6d15be5b79
This commit makes use of the blockEventQueue within the neutrino implementation of FilteredChainView to ensure connected and disconnected blocks are consumed in order by the reader. It also specifies that neutrino is not to send disconnected blocks notifications during rescans, making it consistent with the btcd implementation.
360 lines
11 KiB
Go
360 lines
11 KiB
Go
package chainview
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import (
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"fmt"
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"sync"
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"sync/atomic"
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"github.com/lightninglabs/neutrino"
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"github.com/roasbeef/btcd/chaincfg/chainhash"
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"github.com/roasbeef/btcd/rpcclient"
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"github.com/roasbeef/btcd/wire"
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"github.com/roasbeef/btcutil"
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"github.com/roasbeef/btcutil/gcs/builder"
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"github.com/roasbeef/btcwallet/waddrmgr"
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)
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// CfFilteredChainView is an implementation of the FilteredChainView interface
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// which is supported by an underlying Bitcoin light client which supports
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// client side filtering of Golomb Coded Sets. Rather than fetching all the
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// blocks, the light client is able to query fitlers locally, to test if an
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// item in a block modifies any of our watched set of UTXOs.
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type CfFilteredChainView struct {
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started int32
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stopped int32
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// p2pNode is a pointer to the running GCS-filter supported Bitcoin
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// light clientl
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p2pNode *neutrino.ChainService
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// chainView is the active rescan which only watches our specified
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// sub-set of the UTXO set.
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chainView neutrino.Rescan
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// rescanErrChan is the channel that any errors encountered during the
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// rescan will be sent over.
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rescanErrChan <-chan error
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// blockEventQueue is the ordered queue used to keep the order
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// of connected and disconnected blocks sent to the reader of the
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// chainView.
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blockQueue *blockEventQueue
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// chainFilter is the
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filterMtx sync.RWMutex
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chainFilter map[wire.OutPoint]struct{}
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quit chan struct{}
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wg sync.WaitGroup
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}
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// A compile time check to ensure CfFilteredChainView implements the
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// chainview.FilteredChainView.
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var _ FilteredChainView = (*CfFilteredChainView)(nil)
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// NewCfFilteredChainView creates a new instance of the CfFilteredChainView
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// which is connected to an active neutrino node.
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//
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// NOTE: The node should already be running an syncing before being passed into
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// this function.
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func NewCfFilteredChainView(node *neutrino.ChainService) (*CfFilteredChainView, error) {
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return &CfFilteredChainView{
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blockQueue: newBlockEventQueue(),
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quit: make(chan struct{}),
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rescanErrChan: make(chan error),
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chainFilter: make(map[wire.OutPoint]struct{}),
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p2pNode: node,
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}, nil
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}
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// Start kicks off the FilteredChainView implementation. This function must be
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// called before any calls to UpdateFilter can be processed.
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//
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// NOTE: This is part of the FilteredChainView interface.
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func (c *CfFilteredChainView) Start() error {
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// Already started?
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if atomic.AddInt32(&c.started, 1) != 1 {
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return nil
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}
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log.Infof("FilteredChainView starting")
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// First, we'll obtain the latest block height of the p2p node. We'll
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// start the auto-rescan from this point. Once a caller actually wishes
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// to register a chain view, the rescan state will be rewound
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// accordingly.
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bestHeader, bestHeight, err := c.p2pNode.BlockHeaders.ChainTip()
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if err != nil {
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return err
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}
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startingPoint := &waddrmgr.BlockStamp{
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Height: int32(bestHeight),
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Hash: bestHeader.BlockHash(),
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}
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// Next, we'll create our set of rescan options. Currently it's
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// required that a user MUST set a addr/outpoint/txid when creating a
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// rescan. To get around this, we'll add a "zero" outpoint, that won't
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// actually be matched.
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var zeroPoint wire.OutPoint
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rescanOptions := []neutrino.RescanOption{
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neutrino.StartBlock(startingPoint),
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neutrino.QuitChan(c.quit),
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neutrino.NotificationHandlers(
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rpcclient.NotificationHandlers{
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OnFilteredBlockConnected: c.onFilteredBlockConnected,
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OnFilteredBlockDisconnected: c.onFilteredBlockDisconnected,
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},
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),
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neutrino.WatchOutPoints(zeroPoint),
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}
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// Finally, we'll create our rescan struct, start it, and launch all
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// the goroutines we need to operate this FilteredChainView instance.
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c.chainView = c.p2pNode.NewRescan(rescanOptions...)
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c.rescanErrChan = c.chainView.Start()
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c.blockQueue.Start()
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c.wg.Add(1)
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go c.chainFilterer()
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return nil
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}
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// Stop signals all active goroutines for a graceful shutdown.
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//
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// NOTE: This is part of the FilteredChainView interface.
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func (c *CfFilteredChainView) Stop() error {
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// Already shutting down?
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if atomic.AddInt32(&c.stopped, 1) != 1 {
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return nil
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}
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log.Infof("FilteredChainView stopping")
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close(c.quit)
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c.blockQueue.Stop()
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c.wg.Wait()
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return nil
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}
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// onFilteredBlockConnected is called for each block that's connected to the
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// end of the main chain. Based on our current chain filter, the block may or
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// may not include any relevant transactions.
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func (c *CfFilteredChainView) onFilteredBlockConnected(height int32,
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header *wire.BlockHeader, txns []*btcutil.Tx) {
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mtxs := make([]*wire.MsgTx, len(txns))
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for i, tx := range txns {
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mtx := tx.MsgTx()
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mtxs[i] = mtx
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for _, txIn := range mtx.TxIn {
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c.filterMtx.Lock()
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delete(c.chainFilter, txIn.PreviousOutPoint)
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c.filterMtx.Unlock()
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}
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}
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block := &FilteredBlock{
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Hash: header.BlockHash(),
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Height: uint32(height),
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Transactions: mtxs,
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}
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c.blockQueue.Add(&blockEvent{
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eventType: connected,
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block: block,
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})
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}
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// onFilteredBlockDisconnected is a callback which is executed once a block is
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// disconnected from the end of the main chain.
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func (c *CfFilteredChainView) onFilteredBlockDisconnected(height int32,
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header *wire.BlockHeader) {
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log.Debugf("got disconnected block at height %d: %v", height,
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header.BlockHash())
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filteredBlock := &FilteredBlock{
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Hash: header.BlockHash(),
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Height: uint32(height),
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}
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c.blockQueue.Add(&blockEvent{
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eventType: disconnected,
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block: filteredBlock,
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})
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}
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// chainFilterer is the primary coordination goroutine within the
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// CfFilteredChainView. This goroutine handles errors from the running rescan.
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func (c *CfFilteredChainView) chainFilterer() {
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defer c.wg.Done()
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for {
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select {
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case err := <-c.rescanErrChan:
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log.Errorf("Error encountered during rescan: %v", err)
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case <-c.quit:
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return
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}
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}
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}
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// FilterBlock takes a block hash, and returns a FilteredBlocks which is the
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// result of applying the current registered UTXO sub-set on the block
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// corresponding to that block hash. If any watched UTXO's are spent by the
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// selected lock, then the internal chainFilter will also be updated.
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//
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// NOTE: This is part of the FilteredChainView interface.
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func (c *CfFilteredChainView) FilterBlock(blockHash *chainhash.Hash) (*FilteredBlock, error) {
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// First, we'll fetch the block header itself so we can obtain the
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// height which is part of our return value.
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_, blockHeight, err := c.p2pNode.BlockHeaders.FetchHeader(blockHash)
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if err != nil {
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return nil, err
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}
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filteredBlock := &FilteredBlock{
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Hash: *blockHash,
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Height: blockHeight,
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}
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// If we don't have any items within our current chain filter, then we
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// can exit early as we don't need to fetch the filter.
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c.filterMtx.RLock()
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if len(c.chainFilter) == 0 {
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c.filterMtx.RUnlock()
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return filteredBlock, nil
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}
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c.filterMtx.RUnlock()
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// Next, using the block, hash, we'll fetch the compact filter for this
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// block. We only require the regular filter as we're just looking for
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// outpoint that have been spent.
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filter, err := c.p2pNode.GetCFilter(*blockHash, false)
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if err != nil {
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return nil, err
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}
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// Before we can match the filter, we'll need to map each item in our
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// chain filter to the representation that included in the compact
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// filters.
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c.filterMtx.RLock()
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relevantPoints := make([][]byte, 0, len(c.chainFilter))
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for op := range c.chainFilter {
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opBytes := builder.OutPointToFilterEntry(op)
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relevantPoints = append(relevantPoints, opBytes)
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}
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c.filterMtx.RUnlock()
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// With our relevant points constructed, we can finally match against
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// the retrieved filter.
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matched, err := filter.MatchAny(builder.DeriveKey(blockHash),
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relevantPoints)
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if err != nil {
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return nil, err
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}
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// If there wasn't a match, then we'll return the filtered block as is
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// (void of any transactions).
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if !matched {
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return filteredBlock, nil
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}
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// If we reach this point, then there was a match, so we'll need to
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// fetch the block itself so we can scan it for any actual matches (as
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// there's a fp rate).
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block, err := c.p2pNode.GetBlockFromNetwork(*blockHash)
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if err != nil {
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return nil, err
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}
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// Finally, we'll step through the block, input by input, to see if any
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// transactions spend any outputs from our watched sub-set of the UTXO
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// set.
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for _, tx := range block.Transactions() {
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for _, txIn := range tx.MsgTx().TxIn {
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prevOp := txIn.PreviousOutPoint
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c.filterMtx.RLock()
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_, ok := c.chainFilter[prevOp]
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c.filterMtx.RUnlock()
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if ok {
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filteredBlock.Transactions = append(
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filteredBlock.Transactions,
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tx.MsgTx(),
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)
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c.filterMtx.Lock()
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delete(c.chainFilter, prevOp)
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c.filterMtx.Unlock()
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break
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}
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}
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}
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return filteredBlock, nil
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}
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// UpdateFilter updates the UTXO filter which is to be consulted when creating
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// FilteredBlocks to be sent to subscribed clients. This method is cumulative
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// meaning repeated calls to this method should _expand_ the size of the UTXO
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// sub-set currently being watched. If the set updateHeight is _lower_ than
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// the best known height of the implementation, then the state should be
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// rewound to ensure all relevant notifications are dispatched.
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//
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// NOTE: This is part of the FilteredChainView interface.
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func (c *CfFilteredChainView) UpdateFilter(ops []wire.OutPoint,
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updateHeight uint32) error {
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log.Debugf("Updating chain filter with new UTXO's: %v", ops)
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// First, we'll update the current chain view, by
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// adding any new UTXO's, ignoring duplicates in the
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// process.
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c.filterMtx.Lock()
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for _, op := range ops {
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c.chainFilter[op] = struct{}{}
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}
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c.filterMtx.Unlock()
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// With our internal chain view update, we'll craft a
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// new update to the chainView which includes our new
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// UTXO's, and current update height.
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rescanUpdate := []neutrino.UpdateOption{
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neutrino.AddOutPoints(ops...),
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neutrino.Rewind(updateHeight),
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neutrino.DisableDisconnectedNtfns(true),
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}
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err := c.chainView.Update(rescanUpdate...)
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if err != nil {
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return fmt.Errorf("unable to update rescan: %v", err)
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}
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return nil
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}
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// FilteredBlocks returns the channel that filtered blocks are to be sent over.
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// Each time a block is connected to the end of a main chain, and appropriate
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// FilteredBlock which contains the transactions which mutate our watched UTXO
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// set is to be returned.
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//
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// NOTE: This is part of the FilteredChainView interface.
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func (c *CfFilteredChainView) FilteredBlocks() <-chan *FilteredBlock {
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return c.blockQueue.newBlocks
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}
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// DisconnectedBlocks returns a receive only channel which will be sent upon
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// with the empty filtered blocks of blocks which are disconnected from the
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// main chain in the case of a re-org.
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//
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// NOTE: This is part of the FilteredChainView interface.
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func (c *CfFilteredChainView) DisconnectedBlocks() <-chan *FilteredBlock {
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return c.blockQueue.staleBlocks
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}
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