New PostgresNode implementation (#453)

1) Separated implementations for psycopg2 and pg8000
2) NodeConnection raises own exceptions:
 - NodeConnectionException (base class)
 - NodeConnectionInterfaceException
 - NodeConnectionDatabaseException
 - NodeConnectionDataException
 - NodeConnectionOperationalException
 - NodeConnectionIntegrityException
 - NodeConnectionInternalException
 - NodeConnectionProgrammingException
 - NodeConnectionNotSupportedException
 - NodeConnectionQueryCanceledException
 - NodeConnectionTransactionRollbackException
 - NodeConnectionArrayContentNotSupportedException

Author: dmitry-lipetsk

src/connection.py

@@ -1,117 +1,23 @@
 # coding: utf-8
 # we support both pg8000 and psycopg2
+
+# to backward compatibility
+from .exceptions import NodeConnectionDatabaseException as DatabaseError
+from .exceptions import NodeConnectionOperationalException as OperationalError
+from .exceptions import NodeConnectionInternalException as InternalError
+from .exceptions import NodeConnectionProgrammingException as ProgrammingError
+
 try:
-    import psycopg2 as pglib
+    from .impl.connection_psycopg2 import NodeConnection, pglib
 except ImportError:
     try:
-        import pg8000 as pglib
+        from .impl.connection_pg8000 import NodeConnection, pglib
     except ImportError:
         raise ImportError("You must have psycopg2 or pg8000 modules installed")
 
-from .enums import IsolationLevel
-
-from .defaults import \
-    default_dbname, \
-    default_username2
-
-from .exceptions import QueryException
-
-# export some exceptions
-DatabaseError = pglib.DatabaseError
-InternalError = pglib.InternalError
-ProgrammingError = pglib.ProgrammingError
-OperationalError = pglib.OperationalError
-
-
-class NodeConnection:
-    """
-    Transaction wrapper returned by Node
-    """
-    def __init__(self,
-                 node,
-                 dbname=None,
-                 username=None,
-                 password=None,
-                 autocommit=False):
-
-        # Set default arguments
-        dbname = dbname or default_dbname()
-        username = username or default_username2(node.os_ops)
-
-        self._node = node
-
-        self._connection = pglib.connect(
-            database=dbname,
-            user=username,
-            password=password,
-            host=node.host,
-            port=node.port
-        )
-
-        self._connection.autocommit = autocommit
-        self._cursor = self.connection.cursor()
-
-    @property
-    def node(self):
-        return self._node
-
-    @property
-    def connection(self):
-        return self._connection
-
-    @property
-    def pid(self):
-        return self.execute("select pg_catalog.pg_backend_pid()")[0][0]
-
-    @property
-    def cursor(self):
-        return self._cursor
-
-    def __enter__(self):
-        return self
-
-    def __exit__(self, type, value, traceback):
-        self.close()
-
-    def begin(self, isolation_level=IsolationLevel.ReadCommitted):
-        # Check if level isn't an IsolationLevel
-        if not isinstance(isolation_level, IsolationLevel):
-            # Get name of isolation level
-            level_str = str(isolation_level).lower()
-
-            # Validate level string
-            try:
-                isolation_level = IsolationLevel(level_str)
-            except ValueError:
-                error = 'Invalid isolation level "{}"'
-                raise QueryException(error.format(level_str))
-
-        # Set isolation level
-        cmd = 'SET TRANSACTION ISOLATION LEVEL {}'
-        self.cursor.execute(cmd.format(isolation_level.value))
-
-        return self
-
-    def commit(self):
-        self.connection.commit()
-
-        return self
-
-    def rollback(self):
-        self.connection.rollback()
-
-        return self
-
-    def execute(self, query, *args):
-        self.cursor.execute(query, args)
-
-        if self.cursor.description is None:
-            return None
-
-        # pg8000 might return tuples
-        res = [tuple(t) for t in self.cursor.fetchall()]
-        return res
-
-    def close(self):
-        self.cursor.close()
-        self.connection.close()
+assert DatabaseError.__name__ == "NodeConnectionDatabaseException"
+assert OperationalError.__name__ == "NodeConnectionOperationalException"
+assert InternalError.__name__ == "NodeConnectionInternalException"
+assert ProgrammingError.__name__ == "NodeConnectionProgrammingException"
+assert NodeConnection.__name__ == "NodeConnection"
+assert pglib is not None

src/exceptions.py

@@ -302,6 +302,85 @@ def __repr__(self) -> str:
         return result
 
 
+class NodeConnectionException(TestgresException):
+    _message: typing.Optional[str]
+
+    def __init__(
+        self,
+        message: typing.Optional[str] = None,
+    ):
+        assert message is None or type(message) is str
+        super().__init__(message)
+        self._message = message
+        return
+
+    @property
+    def message(self) -> str:
+        assert self._message is None or type(self._message) is str
+        if self._message is None:
+            return ""
+        return self._message
+
+    def __repr__(self) -> str:
+        args = []
+
+        if self._message is not None:
+            args.append(("message", self._message))
+
+        result = "{}(".format(type(self).__name__)
+        sep = ""
+        for a in args:
+            result += sep + a[0] + "=" + repr(a[1])
+            sep = ", "
+            continue
+        result += ")"
+        return result
+
+
+class NodeConnectionInterfaceException(NodeConnectionException):
+    pass
+
+
+class NodeConnectionDatabaseException(NodeConnectionException):
+    pass
+
+
+class NodeConnectionDataException(NodeConnectionDatabaseException):
+    pass
+
+
+class NodeConnectionOperationalException(NodeConnectionDatabaseException):
+    pass
+
+
+class NodeConnectionIntegrityException(NodeConnectionDatabaseException):
+    pass
+
+
+class NodeConnectionInternalException(NodeConnectionDatabaseException):
+    pass
+
+
+class NodeConnectionProgrammingException(NodeConnectionDatabaseException):
+    pass
+
+
+class NodeConnectionNotSupportedException(NodeConnectionDatabaseException):
+    pass
+
+
+class NodeConnectionQueryCanceledException(NodeConnectionOperationalException):
+    pass
+
+
+class NodeConnectionTransactionRollbackException(NodeConnectionOperationalException):
+    pass
+
+
+class NodeConnectionArrayContentNotSupportedException(NodeConnectionNotSupportedException):
+    pass
+
+
 assert ExecUtilException.__name__ == "ExecUtilException"
 assert InvalidOperationException.__name__ == "InvalidOperationException"
 assert ExecTimeoutException.__name__ == "ExecTimeoutException"