| // Licensed to the Apache Software Foundation (ASF) under one |
| // or more contributor license agreements. See the NOTICE file |
| // distributed with this work for additional information |
| // regarding copyright ownership. The ASF licenses this file |
| // to you under the Apache License, Version 2.0 (the |
| // "License"); you may not use this file except in compliance |
| // with the License. You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, |
| // software distributed under the License is distributed on an |
| // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| // KIND, either express or implied. See the License for the |
| // specific language governing permissions and limitations |
| // under the License. |
| |
| #ifndef IMPALA_EXEC_SUBPLAN_NODE_H_ |
| #define IMPALA_EXEC_SUBPLAN_NODE_H_ |
| |
| #include "exec/exec-node.h" |
| #include "exprs/scalar-expr.h" |
| |
| namespace impala { |
| |
| class TupleRow; |
| |
| /// For every input row from its first child, a SubplanNode evaluates and pulls all |
| /// results from its second child, resetting the second child after every input row. |
| /// A SubplanNode does not create any output rows itself. It merely |
| /// 'forwards' the output rows produced by its second child, accumulating them |
| /// into batches before returning them to its parent in GetNext(). Therefore, it |
| /// may not have any conjuncts, but it may have a limit. |
| /// A SubplanNode exposes the current input row it is processing to UnnestNodes and |
| /// SingularRowSrcNodes that are in the exec-node tree of the second child. |
| /// |
| /// Subplan Memory Management: |
| /// To ensure that the memory backing rows produced by the subplan tree (second child) |
| /// remains valid for the lifetime of an output batch produced in GetNext(), we rely on |
| /// our conventional transfer mechanism. That is, the ownership of memory that is no |
| /// longer used by an exec node inside the subplan tree (second child) is transferred to |
| /// an output row batch in that node's GetNext() at a "convenient" point, typically |
| /// at eos or when the memory usage exceeds some threshold. Note that exec nodes may |
| /// choose not to transfer memory at eos to amortize the cost of memory allocation over |
| /// multiple Reset()/Open()/GetNext()* cycles. |
| /// The resources owned by batches from the first child of this node are always |
| /// transferred to the output batch right before fetching a new batch from the |
| /// first child. |
| class SubplanNode : public ExecNode { |
| public: |
| SubplanNode(ObjectPool* pool, const TPlanNode& tnode, const DescriptorTbl& descs); |
| |
| virtual Status Init(const TPlanNode& tnode, RuntimeState* state); |
| virtual Status Prepare(RuntimeState* state); |
| virtual Status Open(RuntimeState* state); |
| virtual Status GetNext(RuntimeState* state, RowBatch* row_batch, bool* eos); |
| virtual Status Reset(RuntimeState* state, RowBatch* row_batch); |
| virtual void Close(RuntimeState* state); |
| |
| private: |
| friend class SingularRowSrcNode; |
| friend class UnnestNode; |
| |
| /// Sets 'ancestor' as the containing Subplan in all exec nodes inside the exec-node |
| /// tree rooted at 'node' and does any initialization that is required as a result of |
| /// setting the subplan. Doesn't traverse the second child of SubplanNodes within |
| /// 'node'. |
| Status SetContainingSubplan(RuntimeState* state, SubplanNode* ancestor, ExecNode* node); |
| |
| /// Returns the current row from child(0) or NULL if no rows from child(0) have been |
| /// retrieved yet (GetNext() has not yet been called). This function is called by |
| /// singular-row-src and unnest nodes while evaluating child(1). |
| TupleRow* current_row() const { return current_input_row_; } |
| |
| /// Current row batch used to get rows from our first child. |
| boost::scoped_ptr<RowBatch> input_batch_; |
| |
| /// Saved from the last call to GetNext() on our first child. |
| bool input_eos_; |
| |
| /// Index of current row in input_batch_. |
| int input_row_idx_; |
| |
| /// Current row from the first child that dependent nodes in the subplan (unnests and |
| /// nested row sources) will pick up. |
| TupleRow* current_input_row_; |
| |
| /// Indicates whether the subplan (second child) is open. |
| bool subplan_is_open_; |
| |
| /// Saved from the last call to GetNext() on our second child. |
| bool subplan_eos_; |
| }; |
| |
| } |
| |
| #endif |