From 4b5884fb9a2165ea37f545f7f535edc669b2ba03 Mon Sep 17 00:00:00 2001
From: kangkaisen <kangkaisen@live.com>
Date: Tue, 29 Nov 2016 19:51:39 +0800
Subject: [PATCH] add query server scan threshold

---
 .../kylin/storage/gtrecord/SequentialCubeTupleIterator.java   | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/core-storage/src/main/java/org/apache/kylin/storage/gtrecord/SequentialCubeTupleIterator.java b/core-storage/src/main/java/org/apache/kylin/storage/gtrecord/SequentialCubeTupleIterator.java
index bef0e88..c37efc4 100644
--- a/core-storage/src/main/java/org/apache/kylin/storage/gtrecord/SequentialCubeTupleIterator.java
+++ b/core-storage/src/main/java/org/apache/kylin/storage/gtrecord/SequentialCubeTupleIterator.java
@@ -25,6 +25,7 @@ import java.util.Set;
 
 import javax.annotation.Nullable;
 
+import org.apache.kylin.common.KylinConfig;
 import org.apache.kylin.cube.cuboid.Cuboid;
 import org.apache.kylin.metadata.model.FunctionDesc;
 import org.apache.kylin.metadata.model.TblColRef;
@@ -32,6 +33,7 @@ import org.apache.kylin.metadata.tuple.ITuple;
 import org.apache.kylin.metadata.tuple.ITupleIterator;
 import org.apache.kylin.metadata.tuple.TupleInfo;
 import org.apache.kylin.storage.StorageContext;
+import org.apache.kylin.storage.exception.ScanOutOfLimitException;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -43,6 +45,8 @@ public class SequentialCubeTupleIterator implements ITupleIterator {
 
     private static final Logger logger = LoggerFactory.getLogger(SequentialCubeTupleIterator.class);
 
+    private final int SCAN_THRESHOLD = KylinConfig.getInstanceFromEnv().getScanThreshold();
+
     protected List<CubeSegmentScanner> scanners;
     protected List<SegmentCubeTupleIterator> segmentCubeTupleIterators;
     protected Iterator<ITuple> tupleIterator;
@@ -52,6 +56,7 @@ public class SequentialCubeTupleIterator implements ITupleIterator {
     private int scanCount;
     private int scanCountDelta;
 
+
     public SequentialCubeTupleIterator(List<CubeSegmentScanner> scanners, Cuboid cuboid, Set<TblColRef> selectedDimensions, //
             Set<FunctionDesc> selectedMetrics, TupleInfo returnTupleInfo, StorageContext context) {
         this.context = context;
@@ -86,7 +91,11 @@ public class SequentialCubeTupleIterator implements ITupleIterator {
 
     @Override
     public ITuple next() {
-        scanCount++;
+        // prevent the big query to make the Query Server OOM
+        if (scanCount++ > SCAN_THRESHOLD) {
+            throw new ScanOutOfLimitException("Scan count exceed the scan threshold: " + SCAN_THRESHOLD);
+        }
+
         if (++scanCountDelta >= 1000)
             flushScanCountDelta();
 
-- 
2.9.3 (Apple Git-75)