~launchpad-pqm/launchpad/devel

#!/usr/bin/python -S

#

# Copyright 2009 Canonical Ltd.  This software is licensed under the

# GNU Affero General Public License version 3 (see the file LICENSE).

# pylint: disable-msg=C0103,W0403

import _pythonpath

from zope.component import getUtility

from canonical.config import config

from canonical.database.sqlbase import (

    ISOLATION_LEVEL_AUTOCOMMIT, flush_database_updates)

from canonical.launchpad.interfaces import IKarmaCacheManager

from lp.app.errors import NotFoundError

from lp.services.scripts.base import LaunchpadCronScript

class KarmaCacheUpdater(LaunchpadCronScript):

    def main(self):

        """Update the KarmaCache table for all valid Launchpad users.

        For each Launchpad user with a preferred email address, calculate his

        karmavalue for each category of actions we have and update his entry

        in the KarmaCache table. If a user doesn't have an entry for that

        category in KarmaCache a new one will be created.

        Entries in the KarmaTotalCache table will also be created/updated for

        each user which has entries in the KarmaCache table. Any user which

        doesn't have any entries in the KarmaCache table has its entries

        removed from the KarmaTotalCache table as well.

        """

        self.logger.info("Updating Launchpad karma caches")

        # We use the autocommit transaction isolation level to minimize

        # contention. It also allows us to not bother explicitly calling

        # COMMIT all the time. However, if we interrupt this script mid-run

        # it will need to be re-run as the data will be inconsistent (only

        # part of the caches will have been recalculated).

        self.txn.set_isolation_level(ISOLATION_LEVEL_AUTOCOMMIT)

        self.cur = self.txn.conn().cursor()

        self.karmacachemanager = getUtility(IKarmaCacheManager)

        # This method ordering needs to be preserved. In particular,

        # C_add_summed_totals method is called last because we don't want to

        # include the values added in our calculation in A_update_karmacache.

        self.A_update_karmacache()

        self.B_update_karmatotalcache()

        self.C_add_karmacache_sums()

        self.logger.info("Finished updating Launchpad karma caches")

    def A_update_karmacache(self):

        self.logger.info("Step A: Calculating individual KarmaCache entries")

        # Calculate everyones karma. Karma degrades each day, becoming

        # worthless after karma_expires_after. This query produces odd results

        # when datecreated is in the future, but there is really no point

        # adding the extra WHEN clause.

        karma_expires_after = '1 year'

        self.cur.execute("""

            SELECT person, category, product, distribution,

                ROUND(SUM(

                CASE WHEN karma.datecreated + %s::interval

                    <= CURRENT_TIMESTAMP AT TIME ZONE 'UTC' THEN 0

                ELSE points * (1 - extract(

                    EPOCH FROM CURRENT_TIMESTAMP AT TIME ZONE 'UTC' -

                    karma.datecreated

                    ) / extract(EPOCH FROM %s::interval))

                END

                ))

            FROM Karma

            JOIN KarmaAction ON action = KarmaAction.id

            GROUP BY person, category, product, distribution

            """, (karma_expires_after, karma_expires_after))

        # Suck into RAM to avoid tieing up resources on the DB.

        results = list(self.cur.fetchall())

        self.logger.debug("Got %d (person, category) scores", len(results))

        # Note that we don't need to commit each iteration because we are

        # running in autocommit mode.

        scaling = self.calculate_scaling(results)

        for entry in results:

            self.update_one_karma_cache_entry(entry, scaling)

        flush_database_updates()

        # Delete the entries we're going to replace.

        self.cur.execute("DELETE FROM KarmaCache WHERE category IS NULL")

        self.cur.execute("""

            DELETE FROM KarmaCache

            WHERE project IS NOT NULL AND product IS NULL""")

        self.cur.execute("""

            DELETE FROM KarmaCache

            WHERE category IS NOT NULL AND project IS NULL AND product IS NULL

                  AND distribution IS NULL AND sourcepackagename IS NULL""")

        # Don't allow our table to bloat with inactive users.

        self.cur.execute("DELETE FROM KarmaCache WHERE karmavalue <= 0")

        # VACUUM KarmaCache since we have just touched every record in it.

        self.cur.execute("""VACUUM KarmaCache""")

    def B_update_karmatotalcache(self):

        self.logger.info("Step B: Rebuilding KarmaTotalCache")

        # Trash old records

        self.cur.execute("""

            DELETE FROM KarmaTotalCache

            WHERE person NOT IN (SELECT person FROM KarmaCache)

            """)

        # Update existing records.

        self.cur.execute("""

            UPDATE KarmaTotalCache SET karma_total=sum_karmavalue

            FROM (

                SELECT person AS sum_person, SUM(karmavalue) AS sum_karmavalue

                FROM KarmaCache

                GROUP BY person

                ) AS sums

            WHERE KarmaTotalCache.person = sum_person

            """)

        # VACUUM KarmaTotalCache since we have just touched every row in it.

        self.cur.execute("""VACUUM KarmaTotalCache""")

        # Insert new records into the KarmaTotalCache table.

        # XXX: salgado 2007-02-06:

        # If deadlocks ever become a problem, first LOCK the

        # corresponding rows in the Person table so the bulk insert cannot

        # fail. We don't bother at the moment as this would involve granting

        # UPDATE rights on the Person table to the karmacacheupdater user.

        ## cur.execute("BEGIN")

        ## cur.execute("""

        ##     SELECT * FROM Person

        ##     WHERE id NOT IN (SELECT person FROM KarmaTotalCache)

        ##     FOR UPDATE

        ##     """)

        self.cur.execute("""

            INSERT INTO KarmaTotalCache (person, karma_total)

            SELECT person, SUM(karmavalue) FROM KarmaCache

            WHERE person NOT IN (SELECT person FROM KarmaTotalCache)

            GROUP BY person

            """)

        ## self.cur.execute("COMMIT")

    def C_add_karmacache_sums(self):

        self.logger.info("Step C: Calculating KarmaCache sums")

        # We must issue some SUM queries to insert the karma totals for:

        # - All actions of a person on a given product.

        # - All actions of a person on a given distribution.

        # - All actions of a person on a given project.

        # - All actions with a specific category of a person on a given

        #   project.

        # - All actions with a specific category of a person.

        # - All actions with a specific category of a person.

        self.cur.execute("""

            INSERT INTO KarmaCache

                (person, category, karmavalue, product, distribution,

                 sourcepackagename, project)

            SELECT person, category, SUM(karmavalue), NULL, NULL, NULL, NULL

            FROM KarmaCache

            WHERE category IS NOT NULL

            GROUP BY person, category

            """)

        # - All actions of a person on a given product.

        self.cur.execute("""

            INSERT INTO KarmaCache

                (person, category, karmavalue, product, distribution,

                 sourcepackagename, project)

            SELECT person, NULL, SUM(karmavalue), product, NULL, NULL, NULL

            FROM KarmaCache

            WHERE product IS NOT NULL

            GROUP BY person, product

            """)

        # - All actions of a person on a given distribution.

        self.cur.execute("""

            INSERT INTO KarmaCache

                (person, category, karmavalue, product, distribution,

                 sourcepackagename, project)

            SELECT person, NULL, SUM(karmavalue), NULL, distribution, NULL, NULL

            FROM KarmaCache

            WHERE distribution IS NOT NULL

            GROUP BY person, distribution

            """)

        # - All actions of a person on a given project.

        self.cur.execute("""

            INSERT INTO KarmaCache

                (person, category, karmavalue, product, distribution,

                 sourcepackagename, project)

            SELECT person, NULL, SUM(karmavalue), NULL, NULL, NULL,

                   Product.project

            FROM KarmaCache

            JOIN Product ON product = Product.id

            WHERE Product.project IS NOT NULL AND product IS NOT NULL

                  AND category IS NOT NULL

            GROUP BY person, Product.project

            """)

        # - All actions with a specific category of a person on a given project

        # IMPORTANT: This has to be the latest step; otherwise the rows

        # inserted here will be included in the calculation of the overall

        # karma of a person on a given project.

        self.cur.execute("""

            INSERT INTO KarmaCache

                (person, category, karmavalue, product, distribution,

                 sourcepackagename, project)

            SELECT person, category, SUM(karmavalue), NULL, NULL, NULL,

                   Product.project

            FROM KarmaCache

            JOIN Product ON product = Product.id

            WHERE Product.project IS NOT NULL AND product IS NOT NULL

                  AND category IS NOT NULL

            GROUP BY person, category, Product.project

            """)

    def calculate_scaling(self, results):

        """Return a dict of scaling factors keyed on category ID"""

        # Get a list of categories, which we will need shortly.

        categories = {}

        self.cur.execute("SELECT id, name from KarmaCategory")

        for id, name in self.cur.fetchall():

            categories[id] = name

        # Calculate normalization factor for each category. We currently have

        # category bloat, where translators dominate the top karma rankings.

        # By calculating a scaling factor automatically, this slant will be

        # removed even as more events are added or scoring tweaked.

        points_per_category = {}

        for dummy, category, dummy, dummy, points in results:

            if category not in points_per_category:

                points_per_category[category] = 0

            points_per_category[category] += points

        largest_total = max(points_per_category.values())

        scaling = {}

        for category, points in points_per_category.items():

            if points == 0:

                scaling[category] = 1

            else:

                scaling[category] = float(largest_total) / float(points)

            max_scaling = config.karmacacheupdater.max_scaling

            if scaling[category] > max_scaling:

                self.logger.info(

                    'Scaling %s by a factor of %0.4f (capped to %0.4f)'

                    % (categories[category], scaling[category], max_scaling))

                scaling[category] = max_scaling

            else:

                self.logger.info(

                    'Scaling %s by a factor of %0.4f'

                    % (categories[category], scaling[category]))

        return scaling

    def update_one_karma_cache_entry(self, entry, scaling):

        """Updates an individual (non-summed) KarmaCache entry.

        KarmaCache has individual entries, and then it has the summed entries

        that correspond to overall contributions across all categories. Look

        at C_add_summed_totals to see how the summed entries are generated.

        """

        (person_id, category_id, product_id, distribution_id, points) = entry

        points *= scaling[category_id] # Scaled. wow.

        self.logger.debug("Setting person_id=%d, category_id=%d, points=%d"

                          % (person_id, category_id, points))

        points = int(points)

        context = {'product_id': product_id,

                   'distribution_id': distribution_id}

        try:

            self.karmacachemanager.updateKarmaValue(

                points, person_id, category_id, **context)

            self.logger.debug(

                "Updated karmacache for person=%s, points=%s, category=%s, "

                "context=%s" % (person_id, points, category_id, context))

        except NotFoundError:

            # Row didn't exist; do an insert.

            self.karmacachemanager.new(

                points, person_id, category_id, **context)

            self.logger.debug(

                "Created karmacache for person=%s, points=%s, category=%s, "

                "context=%s" % (person_id, points, category_id, context))

if __name__ == '__main__':

    script = KarmaCacheUpdater('karma-update',

        dbuser=config.karmacacheupdater.dbuser)

    script.lock_and_run(implicit_begin=True)