electrum-bitcoinprivate/lib/coinchooser.py

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#!/usr/bin/env python
#
# Electrum - lightweight Bitcoin client
# Copyright (C) 2011 thomasv@gitorious
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
from operator import itemgetter
from bitcoin import MIN_RELAY_TX_FEE
from util import NotEnoughFunds, PrintError, profiler
from transaction import Transaction
class CoinChooser(PrintError):
def __init__(self, wallet):
self.wallet = wallet
def fee(self, tx, fixed_fee, fee_per_kb):
if fixed_fee is not None:
return fixed_fee
return tx.estimated_fee(fee_per_kb)
def dust_threshold(self):
return 182 * 3 * MIN_RELAY_TX_FEE/1000
def make_tx(self, coins, outputs, change_addrs, fixed_fee, fee_per_kb):
'''Select unspent coins to spend to pay outputs.'''
amount = sum(map(lambda x: x[2], outputs))
total = 0
inputs = []
tx = Transaction.from_io(inputs, outputs)
fee = self.fee(tx, fixed_fee, fee_per_kb)
# add inputs, sorted by age
for item in coins:
v = item.get('value')
total += v
self.wallet.add_input_info(item)
tx.add_input(item)
# no need to estimate fee until we have reached desired amount
if total < amount + fee:
continue
fee = self.fee(tx, fixed_fee, fee_per_kb)
if total >= amount + fee:
break
else:
raise NotEnoughFunds()
# remove unneeded inputs.
removed = False
for item in sorted(tx.inputs, key=itemgetter('value')):
v = item.get('value')
if total - v >= amount + fee:
tx.inputs.remove(item)
total -= v
removed = True
continue
else:
break
if removed:
fee = self.fee(tx, fixed_fee, fee_per_kb)
for item in sorted(tx.inputs, key=itemgetter('value')):
v = item.get('value')
if total - v >= amount + fee:
tx.inputs.remove(item)
total -= v
fee = self.fee(tx, fixed_fee, fee_per_kb)
continue
break
self.print_error("using %d inputs" % len(tx.inputs))
# if change is above dust threshold, add a change output.
change_addr = change_addrs[0]
change_amount = total - (amount + fee)
if fixed_fee is not None and change_amount > 0:
tx.outputs.append(('address', change_addr, change_amount))
elif change_amount > self.dust_threshold():
tx.outputs.append(('address', change_addr, change_amount))
# recompute fee including change output
fee = tx.estimated_fee(fee_per_kb)
# remove change output
tx.outputs.pop()
# if change is still above dust threshold, re-add change output.
change_amount = total - (amount + fee)
if change_amount > self.dust_threshold():
tx.outputs.append(('address', change_addr, change_amount))
self.print_error('change', change_amount)
else:
self.print_error('not keeping dust', change_amount)
else:
self.print_error('not keeping dust', change_amount)
return tx