From 64549e4332ffe631a1586fb9a16a3ce72a0ccd79 Mon Sep 17 00:00:00 2001
From: Michael McCandless <mikemccand@apache.org>
Date: Mon, 27 Aug 2012 15:20:17 +0000
Subject: [PATCH] fix test thread safety issue

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1377711 13f79535-47bb-0310-9956-ffa450edef68
---
 .../lucene/search/ShardSearchingTestBase.java | 20 ++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/lucene/test-framework/src/java/org/apache/lucene/search/ShardSearchingTestBase.java b/lucene/test-framework/src/java/org/apache/lucene/search/ShardSearchingTestBase.java
index e99f02d9cca..cf7ca0d6174 100644
--- a/lucene/test-framework/src/java/org/apache/lucene/search/ShardSearchingTestBase.java
+++ b/lucene/test-framework/src/java/org/apache/lucene/search/ShardSearchingTestBase.java
@@ -468,15 +468,17 @@ public abstract class ShardSearchingTestBase extends LuceneTestCase {
 
     // Get the current (fresh) searcher for this node
     public ShardIndexSearcher acquire() {
-      final ShardIndexSearcher s = currentShardSearcher;
-      // TODO: this isn't thread safe.... in theory the
-      // reader could get decRef'd to 0 before we have a
-      // chance to incRef, ie if a reopen happens right
-      // after the above line, this thread gets stalled, and
-      // the old IR is closed.  But because we use SLM in
-      // this test, this will be exceptionally rare:
-      s.getIndexReader().incRef();
-      return s;
+      while(true) {
+        final ShardIndexSearcher s = currentShardSearcher;
+        // In theory the reader could get decRef'd to 0
+        // before we have a chance to incRef, ie if a reopen
+        // happens right after the above line, this thread
+        // gets stalled, and the old IR is closed.  So we
+        // must try/retry until incRef succeeds:
+        if (s.getIndexReader().tryIncRef()) {
+          return s;
+        }
+      }
     }
 
     public void release(ShardIndexSearcher s) throws IOException {