hub/scribe/service.py

264 lines
10 KiB
Python

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