Fix qapi code generation wrt parallel build
Make's multiple output syntax
x.c x.h: x.template
gen < x.template
actually invokes the command once for x.c and once for x.h (with differing $@
in each invocation). During a parallel build, the two commands may be invoked
in parallel; this opens up a race, where the second invocation trashes a file
supposedly produced during the first, and now in use by a dependent command.
The various qapi code generators are susceptible to this; fix by making them
generate just one file per invocation.
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 62de83d..e9d0584 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -139,7 +139,8 @@
name=name)
try:
- opts, args = getopt.gnu_getopt(sys.argv[1:], "p:o:", ["prefix=", "output-dir="])
+ opts, args = getopt.gnu_getopt(sys.argv[1:], "chp:o:",
+ ["source", "header", "prefix=", "output-dir="])
except getopt.GetoptError, err:
print str(err)
sys.exit(1)
@@ -149,11 +150,22 @@
c_file = 'qapi-visit.c'
h_file = 'qapi-visit.h'
+do_c = False
+do_h = False
+
for o, a in opts:
if o in ("-p", "--prefix"):
prefix = a
elif o in ("-o", "--output-dir"):
output_dir = a + "/"
+ elif o in ("-c", "--source"):
+ do_h = True
+ elif o in ("-h", "--header"):
+ do_c = True
+
+if not do_c and not do_h:
+ do_c = True
+ do_h = True
c_file = output_dir + prefix + c_file
h_file = output_dir + prefix + h_file
@@ -164,8 +176,17 @@
if e.errno != errno.EEXIST:
raise
-fdef = open(c_file, 'w')
-fdecl = open(h_file, 'w')
+def maybe_open(really, name, opt):
+ class Null(object):
+ def write(self, str):
+ pass
+ def read(self):
+ return ''
+ if really:
+ return open(name, opt)
+
+fdef = maybe_open(do_c, c_file, 'w')
+fdecl = maybe_open(do_h, h_file, 'w')
fdef.write(mcgen('''
/* THIS FILE IS AUTOMATICALLY GENERATED, DO NOT MODIFY */