Merge pull request python-smpplib#6 from jakob-o/feature/sequence_str…

…ategy

Feature/sequence strategy

README.md

@@ -3,7 +3,6 @@ python-libsmpp
 
 SMPP library for Python. Forked from [google code](https://code.google.com/p/smpplib/).
 
-
 Example:
 ```python
 import logging
@@ -53,5 +52,15 @@ t = Thread(target=client.listen)
 t.start()
 ```
 
+The client supports setting a custom generator that produces sequence numbers for the PDU packages. Per default a simple in memory generator is used which in conclusion is reset on (re)instantiation of the client, e.g. by an application restart. If you want to keep the sequence number to be persisted across restarts you can implement your own storage backed generator.
+
+Example:
+```python
+import smpplib.client
 
+import mymodule
 
+generator = mymodule.PersistentSequenceGenerator()
+client = smpplib.client.Client('example.com', SOMEPORTNUMBER, sequence_generator=generator)
+...
+```

smpplib/client.py

@@ -33,6 +33,24 @@
 
 logger = logging.getLogger('smpplib.client')
 
+class SimpleSequenceGenerator(object):
+
+    MIN_SEQUENCE = 0x00000001
+    MAX_SEQUENCE = 0x7FFFFFFF
+
+    def __init__(self):
+        self._sequence = self.MIN_SEQUENCE
+
+    @property
+    def sequence(self):
+        return self._sequence
+
+    def next_sequence(self):
+        if self._sequence == self.MAX_SEQUENCE:
+            self._sequence = self.MIN_SEQUENCE
+        else:
+            self._sequence += 1
+        return self._sequence
 
 class Client(object):
     """SMPP client class"""
@@ -43,16 +61,19 @@ class Client(object):
     port = None
     vendor = None
     _socket = None
-    sequence = 1
+    sequence_generator = None
 
-    def __init__(self, host, port, timeout=5):
+    def __init__(self, host, port, timeout=5, sequence_generator=None):
         """Initialize"""
 
         self.host = host
         self.port = int(port)
         self._socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
         self._socket.settimeout(timeout)
         self.receiver_mode = False
+        if sequence_generator is None:
+            sequence_generator = SimpleSequenceGenerator()
+        self.sequence_generator = sequence_generator
 
     def __del__(self):
         """Disconnect when client object is destroyed"""
@@ -66,6 +87,13 @@ def __del__(self):
                     logger.warning('%s. Ignored', e)
             self.disconnect()
 
+    @property
+    def sequence(self):
+        return self.sequence_generator.sequence
+
+    def next_sequence(self):
+        return self.sequence_generator.next_sequence()
+
     def connect(self):
         """Connect to SMSC"""
 

smpplib/pdu.py

@@ -71,8 +71,7 @@ def _set_sequence(self, sequence):
 
     def _next_seq(self):
         """Return next sequence number"""
-        self._client.sequence += 1
-        return self._client.sequence
+        return self._client.next_sequence()
 
     def is_vendor(self):
         """Return True if this is a vendor PDU, False otherwise"""