commit 9a7112009057bf40c40ed7644ec5a6e3619b6a8a
parent 199199421da0a47d187521cbded95a5985596193
Author: SomberNight <somber.night@protonmail.com>
Date: Tue, 26 Mar 2019 19:43:02 +0100
blockchain: fix bug when swapping chain with parent
chain might become the parent of some of its former siblings
Diffstat:
2 files changed, 66 insertions(+), 7 deletions(-)
diff --git a/electrum/blockchain.py b/electrum/blockchain.py
@@ -22,7 +22,7 @@
# SOFTWARE.
import os
import threading
-from typing import Optional, Dict
+from typing import Optional, Dict, Mapping, Sequence
from . import util
from .bitcoin import hash_encode, int_to_hex, rev_hex
@@ -187,8 +187,7 @@ class Blockchain(util.PrintError):
return constants.net.CHECKPOINTS
def get_max_child(self) -> Optional[int]:
- with blockchains_lock: chains = list(blockchains.values())
- children = list(filter(lambda y: y.parent==self, chains))
+ children = self.get_direct_children()
return max([x.forkpoint for x in children]) if children else None
def get_max_forkpoint(self) -> int:
@@ -198,6 +197,11 @@ class Blockchain(util.PrintError):
mc = self.get_max_child()
return mc if mc is not None else self.forkpoint
+ def get_direct_children(self) -> Sequence['Blockchain']:
+ with blockchains_lock:
+ return list(filter(lambda y: y.parent==self, blockchains.values()))
+
+
@with_lock
def get_branch_size(self) -> int:
return self.height() - self.get_max_forkpoint() + 1
@@ -318,14 +322,21 @@ class Blockchain(util.PrintError):
self.swap_with_parent()
def swap_with_parent(self) -> None:
- parent_lock = self.parent.lock if self.parent is not None else threading.Lock()
- with parent_lock, self.lock, blockchains_lock: # this order should not deadlock
+ with self.lock, blockchains_lock:
# do the swap; possibly multiple ones
cnt = 0
- while self._swap_with_parent():
+ while True:
+ old_parent = self.parent
+ if not self._swap_with_parent():
+ break
+ # make sure we are making progress
cnt += 1
- if cnt > len(blockchains): # make sure we are making progress
+ if cnt > len(blockchains):
raise Exception(f'swapping fork with parent too many times: {cnt}')
+ # we might have become the parent of some of our former siblings
+ for old_sibling in old_parent.get_direct_children():
+ if self.check_hash(old_sibling.forkpoint - 1, old_sibling._prev_hash):
+ old_sibling.parent = self
def _swap_with_parent(self) -> bool:
"""Check if this chain became stronger than its parent, and swap
@@ -350,6 +361,8 @@ class Blockchain(util.PrintError):
with open(self.path(), 'rb') as f:
my_data = f.read()
self.assert_headers_file_available(parent.path())
+ assert forkpoint > parent.forkpoint, (f"forkpoint of parent chain ({parent.forkpoint}) "
+ f"should be at lower height than children's ({forkpoint})")
with open(parent.path(), 'rb') as f:
f.seek((forkpoint - parent.forkpoint)*HEADER_SIZE)
parent_data = f.read(parent_branch_size*HEADER_SIZE)
diff --git a/electrum/tests/test_blockchain.py b/electrum/tests/test_blockchain.py
@@ -70,6 +70,52 @@ class TestBlockchain(SequentialTestCase):
self.assertTrue(chain.can_connect(header))
chain.save_header(header)
+ def test_parents_after_forking(self):
+ blockchain.blockchains[constants.net.GENESIS] = chain_u = Blockchain(
+ config=self.config, forkpoint=0, parent=None,
+ forkpoint_hash=constants.net.GENESIS, prev_hash=None)
+ open(chain_u.path(), 'w+').close()
+ self._append_header(chain_u, self.HEADERS['A'])
+ self._append_header(chain_u, self.HEADERS['B'])
+ self._append_header(chain_u, self.HEADERS['C'])
+ self._append_header(chain_u, self.HEADERS['D'])
+ self._append_header(chain_u, self.HEADERS['E'])
+ self._append_header(chain_u, self.HEADERS['F'])
+ self._append_header(chain_u, self.HEADERS['O'])
+ self._append_header(chain_u, self.HEADERS['P'])
+ self._append_header(chain_u, self.HEADERS['Q'])
+
+ self.assertEqual(None, chain_u.parent)
+
+ chain_l = chain_u.fork(self.HEADERS['G'])
+ self._append_header(chain_l, self.HEADERS['H'])
+ self._append_header(chain_l, self.HEADERS['I'])
+ self._append_header(chain_l, self.HEADERS['J'])
+ self._append_header(chain_l, self.HEADERS['K'])
+ self._append_header(chain_l, self.HEADERS['L'])
+
+ self.assertEqual(None, chain_l.parent)
+ self.assertEqual(chain_l, chain_u.parent)
+
+ chain_z = chain_l.fork(self.HEADERS['M'])
+ self._append_header(chain_z, self.HEADERS['N'])
+ self._append_header(chain_z, self.HEADERS['X'])
+ self._append_header(chain_z, self.HEADERS['Y'])
+ self._append_header(chain_z, self.HEADERS['Z'])
+
+ self.assertEqual(chain_z, chain_u.parent)
+ self.assertEqual(chain_z, chain_l.parent)
+ self.assertEqual(None, chain_z.parent)
+
+ self._append_header(chain_u, self.HEADERS['R'])
+ self._append_header(chain_u, self.HEADERS['S'])
+ self._append_header(chain_u, self.HEADERS['T'])
+ self._append_header(chain_u, self.HEADERS['U'])
+
+ self.assertEqual(chain_z, chain_u.parent)
+ self.assertEqual(chain_z, chain_l.parent)
+ self.assertEqual(None, chain_z.parent)
+
def test_forking_and_swapping(self):
blockchain.blockchains[constants.net.GENESIS] = chain_u = Blockchain(
config=self.config, forkpoint=0, parent=None,
