From 17a2e1663ac6d9f1928922574665805e96b8c610 Mon Sep 17 00:00:00 2001
From: Zhihong Yu <tedyu@apache.org>
Date: Wed, 19 Sep 2012 17:52:06 +0000
Subject: [PATCH] HBASE-6838 Regionserver may generate identical scanner name
 (Chunhui)

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1387695 13f79535-47bb-0310-9956-ffa450edef68
---
 .../hbase/regionserver/HRegionServer.java     | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java
index d45387b3553..c14665597c3 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java
@@ -281,7 +281,7 @@ public class  HRegionServer implements ClientProtocol,
   // Compactions
   public CompactSplitThread compactSplitThread;
 
-  final Map<String, RegionScanner> scanners =
+  final ConcurrentHashMap<String, RegionScanner> scanners =
       new ConcurrentHashMap<String, RegionScanner>();
 
   /**
@@ -2818,11 +2818,18 @@ public class  HRegionServer implements ClientProtocol,
   }
 
   protected long addScanner(RegionScanner s) throws LeaseStillHeldException {
-    long scannerId = nextLong();
-    String scannerName = String.valueOf(scannerId);
-    scanners.put(scannerName, s);
-    this.leases.createLease(scannerName, this.scannerLeaseTimeoutPeriod, new ScannerListener(
-        scannerName));
+    long scannerId = -1;
+    while (true) {
+      scannerId = rand.nextLong();
+      if (scannerId == -1) continue;
+      String scannerName = String.valueOf(scannerId);
+      RegionScanner existing = scanners.putIfAbsent(scannerName, s);
+      if (existing == null) {
+        this.leases.createLease(scannerName, this.scannerLeaseTimeoutPeriod,
+            new ScannerListener(scannerName));
+        break;
+      }
+    }
     return scannerId;
   }