gpMgmt/sbin/gpoperation.py

#!/usr/bin/env python3
import sys
import pickle
import traceback


class NullDevice():
    def write(self, s):
        pass
    def flush(self):
        pass


# Prevent use of stdout, as it disrupts pickling mechanism
old_stdout = sys.stdout
sys.stdout = NullDevice()

# log initialization must be done only AFTER rerouting stdout
from gppylib import gplog
from gppylib.mainUtils import getProgramName
from gppylib.commands import unix

hostname = unix.getLocalHostname()
username = unix.getUserName()
execname = pickle.load(sys.stdin.buffer)
gplog.setup_tool_logging(execname, hostname, username)
logger = gplog.get_default_logger()

operation = pickle.load(sys.stdin.buffer)

try:
    ret = operation.run()
except Exception as e:
    exc_type, exc_value, exc_traceback = sys.exc_info()
    tb_list = traceback.extract_tb(exc_traceback)
    try:
        # TODO: Build an ExceptionCapsule that can return the traceback
        # to RemoteOperation as well. See Pyro.

        # logger.exception(e)               # logging 'e' could be necessary for traceback

        pickled_ret = pickle.dumps(e) # Pickle exception for stdout transmission
    except Exception as f:
        # logger.exception(f)               # 'f' is not important to us, except for debugging perhaps

        # No hope of pickling a precise Exception back to RemoteOperation.
        # So, provide meaningful trace as text and provide a non-zero return code
        # to signal to RemoteOperation that its Command invocation of gpoperation.py has failed.
        pretty_trace = str(e) + "\n"
        pretty_trace += 'Traceback (most recent call last):\n'
        pretty_trace += ''.join(traceback.format_list(tb_list))
        logger.critical(pretty_trace)
        print(pretty_trace, file=sys.stderr)
        sys.exit(2)  # signal that gpoperation.py has hit unexpected error
else:
    pickled_ret = pickle.dumps(ret)

sys.stdout = old_stdout
sys.stdout.buffer.write(pickled_ret)
sys.exit(0)