optimize util.crc32 (#1304)

Author: ofek

kafka/util.py

@@ -12,14 +12,21 @@
 from kafka.errors import BufferUnderflowError
 
 
-def crc32(data):
-    crc = binascii.crc32(data)
-    # py2 and py3 behave a little differently
-    # CRC is encoded as a signed int in kafka protocol
-    # so we'll convert the py3 unsigned result to signed
-    if six.PY3 and crc >= 2**31:
-        crc -= 2**32
-    return crc
+if six.PY3:
+    MAX_INT = 2 ** 31
+    TO_SIGNED = 2 ** 32
+
+    def crc32(data):
+        crc = binascii.crc32(data)
+        # py2 and py3 behave a little differently
+        # CRC is encoded as a signed int in kafka protocol
+        # so we'll convert the py3 unsigned result to signed
+        if crc >= MAX_INT:
+            crc -= TO_SIGNED
+        return crc
+else:
+    def crc32(data):
+        return binascii.crc32(data)
 
 
 def write_int_string(s):