Synnefo

#

# Business Logic for all Credit related activity

#

# Copyright 2010 Greek Research and Technology Network

#

from datetime import datetime

from db.models import Debit, FlavorCost

from django.db import transaction

@transaction.commit_on_success

def debit_account(user , amount, vm, description):

    """Charges the user with the specified amount of credits for a vm (resource)"""

    date_now = datetime.now()

    user.credit = user.credit - amount

    user.save()

    # then write the debit entry

    debit = Debit()

    debit.user = user

    debit.vm = vm

    debit.when = date_now

    debit.description = description

    debit.save()

@transaction.commit_on_success

def credit_account(self, amount, creditor, description):

    """No clue :)"""

    return

@transaction.commit_on_success

def charge(vm):

    """Charges the owner of this VM.

    Charges the owner of a VM for the period

    from vm.charged to datetime.now(), based on the

    current operating state.

    """

    charged_states = ('STARTED', 'STOPPED')

    start_datetime = vm.charged

    vm.charged = datetime.now()

    # Only charge for a specific set of states

    if vm.operstate in charged_states:

        cost_list = []

        # remember, we charge only for Started and Stopped

        if vm.operstate == 'STARTED':

            cost_list = get_cost_active(vm.flavor, start_datetime, vm.charged)

        elif vm.operstate == 'STOPPED':

            cost_list = get_cost_inactive(vm.flavor, start_datetime, vm.charged)

        # find the total vost

        total_cost = sum([x[1] for x in cost_list])

        # add the debit entry

        description = "Server = %s, charge = %d for state: %s" % (vm.name, total_cost, vm.operstate)

        debit_account(vm.owner, total_cost, vm, description)

    vm.save()

def get_costs(vm, start_datetime, end_datetime, active):

    """Return a list with FlavorCost objects for the specified duration"""

    def between(enh_fc, a_date):

        """Checks if a date is between a FlavorCost duration"""

        if enh_fc.effective_from <= a_date and enh_fc.effective_to is None:

            return True

        return enh_fc.effective_from <= a_date and enh_fc.effective_to >= a_date

    # Get the related FlavorCost objects, sorted.

    price_list = FlavorCost.objects.filter(flavor=vm).order_by('effective_from')

    # add the extra field FlavorCost.effective_to

    for idx in range(0, len(price_list)):

        if idx + 1 == len(price_list):

            price_list[idx].effective_to = None

        else:

            price_list[idx].effective_to = price_list[idx + 1].effective_from

    price_result = []

    found_start = False

    # Find the affected FlavorCost, according to the

    # dates, and put them in price_result

    for p in price_list:

        if between(p, start_datetime):

            found_start = True

            p.effective_from = start_datetime

        if between(p, end_datetime):

            p.effective_to = end_datetime

            price_result.append(p)

            break

        if found_start:

            price_result.append(p)

    results = []

    # Create the list and the result tuples

    for p in price_result:

        if active:

            cost = p.cost_active

        else:

            cost = p.cost_inactive

        results.append( ( p.effective_from, calculate_cost(p.effective_from, p.effective_to, cost)) )

    return results

def calculate_cost(start_date, end_date, cost):

    """Calculate the total cost for the specified duration"""

    td = end_date - start_date

    sec = float(td.microseconds + (td.seconds + td.days * 24 * 3600) * 10**6) / float(10**6)

    total_hours = float(sec) / float(60.0*60.0)

    total_cost = float(cost)*total_hours

    return round(total_cost)

def get_cost_active(vm, start_datetime, end_datetime):

    """Returns a list with the active costs for the specified duration"""

    return get_costs(vm, start_datetime, end_datetime, True)

def get_cost_inactive(vm, start_datetime, end_datetime):

    """Returns a list with the inactive costs for the specified duration"""

    return get_costs(vm, start_datetime, end_datetime, False)