Delete transactions after block is written (#609)

* delete transactions after block is written

* cleanup transaction_exists

* check for duplicate transactions

* delete invalid tx from backlog

* test duplicate transaction

bigchaindb/core.py

@@ -573,11 +573,10 @@ class Bigchain(object):
         block_serialized = rapidjson.dumps(block)
         r.table('bigchain').insert(r.json(block_serialized), durability=durability).run(self.conn)
 
-    # TODO: Decide if we need this method
     def transaction_exists(self, transaction_id):
         response = r.table('bigchain', read_mode=self.read_mode)\
             .get_all(transaction_id, index='transaction_id').run(self.conn)
-        return True if len(response.items) > 0 else False
+        return len(response.items) > 0
 
     def prepare_genesis_block(self):
         """Prepare a genesis block."""

bigchaindb/pipelines/block.py

@@ -45,34 +45,43 @@ class Block:
             tx.pop('assignment_timestamp')
             return tx
 
-    def delete_tx(self, tx):
-        """Delete a transaction.
-
-        Args:
-            tx (dict): the transaction to delete.
-
-        Returns:
-            The transaction.
-        """
-        r.table('backlog')\
-         .get(tx['id'])\
-         .delete(durability='hard')\
-         .run(self.bigchain.conn)
-
-        return tx
-
     def validate_tx(self, tx):
         """Validate a transaction.
 
+        Also checks if the transaction already exists in the blockchain. If it
+        does, or it's invalid, it's deleted from the backlog immediately.
+
         Args:
             tx (dict): the transaction to validate.
 
         Returns:
             The transaction if valid, ``None`` otherwise.
         """
-        tx = self.bigchain.is_valid_transaction(tx)
+        if self.bigchain.transaction_exists(tx['id']):
-        if tx:
+            # if the transaction already exists, we must check whether
+            # it's in a valid or undecided block
+            tx, status = self.bigchain.get_transaction(tx['id'],
+                                                       include_status=True)
+            if status == self.bigchain.TX_VALID \
+               or status == self.bigchain.TX_UNDECIDED:
+                # if the tx is already in a valid or undecided block,
+                # then it no longer should be in the backlog, or added
+                # to a new block. We can delete and drop it.
+                r.table('backlog').get(tx['id']) \
+                        .delete(durability='hard') \
+                        .run(self.bigchain.conn)
+                return None
+
+        tx_validated = self.bigchain.is_valid_transaction(tx)
+        if tx_validated:
             return tx
+        else:
+            # if the transaction is not valid, remove it from the
+            # backlog
+            r.table('backlog').get(tx['id']) \
+                    .delete(durability='hard') \
+                    .run(self.bigchain.conn)
+            return None 
 
     def create(self, tx, timeout=False):
         """Create a block.
@@ -113,6 +122,22 @@ class Block:
         self.bigchain.write_block(block)
         return block
 
+    def delete_tx(self, block):
+        """Delete transactions.
+
+        Args:
+            block (dict): the block containg the transactions to delete.
+
+        Returns:
+            The block.
+        """
+        r.table('backlog')\
+         .get_all(*[tx['id'] for tx in block['block']['transactions']])\
+         .delete(durability='hard')\
+         .run(self.bigchain.conn)
+
+        return block
+
 
 def initial():
     """Return old transactions from the backlog."""
@@ -143,10 +168,10 @@ def create_pipeline():
 
     block_pipeline = Pipeline([
         Node(block.filter_tx),
-        Node(block.delete_tx),
         Node(block.validate_tx, fraction_of_cores=1),
         Node(block.create, timeout=1),
         Node(block.write),
+        Node(block.delete_tx),
     ])
 
     return block_pipeline

tests/pipelines/test_block_creation.py

@@ -74,22 +74,59 @@ def test_write_block(b, user_vk):
     assert r.table('bigchain').get(block_doc['id']).run(b.conn) == block_doc
 
 
+def test_duplicate_transaction(b, user_vk):
+    block_maker = block.Block()
+
+    txs = []
+    for i in range(10):
+        tx = b.create_transaction(b.me, user_vk, None, 'CREATE')
+        tx = b.sign_transaction(tx, b.me_private)
+        txs.append(tx)
+
+    block_doc = b.create_block(txs)
+    block_maker.write(block_doc)
+
+    # block is in bigchain
+    assert r.table('bigchain').get(block_doc['id']).run(b.conn) == block_doc
+
+    b.write_transaction(txs[0])
+
+    # verify tx is in the backlog
+    assert r.table('backlog').get(txs[0]['id']).run(b.conn) is not None
+
+    # try to validate a transaction that's already in the chain; should not
+    # work
+    assert block_maker.validate_tx(txs[0]) is None
+
+    # duplicate tx should be removed from backlog
+    assert r.table('backlog').get(txs[0]['id']).run(b.conn) is None
+
+
 def test_delete_tx(b, user_vk):
     block_maker = block.Block()
 
-    tx = b.create_transaction(b.me, user_vk, None, 'CREATE')
+    for i in range(100):
-    tx = b.sign_transaction(tx, b.me_private)
+        tx = b.create_transaction(b.me, user_vk, None, 'CREATE')
-    b.write_transaction(tx)
+        tx = b.sign_transaction(tx, b.me_private)
+        block_maker.create(tx)
+        # make sure the tx appears in the backlog
+        b.write_transaction(tx)
 
-    tx_backlog = r.table('backlog').get(tx['id']).run(b.conn)
+    # force the output triggering a `timeout`
-    tx_backlog.pop('assignee')
+    block_doc = block_maker.create(None, timeout=True)
-    tx_backlog.pop('assignment_timestamp')
-    assert tx_backlog == tx
 
-    returned_tx = block_maker.delete_tx(tx)
+    for tx in block_doc['block']['transactions']:
+        returned_tx = r.table('backlog').get(tx['id']).run(b.conn)
+        returned_tx.pop('assignee')
+        returned_tx.pop('assignment_timestamp')
+        assert returned_tx == tx
 
-    assert returned_tx == tx
+    returned_block = block_maker.delete_tx(block_doc)
-    assert r.table('backlog').get(tx['id']).run(b.conn) is None
+
+    assert returned_block == block_doc
+
+    for tx in block_doc['block']['transactions']:
+        assert r.table('backlog').get(tx['id']).run(b.conn) is None
 
 
 def test_prefeed(b, user_vk):