better segwit tx size estimation
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0da1d4853b
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a2a25e4738
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@ -91,8 +91,9 @@ class CoinChooserBase(PrintError):
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buckets[key].append(coin)
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def make_Bucket(desc, coins):
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size = sum(Transaction.estimated_input_size(coin)
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weight = sum(Transaction.estimated_input_weight(coin)
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for coin in coins)
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size = Transaction.virtual_size_from_weight(weight)
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value = sum(coin['value'] for coin in coins)
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return Bucket(desc, size, value, coins)
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@ -635,11 +635,11 @@ class Transaction:
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return pk_list, sig_list
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@classmethod
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def serialize_witness(self, txin):
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def serialize_witness(self, txin, estimate_size=False):
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add_w = lambda x: var_int(len(x)//2) + x
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if not self.is_segwit_input(txin):
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return '00'
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pubkeys, sig_list = self.get_siglist(txin)
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pubkeys, sig_list = self.get_siglist(txin, estimate_size)
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if txin['type'] in ['p2wpkh', 'p2wpkh-p2sh']:
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witness = var_int(2) + add_w(sig_list[0]) + add_w(pubkeys[0])
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elif txin['type'] in ['p2wsh', 'p2wsh-p2sh']:
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@ -648,7 +648,10 @@ class Transaction:
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witness = var_int(n) + '00' + ''.join(add_w(x) for x in sig_list) + add_w(witness_script)
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else:
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raise BaseException('wrong txin type')
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value_field = '' if self.is_txin_complete(txin) else var_int(0xffffffff) + int_to_hex(txin['value'], 8)
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if self.is_txin_complete(txin) or estimate_size:
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value_field = ''
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else:
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value_field = var_int(0xffffffff) + int_to_hex(txin['value'], 8)
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return value_field + witness
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@classmethod
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@ -781,7 +784,7 @@ class Transaction:
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if witness and self.is_segwit():
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marker = '00'
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flag = '01'
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witness = ''.join(self.serialize_witness(x) for x in inputs)
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witness = ''.join(self.serialize_witness(x, estimate_size) for x in inputs)
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return nVersion + marker + flag + txins + txouts + witness + nLocktime
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else:
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return nVersion + txins + txouts + nLocktime
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@ -830,13 +833,26 @@ class Transaction:
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weights, but for simplicity we approximate that with (virtual_size)x4
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"""
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weight = self.estimated_weight()
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return weight // 4 + (weight % 4 > 0)
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return self.virtual_size_from_weight(weight)
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@classmethod
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def estimated_input_size(self, txin):
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'''Return an estimated of serialized input size in bytes.'''
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script = self.input_script(txin, True)
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return len(self.serialize_input(txin, script)) // 2
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def estimated_input_weight(cls, txin):
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'''Return an estimate of serialized input weight in weight units.'''
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script = cls.input_script(txin, True)
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input_size = len(cls.serialize_input(txin, script)) // 2
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# note: we should actually branch based on tx.is_segwit()
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# only if none of the inputs have a witness, is the size actually 0
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if cls.is_segwit_input(txin):
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witness_size = len(cls.serialize_witness(txin, True)) // 2
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else:
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witness_size = 0
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return 4 * input_size + witness_size
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@classmethod
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def virtual_size_from_weight(cls, weight):
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return weight // 4 + (weight % 4 > 0)
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def estimated_total_size(self):
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"""Return an estimated total transaction size in bytes."""
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@ -847,7 +863,7 @@ class Transaction:
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if not self.is_segwit():
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return 0
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inputs = self.inputs()
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witness = ''.join(self.serialize_witness(x) for x in inputs)
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witness = ''.join(self.serialize_witness(x, True) for x in inputs)
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witness_size = len(witness) // 2 + 2 # include marker and flag
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return witness_size
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