Require path setting to the Sqlite database

As the previous default value ":memory:" doesn't work as expected
because each connection opens a new database instance, make
the database path setting required.
Also, make the port setting required as it probably makes little sense
to pick 5959 as default and so we can keep the argument order
host, port.

Fixes #5.

Author: eht16

docs/config.rst

@@ -8,7 +8,10 @@ host
     The host of the Logstash server (no default)
 
 port
-    The port of the Logstash server (default 5959)
+    The port of the Logstash server (no default)
+
+database_path
+    The path to the file containing queued events (no default)
 
 transport
     Callable or path to a compatible transport class
@@ -43,9 +46,6 @@ ca_certs
     (default: None)
     Only used for `logstash_async.transport.TcpTransport`.
 
-database_path
-    The path to the file containing queued events (default: ':memory:')
-
 enable
     Flag to enable log processing (default is True, disabling
     might be handy for local testing, etc.)

logstash_async/handler.py

@@ -18,35 +18,35 @@ class ProcessingError(Exception):
 
 class AsynchronousLogstashHandler(Handler):
     """Python logging handler for Logstash. Sends events over TCP.
-    :param host: The host of the logstash server.
-    :param port: The port of the logstash server (default 5959).
+    :param host: The host of the logstash server, required.
+    :param port: The port of the logstash server, required.
+    :param database_path: The path to the file containing queued events, required.
     :param transport: Callable or path to a compatible transport class.
     :param ssl_enable: Should SSL be enabled for the connection? Default is False.
     :param ssl_verify: Should the server's SSL certificate be verified?
     :param keyfile: The path to client side SSL key file (default is None).
     :param certfile: The path to client side SSL certificate file (default is None).
     :param ca_certs: The path to the file containing recognized CA certificates.
-    :param database_path: The path to the file containing queued events.
     :param enable Flag to enable log processing (default is True, disabling
                   might be handy for local testing, etc.)
     """
 
     _worker_thread = None
 
     # ----------------------------------------------------------------------
-    def __init__(self, host, port=5959, transport='logstash_async.transport.TcpTransport',
+    def __init__(self, host, port, database_path, transport='logstash_async.transport.TcpTransport',
                  ssl_enable=False, ssl_verify=True, keyfile=None, certfile=None, ca_certs=None,
-                 database_path=':memory:', enable=True):
+                 enable=True):
         super(AsynchronousLogstashHandler, self).__init__()
         self._host = host
         self._port = port
+        self._database_path = database_path
         self._transport_path = transport
         self._ssl_enable = ssl_enable
         self._ssl_verify = ssl_verify
         self._keyfile = keyfile
         self._certfile = certfile
         self._ca_certs = ca_certs
-        self._database_path = database_path
         self._enable = enable
         self._transport = None
         self._setup_transport()