telepathy-gabble: Avoid having two of the same set of commands run in parallel

[Simon McVittie]

Module: telepathy-gabble
Branch: master
Commit: fa48076ccef7e5c8c4a08a88c399d0dbbb3ac624
URL:    http://cgit.freedesktop.org/telepathy/telepathy-gabble/commit/?id=fa48076ccef7e5c8c4a08a88c399d0dbbb3ac624

Author: Simon McVittie <simon.mcvittie at collabora.co.uk>
Date:   Tue Jun 11 14:39:42 2013 +0100

Avoid having two of the same set of commands run in parallel

A rule like this:

    _gen/x.c _gen/x.h: prerequisites
        $(AM_V_GEN)x-generator

doesn't consider x.c and x.h together. Instead, it expands to two rules,
one to generate x.c and one to generate x.h, which happen to run the
same commands.

This means that in the worst case, you can end up running x-generator
twice in parallel, and they'll race with each other and overwrite or
delete each other's output.

Based on commit 36c2a545c from telepathy-glib.

Bug: https://bugs.freedesktop.org/show_bug.cgi?id=64285
Signed-off-by: Simon McVittie <simon.mcvittie at collabora.co.uk>
Reviewed-by: Xavier Claessens <xavier.claessens at collabora.co.uk>
Conflicts:
	extensions/Makefile.am

---

 extensions/Makefile.am |   28 +++++++++++++++++++---------
 1 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/extensions/Makefile.am b/extensions/Makefile.am
index 8e50ffb..001a39d 100644
--- a/extensions/Makefile.am
+++ b/extensions/Makefile.am
@@ -62,8 +62,11 @@ extensions.html: _gen/all.xml $(tools_dir)/doc-generator.xsl Makefile.am
 		$(tools_dir)/doc-generator.xsl \
 		$< > $@
 
-_gen/svc.c _gen/svc.h _gen/svc-gtk-doc.h: _gen/all.xml $(tools_dir)/glib-ginterface-gen.py \
-	Makefile.am
+_gen/svc.h: _gen/svc.c
+	@: # do nothing, output as a side-effect
+_gen/svc-gtk-doc.h: _gen/svc.c
+	@: # do nothing, output as a side-effect
+_gen/svc.c: _gen/all.xml $(tools_dir)/glib-ginterface-gen.py Makefile.am
 	$(AM_V_GEN)$(PYTHON) $(tools_dir)/glib-ginterface-gen.py \
 		--filename=_gen/svc --signal-marshal-prefix=_gabble_ext \
 		--include='<telepathy-glib/dbus.h>' \
@@ -84,18 +87,25 @@ _gen/signals-marshal.c: _gen/signals-marshal.list Makefile.am
 	$(AM_V_GEN){ echo '#include "_gen/signals-marshal.h"' && \
 	$(GLIB_GENMARSHAL) --body --prefix=_gabble_ext_marshal $< ; } > $@
 
-_gen/enums.h _gen/enums-gtk-doc.h: _gen/all.xml $(tools_dir)/c-constants-gen.py \
-	Makefile.am
+_gen/enums-gtk-doc.h: _gen/enums.h
+	@: # do nothing, output as a side-effect
+_gen/enums.h: _gen/all.xml $(tools_dir)/c-constants-gen.py Makefile.am
 	$(AM_V_GEN)$(PYTHON) $(tools_dir)/c-constants-gen.py Gabble $< _gen/enums
 
-_gen/interfaces.h _gen/interfaces-body.h _gen/interfaces-gtk-doc.h: _gen/all.xml \
-	$(tools_dir)/glib-interfaces-gen.py \
-	Makefile.am
+_gen/interfaces-body.h: _gen/interfaces.h
+	@: # do nothing, output as a side-effect
+_gen/interfaces-gtk-doc.h: _gen/interfaces.h
+	@: # do nothing, output as a side-effect
+_gen/interfaces.h: _gen/all.xml $(tools_dir)/glib-interfaces-gen.py Makefile.am
 	$(AM_V_GEN)$(PYTHON) $(tools_dir)/glib-interfaces-gen.py \
 		Gabble _gen/interfaces-body.h _gen/interfaces.h $<
 
-_gen/gtypes.h _gen/gtypes-body.h _gen/gtypes-gtk-doc.h: _gen/all.xml \
-	$(tools_dir)/glib-gtypes-generator.py Makefile.am
+_gen/gtypes.h: _gen/gtypes-body.h
+	@: # do nothing, output as a side-effect
+_gen/gtypes-gtk-doc.h: _gen/gtypes-body.h
+	@: # do nothing, output as a side-effect
+
+_gen/gtypes-body.h: _gen/all.xml $(tools_dir)/glib-gtypes-generator.py Makefile.am
 	$(AM_V_GEN)$(PYTHON) $(tools_dir)/glib-gtypes-generator.py \
 		$< _gen/gtypes Gabble