Fix for ticket:236, parallel makes are indeterminate.

[debian/gnuradio] / gr-trellis / src / lib / Makefile.am

diff --git a/gr-trellis/src/lib/Makefile.am b/gr-trellis/src/lib/Makefile.am
index 9eeb3e043d6faf93b1a2b91490aa2e7078474292..62a8bc94b1bae7e26ba66dab99221dd12646c179 100644 (file)
--- a/gr-trellis/src/lib/Makefile.am
+++ b/gr-trellis/src/lib/Makefile.am
@@ -54,10 +54,35 @@ CODE_GENERATOR =                            \
 
 include $(srcdir)/Makefile.gen
 
-$(srcdir)/Makefile.gen $(GENERATED_H) $(GENERATED_I) $(GENERATED_CC): $(CODE_GENERATOR)
-       PYTHONPATH=$(top_srcdir)/gnuradio-core/src/python \
-               srcdir=$(srcdir) $(PYTHON) $(srcdir)/generate_all.py
+
+# Ensure parallel does the right thing.
+# http://sources.redhat.com/automake/automake.html#Multiple-Outputs
+
+generate-stamp: $(CODE_GENERATOR)
+       @rm -f generate-tmp
+       @touch generate-tmp
+       PYTHONPATH=$(top_srcdir)/gnuradio-core/src/python srcdir=$(srcdir) $(PYTHON) $(srcdir)/generate_all.py
        touch $(srcdir)/Makefile.in
+       @mv -f generate-tmp $@
+
+$(srcdir)/Makefile.gen $(GENERATED_H) $(GENERATED_I) $(GENERATED_CC): generate-stamp
+## Recover from the removal of $@
+       @if test -f $@; then :; else \
+               trap 'rm -rf generate-lock generate-stamp' 1 2 13 15; \
+               if mkdir generate-lock 2>/dev/null; then \
+## This code is being executed by the first process.
+                 rm -f generate-stamp; \
+                 $(MAKE) $(AM_MAKEFLAGS) generate-stamp; \
+                 rmdir generate-lock; \
+               else \
+## This code is being executed by the follower processes.
+## Wait until the first process is done.
+                 while test -d generate-lock; do sleep 1; done; \
+## Succeed if and only if the first process succeeded.
+                 test -f generate-stamp; exit $$?; \
+               fi; \
+             fi
+
 
 # These files are built by SWIG.  The first is the C++ glue.
 # The second is the python wrapper that loads the _trellis shared library