package chainview import ( "github.com/roasbeef/btcd/chaincfg/chainhash" "github.com/roasbeef/btcd/wire" ) // FilteredChainView represents a subscription to a certain subset of the // UTXO set for a particular chain. This interface is useful from the point of // view of maintaining an up-to-date channel graph for the Lightning Network. // The subset of the UTXO to be subscribed is that of all the currently opened // channels. Each time a channel is closed (the output is spent), a // notification is to be sent allowing the graph to be pruned. // // NOTE: As FilteredBlocks are generated, it is recommended that // implementations reclaim the space occupied by newly spent outputs. type FilteredChainView interface { // FilteredBlocks returns the channel that filtered blocks are to be // sent over. Each time a block is connected to the end of a main // chain, and appropriate FilteredBlock which contains the transactions // which mutate our watched UTXO set is to be returned. In case of a // UpdateFilter call with an updateHeight lower than the current best // height, blocks with the updated filter will be resent, and must be // handled by the receiver as an update to an already known block, NOT // as a new block being connected to the chain. FilteredBlocks() <-chan *FilteredBlock // DisconnectedBlocks returns a receive only channel which will be sent // upon with the empty filtered blocks of blocks which are disconnected // from the main chain in the case of a re-org. // NOTE: In case of a reorg, connected blocks will not be available to // read from the FilteredBlocks() channel before all disconnected block // have been received. DisconnectedBlocks() <-chan *FilteredBlock // UpdateFilter updates the UTXO filter which is to be consulted when // creating FilteredBlocks to be sent to subscribed clients. This // method is cumulative meaning repeated calls to this method should // _expand_ the size of the UTXO sub-set currently being watched. If // the set updateHeight is _lower_ than the best known height of the // implementation, then the state should be rewound to ensure all // relevant notifications are dispatched, meaning blocks with a height // lower than the best known height might be sent over the // FilteredBlocks() channel. UpdateFilter(ops []wire.OutPoint, updateHeight uint32) error // FilterBlock takes a block hash, and returns a FilteredBlocks which // is the result of applying the current registered UTXO sub-set on the // block corresponding to that block hash. // // TODO(roasbeef): make a version that does by height also? FilterBlock(blockHash *chainhash.Hash) (*FilteredBlock, error) // Start starts all goroutine necessary for the operation of the // FilteredChainView implementation. Start() error // Stop stops all goroutines which we launched by the prior call to the // Start method. Stop() error } // FilteredBlock is a block which includes the transactions that modify the // subscribed sub-set of the UTXO set registered to the current // FilteredChainView concrete implementation. type FilteredBlock struct { // Hash is the hash of the newly filtered block. Hash chainhash.Hash // Height is the height of the newly filtered block. Height uint32 // Transactions is the set of transactions which modify (spend) the // subscribed UTXO subset. Transactions []*wire.MsgTx }