96 lines
3.3 KiB
Python
96 lines
3.3 KiB
Python
import six
|
|
from random import Random
|
|
from typing import List
|
|
|
|
from torba.basetransaction import BaseOutputAmountEstimator
|
|
|
|
MAXIMUM_TRIES = 100000
|
|
|
|
|
|
class CoinSelector:
|
|
|
|
def __init__(self, txos, target, cost_of_change, seed=None):
|
|
# type: (List[BaseOutputAmountEstimator], int, int, str) -> None
|
|
self.txos = txos
|
|
self.target = target
|
|
self.cost_of_change = cost_of_change
|
|
self.exact_match = False
|
|
self.tries = 0
|
|
self.available = sum(c.effective_amount for c in self.txos)
|
|
self.random = Random(seed)
|
|
if six.PY3 and seed is not None:
|
|
self.random.seed(seed, version=1)
|
|
|
|
def select(self):
|
|
if not self.txos:
|
|
return
|
|
if self.target > self.available:
|
|
return
|
|
return self.branch_and_bound() or self.single_random_draw()
|
|
|
|
def branch_and_bound(self):
|
|
# see bitcoin implementation for more info:
|
|
# https://github.com/bitcoin/bitcoin/blob/master/src/wallet/coinselection.cpp
|
|
|
|
self.txos.sort(reverse=True)
|
|
|
|
current_value = 0
|
|
current_available_value = self.available
|
|
current_selection = []
|
|
best_waste = self.cost_of_change
|
|
best_selection = []
|
|
|
|
while self.tries < MAXIMUM_TRIES:
|
|
self.tries += 1
|
|
|
|
backtrack = False
|
|
if current_value + current_available_value < self.target or \
|
|
current_value > self.target + self.cost_of_change:
|
|
backtrack = True
|
|
elif current_value >= self.target:
|
|
new_waste = current_value - self.target
|
|
if new_waste <= best_waste:
|
|
best_waste = new_waste
|
|
best_selection = current_selection[:]
|
|
backtrack = True
|
|
|
|
if backtrack:
|
|
while current_selection and not current_selection[-1]:
|
|
current_selection.pop()
|
|
current_available_value += self.txos[len(current_selection)].effective_amount
|
|
|
|
if not current_selection:
|
|
break
|
|
|
|
current_selection[-1] = False
|
|
utxo = self.txos[len(current_selection) - 1]
|
|
current_value -= utxo.effective_amount
|
|
|
|
else:
|
|
utxo = self.txos[len(current_selection)]
|
|
current_available_value -= utxo.effective_amount
|
|
previous_utxo = self.txos[len(current_selection) - 1] if current_selection else None
|
|
if current_selection and not current_selection[-1] and \
|
|
utxo.effective_amount == previous_utxo.effective_amount and \
|
|
utxo.fee == previous_utxo.fee:
|
|
current_selection.append(False)
|
|
else:
|
|
current_selection.append(True)
|
|
current_value += utxo.effective_amount
|
|
|
|
if best_selection:
|
|
self.exact_match = True
|
|
return [
|
|
self.txos[i] for i, include in enumerate(best_selection) if include
|
|
]
|
|
|
|
def single_random_draw(self):
|
|
self.random.shuffle(self.txos, self.random.random)
|
|
selection = []
|
|
amount = 0
|
|
for coin in self.txos:
|
|
selection.append(coin)
|
|
amount += coin.effective_amount
|
|
if amount >= self.target+self.cost_of_change:
|
|
return selection
|