# Copyright (c) 2016-2017, Neil Booth
#
# All rights reserved.
#
# See the file "LICENCE" for information about the copyright
# and warranty status of this software.
'''Class for handling asynchronous connections to a blockchain
daemon.'''
import asyncio
import json
import time
import traceback
import aiohttp
import lib.util as util
class DaemonError(Exception):
'''Raised when the daemon returns an error in its results.'''
class Daemon(util.LoggedClass):
'''Handles connections to a daemon at the given URL.'''
WARMING_UP = -28
class DaemonWarmingUpError(Exception):
'''Raised when the daemon returns an error in its results.'''
def __init__(self, urls):
super().__init__()
self.set_urls(urls)
self._height = None
self._mempool_hashes = set()
self.mempool_refresh_event = asyncio.Event()
# Limit concurrent RPC calls to this number.
# See DEFAULT_HTTP_WORKQUEUE in bitcoind, which is typically 16
self.workqueue_semaphore = asyncio.Semaphore(value=10)
self.down = False
self.last_error_time = 0
def set_urls(self, urls):
'''Set the URLS to the given list, and switch to the first one.'''
if not urls:
raise DaemonError('no daemon URLs provided')
self.urls = urls
self.url_index = 0
for n, url in enumerate(urls):
self.logger.info('daemon #{:d} at {}{}'
.format(n + 1, self.logged_url(url),
'' if n else ' (current)'))
def url(self):
'''Returns the current daemon URL.'''
return self.urls[self.url_index]
def failover(self):
'''Call to fail-over to the next daemon URL.
Returns False if there is only one, otherwise True.
'''
if len(self.urls) > 1:
self.url_index = (self.url_index + 1) % len(self.urls)
self.logger.info('failing over to {}'.format(self.logged_url()))
return True
return False
async def _send_data(self, data):
async with self.workqueue_semaphore:
async with aiohttp.ClientSession() as session:
async with session.post(self.url(), data=data) as resp:
# If bitcoind can't find a tx, for some reason
# it returns 500 but fills out the JSON.
# Should still return 200 IMO.
if resp.status in (200, 500):
return await resp.json()
return (resp.status, resp.reason)
async def _send(self, payload, processor):
'''Send a payload to be converted to JSON.
Handles temporary connection issues. Daemon reponse errors
are raise through DaemonError.
'''
def log_error(error):
self.down = True
now = time.time()
prior_time = self.last_error_time
if now - prior_time > 60:
self.last_error_time = now
if prior_time and self.failover():
secs = 0
else:
self.logger.error('{} Retrying occasionally...'
.format(error))
data = json.dumps(payload)
secs = 1
max_secs = 4
while True:
try:
result = await self._send_data(data)
if not isinstance(result, tuple):
result = processor(result)
if self.down:
self.down = False
self.last_error_time = 0
self.logger.info('connection restored')
return result
log_error('HTTP error code {:d}: {}'
.format(result[0], result[1]))
except asyncio.TimeoutError:
log_error('timeout error.')
except aiohttp.ClientHttpProcessingError:
log_error('HTTP error.')
except aiohttp.ServerDisconnectedError:
log_error('disconnected.')
except aiohttp.ClientConnectionError:
log_error('connection problem - is your daemon running?')
except self.DaemonWarmingUpError:
log_error('starting up checking blocks.')
except (asyncio.CancelledError, DaemonError):
raise
except Exception:
self.log_error(traceback.format_exc())
await asyncio.sleep(secs)
secs = min(max_secs, secs * 2, 1)
def logged_url(self, url=None):
'''The host and port part, for logging.'''
url = url or self.url()
return url[url.rindex('@') + 1:]
async def _send_single(self, method, params=None):
'''Send a single request to the daemon.'''
def processor(result):
err = result['error']
if not err:
return result['result']
if err.get('code') == self.WARMING_UP:
raise self.DaemonWarmingUpError
raise DaemonError(err)
payload = {'method': method}
if params:
payload['params'] = params
return await self._send(payload, processor)
async def _send_vector(self, method, params_iterable, replace_errs=False):
'''Send several requests of the same method.
The result will be an array of the same length as params_iterable.
If replace_errs is true, any item with an error is returned as None,
otherwise an exception is raised.'''
def processor(result):
errs = [item['error'] for item in result if item['error']]
if any(err.get('code') == self.WARMING_UP for err in errs):
raise self.DaemonWarmingUpError
if not errs or replace_errs:
return [item['result'] for item in result]
raise DaemonError(errs)
payload = [{'method': method, 'params': p} for p in params_iterable]
if payload:
return await self._send(payload, processor)
return []
async def block_hex_hashes(self, first, count):
'''Return the hex hashes of count block starting at height first.'''
params_iterable = ((h, ) for h in range(first, first + count))
return await self._send_vector('getblockhash', params_iterable)
async def deserialised_block(self, hex_hash):
'''Return the deserialised block with the given hex hash.'''
return await self._send_single('getblock', (hex_hash, True))
async def raw_blocks(self, hex_hashes):
'''Return the raw binary blocks with the given hex hashes.'''
params_iterable = ((h, False) for h in hex_hashes)
blocks = await self._send_vector('getblock', params_iterable)
# Convert hex string to bytes
return [bytes.fromhex(block) for block in blocks]
async def mempool_hashes(self):
'''Update our record of the daemon's mempool hashes.'''
return await self._send_single('getrawmempool')
async def estimatefee(self, params):
'''Return the fee estimate for the given parameters.'''
return await self._send_single('estimatefee', params)
async def getnetworkinfo(self):
'''Return the result of the 'getnetworkinfo' RPC call.'''
return await self._send_single('getnetworkinfo')
async def relayfee(self):
'''The minimum fee a low-priority tx must pay in order to be accepted
to the daemon's memory pool.'''
network_info = await self.getnetworkinfo()
return network_info['relayfee']
async def getrawtransaction(self, hex_hash):
'''Return the serialized raw transaction with the given hash.'''
return await self._send_single('getrawtransaction', (hex_hash, 0))
async def getrawtransactions(self, hex_hashes, replace_errs=True):
'''Return the serialized raw transactions with the given hashes.
Replaces errors with None by default.'''
params_iterable = ((hex_hash, 0) for hex_hash in hex_hashes)
txs = await self._send_vector('getrawtransaction', params_iterable,
replace_errs=replace_errs)
# Convert hex strings to bytes
return [bytes.fromhex(tx) if tx else None for tx in txs]
async def sendrawtransaction(self, params):
'''Broadcast a transaction to the network.'''
return await self._send_single('sendrawtransaction', params)
async def height(self, mempool=False):
'''Query the daemon for its current height.'''
self._height = await self._send_single('getblockcount')
if mempool:
self._mempool_hashes = set(await self.mempool_hashes())
self.mempool_refresh_event.set()
return self._height
def cached_mempool_hashes(self):
'''Return the cached mempool hashes.'''
return self._mempool_hashes
def cached_height(self):
'''Return the cached daemon height.
If the daemon has not been queried yet this returns None.'''
return self._height