From f98dc9c3514a21fb24a4ca04a7c1d3d414ee8943 Mon Sep 17 00:00:00 2001
From: Neil Booth <kyuupichan@gmail.com>
Date: Thu, 10 Nov 2016 21:22:58 +0900
Subject: [PATCH] Practise optimism like before

---
 server/block_processor.py | 28 ++++++++++++++++++++--------
 server/db.py              |  8 ++++----
 2 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/server/block_processor.py b/server/block_processor.py
index 67a9412..230c2de 100644
--- a/server/block_processor.py
+++ b/server/block_processor.py
@@ -249,7 +249,7 @@ class MemPool(LoggedClass):
             try:
                 infos = (txin_info(txin) for txin in tx.inputs)
                 txin_pairs, unconfs = zip(*infos)
-            except MissingUTXOError:
+            except self.bp.MissingUTXOError:
                 # Drop this TX.  If other mempool txs depend on it
                 # it's harmless - next time the mempool is refreshed
                 # they'll either be cleaned up or the UTXOs will no
@@ -949,6 +949,19 @@ class BlockProcessor(server.db.DB):
             # Probably a strange UTXO
             return NO_CACHE_ENTRY
 
+        # FIXME: this matches what we did previously but until we store
+        # all UTXOs isn't safe
+        if len(db_value) == 25:
+            udb_key = b'u' + db_value + idx_packed
+            utxo_value_packed = self.db.get(udb_key)
+            if utxo_value_packed:
+                # Remove the UTXO from both tables
+                self.db_deletes += 1
+                self.db_cache[db_key] = None
+                self.db_cache[udb_key] = None
+                return db_value + utxo_value_packed
+            # Fall through to below
+
         assert len(db_value) % 25 == 0
 
         # Find which entry, if any, the TX_HASH matches.
@@ -956,15 +969,14 @@ class BlockProcessor(server.db.DB):
             tx_num, = unpack('<I', db_value[n+21:n+25])
             hash, height = self.get_tx_hash(tx_num)
             if hash == tx_hash:
-                self.db_deletes += 1
                 match = db_value[n:n+25]
-                # Remove the UTXO from both tables
-                self.db_cache[db_key] = db_value[:n] + db_value[n + 25:]
-
-                db_key = b'u' + match + idx_packed
-                utxo_value_packed = self.db.get(db_key)
+                udb_key = b'u' + match + idx_packed
+                utxo_value_packed = self.db.get(udb_key)
                 if utxo_value_packed:
-                    self.db_cache[db_key] = None
+                    # Remove the UTXO from both tables
+                    self.db_deletes += 1
+                    self.db_cache[db_key] = db_value[:n] + db_value[n + 25:]
+                    self.db_cache[udb_key] = None
                     return match + utxo_value_packed
 
                 # Uh-oh, this should not happen...
diff --git a/server/db.py b/server/db.py
index d0035ee..fc01c31 100644
--- a/server/db.py
+++ b/server/db.py
@@ -210,12 +210,12 @@ class DB(LoggedClass):
             assert len(db_value) % 25 == 0
 
             # Find which entry, if any, the TX_HASH matches.
-            for n in range(0, len(data), 25):
-                tx_num_packed = data[n + 21: n + 25]
+            for n in range(0, len(db_value), 25):
+                tx_num_packed = db_value[n + 21: n + 25]
                 tx_num, = unpack('<I', tx_num_packed)
                 hash, height = self.fs_tx_hash(tx_num)
                 if hash == tx_hash:
-                    return data[n:n+21], tx_num_packed
+                    return db_value[n:n+21], tx_num_packed
 
         return None, None
 
@@ -230,7 +230,7 @@ class DB(LoggedClass):
         if not hash168:
             # This can happen when the daemon is a block ahead of us
             # and has mempool txs spending new txs in that block
-            raise MissingUTXOError
+            raise self.MissingUTXOError
 
         key = b'u' + hash168 + tx_num_packed + idx_packed
         db_value = self.db.get(key)