STAR-247: Standalone scrubber should use the same default sstable format as specified for the test

Also made a small refactoring of dtest_config.py

(cherry picked from commit 1253168)
(cherry picked from commit 66b7cba)
(cherry picked from commit fb9042e)

Author: jacek-lewandowski

dtest_config.py

@@ -45,8 +45,6 @@ def setup(self, config):
         self.sstable_format = config.getoption("--sstable-format")
         if self.sstable_format:
             assert self.sstable_format in ['bti', 'big'], "SSTable format {} is invalid - must be either bti or big".format(self.sstable_format)
-            default_sstable_format_prop = " -Dcassandra.sstable.format.default=" + self.sstable_format
-            os.environ.update({"JVM_EXTRA_OPTS": (os.environ.get("JVM_EXTRA_OPTS") or "") + default_sstable_format_prop})
 
         self.use_vnodes = config.getoption("--use-vnodes")
         self.use_off_heap_memtables = config.getoption("--use-off-heap-memtables")
@@ -97,6 +95,17 @@ def setup(self, config):
                              "--use-off-heap-memtables, see https://issues.apache.org/jira/browse/CASSANDRA-9472 "
                              "for details" % version)
 
+        self.apply_to_env(os.environ, "JVM_EXTRA_OPTS")
+
+    def apply_to_env(self, env, key="JVM_OPTS"):
+        current = env.get(key) or ""
+        if self.sstable_format:
+            default_sstable_format_prop = " -Dcassandra.sstable.format.default=" + self.sstable_format
+            if not current.__contains__("-Dcassandra.sstable.format.default"):
+                env.update({key: (env.get(key) or "") + default_sstable_format_prop})
+            else:
+                logger.debug("Skipped adding {} because it is already in the env key {}: {}".format(default_sstable_format_prop, key, current))
+
     def get_version_from_build(self):
         # There are times when we want to know the C* version we're testing against
         # before we do any cluster. In the general case, we can't know that -- the

scrub_test.py

@@ -116,6 +116,9 @@ def launch_standalone_scrub(self, ks, cf, reinsert_overflowed_ttl=False, no_vali
         """
         node1 = self.cluster.nodelist()[0]
         env = common.make_cassandra_env(node1.get_install_cassandra_root(), node1.get_node_cassandra_root())
+
+        self.dtest_config.apply_to_env(env, "JVM_OPTS")
+
         scrub_bin = node1.get_tool('sstablescrub')
         logger.debug(scrub_bin)