Support message decompression

kafka/consumer/fetcher.py

@@ -299,15 +299,7 @@ class Fetcher(object):
                           " and update consumed position to %s", tp, next_offset)
                 self._subscriptions.assignment[tp].consumed = next_offset
 
-                # TODO: handle compressed messages
-                for offset, size, msg in messages:
-                    if msg.attributes:
-                        raise Errors.KafkaError('Compressed messages not supported yet')
-                    elif self.config['check_crcs'] and not msg.validate_crc():
-                        raise Errors.InvalidMessageError(msg)
-
-                    key, value = self._deserialize(msg)
-                    record = ConsumerRecord(tp.topic, tp.partition, offset, key, value)
+                for record in self._unpack_message_set(tp, messages):
                     drained[tp].append(record)
             else:
                 # these records aren't next in line based on the last consumed
@@ -316,6 +308,17 @@ class Fetcher(object):
                           tp, fetch_offset)
         return dict(drained)
 
+    def _unpack_message_set(self, tp, messages):
+        for offset, size, msg in messages:
+            if self.config['check_crcs'] and not msg.validate_crc():
+                raise Errors.InvalidMessageError(msg)
+            elif msg.is_compressed():
+                for record in self._unpack_message_set(tp, msg.decompress()):
+                    yield record
+            else:
+                key, value = self._deserialize(msg)
+                yield ConsumerRecord(tp.topic, tp.partition, offset, key, value)
+
     def __iter__(self):
         """Iterate over fetched_records"""
         if self._subscriptions.needs_partition_assignment:
@@ -349,16 +352,9 @@ class Fetcher(object):
                 self._subscriptions.assignment[tp].fetched = consumed
 
             elif fetch_offset == consumed:
-                # TODO: handle compressed messages
-                for offset, size, msg in messages:
-                    if msg.attributes:
-                        raise Errors.KafkaError('Compressed messages not supported yet')
-                    elif self.config['check_crcs'] and not msg.validate_crc():
-                        raise Errors.InvalidMessageError(msg)
-
-                    self._subscriptions.assignment[tp].consumed = offset + 1
-                    key, value = self._deserialize(msg)
-                    yield ConsumerRecord(tp.topic, tp.partition, offset, key, value)
+                for msg in self._unpack_message_set(tp, messages):
+                    self._subscriptions.assignment[tp].consumed = msg.offset + 1
+                    yield msg
             else:
                 # these records aren't next in line based on the last consumed
                 # position, ignore them they must be from an obsolete request

kafka/protocol/message.py

@@ -1,5 +1,6 @@
 import io
 
+from ..codec import gzip_decode, snappy_decode
 from . import pickle
 from .struct import Struct
 from .types import (
@@ -16,6 +17,9 @@ class Message(Struct):
         ('key', Bytes),
         ('value', Bytes)
     )
+    CODEC_MASK = 0x03
+    CODEC_GZIP = 0x01
+    CODEC_SNAPPY = 0x02
 
     def __init__(self, value, key=None, magic=0, attributes=0, crc=0):
         self.crc = crc
@@ -49,6 +53,19 @@ class Message(Struct):
             return True
         return False
 
+    def is_compressed(self):
+        return self.attributes & self.CODEC_MASK != 0
+
+    def decompress(self):
+        codec = self.attributes & self.CODEC_MASK
+        assert codec in (self.CODEC_GZIP, self.CODEC_SNAPPY)
+        if codec == self.CODEC_GZIP:
+            raw_bytes = gzip_decode(self.value)
+        else:
+            raw_bytes = snappy_decode(self.value)
+
+        return MessageSet.decode(raw_bytes, bytes_to_read=len(raw_bytes))
+
 
 class PartialMessage(bytes):
     def __repr__(self):
@@ -81,8 +98,14 @@ class MessageSet(AbstractType):
         return Int32.encode(len(encoded)) + encoded
 
     @classmethod
-    def decode(cls, data):
-        bytes_to_read = Int32.decode(data)
+    def decode(cls, data, bytes_to_read=None):
+        """Compressed messages should pass in bytes_to_read (via message size)
+        otherwise, we decode from data as Int32
+        """
+        if isinstance(data, bytes):
+            data = io.BytesIO(data)
+        if bytes_to_read is None:
+            bytes_to_read = Int32.decode(data)
         items = []
 
         # We need at least 8 + 4 + 14 bytes to read offset + message size + message