HBASE-1102 boolean HTabble.exists()

git-svn-id: https://svn.apache.org/repos/asf/hadoop/hbase/trunk@730361 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -200,6 +200,7 @@ Release 0.19.0 - Unreleased
    HBASE-1066  Master should support close/open/reassignment/enable/disable
                operations on individual regions
    HBASE-1062  Compactions at (re)start on a large table can overwhelm DFS
+   HBASE-1102  boolean HTable.exists()
 
   NEW FEATURES
    HBASE-875   Use MurmurHash instead of JenkinsHash [in bloomfilters]

src/java/org/apache/hadoop/hbase/client/HTable.java

@@ -1207,6 +1207,70 @@ public class HTable {
     );
   }
 
+  /**
+   * Test for the existence of a row in the table.
+   * 
+   * @param row The row
+   * @return true if the row exists, false otherwise
+   * @throws IOException
+   */
+  public boolean exists(final byte [] row) throws IOException {
+    return exists(row, null, HConstants.LATEST_TIMESTAMP, null);
+  }
+
+  /**
+   * Test for the existence of a row and column in the table.
+   * 
+   * @param row The row
+   * @param column The column
+   * @return true if the row exists, false otherwise
+   * @throws IOException
+   */
+  public boolean exists(final byte [] row, final byte[] column)
+  throws IOException {
+    return exists(row, column, HConstants.LATEST_TIMESTAMP, null);
+  }
+
+  /**
+   * Test for the existence of a coordinate in the table.
+   * 
+   * @param row The row
+   * @param column The column
+   * @param timestamp The timestamp
+   * @return true if the specified coordinate exists
+   * @throws IOException
+   */
+  public boolean exists(final byte [] row, final byte [] column,
+      long timestamp) throws IOException {
+    return exists(row, column, timestamp, null);
+  }
+
+  /**
+   * Test for the existence of a coordinate in the table.
+   * 
+   * @param row The row
+   * @param column The column
+   * @param timestamp The timestamp
+   * @param rl Existing row lock
+   * @return true if the specified coordinate exists
+   * @throws IOException
+   */
+  public boolean exists(final byte [] row, final byte [] column,
+      final long timestamp, final RowLock rl) throws IOException {
+    return connection.getRegionServerWithRetries(
+      new ServerCallable<Boolean>(connection, tableName, row) {
+        public Boolean call() throws IOException {
+          long lockId = -1L;
+          if (rl != null) {
+            lockId = rl.getLockId();
+          }
+          return server.exists(location.getRegionInfo().getRegionName(), row,
+            column, timestamp, lockId);
+        }
+      }
+    );
+  }
+
   /**
    * Commit a BatchUpdate to the table.
    * If autoFlush is false, the update is buffered

src/java/org/apache/hadoop/hbase/ipc/HBaseRPCProtocolVersion.java

@@ -64,7 +64,8 @@ public interface HBaseRPCProtocolVersion extends VersionedProtocol {
    * <li>Version 12: HServerLoad extensions (HBASE-1018).</li>
    * <li>Version 13: HBASE-847</li>
    * <li>Version 14: HBASE-900</li>
+   * <li>Version 15: HRegionInterface.exists</li>
    * </ul>
    */
-  public static final long versionID = 14L;
+  public static final long versionID = 15L;
 }

src/java/org/apache/hadoop/hbase/ipc/HRegionInterface.java

@@ -191,7 +191,21 @@ public interface HRegionInterface extends HBaseRPCProtocolVersion {
     long timestamp, long lockId) 
   throws IOException;
 
-  
+  /**
+   * Returns true if any cells exist for the given coordinate.
+   * 
+   * @param regionName The name of the region
+   * @param row The row
+   * @param column The column, or null for any
+   * @param timestamp The timestamp, or LATEST_TIMESTAMP for any
+   * @param lockId lock id
+   * @return true if the row exists, false otherwise
+   * @throws IOException
+   */
+  public boolean exists(byte [] regionName, byte [] row, byte [] column, 
+    long timestamp, long lockID)
+  throws IOException;
+
   //
   // remote scanner interface
   //

src/java/org/apache/hadoop/hbase/regionserver/HRegion.java

@@ -1501,7 +1501,36 @@ public class HRegion implements HConstants {
       update(edits);
     }
   }
-    
+
+  /**
+   * Tests for the existence of any cells for a given coordinate.
+   * 
+   * @param row the row
+   * @param column the column, or null
+   * @param timestamp the timestamp, or HConstants.LATEST_VERSION for any
+   * @param lockid the existing lock, or null 
+   * @return true if cells exist for the row, false otherwise
+   * @throws IOException
+   */
+  public boolean exists(final byte[] row, final byte[] column, 
+    final long timestamp, final Integer lockid) 
+  throws IOException {
+    checkRow(row);
+    Integer lid = getLock(lockid, row);
+    try {
+      HStoreKey origin;
+      if (column != null) {
+        origin = new HStoreKey(row, column, timestamp);
+      } else {
+        origin = new HStoreKey(row, timestamp);
+      }
+      return !getKeys(origin, 1).isEmpty();
+    } finally {
+      if (lockid == null)
+        releaseRowLock(lid);
+    }
+  }
+
   /**
    * @throws IOException Throws exception if region is in read-only mode.
    */

src/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java

@@ -1774,6 +1774,13 @@ public class HRegionServer implements HConstants, HRegionInterface, Runnable {
         getLockFromId(lockId));
   }
 
+  public boolean exists(byte[] regionName, byte[] row, byte[] column,
+      long timestamp, long lockId)
+  throws IOException {
+    return getRegion(regionName).exists(row, column, timestamp, 
+      getLockFromId(lockId));
+  }
+
   public long lockRow(byte [] regionName, byte [] row)
   throws IOException {
     checkOpen();

src/test/org/apache/hadoop/hbase/client/TestHTable.java

@@ -228,7 +228,11 @@ public class TestHTable extends HBaseClusterTestCase implements HConstants {
         batchUpdate.put(COLUMN_FAMILY_STR+i, Bytes.toBytes(i));
       
       table.commit(batchUpdate);
-      
+
+      assertTrue(table.exists(row));
+      for(int i = 0; i < 5; i++)
+        assertTrue(table.exists(row, Bytes.toBytes(COLUMN_FAMILY_STR+i)));
+
       RowResult result = null;
       result = table.getRow(row,  new byte[][] {COLUMN_FAMILY});
       for(int i = 0; i < 5; i++)