Fix listunspent methods to remove mempool spends

Fixes #277

server/controller.py

@@ -795,19 +795,27 @@ class Controller(ServerBase):
         hashX = self.address_to_hashX(address)
         raise RPCError('address.get_proof is not yet implemented')
 
+    async def hashX_listunspent(self, hashX):
+        '''Return the list of UTXOs of a script hash.
+
+        We should remove mempool spends from the in-DB UTXOs.'''
+        utxos = await self.get_utxos(hashX)
+        spends = await self.mempool.spends(hashX)
+
+        return [{'tx_hash': hash_to_str(utxo.tx_hash), 'tx_pos': utxo.tx_pos,
+                 'height': utxo.height, 'value': utxo.value}
+                for utxo in sorted(utxos)
+                if (utxo.tx_hash, utxo.tx_pos) not in spends]
+
     async def address_listunspent(self, address):
         '''Return the list of UTXOs of an address.'''
         hashX = self.address_to_hashX(address)
-        return [{'tx_hash': hash_to_str(utxo.tx_hash), 'tx_pos': utxo.tx_pos,
-                 'height': utxo.height, 'value': utxo.value}
-                for utxo in sorted(await self.get_utxos(hashX))]
+        return await self.hashX_listunspent(hashX)
 
     async def scripthash_listunspent(self, scripthash):
         '''Return the list of UTXOs of a scripthash.'''
         hashX = self.scripthash_to_hashX(scripthash)
-        return [{'tx_hash': hash_to_str(utxo.tx_hash), 'tx_pos': utxo.tx_pos,
-                 'height': utxo.height, 'value': utxo.value}
-                for utxo in sorted(await self.get_utxos(hashX))]
+        return await self.hashX_listunspent(hashX)
 
     def block_get_header(self, height):
         '''The deserialized header at a given height.

server/mempool.py

@@ -260,21 +260,30 @@ class MemPool(util.LoggedClass):
 
         return result, deferred
 
-    async def transactions(self, hashX):
-        '''Generate (hex_hash, tx_fee, unconfirmed) tuples for mempool
-        entries for the hashX.
+    async def raw_transactions(self, hashX):
+        '''Returns an iterable of (hex_hash, raw_tx) pairs for all
+        transactions in the mempool that touch hashX.
 
-        unconfirmed is True if any txin is unconfirmed.
+        raw_tx can be None if the transaction has left the mempool.
         '''
         # hashXs is a defaultdict
         if hashX not in self.hashXs:
             return []
 
-        deserializer = self.coin.DESERIALIZER
         hex_hashes = self.hashXs[hashX]
         raw_txs = await self.daemon.getrawtransactions(hex_hashes)
+        return zip(hex_hashes, raw_txs)
+
+    async def transactions(self, hashX):
+        '''Generate (hex_hash, tx_fee, unconfirmed) tuples for mempool
+        entries for the hashX.
+
+        unconfirmed is True if any txin is unconfirmed.
+        '''
+        deserializer = self.coin.DESERIALIZER
+        pairs = await self.raw_transactions(hashX)
         result = []
-        for hex_hash, raw_tx in zip(hex_hashes, raw_txs):
+        for hex_hash, raw_tx in pairs:
             item = self.txs.get(hex_hash)
             if not item or not raw_tx:
                 continue
@@ -287,6 +296,23 @@ class MemPool(util.LoggedClass):
             result.append((hex_hash, tx_fee, unconfirmed))
         return result
 
+    async def spends(self, hashX):
+        '''Return a set of (prev_hash, prev_idx) pairs from mempool
+        transactions that touch hashX.
+
+        None, some or all of these may be spends of the hashX.
+        '''
+        deserializer = self.coin.DESERIALIZER
+        pairs = await self.raw_transactions(hashX)
+        spends = set()
+        for hex_hash, raw_tx in pairs:
+            if not raw_tx:
+                continue
+            tx, tx_hash = deserializer(raw_tx).read_tx()
+            for txin in tx.inputs:
+                spends.add((txin.prev_hash, txin.prev_idx))
+        return spends
+
     def value(self, hashX):
         '''Return the unconfirmed amount in the mempool for hashX.