bitbake: SignatureGenerator: add method for saving the file checksum cache

Extend the API in order to be able to write out the file checksum cache
onto disk. SignatureGeneratorBasic class now implements a method that
update the fetcher local files checksum cache with the task file
dependency checksums.

(Bitbake rev: ecdabd321d48fa367b89ebffc00aa525b6eaa95c)

Signed-off-by: Markus Lehtonen <markus.lehtonen@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/siggen.py

@@ -44,6 +44,10 @@ class SignatureGenerator(object):
     def get_taskhash(self, fn, task, deps, dataCache):
         return "0"
 
+    def writeout_file_checksum_cache(self):
+        """Write/update the file checksum cache onto disk"""
+        return
+
     def set_taskdata(self, hashes, deps, checksum):
         return
 
@@ -215,6 +219,11 @@ class SignatureGeneratorBasic(SignatureGenerator):
         #d.setVar("BB_TASKHASH_task-%s" % task, taskhash[task])
         return h
 
+    def writeout_file_checksum_cache(self):
+        """Write/update the file checksum cache onto disk"""
+        bb.fetch2.fetcher_parse_save()
+        bb.fetch2.fetcher_parse_done()
+
     def dump_sigtask(self, fn, task, stampbase, runtime):
         k = fn + "." + task
         if runtime == "customfile":