226 lines
8.7 KiB
Python
226 lines
8.7 KiB
Python
import logging
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import asyncio
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import typing
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import signal
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from concurrent.futures.thread import ThreadPoolExecutor
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from prometheus_client import Gauge, Histogram
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from scribe import PROMETHEUS_NAMESPACE, __version__
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from scribe.common import HISTOGRAM_BUCKETS
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from scribe.db.prefixes import DBState
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from scribe.db import HubDB
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from scribe.reader.prometheus import PrometheusServer
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NAMESPACE = f"{PROMETHEUS_NAMESPACE}_reader"
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class BlockchainReaderInterface:
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async def poll_for_changes(self):
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"""
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Detect and handle if the db has advanced to a new block or unwound during a chain reorganization
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If a reorg is detected, this will first unwind() to the branching height and then advance() forward
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to the new block(s).
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"""
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raise NotImplementedError()
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def clear_caches(self):
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"""
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Called after finished advancing, used for invalidating caches
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"""
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pass
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def advance(self, height: int):
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"""
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Called when advancing to the given block height
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Callbacks that look up new values from the added block can be put here
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"""
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raise NotImplementedError()
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def unwind(self):
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"""
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Go backwards one block
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"""
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raise NotImplementedError()
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class BaseBlockchainReader(BlockchainReaderInterface):
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block_count_metric = Gauge(
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"block_count", "Number of processed blocks", namespace=NAMESPACE
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)
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block_update_time_metric = Histogram(
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"block_time", "Block update times", namespace=NAMESPACE, buckets=HISTOGRAM_BUCKETS
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)
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reorg_count_metric = Gauge(
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"reorg_count", "Number of reorgs", namespace=NAMESPACE
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)
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def __init__(self, env, secondary_name: str, thread_workers: int = 1, thread_prefix: str = 'blockchain-reader'):
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self.env = env
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self.log = logging.getLogger(__name__).getChild(self.__class__.__name__)
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self.shutdown_event = asyncio.Event()
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self.cancellable_tasks = []
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self._thread_workers = thread_workers
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self._thread_prefix = thread_prefix
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self._executor = ThreadPoolExecutor(thread_workers, thread_name_prefix=thread_prefix)
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self.db = HubDB(
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env.coin, env.db_dir, env.cache_MB, env.reorg_limit, env.cache_all_claim_txos, env.cache_all_tx_hashes,
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secondary_name=secondary_name, max_open_files=-1, blocking_channel_ids=env.blocking_channel_ids,
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filtering_channel_ids=env.filtering_channel_ids, executor=self._executor
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)
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self.last_state: typing.Optional[DBState] = None
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self._refresh_interval = 0.1
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self._lock = asyncio.Lock()
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self.prometheus_server: typing.Optional[PrometheusServer] = None
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def _detect_changes(self):
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try:
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self.db.prefix_db.try_catch_up_with_primary()
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except:
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self.log.exception('failed to update secondary db')
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raise
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state = self.db.prefix_db.db_state.get()
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if not state or state.height <= 0:
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return
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if self.last_state and self.last_state.height > state.height:
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self.log.warning("reorg detected, waiting until the writer has flushed the new blocks to advance")
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return
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last_height = 0 if not self.last_state else self.last_state.height
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rewound = False
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if self.last_state:
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while True:
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if self.db.headers[-1] == self.db.prefix_db.header.get(last_height, deserialize_value=False):
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self.log.debug("connects to block %i", last_height)
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break
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else:
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self.log.warning("disconnect block %i", last_height)
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self.unwind()
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rewound = True
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last_height -= 1
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if rewound:
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self.reorg_count_metric.inc()
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self.db.read_db_state()
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if not self.last_state or last_height < state.height:
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for height in range(last_height + 1, state.height + 1):
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self.log.info("advancing to %i", height)
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self.advance(height)
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self.clear_caches()
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self.last_state = state
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self.block_count_metric.set(self.last_state.height)
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self.db.blocked_streams, self.db.blocked_channels = self.db.get_streams_and_channels_reposted_by_channel_hashes(
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self.db.blocking_channel_hashes
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)
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self.db.filtered_streams, self.db.filtered_channels = self.db.get_streams_and_channels_reposted_by_channel_hashes(
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self.db.filtering_channel_hashes
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)
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async def poll_for_changes(self):
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"""
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Detect and handle if the db has advanced to a new block or unwound during a chain reorganization
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If a reorg is detected, this will first unwind() to the branching height and then advance() forward
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to the new block(s).
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"""
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await asyncio.get_event_loop().run_in_executor(self._executor, self._detect_changes)
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async def refresh_blocks_forever(self, synchronized: asyncio.Event):
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while True:
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try:
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async with self._lock:
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await self.poll_for_changes()
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except asyncio.CancelledError:
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raise
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except:
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self.log.exception("blockchain reader main loop encountered an unexpected error")
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raise
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await asyncio.sleep(self._refresh_interval)
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synchronized.set()
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def advance(self, height: int):
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tx_count = self.db.prefix_db.tx_count.get(height).tx_count
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assert tx_count not in self.db.tx_counts, f'boom {tx_count} in {len(self.db.tx_counts)} tx counts'
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assert len(self.db.tx_counts) == height, f"{len(self.db.tx_counts)} != {height}"
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self.db.tx_counts.append(tx_count)
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self.db.headers.append(self.db.prefix_db.header.get(height, deserialize_value=False))
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def unwind(self):
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self.db.tx_counts.pop()
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self.db.headers.pop()
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def _start_cancellable(self, run, *args):
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_flag = asyncio.Event()
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self.cancellable_tasks.append(asyncio.ensure_future(run(*args, _flag)))
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return _flag.wait()
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def _iter_start_tasks(self):
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yield self._start_cancellable(self.refresh_blocks_forever)
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def _iter_stop_tasks(self):
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yield self._stop_cancellable_tasks()
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async def _stop_cancellable_tasks(self):
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async with self._lock:
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while self.cancellable_tasks:
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t = self.cancellable_tasks.pop()
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if not t.done():
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t.cancel()
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async def start(self):
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if not self._executor:
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self._executor = ThreadPoolExecutor(self._thread_workers, thread_name_prefix=self._thread_prefix)
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self.db._executor = self._executor
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env = self.env
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# min_str, max_str = env.coin.SESSIONCLS.protocol_min_max_strings()
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self.log.info(f'software version: {__version__}')
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# self.log.info(f'supported protocol versions: {min_str}-{max_str}')
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self.log.info(f'event loop policy: {env.loop_policy}')
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self.log.info(f'reorg limit is {env.reorg_limit:,d} blocks')
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self.db.open_db()
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self.log.info(f'initializing caches')
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await self.db.initialize_caches()
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self.last_state = self.db.read_db_state()
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self.log.info(f'opened db at block {self.last_state.height}')
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self.block_count_metric.set(self.last_state.height)
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await self.start_prometheus()
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for start_task in self._iter_start_tasks():
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await start_task
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self.log.info("finished starting")
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async def stop(self):
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for stop_task in self._iter_stop_tasks():
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await stop_task
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await self.stop_prometheus()
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self.db.close()
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self._executor.shutdown(wait=True)
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self._executor = None
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self.shutdown_event.set()
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async def start_prometheus(self):
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if not self.prometheus_server and self.env.prometheus_port:
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self.prometheus_server = PrometheusServer()
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await self.prometheus_server.start("0.0.0.0", self.env.prometheus_port)
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async def stop_prometheus(self):
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if self.prometheus_server:
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await self.prometheus_server.stop()
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self.prometheus_server = None
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def run(self):
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loop = asyncio.get_event_loop()
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loop.set_default_executor(self._executor)
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def __exit():
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raise SystemExit()
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try:
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loop.add_signal_handler(signal.SIGINT, __exit)
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loop.add_signal_handler(signal.SIGTERM, __exit)
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loop.run_until_complete(self.start())
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loop.run_until_complete(self.shutdown_event.wait())
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except (SystemExit, KeyboardInterrupt):
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pass
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finally:
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loop.run_until_complete(self.stop())
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