From c10195177dc40c40c94a6925e1815069fda99bc2 Mon Sep 17 00:00:00 2001
From: Michael Stack <stack@apache.org>
Date: Thu, 6 Jun 2013 00:44:00 +0000
Subject: [PATCH] HBASE-8402 ScanMetrics depends on number of rpc calls to the
 server

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1490094 13f79535-47bb-0310-9956-ffa450edef68
---
 .../hadoop/hbase/client/ClientScanner.java       | 16 ++++++----------
 .../hadoop/hbase/client/TestFromClientSide.java  |  5 ++---
 2 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientScanner.java b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientScanner.java
index ebab79921ae..362a36f267d 100644
--- a/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientScanner.java
+++ b/hbase-client/src/main/java/org/apache/hadoop/hbase/client/ClientScanner.java
@@ -64,7 +64,8 @@ public class ClientScanner extends AbstractClientScanner {
     private final HConnection connection;
     private final byte[] tableName;
     private final int scannerTimeout;
-
+    private boolean scanMetricsPublished = false;
+    
     /**
      * Create a new ClientScanner for the specified table. An HConnection will be
      * retrieved using the passed Configuration.
@@ -243,12 +244,13 @@ public class ClientScanner extends AbstractClientScanner {
      *
      * scan.setAttribute(SCAN_ATTRIBUTES_METRICS_ENABLE, Bytes.toBytes(Boolean.TRUE))
      */
-    private void writeScanMetrics() throws IOException {
-      if (this.scanMetrics == null) {
+    private void writeScanMetrics() {
+      if (this.scanMetrics == null || scanMetricsPublished) {
         return;
       }
       MapReduceProtos.ScanMetrics pScanMetrics = ProtobufUtil.toScanMetrics(scanMetrics);
       scan.setAttribute(Scan.SCAN_ATTRIBUTES_METRICS_DATA, pScanMetrics.toByteArray());
+      scanMetricsPublished = true;
     }
 
     public Result next() throws IOException {
@@ -390,6 +392,7 @@ public class ClientScanner extends AbstractClientScanner {
     }
 
     public void close() {
+      if (!scanMetricsPublished) writeScanMetrics();
       if (callable != null) {
         callable.setClose();
         try {
@@ -399,13 +402,6 @@ public class ClientScanner extends AbstractClientScanner {
           // have since decided that it's not nice for a scanner's close to
           // throw exceptions. Chances are it was just an UnknownScanner
           // exception due to lease time out.
-        } finally {
-          // we want to output the scan metrics even if an error occurred on close
-          try {
-            writeScanMetrics();
-          } catch (IOException e) {
-            // As above, we still don't want the scanner close() method to throw.
-          }
         }
         callable = null;
       }
diff --git a/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestFromClientSide.java b/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestFromClientSide.java
index ce94325b6bb..7e4ff0c418b 100644
--- a/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestFromClientSide.java
+++ b/hbase-server/src/test/java/org/apache/hadoop/hbase/client/TestFromClientSide.java
@@ -4618,9 +4618,8 @@ public class TestFromClientSide {
     for (Result result : scanner.next(numRecords - 1)) {
     }
     scanner.close();
-    // need to have at one next roundtrip in order to collect metrics
-    // here we have less than <numRecord>+1 KVs, so no metrics were collected
-    assertNull(scan.getAttribute(Scan.SCAN_ATTRIBUTES_METRICS_DATA));
+    // closing the scanner will set the metrics.
+    assertNotNull(scan.getAttribute(Scan.SCAN_ATTRIBUTES_METRICS_DATA));
 
     // set caching to 1, becasue metrics are collected in each roundtrip only
     scan = new Scan();