changes.py

# This file is part of Buildbot.  Buildbot is free software: you can
# redistribute it and/or modify it under the terms of the GNU General Public
# License as published by the Free Software Foundation, version 2.
#
# This program is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
# FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
# details.
#
# You should have received a copy of the GNU General Public License along with
# this program; if not, write to the Free Software Foundation, Inc., 51
# Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#
# Copyright Buildbot Team Members

"""
Support for changes in the database
"""

from buildbot.util import json
import sqlalchemy as sa
from twisted.internet import defer
from buildbot.changes.changes import Change
from buildbot.db import base

class ChangesConnectorComponent(base.DBConnectorComponent):
    """
    A DBConnectorComponent to handle getting changes into and out of the
    database.  An instance is available at C{master.db.changes}.
    """

    changeHorizon = 0
    "maximum number of changes to keep on hand, or 0 to keep all changes forever"
    # TODO: add a threadsafe change cache

    def addChange(self, who, files, comments, isdir=0, links=None,
                 revision=None, when=None, branch=None, category=None,
                 revlink='', properties={}, repository='', project=''):
        """Add the a Change with the given attributes to the database; returns
        a Change instance via a deferred.

        @param who: the author of this change
        @type branch: unicode string

        @param files: a list of filenames that were changed
        @type branch: list of unicode strings

        @param comments: user comments on the change
        @type branch: unicode string

        @param isdir: deprecated

        @param links: a list of links related to this change, e.g., to web
        viewers or review pages
        @type links: list of unicode strings

        @param revision: the revision identifier for this change
        @type revision: unicode string

        @param when: when this change occurs
        @type when: integer (UNIX epoch time)

        @param branch: the branch on which this change took place
        @type branch: unicode string

        @param category: category for this change (arbitrary use by Buildbot
        users)
        @type category: unicode string

        @param revlink: link to a web view of this revision
        @type revlink: unicode string

        @param properties: properties to set on this change
        @type properties: dictionary with string keys and simple values
        (JSON-able)

        @param repository: the repository in which this change took place
        @type repository: unicode string

        @param project: the project this change is a part of
        @type project: unicode string

        @returns: a L{buildbot.changes.changes.Change} instance via Deferred
        """
        assert project is not None, "project must be a string, not None"
        assert repository is not None, "repository must be a string, not None"

        # first create the change, although with no 'number'
        change = Change(who=who, files=files, comments=comments, isdir=isdir,
                links=links, revision=revision, when=when, branch=branch,
                category=category, revlink=revlink, properties=properties,
                repository=repository, project=project)

        # then add it to the database and update its '.number'
        def thd(conn):
            assert change.number is None

            # note that in a read-uncommitted database like SQLite this
            # transaction does not buy atomicitiy - other database users may
            # still come across a change without its links, files, properties,
            # etc.  That's OK, since we don't announce the change until it's
            # all in the database, but beware.

            transaction = conn.begin()

            ins = self.db.model.changes.insert()
            r = conn.execute(ins, dict(
                author=change.who,
                comments=change.comments,
                is_dir=change.isdir,
                branch=change.branch,
                revision=change.revision,
                revlink=change.revlink,
                when_timestamp=change.when,
                category=change.category,
                repository=change.repository,
                project=change.project))
            change.number = r.inserted_primary_key[0]
            if change.links:
                ins = self.db.model.change_links.insert()
                conn.execute(ins, [
                    dict(changeid=change.number, link=l)
                        for l in change.links
                    ])
            if change.files:
                ins = self.db.model.change_files.insert()
                conn.execute(ins, [
                    dict(changeid=change.number, filename=f)
                        for f in change.files
                    ])
            if change.properties:
                ins = self.db.model.change_properties.insert()
                conn.execute(ins, [
                    dict(changeid=change.number,
                        property_name=k,
                        property_value=json.dumps(v))
                    for k,v,s in change.properties.asList()
                ])

            transaction.commit()

            return change
        d = self.db.pool.do(thd)
        return d

    def getChangeInstance(self, changeid):
        """
        Get a L{buildbot.changes.changes.Change} instance for the given changeid,
        or None if no such change exists.

        @param changeid: the id of the change instance to fetch

        @returns: Change instance via Deferred
        """
        assert changeid >= 0
        def thd(conn):
            # get the row from the 'changes' table
            changes_tbl = self.db.model.changes
            q = changes_tbl.select(whereclause=(changes_tbl.c.changeid == changeid))
            rp = conn.execute(q)
            row = rp.fetchone()
            if not row:
                return None
            # and fetch the ancillary data (links, files, properties)
            return self._chdict_from_change_row_thd(conn, row)
        d = self.db.pool.do(thd)

        def make_change(chdict):
            if not chdict:
                return None
            return self._change_from_chdict(chdict)
        d.addCallback(make_change)
        return d

    def getRecentChangeInstances(self, count):
        """
        Get a list of the C{count} most recent
        L{buildbot.changes.changes.Change} instances, or fewer if that many do
        not exist.

        @param count: maximum number of instances to return

        @returns: list of Change instances via Deferred
        """
        def thd(conn):
            # get the row from the 'changes' table
            changes_tbl = self.db.model.changes
            q = changes_tbl.select(
                    order_by=[sa.desc(changes_tbl.c.changeid)],
                    limit=count)
            rp = conn.execute(q)
            changes = []
            for row in rp:
                # note that this does *three* extra queries per row!
                changes.append(self._chdict_from_change_row_thd(conn, row))
            rp.close()
            return reversed(changes)
        d = self.db.pool.do(thd)

        def make_changes(chdict_list):
            return [ self._change_from_chdict(chdict)
                     for chdict in chdict_list ]
        d.addCallback(make_changes)
        return d

    def getLatestChangeid(self):
        """
        Get the most-recently-assigned changeid, or None if there are no
        changes at all.

        @returns: changeid via Deferred
        """
        def thd(conn):
            changes_tbl = self.db.model.changes
            q = sa.select([ changes_tbl.c.changeid ],
                    order_by=sa.desc(changes_tbl.c.changeid),
                    limit=1)
            return conn.scalar(q)
        d = self.db.pool.do(thd)
        return d

    def setChangeHorizon(self, changeHorizon): # TODO: remove
        "this method should go away"
        self.changeHorizon = changeHorizon

    # cache management

    def _flush_cache(self):
        pass # TODO

    # utility methods

    def pruneChanges(self, changeHorizon):
        if not changeHorizon:
            return defer.succeed(None)
        def thd(conn):
            changes_tbl = self.db.model.changes

            # First, get the list of changes to delete.  This could be written
            # as a subquery but then that subquery would be run for every
            # table, which is very inefficient; also, MySQL's subquery support
            # leaves much to be desired, and doesn't support this particular
            # form.
            q = sa.select([changes_tbl.c.changeid],
                          order_by=[sa.desc(changes_tbl.c.changeid)],
                          offset=changeHorizon)
            res = conn.execute(q)
            ids_to_delete = [ r.changeid for r in res ]

            # and delete from all relevant tables, in dependency order
            for table_name in ('scheduler_changes', 'sourcestamp_changes',
                               'change_files', 'change_links',
                               'change_properties', 'changes'):
                table = self.db.model.metadata.tables[table_name]
                conn.execute(
                    table.delete(table.c.changeid.in_(ids_to_delete)))
        return self.db.pool.do(thd)

    def _chdict_from_change_row_thd(self, conn, ch_row):
        # This method must be run in a db.pool thread, and returns a chdict
        # (which can be used to construct a Change object), given a row from
        # the 'changes' table
        change_links_tbl = self.db.model.change_links
        change_files_tbl = self.db.model.change_files
        change_properties_tbl = self.db.model.change_properties

        chdict = dict(
                number=ch_row.changeid,
                who=ch_row.author,
                files=[], # see below
                comments=ch_row.comments,
                isdir=ch_row.is_dir,
                links=[], # see below
                revision=ch_row.revision,
                when=ch_row.when_timestamp,
                branch=ch_row.branch,
                category=ch_row.category,
                revlink=ch_row.revlink,
                properties={}, # see below
                repository=ch_row.repository,
                project=ch_row.project)

        query = change_links_tbl.select(
                whereclause=(change_links_tbl.c.changeid == ch_row.changeid))
        rows = conn.execute(query)
        for r in rows:
            chdict['links'].append(r.link)

        query = change_files_tbl.select(
                whereclause=(change_files_tbl.c.changeid == ch_row.changeid))
        rows = conn.execute(query)
        for r in rows:
            chdict['files'].append(r.filename)

        query = change_properties_tbl.select(
                whereclause=(change_properties_tbl.c.changeid == ch_row.changeid))
        rows = conn.execute(query)
        for r in rows:
            chdict['properties'][r.property_name] = json.loads(r.property_value)

        return chdict

    def _change_from_chdict(self, chdict):
        # create a Change object, given a chdict
        changeid = chdict.pop('number')
        c = Change(**chdict)
        c.number = changeid
        return c