Add compression

src/decentralizepy/communication/TCP.py

 import json
 import logging
+import lzma
 import pickle
 from collections import deque
 
@@ -38,7 +39,9 @@ class TCP(Communication):
         port = rank + 20000
         return "tcp://{}:{}".format(machine_addr, port)
 
-    def __init__(self, rank, machine_id, mapping, total_procs, addresses_filepath):
+    def __init__(
+        self, rank, machine_id, mapping, total_procs, addresses_filepath, compress=False
+    ):
         """
         Constructor
 
@@ -72,6 +75,7 @@ class TCP(Communication):
         self.router.setsockopt(zmq.IDENTITY, self.identity)
         self.router.bind(self.addr(rank, machine_id))
         self.sent_disconnections = False
+        self.compress = compress
 
         self.peer_deque = deque()
         self.peer_sockets = dict()
@@ -99,7 +103,13 @@ class TCP(Communication):
             Encoded data
 
         """
-        return pickle.dumps(data)
+        if self.compress:
+            compressor = lzma.LZMACompressor()
+            output = compressor.compress(pickle.dumps(data)) + compressor.flush()
+        else:
+            output = pickle.dumps(data)
+
+        return output
 
     def decrypt(self, sender, data):
         """
@@ -119,7 +129,10 @@ class TCP(Communication):
 
         """
         sender = int(sender.decode())
-        data = pickle.loads(data)
+        if self.compress:
+            data = pickle.loads(lzma.decompress(data))
+        else:
+            data = pickle.loads(data)
         return sender, data
 
     def connect_neighbors(self, neighbors):