# Copyright 2010 New Relic, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""This module implements a data source for generating metrics about
memory usage.

"""
import os

from newrelic.common.system_info import physical_memory_used, total_physical_memory
from newrelic.samplers.decorators import data_source_generator

PID = os.getpid()


@data_source_generator(name="Memory Usage")
def memory_usage_data_source():
    memory = physical_memory_used()
    total_memory = total_physical_memory()

    # Calculate memory utilization without 0 division errors
    memory_utilization = (memory / total_memory) if total_memory != 0 else 0

    yield ("Memory/Physical", memory)
    yield ("Memory/Physical/%d" % (PID), memory)

    yield ("Memory/Physical/Utilization", memory_utilization)
    yield ("Memory/Physical/Utilization/%d" % (PID), memory_utilization)