On Thu, Feb 20 2014, Austin Clements <amdragon@MIT.EDU> wrote: > Previously, we updated .eldeps only if the file contents actually > needed to change. This was done to avoid unnecessary make restarts > (if the .eldeps rule changes the mtime of .eldeps, make has to restart > to collect the new dependencies). However, this meant that, after a > modification to any .el file that did not change dependencies, .eldeps > would always be out of date, so every make invocation would run the > .eldeps rule, which is both expensive because it starts up Emacs and > noisy. This was true even when there was nothing to do. E.g., > > $ make clean && make > ... > $ touch emacs/notmuch-lib.el && make > ... > $ make > Use "make V=1" to see the verbose compile lines. > EMACS emacs/.eldeps > make: Nothing to be done for `all'. > $ make > Use "make V=1" to see the verbose compile lines. > EMACS emacs/.eldeps > make: Nothing to be done for `all'. > > Fix this by replacing .eldeps with two files with identical content. > One tracks the mtime of the dependency information and triggers the > Emacs call to rebuild dependencies only when it may be necessary. The > other tracks the content only; this rule over-triggers in the same way > the old rule did, but this rule is cheap and quiet. > --- LGTM. Works as expected. Tomi > emacs/Makefile.local | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > diff --git a/emacs/Makefile.local b/emacs/Makefile.local > index 42bfbd9..6a39b32 100644 > --- a/emacs/Makefile.local > +++ b/emacs/Makefile.local > @@ -33,10 +33,19 @@ ifeq ($(HAVE_EMACS),1) > $(dir)/.eldeps: $(dir)/Makefile.local $(dir)/make-deps.el $(emacs_sources) > $(call quiet,EMACS) --directory emacs -batch -l make-deps.el \ > -f batch-make-deps $(emacs_sources) > $@.tmp && \ > - (cmp -s $@.tmp $@ || mv $@.tmp $@) > --include $(dir)/.eldeps > + mv $@.tmp $@ > +# We could include .eldeps directly, but that would cause a make > +# restart whenever any .el file was modified, even if dependencies > +# didn't change, because the mtime of .eldeps will change. Instead, > +# we include a second file, .eldeps.x, which we ensure always has the > +# same content as .eldeps, but its mtime only changes when dependency > +# information changes, in which case a make restart is necessary > +# anyway. > +$(dir)/.eldeps.x: $(dir)/.eldeps > + @cmp -s $^ $@ || cp $^ $@ > +-include $(dir)/.eldeps.x > endif > -CLEAN+=$(dir)/.eldeps $(dir)/.eldeps.tmp > +CLEAN+=$(dir)/.eldeps $(dir)/.eldeps.tmp $(dir)/.eldeps.x > > ifeq ($(HAVE_EMACS),1) > %.elc: %.el $(global_deps) > -- > 1.8.4.rc3 > > _______________________________________________ > notmuch mailing list > notmuch@notmuchmail.org > http://notmuchmail.org/mailman/listinfo/notmuch