bitbake: bitbake: ensure -f causes dependent tasks to be re-run

If -f is specified, force dependent tasks to be re-run next time. This
works by changing the force behaviour so that instead of deleting the
task's stamp, we write a "taint" file into the stamps directory, which
will alter the taskhash randomly and thus trigger the task to re-run
next time we evaluate whether or not that should be done as well as
influencing the taskhashes of any dependent tasks so that they are
similarly re-triggered. As a bonus because we write this file as
<stamp file name>.taskname.taint, the existing code which deletes the
stamp files in OE's do_clean will already handle removing it.

This means you can now do the following:

bitbake somepackage
[ change the source code in the package's WORKDIR ]
bitbake -c compile -f somepackage
bitbake somepackage

and the result will be that all of the tasks that depend on do_compile
(do_install, do_package, etc.) will be re-run in the last step.

Note that to operate in the manner described above you need full hashing
enabled (i.e. BB_SIGNATURE_HANDLER must be set to a signature handler
that inherits from BasicHash). If this is not the case, -f will just
delete the stamp for the specified task as it did before.

This fix is required for [YOCTO #2615] and [YOCTO #2256].

(Bitbake rev: f7b55a94226f9acd985f87946e26d01bd86a35bb)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/siggen.py

@@ -50,6 +50,10 @@ class SignatureGenerator(object):
     def dump_sigtask(self, fn, task, stampbase, runtime):
         return
 
+    def invalidate_task(self, task, d, fn):
+        bb.build.del_stamp(task, d, fn)
+
+
 class SignatureGeneratorBasic(SignatureGenerator):
     """
     """
@@ -148,6 +152,15 @@ class SignatureGeneratorBasic(SignatureGenerator):
                 return False
         return True
 
+    def read_taint(self, fn, task, stampbase):
+        taint = None
+        try:
+            with open(stampbase + '.' + task + '.taint', 'r') as taintf:
+                taint = taintf.read()
+        except IOError:
+            pass
+        return taint
+
     def get_taskhash(self, fn, task, deps, dataCache):
         k = fn + "." + task
         data = dataCache.basetaskhash[k]
@@ -161,6 +174,11 @@ class SignatureGeneratorBasic(SignatureGenerator):
                 bb.fatal("%s is not in taskhash, caller isn't calling in dependency order?", dep)
             data = data + self.taskhash[dep]
             self.runtaskdeps[k].append(dep)
+
+        taint = self.read_taint(fn, task, dataCache.stamp[fn])
+        if taint:
+            data = data + taint
+
         h = hashlib.md5(data).hexdigest()
         self.taskhash[k] = h
         #d.setVar("BB_TASKHASH_task-%s" % task, taskhash[task])
@@ -201,9 +219,14 @@ class SignatureGeneratorBasic(SignatureGenerator):
             for dep in data['runtaskdeps']:
                 data['runtaskhashes'][dep] = self.taskhash[dep]
 
+        taint = self.read_taint(fn, task, stampbase)
+        if taint:
+            data['taint'] = taint
+
         p = pickle.Pickler(file(sigfile, "wb"), -1)
         p.dump(data)
 
+
     def dump_sigs(self, dataCache):
         for fn in self.taskdeps:
             for task in self.taskdeps[fn]:
@@ -230,6 +253,9 @@ class SignatureGeneratorBasicHash(SignatureGeneratorBasic):
             h = self.basehash[k]
         return ("%s.%s.%s.%s" % (stampbase, taskname, h, extrainfo)).rstrip('.')
 
+    def invalidate_task(self, task, d, fn):
+        bb.build.write_taint(task, d, fn)
+
 def dump_this_task(outfile, d):
     import bb.parse
     fn = d.getVar("BB_FILENAME", True)
@@ -330,6 +356,11 @@ def compare_sigfiles(a, b):
             for dep in changed:
                 print "Hash for dependent task %s changed from %s to %s" % (dep, a[dep], b[dep])
 
+    a_taint = a_data.get('taint', None)
+    b_taint = b_data.get('taint', None)
+    if a_taint != b_taint:
+        print "Taint (by forced/invalidated task) changed from %s to %s" % (a_taint, b_taint)
+
 def dump_sigfile(a):
     p1 = pickle.Unpickler(file(a, "rb"))
     a_data = p1.load()
@@ -354,3 +385,6 @@ def dump_sigfile(a):
     if 'runtaskhashes' in a_data:
         for dep in a_data['runtaskhashes']:
             print "Hash for dependent task %s is %s" % (dep, a_data['runtaskhashes'][dep])
+
+    if 'taint' in a_data:
+        print "Tainted (by forced/invalidated task): %s" % a_data['taint']