HBASE-23996 deprecate ZK-coordinated WAL split classes and metrics

Mark the legacy ZooKeeper-coordinated WAL split coordination classes
(ZKSplitLogManagerCoordination, ZkSplitLogWorkerCoordination) and the
associated MetricsMasterFileSystem source as deprecated, since the
procedure-based distributed WAL splitter (SplitWALManager) is the default
and these are only reachable under the legacy
hbase.split.writer.coordinated.by.zk path.

Co-authored-by: Claude <noreply@anthropic.com>

Author: Umeshkumar9414

hbase-hadoop-compat/src/main/java/org/apache/hadoop/hbase/master/MetricsMasterFileSystemSource.java

@@ -21,6 +21,13 @@
 import org.apache.hadoop.hbase.metrics.BaseSource;
 import org.apache.yetus.audience.InterfaceAudience;
 
+/**
+ * @deprecated since 2.4.0 and in 3.0.0, to be removed in 4.0.0, replaced by procedure-based
+ *             distributed WAL splitter; see SplitWALManager. These metrics ({@code hlogSplitTime},
+ *             {@code hlogSplitSize}, {@code metaHlogSplitTime}, {@code metaHlogSplitSize}) are only
+ *             emitted by the deprecated ZK-coordinated WAL split path.
+ */
+@Deprecated
 @InterfaceAudience.Private
 public interface MetricsMasterFileSystemSource extends BaseSource {
 

hbase-hadoop-compat/src/main/java/org/apache/hadoop/hbase/master/MetricsMasterFilesystemSourceImpl.java

@@ -21,6 +21,13 @@
 import org.apache.hadoop.metrics2.MetricHistogram;
 import org.apache.yetus.audience.InterfaceAudience;
 
+/**
+ * @deprecated since 2.4.0 and in 3.0.0, to be removed in 4.0.0, replaced by procedure-based
+ *             distributed WAL splitter; see SplitWALManager. Implementation of the deprecated
+ *             {@link MetricsMasterFileSystemSource}, whose metrics are only emitted by the
+ *             ZK-coordinated WAL split path.
+ */
+@Deprecated
 @InterfaceAudience.Private
 public class MetricsMasterFilesystemSourceImpl extends BaseSourceImpl
   implements MetricsMasterFileSystemSource {

hbase-server/src/main/java/org/apache/hadoop/hbase/coordination/ZKSplitLogManagerCoordination.java

@@ -58,8 +58,11 @@
 import org.slf4j.LoggerFactory;
 
 /**
- * ZooKeeper based implementation of {@link SplitLogManagerCoordination}
+ * ZooKeeper based implementation of {@link SplitLogManagerCoordination}.
+ * @deprecated since 2.4.0 and in 3.0.0, to be removed in 4.0.0, replaced by procedure-based
+ *             distributed WAL splitter; see SplitWALManager.
  */
+@Deprecated
 @InterfaceAudience.Private
 public class ZKSplitLogManagerCoordination extends ZKListener
   implements SplitLogManagerCoordination {

hbase-server/src/main/java/org/apache/hadoop/hbase/coordination/ZkSplitLogWorkerCoordination.java

@@ -57,9 +57,11 @@
 import org.slf4j.LoggerFactory;
 
 /**
- * ZooKeeper based implementation of {@link SplitLogWorkerCoordination} It listen for changes in
- * ZooKeeper and
+ * ZooKeeper based implementation of {@link SplitLogWorkerCoordination}.
+ * @deprecated since 2.4.0 and in 3.0.0, to be removed in 4.0.0, replaced by procedure-based
+ *             distributed WAL splitter; see SplitWALManager.
  */
+@Deprecated
 @InterfaceAudience.Private
 public class ZkSplitLogWorkerCoordination extends ZKListener implements SplitLogWorkerCoordination {
 

hbase-server/src/main/java/org/apache/hadoop/hbase/master/MetricsMasterFileSystem.java

@@ -20,6 +20,13 @@
 import org.apache.hadoop.hbase.CompatibilitySingletonFactory;
 import org.apache.yetus.audience.InterfaceAudience;
 
+/**
+ * @deprecated since 2.4.0 and in 3.0.0, to be removed in 4.0.0, replaced by procedure-based
+ *             distributed WAL splitter; see SplitWALManager. These metrics ({@code hlogSplitTime},
+ *             {@code hlogSplitSize}, {@code metaHlogSplitTime}, {@code metaHlogSplitSize}) are only
+ *             emitted by the deprecated ZK-coordinated WAL split path.
+ */
+@Deprecated
 @InterfaceAudience.Private
 public class MetricsMasterFileSystem {