Neil Booth
8 years ago
3 changed files with 151 additions and 123 deletions
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# Copyright (c) 2016, Neil Booth |
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# |
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# All rights reserved. |
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# |
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# See the file "LICENCE" for information about the copyright |
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# and warranty status of this software. |
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'''Interface to the blockchain database.''' |
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import array |
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import ast |
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import struct |
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from collections import namedtuple |
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from server.cache import FSCache, UTXOCache, NO_CACHE_ENTRY |
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from lib.util import LoggedClass |
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from server.storage import open_db |
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UTXO = namedtuple("UTXO", "tx_num tx_pos tx_hash height value") |
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class DB(LoggedClass): |
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'''Simple wrapper of the backend database for querying. |
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Performs no DB update, though the DB will be cleaned on opening if |
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it was shutdown uncleanly. |
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''' |
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def __init__(self, coin, db_engine): |
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super().__init__() |
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self.coin = coin |
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# Open DB and metadata files. Record some of its state. |
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db_name = '{}-{}'.format(coin.NAME, coin.NET) |
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self.db = open_db(db_name, db_engine) |
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if self.db.is_new: |
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self.logger.info('created new {} database {}' |
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.format(db_engine, db_name)) |
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else: |
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self.logger.info('successfully opened {} database {}' |
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.format(db_engine, db_name)) |
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self.init_state_from_db() |
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self.tx_count = self.db_tx_count |
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self.height = self.db_height |
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self.tip = self.db_tip |
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# Cache wrapping the filesystem and redirected functions |
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self.fs_cache = FSCache(self.coin, self.height, self.tx_count) |
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self.get_tx_hash = self.fs_cache.get_tx_hash |
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self.read_headers = self.fs_cache.read_headers |
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# UTXO cache |
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self.utxo_cache = UTXOCache(self.get_tx_hash, self.db, self.coin) |
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def init_state_from_db(self): |
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if self.db.is_new: |
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self.db_height = -1 |
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self.db_tx_count = 0 |
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self.db_tip = b'\0' * 32 |
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self.flush_count = 0 |
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self.utxo_flush_count = 0 |
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self.wall_time = 0 |
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self.first_sync = True |
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else: |
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state = self.db.get(b'state') |
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state = ast.literal_eval(state.decode()) |
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if state['genesis'] != self.coin.GENESIS_HASH: |
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raise ChainError('DB genesis hash {} does not match coin {}' |
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.format(state['genesis_hash'], |
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self.coin.GENESIS_HASH)) |
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self.db_height = state['height'] |
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self.db_tx_count = state['tx_count'] |
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self.db_tip = state['tip'] |
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self.flush_count = state['flush_count'] |
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self.utxo_flush_count = state['utxo_flush_count'] |
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self.wall_time = state['wall_time'] |
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self.first_sync = state.get('first_sync', True) |
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@staticmethod |
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def _resolve_limit(limit): |
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if limit is None: |
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return -1 |
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assert isinstance(limit, int) and limit >= 0 |
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return limit |
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def get_history(self, hash168, limit=1000): |
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'''Generator that returns an unpruned, sorted list of (tx_hash, |
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height) tuples of confirmed transactions that touched the address, |
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earliest in the blockchain first. Includes both spending and |
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receiving transactions. By default yields at most 1000 entries. |
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Set limit to None to get them all. |
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''' |
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limit = self._resolve_limit(limit) |
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prefix = b'H' + hash168 |
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for key, hist in self.db.iterator(prefix=prefix): |
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a = array.array('I') |
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a.frombytes(hist) |
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for tx_num in a: |
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if limit == 0: |
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return |
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yield self.get_tx_hash(tx_num) |
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limit -= 1 |
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def get_balance(self, hash168): |
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'''Returns the confirmed balance of an address.''' |
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return sum(utxo.value for utxo in self.get_utxos(hash168, limit=None)) |
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def get_utxos(self, hash168, limit=1000): |
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'''Generator that yields all UTXOs for an address sorted in no |
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particular order. By default yields at most 1000 entries. |
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Set limit to None to get them all. |
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''' |
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limit = self._resolve_limit(limit) |
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unpack = struct.unpack |
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prefix = b'u' + hash168 |
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for k, v in self.db.iterator(prefix=prefix): |
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(tx_pos,) = unpack('<H', k[-2:]) |
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for n in range(0, len(v), 12): |
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if limit == 0: |
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return |
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(tx_num,) = unpack('<I', v[n:n + 4]) |
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(value,) = unpack('<Q', v[n + 4:n + 12]) |
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tx_hash, height = self.get_tx_hash(tx_num) |
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yield UTXO(tx_num, tx_pos, tx_hash, height, value) |
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limit -= 1 |
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def get_utxos_sorted(self, hash168): |
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'''Returns all the UTXOs for an address sorted by height and |
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position in the block.''' |
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return sorted(self.get_utxos(hash168, limit=None)) |
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def get_utxo_hash168(self, tx_hash, index): |
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'''Returns the hash168 for a UTXO.''' |
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hash168 = None |
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if 0 <= index <= 65535: |
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idx_packed = struct.pack('<H', index) |
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hash168 = self.utxo_cache.hash168(tx_hash, idx_packed, False) |
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if hash168 == NO_CACHE_ENTRY: |
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hash168 = None |
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return hash168 |
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