~launchpad-pqm/launchpad/devel

= Bug heat view =

Bug heat is represented as four flame icons. The quantity of flames that are

coloured is dependent on the value of the heat field. The function

bugtask_heat_html is used to render the flames.

    >>> MAX_HEAT = 5000.0

    >>> from lp.testing import login, logout

    >>> from zope.security.proxy import removeSecurityProxy

    >>> from BeautifulSoup import BeautifulSoup

    >>> from lp.bugs.browser.bugtask import bugtask_heat_html

    >>> def print_flames(bugtask, target=None):

    ...     html = bugtask_heat_html(bugtask, target=target)

    ...     soup = BeautifulSoup(html)

    ...     for img in soup.span.a.contents:

    ...         print img['src']

    ...         print img['alt']

    ...         print img['title']

    >>> login('foo.bar@canonical.com')

    >>> bug = factory.makeBug()

The maximum heat is defined as a constant in browser/bug.py. A bug with

a heat of half the maximum will result in a display of two coloured flames

and two black-and-white flames.

    >>> removeSecurityProxy(bug.default_bugtask.target).max_bug_heat = MAX_HEAT

    >>> removeSecurityProxy(bug).heat = MAX_HEAT / 2

    >>> print_flames(bug.default_bugtask)

    /@@/bug-heat-2.png

    2 out of 4 heat flames

    Heat: 2500

A bug with a maximum heat will display all four flames coloured.

    >>> removeSecurityProxy(bug).heat = MAX_HEAT

    >>> print_flames(bug.default_bugtask)

    /@@/bug-heat-4.png

    4 out of 4 heat flames

    Heat: 5000

A heat of less than a quarter of the maximum will display no coloured flames.

    >>> removeSecurityProxy(bug).heat = 0.1 * MAX_HEAT

    >>> print_flames(bug.default_bugtask)

    /@@/bug-heat-0.png

    0 out of 4 heat flames

    Heat: 500

== Specifying the target ==

Some bugs can be viewed in a context different from their task's target. For

example, bugs with tasks on packages can be viewed in the context of the entire

distribution. In such cases, we want to explicitly specify the target, rather

than use the bugtask's. We can do that by passing the target as a keyword

parameter.

    >>> bug = factory.makeBug()

    >>> distro = factory.makeDistribution()

    >>> dsp = factory.makeDistributionSourcePackage(distribution=distro)

    >>> dsp_task = bug.addTask(bug.owner, dsp)

    >>> removeSecurityProxy(distro).max_bug_heat = MAX_HEAT

    >>> removeSecurityProxy(dsp).max_bug_heat = MAX_HEAT / 2

    >>> removeSecurityProxy(bug).heat = MAX_HEAT / 4

    >>> print_flames(dsp_task)

    /@@/bug-heat-2.png

    2 out of 4 heat flames

    Heat: 1250

    >>> print_flames(dsp_task, target=distro)

    /@@/bug-heat-0.png

    0 out of 4 heat flames

    Heat: 1250

    >>> logout()

== Scaling Bug Heat ==

To ensure a reasonable proportion of cold and hot bugs, the number used to

calculate the number of flames to display is not a straight-forward ratio.

Instead, we transform it by forcing low heat bugs to produce no flames and

scaling the hottest bugs logarithmically.

    >>> from lp.bugs.browser.bugtask import calculate_heat_display

    >>> from math import floor

Heat values less than a third of the maximum heat don't produce any flames.

    >>> print int(floor((300.0 / 1000.0) * 4))

    1

    >>> print calculate_heat_display(300.0, 1000.0)

    0

Heat values higher than a third of the max but lower than two thirds are treated

as a straightforward ratio.

    >>> print int(floor((500.0 / 1000.0) * 4))

    2

    >>> print calculate_heat_display(500.0, 1000.0)

    2

Heat values higher than two thirds of the maximum heat are scaled upwards.

    >>> print int(floor((700.0 / 1000.0) * 4))

    2

    >>> print calculate_heat_display(800.0, 1000.0)

    3

A max heat value of 1 works too, because we don't divide by

log(max_heat) in this case.

    >>> print calculate_heat_display(1, 1)

    4

Even if the max heat value is smaller than the heat value itself,

calculate_heat_display() does not return a value greater than 4.

    >>> print calculate_heat_display(2000, 1000)

    4