Files
sf_daq_buffer/epics-writer/epics_writer/start.py
T
2020-08-12 16:01:02 +02:00

100 lines
2.9 KiB
Python

import json
from pika import BlockingConnection, ConnectionParameters, BasicProperties
from epics_writer.writer import write_epics_pvs
DEFAULT_BROKER_URL = "127.0.0.1"
REQUEST_EXCHANGE = "request"
STATUS_EXCHANGE = "status"
QUEUE_NAME = "epics"
OUTPUT_FILE_SUFFIX = ".PVCHANNELS.h5"
def update_status(channel, body, action, file, message=None):
status_header = {
"action": action,
"source": "epics_writer",
"routing_key": QUEUE_NAME,
"file": file,
"message": message
}
channel.basic_publish(exchange=STATUS_EXCHANGE,
properties=BasicProperties(
headers=status_header),
routing_key="",
body=body)
def on_message(channel, method_frame, header_frame, body):
output_file = None
try:
request = json.loads(body.decode())
output_prefix = request["output_prefix"]
start_pulse_id = 1
stop_pulse_id = 10
metadata = request["metadata"]
epics_pvs = request["epics_pvs"]
output_file = output_prefix + OUTPUT_FILE_SUFFIX
update_status(channel, body, "write_start", output_file)
write_epics_pvs(output_file=output_file,
start_pulse_id=start_pulse_id,
stop_pulse_id=stop_pulse_id,
metadata=metadata,
epics_pvs=epics_pvs)
except Exception as e:
channel.basic_reject(delivery_tag=method_frame.delivery_tag,
requeue=False)
update_status(channel, body, "write_rejected", output_file, str(e))
else:
channel.basic_ack(delivery_tag=method_frame.delivery_tag)
update_status(channel, body, "write_finished", output_file)
def connect_to_broker(broker_url):
connection = BlockingConnection(ConnectionParameters(broker_url))
channel = connection.channel()
channel.exchange_declare(exchange=STATUS_EXCHANGE,
exchange_type="fanout")
channel.exchange_declare(exchange=REQUEST_EXCHANGE,
exchange_type="topic")
channel.queue_declare(queue=QUEUE_NAME, auto_delete=True)
channel.queue_bind(queue=QUEUE_NAME,
exchange=REQUEST_EXCHANGE,
routing_key="*.%s.*" % QUEUE_NAME)
channel.basic_qos(prefetch_count=1)
channel.basic_consume(QUEUE_NAME, on_message)
try:
channel.start_consuming()
except KeyboardInterrupt:
channel.stop_consuming()
def main():
import argparse
parser = argparse.ArgumentParser(description='Epics HDF5 writer')
parser.add_argument('--broker_url', dest='broker_url',
default=DEFAULT_BROKER_URL,
help='RabbitMQ broker URL')
args = parser.parse_args()
connect_to_broker(broker_url=args.broker_url)
if __name__ == '__main__':
main()