def _decode_message(cls, data, offset):
"""
Decode a single Message
The only caller of this method is decode_message_set_iter.
They are decoupled to support nested messages (compressed MessageSets).
The offset is actually read from decode_message_set_iter (it is part
of the MessageSet payload).
"""
((crc, magic, att), cur) = relative_unpack('>IBB', data, 0)
if crc != crc32(data[4:]):
raise ChecksumError("Message checksum failed")
(key, cur) = read_int_string(data, cur)
(value, cur) = read_int_string(data, cur)
codec = att & ATTRIBUTE_CODEC_MASK
if codec == CODEC_NONE:
yield (offset, Message(magic, att, key, value))
elif codec == CODEC_GZIP:
gz = gzip_decode(value)
for (offset, msg) in KafkaProtocol._decode_message_set_iter(gz):
yield (offset, msg)
elif codec == CODEC_SNAPPY:
snp = snappy_decode(value)
for (offset, msg) in KafkaProtocol._decode_message_set_iter(snp):
yield (offset, msg)
def create_message(payload, key=None):
"""
Construct a Message
Arguments:
payload: bytes, the payload to send to Kafka
key: bytes, a key used for partition routing (optional)
"""
return Message(0, 0, key, payload)
def create_snappy_message(payloads, key=None):
"""
Construct a Snappy Message containing multiple Messages
The given payloads will be encoded, compressed, and sent as a single atomic
message to Kafka.
Arguments:
payloads: list(bytes), a list of payload to send be sent to Kafka
key: bytes, a key used for partition routing (optional)
"""
message_set = KafkaProtocol._encode_message_set(
[create_message(payload, pl_key) for payload, pl_key in payloads])
snapped = snappy_encode(message_set)
codec = ATTRIBUTE_CODEC_MASK & CODEC_SNAPPY
return Message(0, 0x00 | codec, key, snapped)