From 2b4569896236828ae3a1840537cd186bc354c778 Mon Sep 17 00:00:00 2001
From: Neil Booth <kyuupichan@gmail.com>
Date: Sat, 22 Oct 2016 11:38:26 +0900
Subject: [PATCH] Remove Outpoint as a separate object

Hopefully this is a little more efficient
---
 lib/tx.py                 | 47 ++++++++++++++++++---------------------
 server/block_processor.py |  2 +-
 server/cache.py           | 16 ++++++-------
 3 files changed, 31 insertions(+), 34 deletions(-)

diff --git a/lib/tx.py b/lib/tx.py
index dfa417c..c45425c 100644
--- a/lib/tx.py
+++ b/lib/tx.py
@@ -2,11 +2,10 @@
 # and warranty status of this software.
 
 from collections import namedtuple
-import binascii
 import struct
 
 from lib.util import cachedproperty
-from lib.hash import double_sha256
+from lib.hash import double_sha256, hash_to_str
 
 
 class Tx(namedtuple("Tx", "version inputs outputs locktime")):
@@ -15,17 +14,17 @@ class Tx(namedtuple("Tx", "version inputs outputs locktime")):
     def is_coinbase(self):
         return self.inputs[0].is_coinbase
 
-OutPoint = namedtuple("OutPoint", "hash n")
+    # FIXME: add hash as a cached property?
 
-# prevout is an OutPoint object
-class TxInput(namedtuple("TxInput", "prevout script sequence")):
+class TxInput(namedtuple("TxInput", "prev_hash prev_idx script sequence")):
 
     ZERO = bytes(32)
     MINUS_1 = 4294967295
 
     @cachedproperty
     def is_coinbase(self):
-        return self.prevout == (TxInput.ZERO, TxInput.MINUS_1)
+        return (self.prev_hash == TxInput.ZERO
+                and self.prev_idx == TxInput.MINUS_1)
 
     @cachedproperty
     def script_sig_info(self):
@@ -34,11 +33,11 @@ class TxInput(namedtuple("TxInput", "prevout script sequence")):
             return None
         return Script.parse_script_sig(self.script)
 
-    def __repr__(self):
-        script = binascii.hexlify(self.script).decode("ascii")
-        prev_hash = binascii.hexlify(self.prevout.hash).decode("ascii")
-        return ("Input(prevout=({}, {:d}), script={}, sequence={:d})"
-                .format(prev_hash, self.prevout.n, script, self.sequence))
+    def __str__(self):
+        script = self.script.hex()
+        prev_hash = hash_to_str(self.prev_hash)
+        return ("Input({}, {:d}, script={}, sequence={:d})"
+                .format(prev_hash, self.prev_idx, script, self.sequence))
 
 
 class TxOutput(namedtuple("TxOutput", "value pk_script")):
@@ -56,11 +55,12 @@ class Deserializer(object):
         self.cursor = 0
 
     def read_tx(self):
-        version = self.read_le_int32()
-        inputs = self.read_inputs()
-        outputs = self.read_outputs()
-        locktime = self.read_le_uint32()
-        return Tx(version, inputs, outputs, locktime)
+        return Tx(
+            self.read_le_int32(),  # version
+            self.read_inputs(),    # inputs
+            self.read_outputs(),   # outputs
+            self.read_le_uint32()  # locktime
+        )
 
     def read_block(self):
         tx_hashes = []
@@ -81,15 +81,12 @@ class Deserializer(object):
         return [self.read_input() for i in range(n)]
 
     def read_input(self):
-        prevout = self.read_outpoint()
-        script = self.read_varbytes()
-        sequence = self.read_le_uint32()
-        return TxInput(prevout, script, sequence)
-
-    def read_outpoint(self):
-        hash = self.read_nbytes(32)
-        n = self.read_le_uint32()
-        return OutPoint(hash, n)
+        return TxInput(
+            self.read_nbytes(32),  # prev_hash
+            self.read_le_uint32(), # prev_idx
+            self.read_varbytes(),  # script
+            self.read_le_uint32()  # sequence
+        )
 
     def read_outputs(self):
         n = self.read_varint()
diff --git a/server/block_processor.py b/server/block_processor.py
index 94ca616..35a7f2f 100644
--- a/server/block_processor.py
+++ b/server/block_processor.py
@@ -439,7 +439,7 @@ class BlockProcessor(LoggedClass):
             hash168s = cache.add_many(tx_hash, tx_num, tx.outputs)
             if not tx.is_coinbase:
                 for txin in tx.inputs:
-                    hash168s.add(cache.spend(txin.prevout))
+                    hash168s.add(cache.spend(txin))
 
             for hash168 in hash168s:
                 self.history[hash168].append(tx_num)
diff --git a/server/cache.py b/server/cache.py
index 315f1a4..7cf8978 100644
--- a/server/cache.py
+++ b/server/cache.py
@@ -120,21 +120,21 @@ class UTXOCache(LoggedClass):
 
         return hash168s
 
-    def spend(self, prevout):
+    def spend(self, txin):
         '''Spend a UTXO and return the address spent.
 
         If the UTXO is not in the cache it must be on disk.
         '''
         # Fast track is it's in the cache
         pack = struct.pack
-        key = prevout.hash + pack('<H', prevout.n)
+        key = txin.prev_hash + pack('<H', txin.prev_idx)
         value = self.cache.pop(key, None)
         if value:
             self.cache_hits += 1
             return value[:21]
 
         # Oh well.  Find and remove it from the DB.
-        hash168 = self.hash168(prevout.hash, prevout.n)
+        hash168 = self.hash168(txin.prev_hash, txin.prev_idx)
         if not hash168:
             return None
 
@@ -142,14 +142,14 @@ class UTXOCache(LoggedClass):
 
         # Read the UTXO through the cache from the disk.  We have to
         # go through the cache because compressed keys can collide.
-        key = (b'u' + hash168 + prevout.hash[:UTXO_TX_HASH_LEN]
-               + pack('<H', prevout.n))
+        key = (b'u' + hash168 + txin.prev_hash[:UTXO_TX_HASH_LEN]
+               + pack('<H', txin.prev_idx))
         data = self.cache_get(key)
         if data is None:
             # Uh-oh, this should not happen...
             self.logger.error('found no UTXO for {} / {:d} key {}'
-                             .format(hash_to_str(prevout.hash),
-                                     prevout.n, bytes(key).hex()))
+                             .format(hash_to_str(txin.prev_hash),
+                                     txin.prev_idx, bytes(key).hex()))
             return hash168
 
         if len(data) == 12:
@@ -163,7 +163,7 @@ class UTXOCache(LoggedClass):
         for n in range(0, len(data), 12):
             (tx_num, ) = struct.unpack('<I', data[n:n+4])
             tx_hash, height = self.parent.get_tx_hash(tx_num)
-            if prevout.hash == tx_hash:
+            if txin.prev_hash == tx_hash:
                 data = data[:n] + data[n + 12:]
                 self.cache_write(key, data)
                 return hash168