siggen.py: Abstract the runtime task dependency handling code in the generators

index d9d0294..f31d66a 100644
@@ -62,9 +62,13 @@ class SignatureGeneratorBasic(SignatureGenerator):
         self.runtaskdeps = {}
         self.gendeps = {}
         self.lookupcache = {}
+        self.pkgnameextract = re.compile("(?P<fn>.*)\..*")
         self.basewhitelist = set((data.getVar("BB_HASHBASE_WHITELIST", True) or "").split())
-        self.taskwhitelist = data.getVar("BB_HASHTASK_WHITELIST", True) or None
+        self.taskwhitelist = None
+        self.init_rundepcheck(data)
 
+    def init_rundepcheck(self, data):
+        self.taskwhitelist = data.getVar("BB_HASHTASK_WHITELIST", True) or None
         if self.taskwhitelist:
             self.twl = re.compile(self.taskwhitelist)
         else:

@@ -131,17 +135,24 @@ class SignatureGeneratorBasic(SignatureGenerator):
         for task in taskdeps:
             d.setVar("BB_BASEHASH_task-%s" % task, self.basehash[fn + "." + task])
 
+    def rundep_check(self, fn, recipename, task, dep, depname):
+        # Return True if we should keep the dependency, False to drop it
+        # We only manipulate the dependencies for packages not in the whitelist
+        if self.twl and not self.twl.search(recipename):
+            # then process the actual dependencies
+            if self.twl.search(depname):
+                return False
+        return True
+
     def get_taskhash(self, fn, task, deps, dataCache):
         k = fn + "." + task
         data = dataCache.basetaskhash[k]
         self.runtaskdeps[k] = []
+        recipename = dataCache.pkg_fn[fn]
         for dep in sorted(deps, key=clean_basepath):
-            # We only manipulate the dependencies for packages not in the whitelist
-            if self.twl and not self.twl.search(dataCache.pkg_fn[fn]):
-                # then process the actual dependencies
-                dep_fn = re.search("(?P<fn>.*)\..*", dep).group('fn')
-                if self.twl.search(dataCache.pkg_fn[dep_fn]):
-                    continue
+            depname = dataCache.pkg_fn[self.pkgnameextract.search(dep).group('fn')]
+            if not self.rundep_check(fn, recipename, task, dep, depname):
+                continue
             if dep not in self.taskhash:
                 bb.fatal("%s is not in taskhash, caller isn't calling in dependency order?", dep)
             data = data + self.taskhash[dep]