HBASE-22230 REST Server drops connection on long scan

Signed-off-by: stack <stack@apache.org>

hbase-rest/src/main/java/org/apache/hadoop/hbase/rest/RESTServlet.java

@@ -46,8 +46,8 @@ public class RESTServlet implements Constants {
   private final UserGroupInformation realUser;
   private final JvmPauseMonitor pauseMonitor;
 
-  static final String CLEANUP_INTERVAL = "hbase.rest.connection.cleanup-interval";
+  public static final String CLEANUP_INTERVAL = "hbase.rest.connection.cleanup-interval";
-  static final String MAX_IDLETIME = "hbase.rest.connection.max-idletime";
+  public static final String MAX_IDLETIME = "hbase.rest.connection.max-idletime";
   static final String HBASE_REST_SUPPORT_PROXYUSER = "hbase.rest.support.proxyuser";
 
   UserGroupInformation getRealUser() {
@@ -62,6 +62,13 @@ public class RESTServlet implements Constants {
     return INSTANCE;
   }
 
+  /**
+   * @return the ConnectionCache instance
+   */
+  public ConnectionCache getConnectionCache() {
+    return connectionCache;
+  }
+
   /**
    * @param conf Existing configuration to use in rest servlet
    * @param userProvider the login user provider

hbase-rest/src/main/java/org/apache/hadoop/hbase/rest/ScannerInstanceResource.java

@@ -82,6 +82,9 @@ public class ScannerInstanceResource extends ResourceBase {
       return Response.status(Response.Status.NOT_FOUND)
         .type(MIMETYPE_TEXT).entity("Not found" + CRLF)
         .build();
+    } else {
+      // Updated the connection access time for each client next() call
+      RESTServlet.getInstance().getConnectionCache().updateConnectionAccessTime();
     }
     CellSetModel model = new CellSetModel();
     RowModel rowModel = null;

hbase-rest/src/test/java/org/apache/hadoop/hbase/rest/client/TestRemoteTable.java

@@ -44,6 +44,7 @@ import org.apache.hadoop.hbase.client.ResultScanner;
 import org.apache.hadoop.hbase.client.Scan;
 import org.apache.hadoop.hbase.client.Table;
 import org.apache.hadoop.hbase.rest.HBaseRESTTestingUtility;
+import org.apache.hadoop.hbase.rest.RESTServlet;
 import org.apache.hadoop.hbase.testclassification.MediumTests;
 import org.apache.hadoop.hbase.testclassification.RestTests;
 import org.apache.hadoop.hbase.util.Bytes;
@@ -576,5 +577,60 @@ public class TestRemoteTable {
     assertTrue(response.hasBody());
   }
 
-}
+  /**
+   * Tests keeping a HBase scanner alive for long periods of time. Each call to next() should reset
+   * the ConnectionCache timeout for the scanner's connection
+   * @throws Exception
+   */
+  @Test
+  public void testLongLivedScan() throws Exception {
+    int numTrials = 6;
+    int trialPause = 1000;
+    int cleanUpInterval = 100;
 
+    // Shutdown the Rest Servlet container
+    REST_TEST_UTIL.shutdownServletContainer();
+
+    // Set the ConnectionCache timeout to trigger halfway through the trials
+    TEST_UTIL.getConfiguration().setLong(RESTServlet.MAX_IDLETIME, (numTrials / 2) * trialPause);
+    TEST_UTIL.getConfiguration().setLong(RESTServlet.CLEANUP_INTERVAL, cleanUpInterval);
+
+    // Start the Rest Servlet container
+    REST_TEST_UTIL.startServletContainer(TEST_UTIL.getConfiguration());
+
+    // Truncate the test table for inserting test scenarios rows keys
+    TEST_UTIL.getHBaseAdmin().disableTable(TABLE);
+    TEST_UTIL.getHBaseAdmin().truncateTable(TABLE, false);
+
+    remoteTable = new RemoteHTable(
+        new Client(new Cluster().add("localhost", REST_TEST_UTIL.getServletPort())),
+        TEST_UTIL.getConfiguration(), TABLE.toBytes());
+
+    String row = "testrow";
+
+    try (Table table = TEST_UTIL.getConnection().getTable(TABLE)) {
+      List<Put> puts = new ArrayList<Put>();
+      Put put = null;
+      for (int i = 1; i <= numTrials; i++) {
+        put = new Put(Bytes.toBytes(row + i));
+        put.addColumn(COLUMN_1, QUALIFIER_1, TS_2, Bytes.toBytes("testvalue" + i));
+        puts.add(put);
+      }
+      table.put(puts);
+    }
+
+    Scan scan = new Scan();
+    scan.setCaching(1);
+    scan.setBatch(1);
+
+    ResultScanner scanner = remoteTable.getScanner(scan);
+    Result result = null;
+    // get scanner and rows
+    for (int i = 1; i <= numTrials; i++) {
+      // Make sure that the Scanner doesn't throw an exception after the ConnectionCache timeout
+      result = scanner.next();
+      assertEquals(row + i, Bytes.toString(result.getRow()));
+      Thread.sleep(trialPause);
+    }
+  }
+}