Re: [PATCH] Avoid rebuilds when unimportant morphology contents change

This changes the cache key generation so that it will ignore unimportant fields of the morphology, e.g. description, build-depends, chunks. description is unimportant because it does not affect building, and build-depends/chunks are unimportant because they are already considered --- morphlib/cachekeycomputer.py | 8 +++++ ...hology-contents-do-not-change-cache-keys.script | 41 ++++++++++++++++++++++ 2 files changed, 49 insertions(+) create mode 100755 tests.as-root/unimportant-morphology-contents-do-not-change-cache-keys.script diff --git a/morphlib/cachekeycomputer.py b/morphlib/cachekeycomputer.py index a11334e..a4ea10e 100644 --- a/morphlib/cachekeycomputer.py +++ b/morphlib/cachekeycomputer.py @@ -91,6 +91,14 @@ class CacheKeyComputer(object): elif kind in ('system', 'stratum'): morphology = artifact.source.morphology le_dict = dict((k, morphology[k]) for k in morphology.keys()) + + # Disregard all fields of a morphology that aren't important + ignored_fields = ('strata', 'build-depends', 'description', + 'chunks') + for ignored_field in ignored_fields: + if ignored_field in le_dict: + del le_dict[ignored_field] + checksum = hashlib.sha1() self._hash_thing(checksum, le_dict) keys['morphology-sha1'] = checksum.hexdigest() diff --git a/tests.as-root/unimportant-morphology-contents-do-not-change-cache-keys.script b/tests.as-root/unimportant-morphology-contents-do-not-change-cache-keys.script new file mode 100755 index 0000000..27adf8c --- /dev/null +++ b/tests.as-root/unimportant-morphology-contents-do-not-change-cache-keys.script @@ -0,0 +1,41 @@ +#!/bin/bash +# +# Copyright (C) 2012 Codethink Limited +# +# This program 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 of the License. +# +# 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. + +## Some contents of morphologies (description, build-depends, chunks) +## should not change the cache keys of those morphs because they are +## either already considered (build-depends and chunks) or do not affect +## building (description). This test checks that changes to these parts +## of a morphology do not force rebuilds. + +set -eu + +# Disable test on versions of Python before 2.7. +source "$SRCDIR/scripts/python-check" + +source "$SRCDIR/tests.as-root/setup-build" + +# Build once. +cd "$DATADIR/workspace" +"$SRCDIR/scripts/test-morph" build linux-system +ARTIFACT_COUNT="$(ls "$DATADIR/cache/artifacts" | wc -l)" + +# Petrify the refs, so the morphologies will be different +"$SRCDIR/scripts/test-morph" petrify + +# Build with the petrified morphologies. +"$SRCDIR/scripts/test-morph" build linux-system +[ "$ARTIFACT_COUNT" -eq $(ls "$DATADIR/cache/artifacts" | wc -l) ]