From 29ae9aef92e03c640a3d14a5591d98fcab8851e3 Mon Sep 17 00:00:00 2001 From: David Arthur Date: Mon, 24 Sep 2012 09:01:29 -0400 Subject: Setting up a stand-alone repository for this --- LICENSE | 203 ++++++++++++++++++++++++++ README.md | 75 ++++++++++ example.py | 29 ++++ kafka.py | 475 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 782 insertions(+) create mode 100644 LICENSE create mode 100644 README.md create mode 100644 example.py create mode 100644 kafka.py diff --git a/LICENSE b/LICENSE new file mode 100644 index 0000000..6b0b127 --- /dev/null +++ b/LICENSE @@ -0,0 +1,203 @@ + + Apache License + Version 2.0, January 2004 + http://www.apache.org/licenses/ + + TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION + + 1. 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It implements the five basic request types (and their responses): Produce, Fetch, MultiFetch, MultiProduce, and Offsets. + +Compatible with Apache Kafka 0.7x. + +# License + +Copyright 2012, David Arthur under Apache License, v2.0. See `LICENSE` + +# Usage + +## Send a message to a topic + +You need to specify the topic and partition + + kafka = KafkaClient("localhost", 9092) + kafka.send_messages_simple("my-topic", 0, "some message") + kafka.close() + +## Send several messages to a topic + +Same as before, just add more arguments to `send_simple` + + kafka = KafkaClient("localhost", 9092) + kafka.send_messages_simple("my-topic", 0, "some message", "another message", "and another") + kafka.close() + +## Recieve some messages from a topic + +Supply `get_message_set` with a `FetchRequest`, get back the messages and new `FetchRequest` + + kafka = KafkaClient("localhost", 9092) + req = FetchRequest("my-topic", 0, 0, 1024*1024) + (messages, req1) = kafka.get_message_set(req) + kafka.close() + +The returned `FetchRequest` includes the offset of the next message. This makes +paging through the queue very simple. + +## Send multiple messages to multiple topics + +For this we use the `send_multi_message_set` method along with `ProduceRequest` objects. + + kafka = KafkaClient("localhost", 9092) + req1 = ProduceRequest("my-topic-1", 0, [ + create_message_from_string("message one"), + create_message_from_string("message two") + ]) + req2 = ProduceRequest("my-topic-2", 0, [ + create_message_from_string("nachricht ein"), + create_message_from_string("nachricht zwei") + ]) + kafka.sent_multi_message_set([req1, req1]) + kafka.close() + +## Iterate through all messages from an offset + +The `iter_messages` method will make the underlying calls to `get_message_set` +to provide a generator that returns every message available. + + kafka = KafkaClient("localhost", 9092) + for msg in kafka.iter_messages(FetchRequest("my-topic", 0, 0, 1024*1024)): + print(msg.payload) + kafka.close() + +An optional `auto` argument will control auto-paging through results + + kafka = KafkaClient("localhost", 9092) + for msg in kafka.iter_messages(FetchRequest("my-topic", 0, 0, 1024*1024), False): + print(msg.payload) + kafka.close() + +This will only iterate through messages in the first byte range of +(0, 1024\*1024) diff --git a/example.py b/example.py new file mode 100644 index 0000000..c58751b --- /dev/null +++ b/example.py @@ -0,0 +1,29 @@ +import logging + +from kafka import KafkaClient, FetchRequest, ProduceRequest +from kafka import create_message_from_string + +def produce_example(kafka): + message = create_message_from_string("test") + request = ProduceRequest("my-topic", 0, [message]) + print("Sending %s" % str(request)) + kafka.send_message_set(request) + +def consume_example(kafka): + request = FetchRequest("my-topic", 0, 0, 64) + print("Sending %s" % str(request)) + (messages, nextRequest) = kafka.get_message_set(request) + print("Got %d messages:" % len(messages)) + for message in messages: + print("\t%s" % message.payload) + print("Next request %s" % str(nextRequest)) + +def main(): + kafka = KafkaClient("localhost", 9092) + produce_example(kafka) + consume_example(kafka) + + +if __name__ == "__main__": + logging.basicConfig(level=logging.DEBUG) + main() diff --git a/kafka.py b/kafka.py new file mode 100644 index 0000000..3439238 --- /dev/null +++ b/kafka.py @@ -0,0 +1,475 @@ +from collections import namedtuple +import logging +import select +import socket +import struct +import zlib + +log = logging.getLogger("org.apache.kafka") + +def length_prefix_message(msg): + """ + Prefix a message with it's length as an int + """ + return struct.pack('>i', len(msg)) + msg + + +def create_message_from_string(payload): + return Message(1, 0, zlib.crc32(payload), payload) + +error_codes = { + -1: "UnknownError", + 0: None, + 1: "OffsetOutOfRange", + 2: "InvalidMessage", + 3: "WrongPartition", + 4: "InvalidFetchSize" +} + +class KafkaException(Exception): + def __init__(self, errorType): + self.errorType = errorType + def __str__(self): + return str(errorType) + + +Message = namedtuple("Message", ["magic", "attributes", "crc", "payload"]) +FetchRequest = namedtuple("FetchRequest", ["topic", "partition", "offset", "size"]) +ProduceRequest = namedtuple("ProduceRequest", ["topic", "partition", "messages"]) +OffsetRequest = namedtuple("OffsetRequest", ["topic", "partition", "time", "maxOffsets"]) + +class KafkaClient(object): + """ + Request Structure + ================= + + ::= + ::= + ::= 0 | 1 | 2 | 3 | 4 + ::= | | | | + + Response Structure + ================== + + ::= + ::= + ::= -1 | 0 | 1 | 2 | 3 | 4 + ::= | | | | + + Messages are big-endian byte order + """ + + PRODUCE_KEY = 0 + FETCH_KEY = 1 + MULTIFETCH_KEY = 2 + MULTIPRODUCE_KEY = 3 + OFFSET_KEY = 4 + + def __init__(self, host, port): + self.host = host + self.port = port + self._sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) + self._sock.connect((host, port)) + log.debug("Connected to %s on %d", host, port) + + ###################### + # Protocol Stuff # + ###################### + + def _consume_response_iter(self): + """ + This method handles the response header and error messages. It + then returns an iterator for the chunks of the response + """ + log.debug("Handling response from Kafka") + # Header + resp = self._sock.recv(6) + if resp == "": + raise Exception("Got no response from Kafka") + (size, err) = struct.unpack('>iH', resp) + + log.debug("About to read %d bytes from Kafka", size-2) + # Handle error + error = error_codes.get(err) + if error is not None: + raise KafkaException(error) + + # Response iterator + total = 0 + while total < (size-2): + resp = self._sock.recv(1024) + log.debug("Read %d bytes from Kafka", len(resp)) + if resp == "": + raise Exception("Underflow") + total += len(resp) + yield resp + + def _consume_response(self): + """ + Fully consumer the response iterator + """ + data = "" + for chunk in self._consume_response_iter(): + data += chunk + return data + + + def create_message(self, message): + """ + Create a Message from a Message tuple + + Params + ====== + message: Message + + Wire Format + =========== + ::= | + ::= 0 + ::= 1 + ::= + ::= + ::= + ::= + ::= + ::= + + The crc is a crc32 checksum of the message payload. The attributes are bitmask + used for indicating the compression algorithm. + """ + if message.magic == 0: + return struct.pack('>Bi%ds' % len(message.payload), + message.magic, message.crc, message.payload) + elif message.magic == 1: + return struct.pack('>BBi%ds' % len(message.payload), + message.magic, message.attributes, message.crc, message.payload) + else: + raise Exception("Unknown message version: %d" % message.magic) + + def create_message_set(self, messages): + message_set = "" + for message in messages: + encoded_message = self.create_message(message) + message_set += length_prefix_message(encoded_message) + return message_set + + def create_produce_request(self, produceRequest): + """ + Create a ProduceRequest + + Wire Format + =========== + ::= + ::= 0 + ::= + ::= + ::= + ::= + + The request-key (0) is encoded as a short (int16). len is the length of the proceeding MessageSet + """ + (topic, partition, messages) = produceRequest + message_set = self.create_message_set(messages) + req = struct.pack('>HH%dsii%ds' % (len(topic), len(message_set)), + KafkaClient.PRODUCE_KEY, len(topic), topic, partition, len(message_set), message_set) + return req + + def create_multi_produce_request(self, produceRequests): + req = struct.pack('>HH', KafkaClient.MULTIPRODUCE_KEY, len(produceRequests)) + for (topic, partition, messages) in produceRequests: + message_set = self.create_message_set(messages) + req += struct.pack('>H%dsii%ds' % (len(topic), len(message_set)), + len(topic), topic, partition, len(message_set), message_set) + return req + + def create_fetch_request(self, fetchRequest): + """ + Create a FetchRequest message + + Wire Format + =========== + ::= + ::= 1 + ::= + ::= + ::= + ::= + ::= + + The request-key (1) is encoded as a short (int16). + """ + (topic, partition, offset, size) = fetchRequest + req = struct.pack('>HH%dsiqi' % len(topic), + KafkaClient.FETCH_KEY, len(topic), topic, partition, offset, size) + return req + + def create_multi_fetch_request(self, fetchRequests): + """ + Create the MultiFetchRequest message from a list of FetchRequest objects + + Params + ====== + fetchRequests: list of FetchRequest + + Returns + ======= + req: bytes, The message to send to Kafka + + Wire Format + =========== + ::= [ ] + ::= 2 + ::= + ::= [ ] + ::= + ::= + ::= + ::= + ::= + ::= + + The request-key (2) is encoded as a short (int16). + """ + req = struct.pack('>HH', KafkaClient.MULTIFETCH_KEY, len(fetchRequests)) + for (topic, partition, offset, size) in fetchRequests: + req += struct.pack('>H%dsiqi' % len(topic), len(topic), topic, partition, offset, size) + return req + + def create_offset_request(self, offsetRequest): + """ + Create an OffsetRequest message + + Wire Format + =========== + ::=