Merge branch 'master' into develop

Conflicts:
	test/test_unit.py

Author: mrtheb

README.md

@@ -29,7 +29,7 @@ from kafka.client import KafkaClient
 from kafka.consumer import SimpleConsumer
 from kafka.producer import SimpleProducer, KeyedProducer
 
-kafka = KafkaClient("localhost", 9092)
+kafka = KafkaClient("localhost:9092")
 
 # To send messages synchronously
 producer = SimpleProducer(kafka)
@@ -80,7 +80,7 @@ from kafka.client import KafkaClient
 from kafka.producer import KeyedProducer
 from kafka.partitioner import HashedPartitioner, RoundRobinPartitioner
 
-kafka = KafkaClient("localhost", 9092)
+kafka = KafkaClient("localhost:9092")
 
 # HashedPartitioner is default
 producer = KeyedProducer(kafka)
@@ -95,7 +95,7 @@ producer = KeyedProducer(kafka, partitioner=RoundRobinPartitioner)
 from kafka.client import KafkaClient
 from kafka.consumer import MultiProcessConsumer
 
-kafka = KafkaClient("localhost", 9092)
+kafka = KafkaClient("localhost:9092")
 
 # This will split the number of partitions among two processes
 consumer = MultiProcessConsumer(kafka, "my-group", "my-topic", num_procs=2)
@@ -115,7 +115,7 @@ for message in consumer.get_messages(count=5, block=True, timeout=4):
 
 ```python
 from kafka.client import KafkaClient
-kafka = KafkaClient("localhost", 9092)
+kafka = KafkaClient("localhost:9092")
 req = ProduceRequest(topic="my-topic", partition=1,
     messages=[KafkaProdocol.encode_message("some message")])
 resps = kafka.send_produce_request(payloads=[req], fail_on_error=True)

example.py

@@ -14,7 +14,7 @@ def consume_example(client):
         print(message)
 
 def main():
-    client = KafkaClient("localhost", 9092)
+    client = KafkaClient("localhost:9092")
     produce_example(client)
     consume_example(client)
 

kafka/NOTES.md

@@ -18,7 +18,7 @@ There are a few levels of abstraction:
 
 # Possible API
 
-    client = KafkaClient("localhost", 9092)
+    client = KafkaClient("localhost:9092")
 
     producer = KafkaProducer(client, "topic")
     producer.send_string("hello")

kafka/__init__.py

@@ -1,5 +1,5 @@
 __title__ = 'kafka'
-__version__ = '0.2-alpha'
+__version__ = '0.9.0'
 __author__ = 'David Arthur'
 __license__ = 'Apache License 2.0'
 __copyright__ = 'Copyright 2012, David Arthur under Apache License, v2.0'

kafka/client.py

@@ -11,7 +11,7 @@
                           LeaderUnavailableError,
                           KafkaUnavailableError)
 
-from kafka.conn import KafkaConnection, DEFAULT_SOCKET_TIMEOUT_SECONDS
+from kafka.conn import collect_hosts, KafkaConnection, DEFAULT_SOCKET_TIMEOUT_SECONDS
 from kafka.protocol import KafkaProtocol
 
 log = logging.getLogger("kafka")
@@ -25,14 +25,15 @@ class KafkaClient(object):
     # NOTE: The timeout given to the client should always be greater than the
     # one passed to SimpleConsumer.get_message(), otherwise you can get a
     # socket timeout.
-    def __init__(self, host, port, client_id=CLIENT_ID,
+    def __init__(self, hosts, client_id=CLIENT_ID,
                  timeout=DEFAULT_SOCKET_TIMEOUT_SECONDS):
         # We need one connection to bootstrap
         self.client_id = client_id
         self.timeout = timeout
-        self.conns = {               # (host, port) -> KafkaConnection
-            (host, port): KafkaConnection(host, port, timeout=timeout)
-        }
+        self.hosts = collect_hosts(hosts)
+
+        # create connections only when we need them
+        self.conns = {}
         self.brokers = {}            # broker_id -> BrokerMetadata
         self.topics_to_brokers = {}  # topic_id -> broker_id
         self.topic_partitions = {}   # topic_id -> [0, 1, 2, ...]
@@ -42,6 +43,15 @@ def __init__(self, host, port, client_id=CLIENT_ID,
     #   Private API  #
     ##################
 
+    def _get_conn(self, host, port):
+        "Get or create a connection to a broker using host and port"
+
+        host_key = (host, port)
+        if host_key not in self.conns:
+            self.conns[host_key] = KafkaConnection(host, port)
+
+        return self.conns[host_key]
+
     def _get_conn_for_broker(self, broker):
         """
         Get or create a connection to a broker
@@ -50,7 +60,7 @@ def _get_conn_for_broker(self, broker):
             self.conns[(broker.host, broker.port)] = \
                 KafkaConnection(broker.host, broker.port, timeout=self.timeout)
 
-        return self.conns[(broker.host, broker.port)]
+        return self._get_conn(broker.host, broker.port)
 
     def _get_leader_for_partition(self, topic, partition):
         """
@@ -83,14 +93,15 @@ def _send_broker_unaware_request(self, requestId, request):
         Attempt to send a broker-agnostic request to one of the available
         brokers. Keep trying until you succeed.
         """
-        for conn in self.conns.values():
+        for (host, port) in self.hosts:
             try:
+                conn = self._get_conn(host, port)
                 conn.send(requestId, request)
                 response = conn.recv(requestId)
                 return response
             except Exception, e:
-                log.warning("Could not send request [%r] to server %s, "
-                            "trying next server: %s" % (request, conn, e))
+                log.warning("Could not send request [%r] to server %s:%i, "
+                            "trying next server: %s" % (request, host, port, e))
                 continue
 
         raise KafkaUnavailableError("All servers failed to process request")

kafka/codec.py

@@ -1,5 +1,9 @@
 from cStringIO import StringIO
 import gzip
+import struct
+
+_XERIAL_V1_HEADER = (-126, 'S', 'N', 'A', 'P', 'P', 'Y', 0, 1, 1)
+_XERIAL_V1_FORMAT = 'bccccccBii'
 
 try:
     import snappy
@@ -36,13 +40,101 @@ def gzip_decode(payload):
     return result
 
 
-def snappy_encode(payload):
+def snappy_encode(payload, xerial_compatible=False, xerial_blocksize=32 * 1024):
+    """Encodes the given data with snappy if xerial_compatible is set then the
+       stream is encoded in a fashion compatible with the xerial snappy library
+
+       The block size (xerial_blocksize) controls how frequent the blocking occurs
+       32k is the default in the xerial library.
+
+       The format winds up being
+        +-------------+------------+--------------+------------+--------------+
+        |   Header    | Block1 len | Block1 data  | Blockn len | Blockn data  |
+        |-------------+------------+--------------+------------+--------------|
+        |  16 bytes   |  BE int32  | snappy bytes |  BE int32  | snappy bytes |
+        +-------------+------------+--------------+------------+--------------+
+
+        It is important to not that the blocksize is the amount of uncompressed
+        data presented to snappy at each block, whereas the blocklen is the
+        number of bytes that will be present in the stream, that is the
+        length will always be <= blocksize.
+    """
+
     if not _has_snappy:
         raise NotImplementedError("Snappy codec is not available")
-    return snappy.compress(payload)
+
+    if xerial_compatible:
+        def _chunker():
+            for i in xrange(0, len(payload), xerial_blocksize):
+                yield payload[i:i+xerial_blocksize]
+
+        out = StringIO()
+
+        header = ''.join([struct.pack('!' + fmt, dat) for fmt, dat
+            in zip(_XERIAL_V1_FORMAT, _XERIAL_V1_HEADER)])
+
+        out.write(header)
+        for chunk in _chunker():
+            block = snappy.compress(chunk)
+            block_size = len(block)
+            out.write(struct.pack('!i', block_size))
+            out.write(block)
+
+        out.seek(0)
+        return out.read()
+
+    else:
+        return snappy.compress(payload)
+
+
+def _detect_xerial_stream(payload):
+    """Detects if the data given might have been encoded with the blocking mode
+        of the xerial snappy library.
+
+        This mode writes a magic header of the format:
+            +--------+--------------+------------+---------+--------+
+            | Marker | Magic String | Null / Pad | Version | Compat |
+            |--------+--------------+------------+---------+--------|
+            |  byte  |   c-string   |    byte    |  int32  | int32  |
+            |--------+--------------+------------+---------+--------|
+            |  -126  |   'SNAPPY'   |     \0     |         |        |
+            +--------+--------------+------------+---------+--------+
+
+        The pad appears to be to ensure that SNAPPY is a valid cstring
+        The version is the version of this format as written by xerial,
+        in the wild this is currently 1 as such we only support v1.
+
+        Compat is there to claim the miniumum supported version that
+        can read a xerial block stream, presently in the wild this is
+        1.
+    """
+
+    if len(payload) > 16:
+        header = header = struct.unpack('!' + _XERIAL_V1_FORMAT, bytes(payload)[:16])
+        return header == _XERIAL_V1_HEADER
+    return False
 
 
 def snappy_decode(payload):
     if not _has_snappy:
         raise NotImplementedError("Snappy codec is not available")
-    return snappy.decompress(payload)
+
+    if _detect_xerial_stream(payload):
+        # TODO ? Should become a fileobj ?
+        out = StringIO()
+        byt = buffer(payload[16:])
+        length = len(byt)
+        cursor = 0
+
+        while cursor < length:
+            block_size = struct.unpack_from('!i', byt[cursor:])[0]
+            # Skip the block size
+            cursor += 4
+            end = cursor + block_size
+            out.write(snappy.decompress(byt[cursor:end]))
+            cursor = end
+
+        out.seek(0)
+        return out.read()
+    else:
+        return snappy.decompress(payload)

kafka/conn.py

@@ -2,13 +2,39 @@
 import logging
 import socket
 import struct
+from random import shuffle
 from threading import local
 
 from kafka.common import ConnectionError
 
 log = logging.getLogger("kafka")
 
 DEFAULT_SOCKET_TIMEOUT_SECONDS = 120
+DEFAULT_KAFKA_PORT = 9092
+
+
+def collect_hosts(hosts, randomize=True):
+    """
+    Collects a comma-separated set of hosts (host:port) and optionally
+    randomize the returned list.
+    """
+
+    if isinstance(hosts, str):
+        hosts = hosts.strip().split(',')
+
+    result = []
+    for host_port in hosts:
+
+        res = host_port.split(':')
+        host = res[0]
+        port = int(res[1]) if len(res) > 1 else DEFAULT_KAFKA_PORT
+        result.append((host.strip(), port))
+
+    if randomize:
+        shuffle(result)
+
+    return result
+
 
 class KafkaConnection(local):
     """
@@ -81,7 +107,7 @@ def send(self, request_id, payload):
             sent = self._sock.sendall(payload)
             if sent is not None:
                 self._raise_connection_error()
-        except socket.error, e:
+        except socket.error:
             log.exception('Unable to send payload to Kafka')
             self._raise_connection_error()
 

setup.py

@@ -4,6 +4,7 @@
 
 
 class Tox(Command):
+
     user_options = []
 
     def initialize_options(self):

test/test_integration.py

@@ -33,7 +33,7 @@ def ensure_topic_creation(client, topic_name):
 
 class KafkaTestCase(unittest.TestCase):
     def setUp(self):
-        self.topic = "%s-%s" % (self.id()[self.id().rindex(".")+1:], random_string(10))
+        self.topic = "%s-%s" % (self.id()[self.id().rindex(".") + 1:], random_string(10))
         ensure_topic_creation(self.client, self.topic)
 
 
@@ -42,7 +42,7 @@ class TestKafkaClient(KafkaTestCase):
     def setUpClass(cls):  # noqa
         cls.zk = ZookeeperFixture.instance()
         cls.server = KafkaFixture.instance(0, cls.zk.host, cls.zk.port)
-        cls.client = KafkaClient(cls.server.host, cls.server.port)
+        cls.client = KafkaClient('%s:%d' % (cls.server.host, cls.server.port))
 
     @classmethod
     def tearDownClass(cls):  # noqa
@@ -578,7 +578,7 @@ def setUpClass(cls):
         cls.zk = ZookeeperFixture.instance()
         cls.server1 = KafkaFixture.instance(0, cls.zk.host, cls.zk.port)
         cls.server2 = KafkaFixture.instance(1, cls.zk.host, cls.zk.port)
-        cls.client = KafkaClient(cls.server2.host, cls.server2.port)
+        cls.client = KafkaClient('%s:%d' % (cls.server2.host, cls.server2.port))
 
     @classmethod
     def tearDownClass(cls):  # noqa
@@ -826,23 +826,26 @@ def test_large_messages(self):
 
 class TestFailover(KafkaTestCase):
 
-    def setUp(self):
+    @classmethod
+    def setUpClass(cls):  # noqa
         zk_chroot = random_string(10)
         replicas = 2
         partitions = 2
 
         # mini zookeeper, 2 kafka brokers
-        self.zk = ZookeeperFixture.instance()
-        kk_args = [self.zk.host, self.zk.port, zk_chroot, replicas, partitions]
-        self.brokers = [KafkaFixture.instance(i, *kk_args) for i in range(replicas)]
-        self.client = KafkaClient(self.brokers[0].host, self.brokers[0].port)
-        super(TestFailover, self).setUp()
-
-    def tearDown(self):
-        self.client.close()
-        for broker in self.brokers:
+        cls.zk = ZookeeperFixture.instance()
+        kk_args = [cls.zk.host, cls.zk.port, zk_chroot, replicas, partitions]
+        cls.brokers = [KafkaFixture.instance(i, *kk_args) for i in range(replicas)]
+
+        hosts = ['%s:%d' % (b.host, b.port) for b in cls.brokers]
+        cls.client = KafkaClient(hosts)
+
+    @classmethod
+    def tearDownClass(cls):
+        cls.client.close()
+        for broker in cls.brokers:
             broker.close()
-        self.zk.close()
+        cls.zk.close()
 
     def test_switch_leader(self):
         key, topic, partition = random_string(5), self.topic, 0
@@ -918,7 +921,8 @@ def _kill_leader(self, topic, partition):
         return broker
 
     def _count_messages(self, group, topic):
-        client = KafkaClient(self.brokers[0].host, self.brokers[0].port)
+        hosts = '%s:%d' % (self.brokers[0].host, self.brokers[0].port)
+        client = KafkaClient(hosts)
         consumer = SimpleConsumer(client, group, topic, auto_commit=False, iter_timeout=0)
         all_messages = []
         for message in consumer: