Stacktack overview

class Lifecycle(models.Model):
    """The Lifecycle table is the Master for a group of
    Timing detail records. There is one Lifecycle row for
    each instance seen in the event stream. The Timings
    relate to the execution time for each .start/.end event
    pair for this instance. These pairs are over the entire
    lifespan of the instance, even across multiple api requests."""
    instance = models.CharField(max_length=50, null=True,
                                blank=True, db_index=True)
    last_state = models.CharField(max_length=50, null=True,
                             blank=True, db_index=True)
    last_task_state = models.CharField(max_length=50, null=True,
                             blank=True, db_index=True)
    last_raw = models.ForeignKey(RawData, null=True)

class Timing(models.Model):
    """Each Timing record corresponds to a .start/.end event pair
    for an instance. It tracks how long it took this operation
    to execute."""
    name = models.CharField(max_length=50, db_index=True)
    lifecycle = models.ForeignKey(Lifecycle)
    start_raw = models.ForeignKey(RawData, related_name='+', null=True)
    end_raw = models.ForeignKey(RawData, related_name='+', null=True)

start_when = models.DecimalField(null=True, max_digits=20,
                                     decimal_places=6)
    end_when = models.DecimalField(null=True, max_digits=20, decimal_places=6)

diff = models.DecimalField(null=True, max_digits=20, decimal_places=6,
                               db_index=True)

def aggregate_lifecycle(raw):
    """Roll up the raw event into a Lifecycle object
    and a bunch of Timing objects.

We can use this for summarized timing reports.