troggle/core/utils.py

import string
import os
import datetime
import re
import resource
import random
import logging
from subprocess import call

from urllib.parse import urljoin
from decimal import Decimal, getcontext
getcontext().prec=2 #use 2 significant figures for decimal calculations

import settings

from django.db import models
from django.contrib import admin
from django.contrib.auth.models import User
from django.contrib.contenttypes.models import ContentType
from django.conf import settings

from django.urls import reverse
from django.template import Context, loader

'''This file declares TROG a globally visible object for caches.

TROG is a dictionary holding gloablly visible indexes and cache functions.
It is a Global Object, see https://python-patterns.guide/python/module-globals/
troggle.utils.TROG

chaosmonkey(n) - used by survex import to regenerate some .3d files
save_carefully() - core function that saves troggle objects in the database

'''

TROG = {
    'pagecache' : {
        'expedition' : {}
    }
}

# This is module-level executable. This is a Bad Thing. Especially when it touches the file system.
try:
    logging.basicConfig(level=logging.DEBUG,
        filename=settings.LOGFILE,
        filemode='w')
except:
    # Opening of file for writing is going to fail currently, so decide it doesn't matter for now    
    pass

def get_process_memory():
    usage=resource.getrusage(resource.RUSAGE_SELF)
    return usage[2]/1024.0 

def chaosmonkey(n):
    # returns True once every n calls - randomly
    if random.randrange(0,n) != 0:
        return False
    # print("CHAOS strikes !", file=sys.stderr)
    return True


def save_carefully(objectType, lookupAttribs={}, nonLookupAttribs={}):
    """Looks up instance using lookupAttribs and carries out the following:
            -if instance does not exist in DB: add instance to DB, return (new instance, True)
            -if instance exists in DB and was modified using Troggle: do nothing, return (existing instance, False)
            -if instance exists in DB and was not modified using Troggle: overwrite instance, return (instance, False)
            
        The checking is accomplished using Django's get_or_create and the new_since_parsing boolean field
        defined in core.models.TroggleModel.
    
    """
    try:
        instance, created = objectType.objects.get_or_create(defaults=nonLookupAttribs, **lookupAttribs)
    except:
        print(" !! - SAVE CAREFULLY   ===================", objectType)
        print(" !! - -- objects.get_or_create()")
        print(" !! - lookupAttribs:{}\n !! - nonLookupAttribs:{}".format(lookupAttribs,nonLookupAttribs))
        raise
    if not created and not instance.new_since_parsing:
        for k, v in list(nonLookupAttribs.items()): #overwrite the existing attributes from the logbook text (except date and title)
            setattr(instance, k, v)
        try:
            instance.save()
        except:
            print(" !! - SAVE CAREFULLY   ===================", objectType)
            print(" !! - -- instance.save()")
            print(" !! - lookupAttribs:{}\n !! - nonLookupAttribs:{}".format(lookupAttribs,nonLookupAttribs))
            raise
    try:
        msg = str(instance)
    except:
        msg = "FAULT getting __str__ for instance with lookupattribs: {}:".format(lookupAttribs)
    if created:
        logging.info(str(instance) + ' was just added to the database for the first time. \n')
    
    if not created and instance.new_since_parsing:
        logging.info(str(instance) + " has been modified using Troggle, so the current script left it as is. \n")

    if not created and not instance.new_since_parsing:
        logging.info(str(instance) + " existed in the database unchanged since last parse. It was overwritten by the current script. \n")
    return (instance, created)