tests: added test verifying if periodic flushing works correctly

Signed-off-by: Michal Maslanka <michal@redpanda.com>

tests/rptest/tests/raft_periodic_flush_test.py

@@ -0,0 +1,74 @@
+# Copyright 2022 Redpanda Data, Inc.
+#
+# Use of this software is governed by the Business Source License
+# included in the file licenses/BSL.md
+#
+# As of the Change Date specified in that file, in accordance with
+# the Business Source License, use of this software will be governed
+# by the Apache License, Version 2.0
+
+from rptest.services.admin import Admin
+from rptest.services.cluster import cluster
+from rptest.clients.types import TopicSpec
+from rptest.tests.end_to_end import EndToEndTest
+from rptest.util import wait_until
+
+
+class PeriodicFlushWithRelaxedConsistencyTest(EndToEndTest):
+    @cluster(num_nodes=5)
+    def test_changing_periodic_flush_threshold(self):
+
+        self.start_redpanda(num_nodes=3)
+        # set raft_max_not_flushed_bytes to high value
+        self.redpanda.set_cluster_config(
+            {"raft_replica_max_pending_flush_bytes": 10 * (1024 * 1024)})
+
+        # create topic with single partition
+        spec = TopicSpec(partition_count=1, replication_factor=3)
+        self.client().create_topic(spec)
+
+        self.topic = spec.name
+
+        self.start_producer(1, throughput=1000, acks=1)
+        self.start_consumer()
+        self.consumer.start()
+        msg_count = 10000
+        wait_until(
+            lambda: len(self.producer.acked_values) >= msg_count,
+            timeout_sec=60,
+            backoff_sec=1,
+            err_msg=f"Producer didn't end producing {msg_count} messages")
+        # wait for at least 15000 records to be consumed
+
+        self.producer.stop()
+        self.run_validation(min_records=msg_count,
+                            producer_timeout_sec=300,
+                            consumer_timeout_sec=300)
+
+        admin = Admin(self.redpanda)
+        p_state = admin.get_partition_state(namespace='kafka',
+                                            topic=self.topic,
+                                            partition=0)
+        self.logger.info(f"initial partition state: {p_state}")
+        assert all([
+            r['committed_offset'] < r['dirty_offset']
+            for r in p_state['replicas']
+        ]), "With ACKS=1, committed offset should not be advanced immediately"
+
+        self.redpanda.set_cluster_config(
+            {"raft_replica_max_pending_flush_bytes": 1})
+
+        def committed_offset_advanced():
+            p_state = admin.get_partition_state(namespace='kafka',
+                                                topic=self.topic,
+                                                partition=0)
+
+            return all([
+                r['committed_offset'] == r['dirty_offset']
+                for r in p_state['replicas']
+            ])
+
+        wait_until(
+            committed_offset_advanced, 30, 1,
+            "committed offset did not advance after the change of max flushed bytes"
+        )