bitbake: data_smart: implement remote datastore functionality

This allows you to maintain a local reference to a remote datastore. The
actual implementation of the remote connection is delegated to a
connector object that the caller must define and supply. There is
support for getting variable values and expanding python references
(i.e. ${@...} remotely, however setting variables remotely is not
supported - any variable setting is done locally as if the datastore
were a copy (which it kind of is).

Loosely based on an earlier prototype implementation by Qing He.

(Bitbake rev: a3edc3eefa2d03c4ad5d12187b32fa4dc495082a)

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

bitbake/lib/bb/tests/data.py

@@ -444,3 +444,42 @@ class Contains(unittest.TestCase):
 
         self.assertFalse(bb.utils.contains_any("SOMEFLAG", "x", True, False, self.d))
         self.assertFalse(bb.utils.contains_any("SOMEFLAG", "x y z", True, False, self.d))
+
+
+class Remote(unittest.TestCase):
+    def test_remote(self):
+        class TestConnector:
+            d = None
+            def __init__(self, d):
+                self.d = d
+            def getVar(self, name):
+                return self.d._findVar(name)
+            def getKeys(self):
+                return self.d.localkeys()
+            def getVarHistory(self, name):
+                return self.d.varhistory.variable(name)
+            def expandPythonRef(self, varname, expr):
+                varparse = bb.data_smart.VariableParse(varname, self.d)
+                return varparse.python_sub(expr)
+            def setVar(self, name, value):
+                self.d.setVar(name, value)
+
+        d1 = bb.data.init()
+        d1.enableTracking()
+        d2 = bb.data.init()
+        d2.enableTracking()
+        connector = TestConnector(d1)
+
+        d2.setVar('_remote_data', connector)
+
+        d1.setVar('HELLO', 'world')
+        d1.setVarFlag('OTHER', 'flagname', 'flagvalue')
+        self.assertEqual(d2.getVar('HELLO'), 'world')
+        self.assertEqual(d2.expand('${HELLO}'), 'world')
+        self.assertEqual(d2.expand('${@d.getVar("HELLO")}'), 'world')
+        self.assertIn('flagname', d2.getVarFlags('OTHER'))
+        self.assertEqual(d2.getVarFlag('OTHER', 'flagname'), 'flagvalue')
+        self.assertEqual(d1.varhistory.variable('HELLO'), d2.varhistory.variable('HELLO'))
+        # Test setVar on client side affects server
+        d2.setVar('HELLO', 'other-world')
+        self.assertEqual(d1.getVar('HELLO'), 'other-world')