nvharikrishna commented on code in PR #321:
URL: https://github.com/apache/cassandra-sidecar/pull/321#discussion_r2955220778
##########
server/src/main/java/org/apache/cassandra/sidecar/livemigration/DataCopyTaskManager.java:
##########
@@ -101,39 +103,83 @@ Future<LiveMigrationTask>
createDataCopyTask(LiveMigrationDataCopyRequest reques
String source,
InstanceMetadata
localInstanceMetadata)
{
- LiveMigrationTask newTask = createTask(request,
- source,
-
sidecarConfiguration.serviceConfiguration().port(),
- localInstanceMetadata);
-
- // It is possible to serve only one live migration data copy request
per instance at a time.
- // Checking if there is another migration is in progress before
accepting new one.
- boolean accepted = currentTasks.compute(localInstanceMetadata.id(),
(integer, taskInMap) -> {
- if (taskInMap == null)
- {
- return newTask;
- }
+ // Fast local JMX check before creating task - prevents task creation
if Cassandra is running
+ return verifyCassandraNotRunning(localInstanceMetadata)
+ .compose(v -> {
+ LiveMigrationTask newTask = createTask(request,
+ source,
+
sidecarConfiguration.serviceConfiguration().port(),
+
localInstanceMetadata);
+
+ // It is possible to serve only one live migration data
copy request per instance at a time.
+ // Checking if there is another migration is in progress
before accepting new one.
+ boolean accepted =
currentTasks.compute(localInstanceMetadata.id(), (integer, taskInMap) -> {
+ if (taskInMap == null)
+ {
+ return newTask;
+ }
+
+ if (!taskInMap.isCompleted())
+ {
+ // Accept new task if and only if the existing task
has completed.
+ return taskInMap;
+ }
+ else
+ {
+ return newTask;
+ }
+ }) == newTask;
+
+ if (!accepted)
+ {
+ return Future.failedFuture(
+ new LiveMigrationDataCopyInProgressException("Another
task is already under progress. Cannot accept new task."));
+ }
+ LOGGER.info("Starting data copy task with id={}, source={},
destination={}",
+ newTask.id(), source,
localInstanceMetadata.host());
+ newTask.start();
+ return Future.succeededFuture(newTask);
+ });
+ }
- if (!taskInMap.isCompleted())
- {
- // Accept new task if and only if the existing task has
completed.
- return taskInMap;
- }
- else
+ /**
+ * Initiating data copy once a Cassandra instance starts is not
acceptable. This method checks whether
+ * Cassandra is running or not at the moment on the destination instance
by checking if Sidecar
+ * was able to connect to the Cassandra instance's JMX port. It returns a
failed future if Sidecar
+ * is able to connect to the JMX port of Cassandra.
+ *
+ * @param localInstance metadata for the local Cassandra instance
+ * @return Future that succeeds if Cassandra is not running, fails if it
is running
+ */
+ private Future<Void> verifyCassandraNotRunning(InstanceMetadata
localInstance)
+ {
+ try
+ {
+ CassandraAdapterDelegate delegate = localInstance.delegate();
+
+ if (delegate.isJmxUp())
Review Comment:
Makes sense, made the changes.
##########
CHANGES.txt:
##########
@@ -1,5 +1,6 @@
0.3.0
-----
+ * Adding gossip based safety check to Live Migration data copy task endpoint
(CASSSIDECAR-409)
Review Comment:
done
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