Small optimization for large wallets

Previously the verifier job would scan all transactions in
unverified_tx each time it ran.
Nothing was ever removed from this map; it would essentially
be the full set of transactions.
As the job runs about 10 times a second, for a wallet with 500 txs
this would be 5,000 useless loops a second.
This patch makes unverified_tx be simply the set of confirmed
transactions that haven't yet been verified.  txs are added once
confirmed, and removed once verified.  Hence it will almost always be
empty.

lib/verifier.py

@@ -33,9 +33,11 @@ class SPV(ThreadJob):
         self.merkle_roots = {}
 
     def run(self):
+        lh = self.wallet.get_local_height()
         unverified = self.wallet.get_unverified_txs()
-        for (tx_hash, tx_height) in unverified:
+        for tx_hash, tx_height in unverified.items():
-            if tx_hash not in self.merkle_roots:
+            # do not request merkle branch before headers are available
+            if tx_hash not in self.merkle_roots and tx_height <= lh:
                 request = ('blockchain.transaction.get_merkle',
                            [tx_hash, tx_height])
                 if self.network.send([request], self.merkle_response):
@@ -64,6 +66,8 @@ class SPV(ThreadJob):
         merkle_root = self.hash_merkle_root(merkle['merkle'], tx_hash, pos)
         header = header.get('result')
         if not header or header.get('merkle_root') != merkle_root:
+            # FIXME: we should make a fresh connection to a server to
+            # recover from this, as this TX will now never verify
             self.print_error("merkle verification failed for", tx_hash)
             return
 

lib/wallet.py

@@ -417,10 +417,13 @@ class Abstract_Wallet(object):
         return decrypted
 
     def add_unverified_tx(self, tx_hash, tx_height):
-        if tx_height > 0:
+        # Only add if confirmed and not verified
+        if tx_height > 0 and tx_hash not in self.verified_tx:
             self.unverified_tx[tx_hash] = tx_height
 
     def add_verified_tx(self, tx_hash, info):
+        # Remove from the unverified map and add to the verified map and
+        self.unverified_tx.pop(tx_hash, None)
         with self.lock:
             self.verified_tx[tx_hash] = info  # (tx_height, timestamp, pos)
         self.storage.put('verified_tx3', self.verified_tx, True)
@@ -429,14 +432,8 @@ class Abstract_Wallet(object):
         self.network.trigger_callback('verified', (tx_hash, conf, timestamp))
 
     def get_unverified_txs(self):
-        '''Returns a list of tuples (tx_hash, height) that are unverified
+        '''Returns a map from tx hash to transaction height'''
-        and not beyond local height'''
+        return self.unverified_tx
-        txs = []
-        for tx_hash, tx_height in self.unverified_tx.items():
-            # do not request merkle branch before headers are available
-            if tx_hash not in self.verified_tx and tx_height <= self.get_local_height():
-                txs.append((tx_hash, tx_height))
-        return txs
 
     def undo_verifications(self, height):
         '''Used by the verifier when a reorg has happened'''