[hbase10] Address #701 by mimicking the same locks from the HBase 0.9… (#1028)

* [hbase10] Fix #701 by mimicking the same locks from the HBase 0.98 client in the HBase 10 client.

* Address CR comments, thanks @allanbank.

* Addressed the table lock.

* Restore the lock on the connection shutdown.

hbase10/src/main/java/com/yahoo/ycsb/db/HBaseClient10.java

@@ -66,10 +66,10 @@ import static com.yahoo.ycsb.workloads.CoreWorkload.TABLENAME_PROPERTY_DEFAULT;
  * durability.
  */
 public class HBaseClient10 extends com.yahoo.ycsb.DB {
+  private static final AtomicInteger THREAD_COUNT = new AtomicInteger(0);
+  
   private Configuration config = HBaseConfiguration.create();
-
-  private static AtomicInteger threadCount = new AtomicInteger(0);
-
+  
   private boolean debug = false;
 
   private String tableName = "";
@@ -82,7 +82,6 @@ public class HBaseClient10 extends com.yahoo.ycsb.DB {
    * @See #CONNECTION_LOCK.
    */
   private static Connection connection = null;
-  private static final Object CONNECTION_LOCK = new Object();
 
   // Depending on the value of clientSideBuffering, either bufferedMutator
   // (clientSideBuffering) or currentTable (!clientSideBuffering) will be used.
@@ -144,12 +143,19 @@ public class HBaseClient10 extends com.yahoo.ycsb.DB {
       }
     }
 
+    String table = getProperties().getProperty(TABLENAME_PROPERTY, TABLENAME_PROPERTY_DEFAULT);
     try {
-      threadCount.getAndIncrement();
-      synchronized (CONNECTION_LOCK) {
+      THREAD_COUNT.getAndIncrement();
+      synchronized (THREAD_COUNT) {
         if (connection == null) {
           // Initialize if not set up already.
           connection = ConnectionFactory.createConnection(config);
+          
+          // Terminate right now if table does not exist, since the client
+          // will not propagate this error upstream once the workload
+          // starts.
+          final TableName tName = TableName.valueOf(table);
+          connection.getTable(tName).getTableDescriptor();
         }
       }
     } catch (java.io.IOException e) {
@@ -172,19 +178,6 @@ public class HBaseClient10 extends com.yahoo.ycsb.DB {
       throw new DBException("No columnfamily specified");
     }
     columnFamilyBytes = Bytes.toBytes(columnFamily);
-
-    // Terminate right now if table does not exist, since the client
-    // will not propagate this error upstream once the workload
-    // starts.
-    String table = getProperties().getProperty(TABLENAME_PROPERTY, TABLENAME_PROPERTY_DEFAULT);
-    try {
-      final TableName tName = TableName.valueOf(table);
-      synchronized (CONNECTION_LOCK) {
-        connection.getTable(tName).getTableDescriptor();
-      }
-    } catch (IOException e) {
-      throw new DBException(e);
-    }
   }
 
   /**
@@ -208,14 +201,14 @@ public class HBaseClient10 extends com.yahoo.ycsb.DB {
       long en = System.nanoTime();
       final String type = clientSideBuffering ? "UPDATE" : "CLEANUP";
       measurements.measure(type, (int) ((en - st) / 1000));
-      threadCount.decrementAndGet();
-      if (threadCount.get() <= 0) {
+      int threadCount = THREAD_COUNT.decrementAndGet();
+      if (threadCount <= 0) {
         // Means we are done so ok to shut down the Connection.
-        synchronized (CONNECTION_LOCK) {
-          if (connection != null) {
-            connection.close();
-            connection = null;
-          }
+        synchronized (THREAD_COUNT) {
+          if (connection != null) {   
+            connection.close();   
+            connection = null;    
+          }   
         }
       }
     } catch (IOException e) {
@@ -225,13 +218,11 @@ public class HBaseClient10 extends com.yahoo.ycsb.DB {
 
   public void getHTable(String table) throws IOException {
     final TableName tName = TableName.valueOf(table);
-    synchronized (CONNECTION_LOCK) {
-      this.currentTable = connection.getTable(tName);
-      if (clientSideBuffering) {
-        final BufferedMutatorParams p = new BufferedMutatorParams(tName);
-        p.writeBufferSize(writeBufferSize);
-        this.bufferedMutator = connection.getBufferedMutator(p);
-      }
+    this.currentTable = connection.getTable(tName);
+    if (clientSideBuffering) {
+      final BufferedMutatorParams p = new BufferedMutatorParams(tName);
+      p.writeBufferSize(writeBufferSize);
+      this.bufferedMutator = connection.getBufferedMutator(p);
     }
   }