HBASE-9263 Add initialize method to load balancer interface

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1516310 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -836,6 +836,12 @@ MasterServices, Server {
     Set<ServerName> previouslyFailedMetaRSs = getPreviouselyFailedMetaServersFromZK();
 
     this.initializationBeforeMetaAssignment = true;
+
+    //initialize load balancer
+    this.balancer.setClusterStatus(getClusterStatus());
+    this.balancer.setMasterServices(this);
+    this.balancer.initialize();
+
     // Make sure meta assigned before proceeding.
     status.setStatus("Assigning Meta Region");
     assignMeta(status);
@@ -877,11 +883,11 @@ MasterServices, Server {
     org.apache.hadoop.hbase.catalog.MetaMigrationConvertingToPB
       .updateMetaIfNecessary(this);
 
-    this.balancer.setMasterServices(this);
     // Fix up assignment manager status
     status.setStatus("Starting assignment manager");
     this.assignmentManager.joinCluster();
 
+    //set cluster status again after user regions are assigned
     this.balancer.setClusterStatus(getClusterStatus());
 
     if (!masterRecovery) {

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

@@ -27,6 +27,7 @@ import org.apache.hadoop.hbase.ClusterStatus;
 import org.apache.hadoop.hbase.HBaseIOException;
 import org.apache.hadoop.hbase.HRegionInfo;
 import org.apache.hadoop.hbase.ServerName;
+import org.apache.hadoop.hbase.Stoppable;
 
 /**
  * Makes decisions about the placement and movement of Regions across
@@ -45,7 +46,7 @@ import org.apache.hadoop.hbase.ServerName;
  * <p>This classes produces plans for the {@link AssignmentManager} to execute.
  */
 @InterfaceAudience.Public
-public interface LoadBalancer extends Configurable {
+public interface LoadBalancer extends Configurable, Stoppable {
 
   /**
    * Set the current cluster status.  This allows a LoadBalancer to map host name to a server
@@ -110,4 +111,10 @@ public interface LoadBalancer extends Configurable {
   ServerName randomAssignment(
     HRegionInfo regionInfo, List<ServerName> servers
   ) throws HBaseIOException;
+
+  /**
+   * Initialize the load balancer. Must be called after setters.
+   * @throws HBaseIOException
+   */
+  void initialize() throws HBaseIOException;
 }

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

@@ -33,6 +33,7 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hbase.ClusterStatus;
+import org.apache.hadoop.hbase.HBaseIOException;
 import org.apache.hadoop.hbase.HRegionInfo;
 import org.apache.hadoop.hbase.RegionLoad;
 import org.apache.hadoop.hbase.ServerName;
@@ -51,6 +52,7 @@ import com.google.common.collect.Sets;
  *
  */
 public abstract class BaseLoadBalancer implements LoadBalancer {
+  private volatile boolean stopped = false;
 
   /**
    * An efficient array based implementation similar to ClusterState for keeping
@@ -566,4 +568,18 @@ public abstract class BaseLoadBalancer implements LoadBalancer {
     return assignments;
   }
 
+  @Override
+  public void initialize() throws HBaseIOException{
+  }
+
+  @Override
+  public boolean isStopped() {
+    return stopped;
+  }
+
+  @Override
+  public void stop(String why) {
+    LOG.info("Load Balancer stop requested: "+why);
+    stopped = true;
+  }
 }