Add support for zstd compression (#2021)

Author: Tincu Gabriel

.travis.yml

@@ -22,6 +22,7 @@ addons:
   apt:
     packages:
       - libsnappy-dev
+      - libzstd-dev
       - openjdk-8-jdk
 
 cache:

docs/index.rst

@@ -122,11 +122,12 @@ multiprocessing is recommended.
 Compression
 ***********
 
-kafka-python supports gzip compression/decompression natively. To produce or
-consume lz4 compressed messages, you should install python-lz4 (pip install lz4).
-To enable snappy, install python-snappy (also requires snappy library).
-See `Installation <install.html#optional-snappy-install>`_ for more information.
+kafka-python supports multiple compression types:
 
+ - gzip : supported natively
+ - lz4 : requires `python-lz4 <https://pypi.org/project/lz4/>`_ installed
+ - snappy : requires the `python-snappy <https://pypi.org/project/python-snappy/>`_  package (which requires the snappy C library)
+ - zstd : requires the `python-zstandard <https://github.com/indygreg/python-zstandard>`_ package installed
 
 Protocol
 ********

kafka/codec.py

@@ -10,12 +10,18 @@
 
 _XERIAL_V1_HEADER = (-126, b'S', b'N', b'A', b'P', b'P', b'Y', 0, 1, 1)
 _XERIAL_V1_FORMAT = 'bccccccBii'
+ZSTD_MAX_OUTPUT_SIZE = 1024 * 1024
 
 try:
     import snappy
 except ImportError:
     snappy = None
 
+try:
+    import zstandard as zstd
+except ImportError:
+    zstd = None
+
 try:
     import lz4.frame as lz4
 
@@ -58,6 +64,10 @@ def has_snappy():
     return snappy is not None
 
 
+def has_zstd():
+    return zstd is not None
+
+
 def has_lz4():
     if lz4 is not None:
         return True
@@ -299,3 +309,18 @@ def lz4_decode_old_kafka(payload):
         payload[header_size:]
     ])
     return lz4_decode(munged_payload)
+
+
+def zstd_encode(payload):
+    if not zstd:
+        raise NotImplementedError("Zstd codec is not available")
+    return zstd.ZstdCompressor().compress(payload)
+
+
+def zstd_decode(payload):
+    if not zstd:
+        raise NotImplementedError("Zstd codec is not available")
+    try:
+        return zstd.ZstdDecompressor().decompress(payload)
+    except zstd.ZstdError:
+        return zstd.ZstdDecompressor().decompress(payload, max_output_size=ZSTD_MAX_OUTPUT_SIZE)

kafka/producer/kafka.py

@@ -12,7 +12,7 @@
 
 import kafka.errors as Errors
 from kafka.client_async import KafkaClient, selectors
-from kafka.codec import has_gzip, has_snappy, has_lz4
+from kafka.codec import has_gzip, has_snappy, has_lz4, has_zstd
 from kafka.metrics import MetricConfig, Metrics
 from kafka.partitioner.default import DefaultPartitioner
 from kafka.producer.future import FutureRecordMetadata, FutureProduceResult
@@ -119,7 +119,7 @@ class KafkaProducer(object):
                 available guarantee.
             If unset, defaults to acks=1.
         compression_type (str): The compression type for all data generated by
-            the producer. Valid values are 'gzip', 'snappy', 'lz4', or None.
+            the producer. Valid values are 'gzip', 'snappy', 'lz4', 'zstd' or None.
             Compression is of full batches of data, so the efficacy of batching
             will also impact the compression ratio (more batching means better
             compression). Default: None.
@@ -339,6 +339,7 @@ class KafkaProducer(object):
         'gzip': (has_gzip, LegacyRecordBatchBuilder.CODEC_GZIP),
         'snappy': (has_snappy, LegacyRecordBatchBuilder.CODEC_SNAPPY),
         'lz4': (has_lz4, LegacyRecordBatchBuilder.CODEC_LZ4),
+        'zstd': (has_zstd, DefaultRecordBatchBuilder.CODEC_ZSTD),
         None: (lambda: True, LegacyRecordBatchBuilder.CODEC_NONE),
     }
 
@@ -388,6 +389,9 @@ def __init__(self, **configs):
         if self.config['compression_type'] == 'lz4':
             assert self.config['api_version'] >= (0, 8, 2), 'LZ4 Requires >= Kafka 0.8.2 Brokers'
 
+        if self.config['compression_type'] == 'zstd':
+            assert self.config['api_version'] >= (2, 1, 0), 'Zstd Requires >= Kafka 2.1.0 Brokers'
+
         # Check compression_type for library support
         ct = self.config['compression_type']
         if ct not in self._COMPRESSORS:

kafka/protocol/message.py

@@ -3,8 +3,8 @@
 import io
 import time
 
-from kafka.codec import (has_gzip, has_snappy, has_lz4,
-                     gzip_decode, snappy_decode,
+from kafka.codec import (has_gzip, has_snappy, has_lz4, has_zstd,
+                     gzip_decode, snappy_decode, zstd_decode,
                      lz4_decode, lz4_decode_old_kafka)
 from kafka.protocol.frame import KafkaBytes
 from kafka.protocol.struct import Struct
@@ -35,6 +35,7 @@ class Message(Struct):
     CODEC_GZIP = 0x01
     CODEC_SNAPPY = 0x02
     CODEC_LZ4 = 0x03
+    CODEC_ZSTD = 0x04
     TIMESTAMP_TYPE_MASK = 0x08
     HEADER_SIZE = 22  # crc(4), magic(1), attributes(1), timestamp(8), key+value size(4*2)
 
@@ -119,7 +120,7 @@ def is_compressed(self):
 
     def decompress(self):
         codec = self.attributes & self.CODEC_MASK
-        assert codec in (self.CODEC_GZIP, self.CODEC_SNAPPY, self.CODEC_LZ4)
+        assert codec in (self.CODEC_GZIP, self.CODEC_SNAPPY, self.CODEC_LZ4, self.CODEC_ZSTD)
         if codec == self.CODEC_GZIP:
             assert has_gzip(), 'Gzip decompression unsupported'
             raw_bytes = gzip_decode(self.value)
@@ -132,6 +133,9 @@ def decompress(self):
                 raw_bytes = lz4_decode_old_kafka(self.value)
             else:
                 raw_bytes = lz4_decode(self.value)
+        elif codec == self.CODEC_ZSTD:
+            assert has_zstd(), "ZSTD decompression unsupported"
+            raw_bytes = zstd_decode(self.value)
         else:
             raise Exception('This should be impossible')
 

kafka/record/default_records.py

@@ -62,8 +62,8 @@
 )
 from kafka.errors import CorruptRecordException, UnsupportedCodecError
 from kafka.codec import (
-    gzip_encode, snappy_encode, lz4_encode,
-    gzip_decode, snappy_decode, lz4_decode
+    gzip_encode, snappy_encode, lz4_encode, zstd_encode,
+    gzip_decode, snappy_decode, lz4_decode, zstd_decode
 )
 import kafka.codec as codecs
 
@@ -97,6 +97,7 @@ class DefaultRecordBase(object):
     CODEC_GZIP = 0x01
     CODEC_SNAPPY = 0x02
     CODEC_LZ4 = 0x03
+    CODEC_ZSTD = 0x04
     TIMESTAMP_TYPE_MASK = 0x08
     TRANSACTIONAL_MASK = 0x10
     CONTROL_MASK = 0x20
@@ -111,6 +112,8 @@ def _assert_has_codec(self, compression_type):
             checker, name = codecs.has_snappy, "snappy"
         elif compression_type == self.CODEC_LZ4:
             checker, name = codecs.has_lz4, "lz4"
+        elif compression_type == self.CODEC_ZSTD:
+            checker, name = codecs.has_zstd, "zstd"
         if not checker():
             raise UnsupportedCodecError(
                 "Libraries for {} compression codec not found".format(name))
@@ -185,6 +188,8 @@ def _maybe_uncompress(self):
                     uncompressed = snappy_decode(data.tobytes())
                 if compression_type == self.CODEC_LZ4:
                     uncompressed = lz4_decode(data.tobytes())
+                if compression_type == self.CODEC_ZSTD:
+                    uncompressed = zstd_decode(data.tobytes())
                 self._buffer = bytearray(uncompressed)
                 self._pos = 0
         self._decompressed = True
@@ -517,6 +522,8 @@ def _maybe_compress(self):
                 compressed = snappy_encode(data)
             elif self._compression_type == self.CODEC_LZ4:
                 compressed = lz4_encode(data)
+            elif self._compression_type == self.CODEC_ZSTD:
+                compressed = zstd_encode(data)
             compressed_size = len(compressed)
             if len(data) <= compressed_size:
                 # We did not get any benefit from compression, lets send

kafka/record/memory_records.py

@@ -117,7 +117,7 @@ class MemoryRecordsBuilder(object):
 
     def __init__(self, magic, compression_type, batch_size):
         assert magic in [0, 1, 2], "Not supported magic"
-        assert compression_type in [0, 1, 2, 3], "Not valid compression type"
+        assert compression_type in [0, 1, 2, 3, 4], "Not valid compression type"
         if magic >= 2:
             self._builder = DefaultRecordBatchBuilder(
                 magic=magic, compression_type=compression_type,

test/test_codec.py

@@ -7,11 +7,12 @@
 from kafka.vendor.six.moves import range
 
 from kafka.codec import (
-    has_snappy, has_lz4,
+    has_snappy, has_lz4, has_zstd,
     gzip_encode, gzip_decode,
     snappy_encode, snappy_decode,
     lz4_encode, lz4_decode,
     lz4_encode_old_kafka, lz4_decode_old_kafka,
+    zstd_encode, zstd_decode,
 )
 
 from test.testutil import random_string
@@ -113,3 +114,11 @@ def test_lz4_incremental():
         b2 = lz4_decode(lz4_encode(b1))
         assert len(b1) == len(b2)
         assert b1 == b2
+
+
+@pytest.mark.skipif(not has_zstd(), reason="Zstd not available")
+def test_zstd():
+    for _ in range(1000):
+        b1 = random_string(100).encode('utf-8')
+        b2 = zstd_decode(zstd_encode(b1))
+        assert b1 == b2

test/test_producer.py

@@ -23,16 +23,16 @@ def test_buffer_pool():
 
 
 @pytest.mark.skipif(not env_kafka_version(), reason="No KAFKA_VERSION set")
-@pytest.mark.parametrize("compression", [None, 'gzip', 'snappy', 'lz4'])
+@pytest.mark.parametrize("compression", [None, 'gzip', 'snappy', 'lz4', 'zstd'])
 def test_end_to_end(kafka_broker, compression):
-
     if compression == 'lz4':
-        # LZ4 requires 0.8.2
         if env_kafka_version() < (0, 8, 2):
-            return
-        # python-lz4 crashes on older versions of pypy
+            pytest.skip('LZ4 requires 0.8.2')
         elif platform.python_implementation() == 'PyPy':
-            return
+            pytest.skip('python-lz4 crashes on older versions of pypy')
+
+    if compression == 'zstd' and env_kafka_version() < (2, 1, 0):
+        pytest.skip('zstd requires kafka 2.1.0 or newer')
 
     connect_str = ':'.join([kafka_broker.host, str(kafka_broker.port)])
     producer = KafkaProducer(bootstrap_servers=connect_str,
@@ -81,8 +81,10 @@ def test_kafka_producer_gc_cleanup():
 
 
 @pytest.mark.skipif(not env_kafka_version(), reason="No KAFKA_VERSION set")
-@pytest.mark.parametrize("compression", [None, 'gzip', 'snappy', 'lz4'])
+@pytest.mark.parametrize("compression", [None, 'gzip', 'snappy', 'lz4', 'zstd'])
 def test_kafka_producer_proper_record_metadata(kafka_broker, compression):
+    if compression == 'zstd' and env_kafka_version() < (2, 1, 0):
+        pytest.skip('zstd requires 2.1.0 or more')
     connect_str = ':'.join([kafka_broker.host, str(kafka_broker.port)])
     producer = KafkaProducer(bootstrap_servers=connect_str,
                              retries=5,
@@ -124,10 +126,8 @@ def test_kafka_producer_proper_record_metadata(kafka_broker, compression):
     if headers:
         assert record.serialized_header_size == 22
 
-    # generated timestamp case is skipped for broker 0.9 and below
     if magic == 0:
-        return
-
+        pytest.skip('generated timestamp case is skipped for broker 0.9 and below')
     send_time = time.time() * 1000
     future = producer.send(
         topic,

tox.ini

@@ -15,6 +15,7 @@ deps =
     pytest-mock
     mock
     python-snappy
+    zstandard
     lz4
     xxhash
     crc32c