From ccf3cdab8ff4557bcb98485dbfe2512f6df345b6 Mon Sep 17 00:00:00 2001
From: Henning Baldersheim <balder@yahoo-inc.com>
Date: Wed, 25 Jan 2017 16:08:54 +0100
Subject: Ensure that we detect out of order collection also after passing the
 array limit.

---
 .../src/tests/hitcollector/hitcollector_test.cpp   | 23 ++++++++++++++++++++++
 searchlib/src/vespa/searchlib/common/resultset.h   |  2 +-
 .../src/vespa/searchlib/queryeval/hitcollector.cpp |  6 ++++++
 3 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/searchlib/src/tests/hitcollector/hitcollector_test.cpp b/searchlib/src/tests/hitcollector/hitcollector_test.cpp
index c76c9d16160..edb2ecdcaaa 100644
--- a/searchlib/src/tests/hitcollector/hitcollector_test.cpp
+++ b/searchlib/src/tests/hitcollector/hitcollector_test.cpp
@@ -509,4 +509,27 @@ TEST("require that hits can be added out of order when passing array limit") {
     TEST_DO(checkResult(*rs.get(), nullptr));
 }
 
+TEST("require that hits can be added out of order only after passing array limit") {
+    HitCollector hc(10000, 100, 10);
+    std::vector<RankedHit> expRh;
+    // produce expected result in normal order
+    const size_t numHits = 150;
+    for (uint32_t i = 0; i < numHits; ++i) {
+        expRh.push_back(RankedHit());
+        expRh.back()._docId = i;
+        expRh.back()._rankValue = (i < 50) ? 0 : (i + 100);
+    }
+    // add results in reverse order
+    const uint32_t numInOrder = numHits - 30;
+    for (uint32_t i = 0; i < numInOrder; i++) {
+        hc.addHit(i, i + 100);
+    }
+    for (uint32_t i = numHits; i-- > numInOrder; ) {
+        hc.addHit(i, i + 100);
+    }
+    std::unique_ptr<ResultSet> rs = hc.getResultSet();
+    TEST_DO(checkResult(*rs.get(), expRh));
+    TEST_DO(checkResult(*rs.get(), nullptr));
+}
+
 TEST_MAIN() { TEST_RUN_ALL(); }
diff --git a/searchlib/src/vespa/searchlib/common/resultset.h b/searchlib/src/vespa/searchlib/common/resultset.h
index 1ea32cc9cee..95c191682a4 100644
--- a/searchlib/src/vespa/searchlib/common/resultset.h
+++ b/searchlib/src/vespa/searchlib/common/resultset.h
@@ -4,7 +4,7 @@
 
 #pragma once
 
-#include <vespa/searchlib/common/rankedhit.h>
+#include "rankedhit.h"
 #include <vespa/vespalib/util/alloc.h>
 
 namespace search {
diff --git a/searchlib/src/vespa/searchlib/queryeval/hitcollector.cpp b/searchlib/src/vespa/searchlib/queryeval/hitcollector.cpp
index 47c9f62ef51..6cb567a6043 100644
--- a/searchlib/src/vespa/searchlib/queryeval/hitcollector.cpp
+++ b/searchlib/src/vespa/searchlib/queryeval/hitcollector.cpp
@@ -141,6 +141,12 @@ HitCollector::DocIdCollector<CollectRankedHit>::collect(uint32_t docId, feature_
     }
     HitCollector & hc = this->_hc;
     if (hc._docIdVector.size() < hc._maxDocIdVectorSize) {
+        if (__builtin_expect(((hc._docIdVector.size() > 0) &&
+                              (docId < hc._docIdVector.back()) &&
+                              (hc._unordered == false)), false))
+        {
+            hc._unordered = true;
+        }
         hc._docIdVector.push_back(docId);
     } else {
         collectAndChangeCollector(docId);
-- 
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