil
}
// Init initializes the enabled indexes. This is called during chain
// initialization and primarily consists of catching up all indexes to the
// current best chain tip. This is necessary since each index can be disabled
// and re-enabled at any time and attempting to catch-up indexes at the same
// time new blocks are being downloaded would lead to an overall longer time to
// catch up due to the I/O contention.
//
// This is part of the blockchain.IndexManager interface.
func (m *Manager) Init(chain *blockchain.BlockChain) error {
// Nothing to do when no indexes are enabled.
if len(m.enabledIndexes) == 0 {
return nil
}
// Finish and drops that were previously interrupted.
if err := m.maybeFinishDrops(); err != nil {
return err
}
// Create the initial state for the indexes as needed.
err := m.db.Update(func(dbTx database.Tx) error {
// Create the bucket for the current tips as needed.
meta := dbTx.Metadata()
_, err := meta.CreateBucketIfNotExists(indexTipsBucketName)
if err != nil {
return err
}
return m.maybeCreateIndexes(dbTx)
})
if err != nil {
return err
}
// Initialize each of the enabled indexes.
for _, indexer := range m.enabledIndexes {
if err := indexer.Init(); err != nil {
return err
}
}
// Rollback indexes to the main chain if their tip is an orphaned fork.
// This is fairly unlikely, but it can happen if the chain is
// reorganized while the index is disabled. This has to be done in
// reverse order because later indexes can depend on earlier ones.
for i := len(m.enabledIndexes); i > 0; i-- {
indexer := m.enabledIndexes[i-1]
// Fetch the current tip for the index.
var height int32
var hash *chainhash.Hash
err := m.db.View(func(dbTx database.Tx) error {
idxKey := indexer.Key()
hash, height, err = dbFetchIndexerTip(dbTx, idxKey)
return err
})
if err != nil {
return err
}
// Nothing to do if the index does not have any entries yet.
if height == -1 {
continue
}
// Loop until the tip is a block that exists in the main chain.
initialHeight := height
for {
exists, err := chain.MainChainHasBlock(hash)
if err != nil {
return err
}
if exists {
break
}
// At this point the index tip is orphaned, so load the
// orphaned block from the database directly and
// disconnect it from the index. The block has to be
// loaded directly since it is no longer in the main
// chain and thus the chain.BlockByHash function would
// error.
err = m.db.Update(func(dbTx database.Tx) error {
blockBytes, err := dbTx.FetchBlock(hash)
if err != nil {
return err
}
block, err := btcutil.NewBlockFromBytes(blockBytes)
if err != nil {
return err
}
block.SetHeight(height)
// When the index requires all of the referenced
// txouts they need to be retrieved from the
// transaction index.
var view *blockchain.UtxoViewpoint
if indexNeedsInputs(indexer) {
var err error
view, err = makeUtxoView(dbTx, block)
if err != nil {
return err
}
}
// Remove all of the index entries associated
// with the block and update the indexer tip.
err = dbIndexDisconnectBlock(dbTx, indexer,
block, view)
if err != nil {
return err
}
// Update the tip to the previous block.
hash = &block.MsgBlock().Header.PrevBlock
height--
return nil
})
if err != nil {
return err
}
}
if initialHeight != height {
log.Infof("Removed %d orphaned blocks from %s "+
"(heights %d to %d)", initialHeight-height,
indexer.Name(), height+1, initialHeight)
}
}
// Fetch the current tip heights for each index along with tracking the
// lowest one so the catchup code only needs to start at the earliest
// block and is able to skip connecting the block for the indexes that
// don't need it.
bestHeight := chain.BestSnapshot().Height
lowestHeight := bestHeight
indexerHeights := make([]int32, len(m.enabledIndexes))
err = m.db.View(func(dbTx database.Tx) error {
for i, indexer := range m.enabledIndexes {
idxKey := indexer.Key()
hash, height, err := dbFetchIndexerTip(dbTx, idxKey)
if err != nil {
return err
}
log.Debugf("Current %s tip (height %d, hash %v)",
indexer.Name(), height, hash)
indexerHeights[i] = height
if height < lowestHeight {
lowestHeight = height
}
}
return nil
})
if err != nil {
return err
}
// Nothing to index if all of the indexes are caught up.
if lowestHeight == bestHeight {
return nil
}
// Create a progress logger for the indexing process below.
progressLogger := newBlockProgressLogger("Indexed", log)
// At this point, one or more indexes are behind the current best chain
// tip and need to be caught up, so log the details and loop through
// each block that needs to be indexed.
log.Infof("Catching up indexes from height %d to %d", lowestHeight,
bestHeight)
for height := lowestHeight + 1; height <= bestHeight; height++ {
// Load the block for the height since it is required to index
// it.
block, err := chain.BlockByHeight(height)
if err != nil {
return err
}
// Connect the block for all indexes that need it.
var view *blockchain.UtxoViewpoint
for i, indexer := range m.enabledIndexes {
// Skip indexes that don't need to be updated with this
// block.
if indexerHeights[i] >= height {
continue
}
err := m.db.Update(func(dbTx database.Tx) error {
// When the index requires all of the referenced
// txouts and they haven't been loaded yet, they
// need to be retrieved from the transaction
// index.
if view == nil && indexNeedsInputs(indexer) {
var err error
view, err = makeUtxoView(dbTx, block)
if err != nil {
return err
}
}
return dbIndexConnectBlock(dbTx, indexer, block,
view)
})
if err != nil {
return err
}
indexerHeights[i] = height
}
// Log indexing progress.
progressLogger.LogBlockHeight(block)
}
log.Infof("Indexes caught up to height %d", bestHeight)
return nil
}