mirror of
https://github.com/bitcoinbook/bitcoinbook
synced 2024-10-31 20:48:58 +00:00
72 lines
2.6 KiB
Python
72 lines
2.6 KiB
Python
# Selects outputs from a UTXO list using a greedy algorithm.
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from sys import argv
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try:
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long # Python 2
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except NameError:
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long = int # Python 3
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class OutputInfo:
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def __init__(self, tx_hash, tx_index, value):
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self.tx_hash = tx_hash
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self.tx_index = tx_index
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self.value = value
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def __repr__(self):
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return "<%s:%s with %s Satoshis>" % (self.tx_hash, self.tx_index,
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self.value)
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# Select optimal outputs for a send from unspent outputs list.
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# Returns output list and remaining change to be sent to
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# a change address.
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def select_outputs_greedy(unspent, min_value):
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# Fail if empty.
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if not unspent:
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return None
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# Partition into 2 lists.
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lessers = [utxo for utxo in unspent if utxo.value < min_value]
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greaters = [utxo for utxo in unspent if utxo.value >= min_value]
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key_func = lambda utxo: utxo.value
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if greaters:
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# Not-empty. Find the smallest greater.
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min_greater = min(greaters, key=key_func)
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change = min_greater.value - min_value
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return [min_greater], "Change: %d Satoshis" % change
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# Not found in greaters. Try several lessers instead.
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# Rearrange them from biggest to smallest. We want to use the least
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# amount of inputs as possible.
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lessers.sort(key=key_func, reverse=True)
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result = []
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accum = 0
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for utxo in lessers:
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result.append(utxo)
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accum += utxo.value
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if accum >= min_value:
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change = accum - min_value
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return result, "Change: %d Satoshis" % change
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# No results found.
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return None, 0
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def main():
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unspent = [
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OutputInfo("ebadfaa92f1fd29e2fe296eda702c48bd11ffd52313e986e99ddad9084062167", 1, 8000000),
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OutputInfo("6596fd070679de96e405d52b51b8e1d644029108ec4cbfe451454486796a1ecf", 0, 16050000),
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OutputInfo("b2affea89ff82557c60d635a2a3137b8f88f12ecec85082f7d0a1f82ee203ac4", 0, 10000000),
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OutputInfo("7dbc497969c7475e45d952c4a872e213fb15d45e5cd3473c386a71a1b0c136a1", 0, 25000000),
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OutputInfo("55ea01bd7e9afd3d3ab9790199e777d62a0709cf0725e80a7350fdb22d7b8ec6", 17, 5470541),
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OutputInfo("12b6a7934c1df821945ee9ee3b3326d07ca7a65fd6416ea44ce8c3db0c078c64", 0, 10000000),
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OutputInfo("7f42eda67921ee92eae5f79bd37c68c9cb859b899ce70dba68c48338857b7818", 0, 16100000),
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]
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target = long(argv[1]) if len(argv) > 1 else 55000000
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print("For transaction amount %d Satoshis (%f bitcoin) use: " %
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(target, target / 10.0 ** 8))
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print(select_outputs_greedy(unspent, target))
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if __name__ == "__main__":
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main()
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