Handle duplicate tx attempts

chainqueue/enum.py

@@ -42,7 +42,6 @@ class StatusEnum(enum.IntEnum):
     """
     PENDING = 0
     """Transaction has been added but no processing has been performed"""
-
     SENDFAIL = StatusBits.DEFERRED | StatusBits.LOCAL_ERROR
     """Temporary error occurred when sending transaction to node"""
     RETRY = StatusBits.QUEUED | StatusBits.DEFERRED 

chainqueue/error.py

@@ -29,3 +29,8 @@ class BackendIntegrityError(ChainQueueException):
     """
     pass
 
+
+class DuplicateTxError(ChainQueueException):
+    """Backend already knows transaction
+    """
+    pass

chainqueue/store/base.py

@@ -6,7 +6,9 @@ import logging
 # local imports
 from chainqueue.cache import CacheTx
 from chainqueue.entry import QueueEntry
-from chainqueue.error import NotLocalTxError
+from chainqueue.error import (
+        NotLocalTxError,
+        )
 
 logg = logging.getLogger(__name__)
 
@@ -53,8 +55,8 @@ class Store:
         n = self.counter.next()
         t = datetime.datetime.now().timestamp()
         s = to_key(t, n, k)
-        self.state_store.put(s, v)
         self.index_store.put(k, s)
+        self.state_store.put(s, v)
         if self.cache != None:
             self.cache.put(self.chain_spec, tx) 
         return (s, k,)

chainqueue/store/fs.py

@@ -5,6 +5,9 @@ import logging
 # external imports
 from leveldir.hex import HexDir
 
+# local imports
+from chainqueue.error import DuplicateTxError
+
 logg = logging.getLogger(__name__)
 
 
@@ -15,9 +18,20 @@ class IndexStore(HexDir):
         self.store = HexDir(root_path, digest_bytes)
 
     
+    def __exists(self, k):
+        existing = None
+        try:
+            existing = self.get(k)
+        except FileNotFoundError:
+            pass
+        return existing != None
+
+
     def put(self, k, v):
         kb = bytes.fromhex(k)
         vb = v.encode('utf-8')
+        if self.__exists(k):
+            raise DuplicateTxError(k)
         self.store.add(kb, vb)
 
 

tests/test_store.py

@@ -12,6 +12,7 @@ from chainqueue.store.fs import (
         IndexStore,
         CounterStore,
         )
+from chainqueue.error import DuplicateTxError
 
 
 logging.basicConfig(level=logging.DEBUG)
@@ -48,5 +49,14 @@ class TestStoreImplementations(unittest.TestCase):
         self.assertEqual(v, 2)
 
 
+    def test_duplicate(self):
+        store = IndexStore(self.path)
+        hx = os.urandom(32).hex()
+        data = 'foo_bar_baz'
+        store.put(hx, data)
+        with self.assertRaises(DuplicateTxError):
+            store.put(hx, data)
+
+
 if __name__ == '__main__':
     unittest.main()