import time import asyncio from struct import pack, unpack from concurrent.futures.thread import ThreadPoolExecutor from typing import Optional import lbry from lbry.schema.claim import Claim from lbry.wallet.server.db.writer import SQLDB from lbry.wallet.server.daemon import DaemonError from lbry.wallet.server.hash import hash_to_hex_str, HASHX_LEN from lbry.wallet.server.util import chunks, class_logger from lbry.wallet.server.leveldb import FlushData from lbry.wallet.server.prometheus import BLOCK_COUNT, BLOCK_UPDATE_TIMES, REORG_COUNT class Prefetcher: """Prefetches blocks (in the forward direction only).""" def __init__(self, daemon, coin, blocks_event): self.logger = class_logger(__name__, self.__class__.__name__) self.daemon = daemon self.coin = coin self.blocks_event = blocks_event self.blocks = [] self.caught_up = False # Access to fetched_height should be protected by the semaphore self.fetched_height = None self.semaphore = asyncio.Semaphore() self.refill_event = asyncio.Event() # The prefetched block cache size. The min cache size has # little effect on sync time. self.cache_size = 0 self.min_cache_size = 10 * 1024 * 1024 # This makes the first fetch be 10 blocks self.ave_size = self.min_cache_size // 10 self.polling_delay = 5 async def main_loop(self, bp_height): """Loop forever polling for more blocks.""" await self.reset_height(bp_height) while True: try: # Sleep a while if there is nothing to prefetch await self.refill_event.wait() if not await self._prefetch_blocks(): await asyncio.sleep(self.polling_delay) except DaemonError as e: self.logger.info(f'ignoring daemon error: {e}') def get_prefetched_blocks(self): """Called by block processor when it is processing queued blocks.""" blocks = self.blocks self.blocks = [] self.cache_size = 0 self.refill_event.set() return blocks async def reset_height(self, height): """Reset to prefetch blocks from the block processor's height. Used in blockchain reorganisations. This coroutine can be called asynchronously to the _prefetch_blocks coroutine so we must synchronize with a semaphore. """ async with self.semaphore: self.blocks.clear() self.cache_size = 0 self.fetched_height = height self.refill_event.set() daemon_height = await self.daemon.height() behind = daemon_height - height if behind > 0: self.logger.info(f'catching up to daemon height {daemon_height:,d} ' f'({behind:,d} blocks behind)') else: self.logger.info(f'caught up to daemon height {daemon_height:,d}') async def _prefetch_blocks(self): """Prefetch some blocks and put them on the queue. Repeats until the queue is full or caught up. """ daemon = self.daemon daemon_height = await daemon.height() async with self.semaphore: while self.cache_size < self.min_cache_size: # Try and catch up all blocks but limit to room in cache. # Constrain fetch count to between 0 and 500 regardless; # testnet can be lumpy. cache_room = self.min_cache_size // self.ave_size count = min(daemon_height - self.fetched_height, cache_room) count = min(500, max(count, 0)) if not count: self.caught_up = True return False first = self.fetched_height + 1 hex_hashes = await daemon.block_hex_hashes(first, count) if self.caught_up: self.logger.info('new block height {:,d} hash {}' .format(first + count-1, hex_hashes[-1])) blocks = await daemon.raw_blocks(hex_hashes) assert count == len(blocks) # Special handling for genesis block if first == 0: blocks[0] = self.coin.genesis_block(blocks[0]) self.logger.info(f'verified genesis block with hash {hex_hashes[0]}') # Update our recent average block size estimate size = sum(len(block) for block in blocks) if count >= 10: self.ave_size = size // count else: self.ave_size = (size + (10 - count) * self.ave_size) // 10 self.blocks.extend(blocks) self.cache_size += size self.fetched_height += count self.blocks_event.set() self.refill_event.clear() return True class ChainError(Exception): """Raised on error processing blocks.""" class BlockProcessor: """Process blocks and update the DB state to match. Employ a prefetcher to prefetch blocks in batches for processing. Coordinate backing up in case of chain reorganisations. """ def __init__(self, env, db, daemon, notifications): self.env = env self.db = db self.daemon = daemon self.notifications = notifications self.coin = env.coin self.blocks_event = asyncio.Event() self.prefetcher = Prefetcher(daemon, env.coin, self.blocks_event) self.logger = class_logger(__name__, self.__class__.__name__) self.executor = ThreadPoolExecutor(1) # Meta self.next_cache_check = 0 self.touched = set() self.reorg_count = 0 # Caches of unflushed items. self.headers = [] self.tx_hashes = [] self.undo_infos = [] # UTXO cache self.utxo_cache = {} self.db_deletes = [] # If the lock is successfully acquired, in-memory chain state # is consistent with self.height self.state_lock = asyncio.Lock() self.search_cache = {} async def run_in_thread_with_lock(self, func, *args): # Run in a thread to prevent blocking. Shielded so that # cancellations from shutdown don't lose work - when the task # completes the data will be flushed and then we shut down. # Take the state lock to be certain in-memory state is # consistent and not being updated elsewhere. async def run_in_thread_locked(): async with self.state_lock: return await asyncio.get_event_loop().run_in_executor(self.executor, func, *args) return await asyncio.shield(run_in_thread_locked()) async def check_and_advance_blocks(self, raw_blocks): """Process the list of raw blocks passed. Detects and handles reorgs. """ if not raw_blocks: return first = self.height + 1 blocks = [self.coin.block(raw_block, first + n) for n, raw_block in enumerate(raw_blocks)] headers = [block.header for block in blocks] hprevs = [self.coin.header_prevhash(h) for h in headers] chain = [self.tip] + [self.coin.header_hash(h) for h in headers[:-1]] if hprevs == chain: start = time.perf_counter() await self.run_in_thread_with_lock(self.advance_blocks, blocks) for cache in self.search_cache.values(): cache.clear() await self._maybe_flush() processed_time = time.perf_counter() - start BLOCK_COUNT.set(self.height) BLOCK_UPDATE_TIMES.observe(processed_time) if not self.db.first_sync: s = '' if len(blocks) == 1 else 's' self.logger.info('processed {:,d} block{} in {:.1f}s'.format(len(blocks), s, processed_time)) if self._caught_up_event.is_set(): await self.notifications.on_block(self.touched, self.height) self.touched = set() elif hprevs[0] != chain[0]: await self.reorg_chain() else: # It is probably possible but extremely rare that what # bitcoind returns doesn't form a chain because it # reorg-ed the chain as it was processing the batched # block hash requests. Should this happen it's simplest # just to reset the prefetcher and try again. self.logger.warning('daemon blocks do not form a chain; ' 'resetting the prefetcher') await self.prefetcher.reset_height(self.height) async def reorg_chain(self, count: Optional[int] = None): """Handle a chain reorganisation. Count is the number of blocks to simulate a reorg, or None for a real reorg.""" if count is None: self.logger.info('chain reorg detected') else: self.logger.info(f'faking a reorg of {count:,d} blocks') await self.flush(True) async def get_raw_blocks(last_height, hex_hashes): heights = range(last_height, last_height - len(hex_hashes), -1) try: blocks = [self.db.read_raw_block(height) for height in heights] self.logger.info(f'read {len(blocks)} blocks from disk') return blocks except FileNotFoundError: return await self.daemon.raw_blocks(hex_hashes) def flush_backup(): # self.touched can include other addresses which is # harmless, but remove None. self.touched.discard(None) self.db.flush_backup(self.flush_data(), self.touched) start, last, hashes = await self.reorg_hashes(count) # Reverse and convert to hex strings. hashes = [hash_to_hex_str(hash) for hash in reversed(hashes)] for hex_hashes in chunks(hashes, 50): raw_blocks = await get_raw_blocks(last, hex_hashes) await self.run_in_thread_with_lock(self.backup_blocks, raw_blocks) await self.run_in_thread_with_lock(flush_backup) last -= len(raw_blocks) await self.run_in_thread_with_lock(self.db.sql.delete_claims_above_height, self.height) await self.prefetcher.reset_height(self.height) REORG_COUNT.inc() async def reorg_hashes(self, count): """Return a pair (start, last, hashes) of blocks to back up during a reorg. The hashes are returned in order of increasing height. Start is the height of the first hash, last of the last. """ start, count = await self.calc_reorg_range(count) last = start + count - 1 s = '' if count == 1 else 's' self.logger.info(f'chain was reorganised replacing {count:,d} ' f'block{s} at heights {start:,d}-{last:,d}') return start, last, await self.db.fs_block_hashes(start, count) async def calc_reorg_range(self, count: Optional[int]): """Calculate the reorg range""" def diff_pos(hashes1, hashes2): """Returns the index of the first difference in the hash lists. If both lists match returns their length.""" for n, (hash1, hash2) in enumerate(zip(hashes1, hashes2)): if hash1 != hash2: return n return len(hashes) if count is None: # A real reorg start = self.height - 1 count = 1 while start > 0: hashes = await self.db.fs_block_hashes(start, count) hex_hashes = [hash_to_hex_str(hash) for hash in hashes] d_hex_hashes = await self.daemon.block_hex_hashes(start, count) n = diff_pos(hex_hashes, d_hex_hashes) if n > 0: start += n break count = min(count * 2, start) start -= count count = (self.height - start) + 1 else: start = (self.height - count) + 1 return start, count def estimate_txs_remaining(self): # Try to estimate how many txs there are to go daemon_height = self.daemon.cached_height() coin = self.coin tail_count = daemon_height - max(self.height, coin.TX_COUNT_HEIGHT) # Damp the initial enthusiasm realism = max(2.0 - 0.9 * self.height / coin.TX_COUNT_HEIGHT, 1.0) return (tail_count * coin.TX_PER_BLOCK + max(coin.TX_COUNT - self.tx_count, 0)) * realism # - Flushing def flush_data(self): """The data for a flush. The lock must be taken.""" assert self.state_lock.locked() return FlushData(self.height, self.tx_count, self.headers, self.tx_hashes, self.undo_infos, self.utxo_cache, self.db_deletes, self.tip) async def flush(self, flush_utxos): def flush(): self.db.flush_dbs(self.flush_data(), flush_utxos, self.estimate_txs_remaining) await self.run_in_thread_with_lock(flush) async def _maybe_flush(self): # If caught up, flush everything as client queries are # performed on the DB. if self._caught_up_event.is_set(): await self.flush(True) elif time.time() > self.next_cache_check: flush_arg = self.check_cache_size() if flush_arg is not None: await self.flush(flush_arg) self.next_cache_check = time.time() + 30 def check_cache_size(self): """Flush a cache if it gets too big.""" # Good average estimates based on traversal of subobjects and # requesting size from Python (see deep_getsizeof). one_MB = 1000*1000 utxo_cache_size = len(self.utxo_cache) * 205 db_deletes_size = len(self.db_deletes) * 57 hist_cache_size = self.db.history.unflushed_memsize() # Roughly ntxs * 32 + nblocks * 42 tx_hash_size = ((self.tx_count - self.db.fs_tx_count) * 32 + (self.height - self.db.fs_height) * 42) utxo_MB = (db_deletes_size + utxo_cache_size) // one_MB hist_MB = (hist_cache_size + tx_hash_size) // one_MB self.logger.info('our height: {:,d} daemon: {:,d} ' 'UTXOs {:,d}MB hist {:,d}MB' .format(self.height, self.daemon.cached_height(), utxo_MB, hist_MB)) # Flush history if it takes up over 20% of cache memory. # Flush UTXOs once they take up 80% of cache memory. cache_MB = self.env.cache_MB if utxo_MB + hist_MB >= cache_MB or hist_MB >= cache_MB // 5: return utxo_MB >= cache_MB * 4 // 5 return None def advance_blocks(self, blocks): """Synchronously advance the blocks. It is already verified they correctly connect onto our tip. """ min_height = self.db.min_undo_height(self.daemon.cached_height()) height = self.height for block in blocks: height += 1 undo_info = self.advance_txs( height, block.transactions, self.coin.electrum_header(block.header, height) ) if height >= min_height: self.undo_infos.append((undo_info, height)) self.db.write_raw_block(block.raw, height) headers = [block.header for block in blocks] self.height = height self.headers.extend(headers) self.tip = self.coin.header_hash(headers[-1]) def advance_txs(self, height, txs, header): self.tx_hashes.append(b''.join(tx_hash for tx, tx_hash in txs)) # Use local vars for speed in the loops undo_info = [] tx_num = self.tx_count script_hashX = self.coin.hashX_from_script s_pack = pack put_utxo = self.utxo_cache.__setitem__ spend_utxo = self.spend_utxo undo_info_append = undo_info.append update_touched = self.touched.update hashXs_by_tx = [] append_hashXs = hashXs_by_tx.append for tx, tx_hash in txs: hashXs = [] append_hashX = hashXs.append tx_numb = s_pack('= len(raw_blocks) coin = self.coin for raw_block in raw_blocks: # Check and update self.tip block = coin.block(raw_block, self.height) header_hash = coin.header_hash(block.header) if header_hash != self.tip: raise ChainError('backup block {} not tip {} at height {:,d}' .format(hash_to_hex_str(header_hash), hash_to_hex_str(self.tip), self.height)) self.tip = coin.header_prevhash(block.header) self.backup_txs(block.transactions) self.height -= 1 self.db.tx_counts.pop() self.logger.info(f'backed up to height {self.height:,d}') def backup_txs(self, txs): # Prevout values, in order down the block (coinbase first if present) # undo_info is in reverse block order undo_info = self.db.read_undo_info(self.height) if undo_info is None: raise ChainError(f'no undo information found for height {self.height:,d}') n = len(undo_info) # Use local vars for speed in the loops s_pack = pack put_utxo = self.utxo_cache.__setitem__ spend_utxo = self.spend_utxo script_hashX = self.coin.hashX_from_script touched = self.touched undo_entry_len = 12 + HASHX_LEN for tx, tx_hash in reversed(txs): for idx, txout in enumerate(tx.outputs): # Spend the TX outputs. Be careful with unspendable # outputs - we didn't save those in the first place. hashX = script_hashX(txout.pk_script) if hashX: cache_value = spend_utxo(tx_hash, idx) touched.add(cache_value[:-12]) # Restore the inputs for txin in reversed(tx.inputs): if txin.is_generation(): continue n -= undo_entry_len undo_item = undo_info[n:n + undo_entry_len] put_utxo(txin.prev_hash + s_pack(' 1: tx_num, = unpack('False state. first_sync = self.db.first_sync self.db.first_sync = False await self.flush(True) if first_sync: self.logger.info(f'{lbry.__version__} synced to ' f'height {self.height:,d}') # Reopen for serving await self.db.open_for_serving() async def _first_open_dbs(self): await self.db.open_for_sync() self.height = self.db.db_height self.tip = self.db.db_tip self.tx_count = self.db.db_tx_count # --- External API async def fetch_and_process_blocks(self, caught_up_event): """Fetch, process and index blocks from the daemon. Sets caught_up_event when first caught up. Flushes to disk and shuts down cleanly if cancelled. This is mainly because if, during initial sync ElectrumX is asked to shut down when a large number of blocks have been processed but not written to disk, it should write those to disk before exiting, as otherwise a significant amount of work could be lost. """ self._caught_up_event = caught_up_event try: await self._first_open_dbs() await asyncio.wait([ self.prefetcher.main_loop(self.height), self._process_prefetched_blocks() ]) except asyncio.CancelledError: raise except: self.logger.exception("Block processing failed!") raise finally: # Shut down block processing self.logger.info('flushing to DB for a clean shutdown...') await self.flush(True) self.db.close() self.executor.shutdown(wait=True) def force_chain_reorg(self, count): """Force a reorg of the given number of blocks. Returns True if a reorg is queued, false if not caught up. """ if self._caught_up_event.is_set(): self.reorg_count = count self.blocks_event.set() return True return False class Timer: def __init__(self, name): self.name = name self.total = 0 self.count = 0 self.sub_timers = {} self._last_start = None def add_timer(self, name): if name not in self.sub_timers: self.sub_timers[name] = Timer(name) return self.sub_timers[name] def run(self, func, *args, forward_timer=False, timer_name=None, **kwargs): t = self.add_timer(timer_name or func.__name__) t.start() try: if forward_timer: return func(*args, **kwargs, timer=t) else: return func(*args, **kwargs) finally: t.stop() def start(self): self._last_start = time.time() return self def stop(self): self.total += (time.time() - self._last_start) self.count += 1 self._last_start = None return self def show(self, depth=0, height=None): if depth == 0: print('='*100) if height is not None: print(f'STATISTICS AT HEIGHT {height}') print('='*100) else: print( f"{' '*depth} {self.total/60:4.2f}mins {self.name}" # f"{self.total/self.count:.5f}sec/call, " ) for sub_timer in self.sub_timers.values(): sub_timer.show(depth+1) if depth == 0: print('='*100) class LBRYBlockProcessor(BlockProcessor): def __init__(self, *args, **kwargs): super().__init__(*args, **kwargs) if self.env.coin.NET == "regtest": self.prefetcher.polling_delay = 0.5 self.should_validate_signatures = self.env.boolean('VALIDATE_CLAIM_SIGNATURES', False) self.logger.info(f"LbryumX Block Processor - Validating signatures: {self.should_validate_signatures}") self.sql: SQLDB = self.db.sql self.timer = Timer('BlockProcessor') def advance_blocks(self, blocks): self.sql.begin() try: self.timer.run(super().advance_blocks, blocks) except: self.logger.exception(f'Error while advancing transaction in new block.') raise finally: self.sql.commit() if self.db.first_sync and self.height == self.daemon.cached_height(): self.timer.run(self.sql.execute, self.sql.SEARCH_INDEXES, timer_name='executing SEARCH_INDEXES') if self.env.individual_tag_indexes: self.timer.run(self.sql.execute, self.sql.TAG_INDEXES, timer_name='executing TAG_INDEXES') def advance_txs(self, height, txs, header): timer = self.timer.sub_timers['advance_blocks'] undo = timer.run(super().advance_txs, height, txs, header, timer_name='super().advance_txs') timer.run(self.sql.advance_txs, height, txs, header, self.daemon.cached_height(), forward_timer=True) if (height % 10000 == 0 or not self.db.first_sync) and self.logger.isEnabledFor(10): self.timer.show(height=height) return undo def _checksig(self, value, address): try: claim_dict = Claim.from_bytes(value) cert_id = claim_dict.signing_channel_hash if not self.should_validate_signatures: return cert_id if cert_id: cert_claim = self.db.get_claim_info(cert_id) if cert_claim: certificate = Claim.from_bytes(cert_claim.value) claim_dict.validate_signature(address, certificate) return cert_id except Exception: pass