IMPALA-9101: Add support for detecting self-events on partition events

This commit redoes some of the self-event detection logic, specifically
for the partition events. Before the patch, the self-event identifiers
for a partition were stored at a table level when generating the
partition events. This was problematic since unlike ADD_PARTITION and
DROP_PARTITION event, ALTER_PARTITION event is generated one per
partition. Due to this if there are multiple ALTER_PARTITION events
generated, only the first event is identified as a self-event and the
rest of the events are processed. This patch fixes this by adding the
self-event identifiers to each partition so that when the event is later
received, each ALTER_PARTITION uses the state stored in HdfsPartition to
valuate the self-events. The patch makes sure that the event processor
takes a table lock during self-event evaluation to avoid races with
other parts of the code which try to modify the table at the same time.

Additionally, this patch also changes the event processor to refresh a
loaded table (incomplete tables are not refreshed) when a ALTER_TABLE
event is received instead of invalidating the table. This makes the
events processor consistent with respect to all the other event types.
In future, we should add a flag to choose the behavior preference
(prefer invalidate or refresh).

Also, this patch fixes the following related issues:
1. Self-event logic was not triggered for alter database events when
user modifies the comment on the database.
2. In case of queries like "alter table add if not exists partition...",
the partition is not added since its pre-existing. The self-event
identifiers should not be added in such cases since no event is expected
from such queries.
3. Changed wait_for_event_processing test util method in
EventProcessorUtils to use a more deterministic way to determine if the
catalog updates have propogated to impalad instead of waiting for a
random duration of time.  This also speeds up the event processing tests
significantly.

Testing Done:
1. Added a e2e self-events test which runs multiple impala
queries and makes sure that the event is skips processing.
2. Ran MetastoreEventsProcessorTest
3. Ran core tests on CDH and CDP builds.

Change-Id: I9b4148f6be0f9f946c8ad8f314d64b095731744c
Reviewed-on: http://gerrit.cloudera.org:8080/14799
Reviewed-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>

tests/util/event_processor_utils.py

@@ -19,37 +19,45 @@
 # modifies the metadata via Hive and checks that the modification
 # succeeded by querying Impala, or vice versa.
 
+import logging
 import requests
 import time
 import json
-from tests.common.environ import build_flavor_timeout
-
 
+LOG = logging.getLogger('event_processor_utils')
+LOG.setLevel(level=logging.DEBUG)
 class EventProcessorUtils(object):
 
   DEFAULT_CATALOG_URL = "http://localhost:25020"
 
   @staticmethod
-  def wait_for_event_processing(hive_client, timeout=10):
+  def wait_for_event_processing(test_suite, timeout=10):
       """Waits till the event processor has synced to the latest event id from metastore
          or the timeout value in seconds whichever is earlier"""
       success = False
       assert timeout > 0
-      assert hive_client is not None
-      current_event_id = EventProcessorUtils.get_current_notification_id(hive_client)
+      assert test_suite.hive_client is not None
+      current_event_id = EventProcessorUtils.get_current_notification_id(
+        test_suite.hive_client)
+      LOG.info("Waiting until events processor syncs to event id:" + str(current_event_id))
       end_time = time.time() + timeout
       while time.time() < end_time:
-        new_event_id = EventProcessorUtils.get_last_synced_event_id()
-        if new_event_id >= current_event_id:
+        last_synced_id = EventProcessorUtils.get_last_synced_event_id()
+        if last_synced_id >= current_event_id:
+          LOG.debug(
+            "Metric last-synced-event-id has reached the desired value:" + str(
+              last_synced_id))
           success = True
           break
         time.sleep(0.1)
       if not success:
         raise Exception(
-          "Event processor did not sync till last known event id{0} \
+          "Event processor did not sync till last known event id {0} \
           within {1} seconds".format(current_event_id, timeout))
-      # Wait for catalog update to be propagated.
-      time.sleep(build_flavor_timeout(6, slow_build_timeout=10))
+      # Wait until the impalad catalog versions agree with the catalogd's version.
+      catalogd_version = test_suite.cluster.catalogd.service.get_catalog_version()
+      for impalad in test_suite.cluster.impalads:
+        impalad.service.wait_for_metric_value("catalog.curr-version", catalogd_version)
       return success
 
   @staticmethod
@@ -68,6 +76,14 @@ class EventProcessorUtils(object):
      pairs = [strip_pair(kv.split(':')) for kv in metrics if kv]
      return dict(pairs)
 
+  @staticmethod
+  def get_event_processor_metric(metric_key, default_val=None):
+    """Returns the event processor metric from the /events catalog debug page"""
+    metrics = EventProcessorUtils.get_event_processor_metrics()
+    if metric_key not in metrics:
+      return default_val
+    return metrics[metric_key]
+
   @staticmethod
   def get_last_synced_event_id():
     """Returns the last_synced_event_id."""
@@ -88,4 +104,4 @@ class EventProcessorUtils(object):
   def get_current_notification_id(hive_client):
     """Returns the current notification from metastore"""
     assert hive_client is not None
-    return hive_client.get_current_notificationEventId()
+    return int(hive_client.get_current_notificationEventId().eventId)