Add Python txn get_approximate_size API and test

bindings/python/fdb/impl.py

@@ -541,6 +541,11 @@ class Transaction(TransactionRead):
         self.capi.fdb_transaction_get_committed_version(self.tpointer, ctypes.byref(version))
         return version.value
 
+    def get_approximate_size(self):
+        size = ctypes.c_int()
+        self.capi.fdb_transaction_get_approximate_size(self.tpointer, ctypes.byref(size))
+        return size.value
+
     def get_versionstamp(self):
         return Key(self.capi.fdb_transaction_get_versionstamp(self.tpointer))
 
@@ -1453,6 +1458,10 @@ def init_c_api():
     _capi.fdb_transaction_get_committed_version.restype = ctypes.c_int
     _capi.fdb_transaction_get_committed_version.errcheck = check_error_code
 
+    _capi.fdb_transaction_get_approximate_size.argtypes = [ctypes.c_void_p, ctypes.POINTER(ctypes.c_int)]
+    _capi.fdb_transaction_get_approximate_size.restype = ctypes.c_int
+    _capi.fdb_transaction_get_approximate_size.errcheck = check_error_code
+
     _capi.fdb_transaction_get_versionstamp.argtypes = [ctypes.c_void_p]
     _capi.fdb_transaction_get_versionstamp.restype = ctypes.c_void_p
 

bindings/python/tests/size_limit_tests.py

@@ -68,9 +68,36 @@ def test_size_limit_option(db):
     except fdb.FDBError as e:
         assert(e.code == 2101)  # Transaction exceeds byte limit (2101)
 
+@fdb.transactional
+def test_get_approximate_size(tr):
+    tr[b'key1'] = b'value1'
+    s1 = tr.get_approximate_size()
+    print "s1: ", s1
+
+    tr[b'key2'] = b'value2'
+    s2 = tr.get_approximate_size()
+    print "s2: ", s2
+    assert(s1 < s2)
+
+    tr.clear(b'key3')
+    s3 = tr.get_approximate_size()
+    print "s3: ", s3
+    assert(s2 < s3)
+
+    tr.add_read_conflict_key(b'key3')
+    s4 = tr.get_approximate_size()
+    print "s4: ", s4
+    assert(s3 < s4)
+
+    tr.add_write_conflict_key(b'key4')
+    s5 = tr.get_approximate_size()
+    print "s5: ", s5
+    assert(s4 < s5)
+
 # Expect a cluster file as input. This test will write to the FDB cluster, so
 # be aware of potential side effects.
 if __name__ == '__main__':
     clusterFile = sys.argv[1]
     db = fdb.open(clusterFile)
     test_size_limit_option(db)
+    test_get_approximate_size(db)