From: Tomi Ollila Date: Wed, 19 Feb 2014 20:47:49 +0000 (+0200) Subject: Re: [PATCH 1/1] emacs: always write emacs/.eldeps when the target is remade X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=2c2aa7339a5a366d6ad3a97f347604f2b2353dc3;p=notmuch-archives.git Re: [PATCH 1/1] emacs: always write emacs/.eldeps when the target is remade --- diff --git a/cc/71ae363942c68084bf3f600be1ee64fa9fd00f b/cc/71ae363942c68084bf3f600be1ee64fa9fd00f new file mode 100644 index 000000000..8d8073616 --- /dev/null +++ b/cc/71ae363942c68084bf3f600be1ee64fa9fd00f @@ -0,0 +1,223 @@ +Return-Path: +X-Original-To: notmuch@notmuchmail.org +Delivered-To: notmuch@notmuchmail.org +Received: from localhost (localhost [127.0.0.1]) + by olra.theworths.org (Postfix) with ESMTP id 45829431FC2 + for ; Wed, 19 Feb 2014 12:48:04 -0800 (PST) +X-Virus-Scanned: Debian amavisd-new at olra.theworths.org +X-Spam-Flag: NO +X-Spam-Score: 0 +X-Spam-Level: +X-Spam-Status: No, score=0 tagged_above=-999 required=5 tests=[none] + autolearn=disabled +Received: from olra.theworths.org ([127.0.0.1]) + by localhost (olra.theworths.org [127.0.0.1]) (amavisd-new, port 10024) + with ESMTP id joXR-w6iEAcP for ; + Wed, 19 Feb 2014 12:47:56 -0800 (PST) +Received: from guru.guru-group.fi (guru.guru-group.fi [46.183.73.34]) + by olra.theworths.org (Postfix) with ESMTP id 764CA431FBF + for ; Wed, 19 Feb 2014 12:47:56 -0800 (PST) +Received: from guru.guru-group.fi (localhost [IPv6:::1]) + by guru.guru-group.fi (Postfix) with ESMTP id 1BD8010005E; + Wed, 19 Feb 2014 22:47:50 +0200 (EET) +From: Tomi Ollila +To: Austin Clements +Subject: Re: [PATCH 1/1] emacs: always write emacs/.eldeps when the target is + remade +In-Reply-To: <20140219195457.GD13537@mit.edu> +References: <1390645309-2326-1-git-send-email-tomi.ollila@iki.fi> + <20140213071026.GX4375@mit.edu> + <20140213074944.GY4375@mit.edu> + <20140214215736.GD4375@mit.edu> <20140219195457.GD13537@mit.edu> +User-Agent: Notmuch/0.17+69~g761b031 (http://notmuchmail.org) Emacs/24.3.1 + (x86_64-unknown-linux-gnu) +X-Face: HhBM'cA~ +MIME-Version: 1.0 +Content-Type: text/plain +Cc: notmuch@notmuchmail.org +X-BeenThere: notmuch@notmuchmail.org +X-Mailman-Version: 2.1.13 +Precedence: list +List-Id: "Use and development of the notmuch mail system." + +List-Unsubscribe: , + +List-Archive: +List-Post: +List-Help: +List-Subscribe: , + +X-List-Received-Date: Wed, 19 Feb 2014 20:48:04 -0000 + +On Wed, Feb 19 2014, Austin Clements wrote: + +> Quoth myself on Feb 14 at 4:58 pm: +>> Quoth Tomi Ollila on Feb 14 at 9:24 pm: +>> > On Thu, Feb 13 2014, Austin Clements wrote: +>> > +>> > > Quoth Tomi Ollila on Feb 13 at 9:26 am: +>> > >> On Thu, Feb 13 2014, Austin Clements wrote: +>> > >> +>> > >> > Quoth Tomi Ollila on Jan 25 at 12:21 pm: +>> > >> >> So that the target is newer than its prerequisites. +>> > >> >> --- +>> > >> >> emacs/Makefile.local | 3 +-- +>> > >> >> 1 file changed, 1 insertion(+), 2 deletions(-) +>> > >> >> +>> > >> >> diff --git a/emacs/Makefile.local b/emacs/Makefile.local +>> > >> >> index 42bfbd9..d5d402e 100644 +>> > >> >> --- a/emacs/Makefile.local +>> > >> >> +++ b/emacs/Makefile.local +>> > >> >> @@ -32,8 +32,7 @@ emacs_bytecode = $(emacs_sources:.el=.elc) +>> > >> >> ifeq ($(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 $@) +>> > >> >> + -f batch-make-deps $(emacs_sources) > $@.tmp && mv $@.tmp $@ +>> > >> >> -include $(dir)/.eldeps +>> > >> >> endif +>> > >> >> CLEAN+=$(dir)/.eldeps $(dir)/.eldeps.tmp +>> > >> > +>> > >> > Is this just so the rule doesn't get run again on the next make +>> > >> > invocation (unless, of course, a dependent changed)? +>> > >> +>> > >> Basically yes. I did multiple builds in rapid succession when developing +>> > >> something and this thing confused me quite a lot in the beginning... +>> > >> +>> > >> > Interestingly, if any of the dependents have changed, but in ways that +>> > >> > don't affect .eldeps, this change will make the build more expensive +>> > >> > because it will trigger a make restart after .eldeps is updated. +>> > >> +>> > >> I wondered what was the reason for the recipe you've chosen here, has +>> > >> it something to do with inodes or something ;) (and were going to ask +>> > >> an alternative to touch (or even : > $@) the target... +>> > >> +>> > >> ... but now I understand. E.g. change in notmuch-lib.el will cause *all* +>> > >> .el files to be re-bytecompiled after this change. +>> > > +>> > > This is unrelated to the cmp in the recipe. A change in +>> > > notmuch-lib.el *must* cause almost all .el files to be recompiled +>> > > because they almost all require it and may use macros from it. If you +>> > > touch, e.g., notmuch-hello.el, you'll see that very little is rebuilt +>> > > (with or without this patch). +>> > > +>> > >> An alternative to this patch would be adding a message to the rule +>> > >> which informs user to touch .eldeps to avoid re-doing .eldeps if +>> > >> that irritates one :D +>> > >> +>> > >> something like: +>> > >> +>> > >> (cmp -s $@.tmp $@ && \ +>> > >> echo "touch $@ to avoid redoing this target" || mv $@.tmp $@) +>> > > +>> > > I think this patch is good as it is; I was just pointing out that the +>> > > change also has a performance drawback in some situations. (Knowing +>> > > make, there's probably *some* way to get the best of both worlds and +>> > > it's probably really ugly.) +>> > +>> > Ah, now I understand, because emacs/Makefile.local includes emacs/.eldeps +>> > when it notices mtime of emacs/.eldeps changes it restarts itself... +>> > +>> > ... to compare with current behaviour: +>> > +>> > $ make +>> > ... +>> > $ touch emacs/notmuch.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'. +>> > $ make +>> > Use "make V=1" to see the verbose compile lines. +>> > EMACS emacs/.eldeps +>> > make: Nothing to be done for `all'. +>> > +>> > It will rerun emacs -L emacs -batch -l make-deps.el -f batch-make-deps ... +>> > over and over again... +>> > +>> > I thought I figured out a solution involving .eldeps.stamp file but +>> > that turned out to be no-go... (circular dependency netween .eldeps.stamp +>> > and Makefile.local). +>> > +>> > So, with this if one edits emacs/* files and keeps building byte-compiled +>> > versions often, make will both run EMACS emacs/.eldeps and restarting +>> > -- and when moving to edit other files both of the above stops. Without +>> > this change after editing emacs/* files EMACS emacs/.eldeps will be +>> > executed until it is touched or make clean executed (I wonder how make +>> > handles rebuilding emacs/.eldeps while doing make clean ;) +>> > +>> > +>> > Tomi +>> +>> Here's a way that works, but it's more complicated than your patch and +>> doesn't seem to perform any better: +>> +>> diff --git a/emacs/Makefile.local b/emacs/Makefile.local +>> index 42bfbd9..8a1f1c2 100644 +>> --- a/emacs/Makefile.local +>> +++ b/emacs/Makefile.local +>> @@ -29,14 +29,28 @@ emacs_bytecode = $(emacs_sources:.el=.elc) +>> # the byte compiler may load an old .elc file when processing a +>> # "require" or we may fail to rebuild a .elc that depended on a macro +>> # from an updated file. +>> +# +>> +# We do this in two rules. .eldeps is the "real" dependencies file +>> +# and will be rebuilt if and only if a .el source file changes. We +>> +# could include this directly, but then whenever a .el file changed +>> +# (and .eldeps's mtime changed), make would restart immediately after +>> +# the include below. To avoid this, we create a second file, +>> +# .eldeps.x, that we only update when its *contents* differ from +>> +# .eldeps. .eldeps will often have an mtime older than .eldeps.x (any +>> +# .el file change that does not change dependencies will cause this), +>> +# so the .eldeps.x rule will often run, but it executes quickly and +>> +# quietly and will not trigger a make restart unless the dependencies +>> +# actually change. +> +> Here's a version of this comment that gets to the point directly: +> +> # We could include .eldeps directly, but that would cause a make +> # restart whenever any .el file was modified, even if dependencies +> # didn't change, because the mtime of .eldeps will change. Instead, +> # we include a second file, .eldeps.x, which we ensure always has the +> # same content as .eldeps, but its mtime only changes when dependency +> # information changes, in which case a make restart is necessary +> # anyway. + +I think this behaviour is tolerable: instead of verbosely re-run emacs to +re-create .eldeps every time just to see the new .eldeps is not going to be +used we just silently re-run only lightweight cmp. + +Tomi + +> +>> ifeq ($(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 $@ +>> +$(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) +> _______________________________________________ +> notmuch mailing list +> notmuch@notmuchmail.org +> http://notmuchmail.org/mailman/listinfo/notmuch