Merge branch 'merger/215' of https://github.com/iamhuzl/sharding-jdbc into iamhuzl-merger/215

sharding-jdbc-core/src/main/java/com/dangdang/ddframe/rdb/sharding/merger/pipeline/reducer/StreamingOrderByReducerResultSet.java

@@ -39,48 +39,70 @@ public final class StreamingOrderByReducerResultSet extends AbstractDelegateResu
     
     private final List<OrderByColumn> orderByColumns;
     
-    private final List<ResultSet> resultSets = new LinkedList<>();
-    
+    private final List<OrderByDelegateResultSet> delegateResultSets = new LinkedList<>();
+    private OrderByDelegateResultSet lastDelegateResultSet ;
+
+
     public StreamingOrderByReducerResultSet(final ResultSetMergeContext resultSetMergeContext) throws SQLException {
         super(resultSetMergeContext.getShardingResultSets().getResultSets());
         orderByColumns = resultSetMergeContext.getCurrentOrderByKeys();
-        resultSets.addAll(resultSetMergeContext.getShardingResultSets().getResultSets());
+        List<ResultSet> mergeResultSets = resultSetMergeContext.getShardingResultSets().getResultSets();
+        for(ResultSet each: mergeResultSets){
+            delegateResultSets.add(new OrderByDelegateResultSet(each,orderByColumns));
+        }
     }
     
     @Override
     protected boolean firstNext() throws SQLException {
-        initialResultSetCursors();
-        return doNext();
-    }
-    
-    private void initialResultSetCursors() throws SQLException {
-        for (ResultSet each : resultSets) {
+        for (OrderByDelegateResultSet each : delegateResultSets) {
             each.next();
         }
+        return doNext();
     }
-    
+
     @Override
     protected boolean afterFirstNext() throws SQLException {
-        if (!getDelegate().next()) {
-            resultSets.remove(getDelegate());
-        }
+        lastDelegateResultSet.next();
         return doNext();
     }
     
     private boolean doNext() throws SQLException {
         setDelegateResultSet();
-        return !resultSets.isEmpty();
+        return !delegateResultSets.isEmpty();
     }
     
     private void setDelegateResultSet() throws SQLException {
         OrderByResultSetRow chosenOrderByValue = null;
-        for (ResultSet each : resultSets) {
-            OrderByResultSetRow eachOrderByValue = new OrderByResultSetRow(each, orderByColumns);
+        for (OrderByDelegateResultSet each : delegateResultSets) {
+            OrderByResultSetRow eachOrderByValue = each.orderByValue;
             if (null == chosenOrderByValue || chosenOrderByValue.compareTo(eachOrderByValue) > 0) {
                 chosenOrderByValue = eachOrderByValue;
-                setDelegate(each);
+                setDelegate(each.delegate);
+                lastDelegateResultSet = each;
             }
         }
         log.trace("Chosen order by value: {}, current result set hashcode: {}", chosenOrderByValue, getDelegate().hashCode());
     }
+
+    class OrderByDelegateResultSet {
+        private ResultSet delegate;
+        private List<OrderByColumn> orderByColumns;
+        private OrderByResultSetRow orderByValue ;
+
+        public OrderByDelegateResultSet(ResultSet delegate, List<OrderByColumn> orderByColumns) throws SQLException {
+            this.delegate = delegate;
+            this.orderByColumns = orderByColumns;
+        }
+
+        public boolean next() throws SQLException {
+            boolean result = delegate.next();
+            if(result) {
+                orderByValue = new OrderByResultSetRow(delegate, orderByColumns);
+            }else {
+                delegateResultSets.remove(this);
+            }
+            return result;
+        }
+
+    }
 }