doris/be/src/vec/exec/vtable_function_node.cpp

// Licensed to the Apache Software Foundation (ASF) under one
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// 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
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// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

#include "vec/exec/vtable_function_node.h"

#include "vec/exprs/table_function/table_function.h"
#include "vec/exprs/table_function/table_function_factory.h"
#include "vec/exprs/vexpr.h"

namespace doris::vectorized {

VTableFunctionNode::VTableFunctionNode(doris::ObjectPool* pool, const TPlanNode& tnode,
                                       const DescriptorTbl& descs)
        : ExecNode(pool, tnode, descs) {}

Status VTableFunctionNode::init(const TPlanNode& tnode, RuntimeState* state) {
    RETURN_IF_ERROR(ExecNode::init(tnode, state));

    for (const TExpr& texpr : tnode.table_function_node.fnCallExprList) {
        VExprContext* ctx = nullptr;
        RETURN_IF_ERROR(VExpr::create_expr_tree(_pool, texpr, &ctx));
        _vfn_ctxs.push_back(ctx);

        VExpr* root = ctx->root();
        const std::string& tf_name = root->fn().name.function_name;
        TableFunction* fn = nullptr;
        RETURN_IF_ERROR(TableFunctionFactory::get_fn(tf_name, _pool, &fn));
        fn->set_vexpr_context(ctx);
        _fns.push_back(fn);
    }
    _fn_num = _fns.size();
    _fn_values.resize(_fn_num);
    _fn_value_lengths.resize(_fn_num);

    // Prepare output slot ids
    RETURN_IF_ERROR(_prepare_output_slot_ids(tnode));
    return Status::OK();
}

Status VTableFunctionNode::_prepare_output_slot_ids(const TPlanNode& tnode) {
    // Prepare output slot ids
    if (tnode.table_function_node.outputSlotIds.empty()) {
        return Status::InternalError("Output slots of table function node is empty");
    }
    SlotId max_id = -1;
    for (auto slot_id : tnode.table_function_node.outputSlotIds) {
        if (slot_id > max_id) {
            max_id = slot_id;
        }
    }
    _output_slot_ids = std::vector<bool>(max_id + 1, false);
    for (auto slot_id : tnode.table_function_node.outputSlotIds) {
        _output_slot_ids[slot_id] = true;
    }

    return Status::OK();
}

bool VTableFunctionNode::_is_inner_and_empty() {
    for (int i = 0; i < _fn_num; i++) {
        // if any table function is not outer and has empty result, go to next child row
        if (!_fns[i]->is_outer() && _fns[i]->current_empty()) {
            return true;
        }
    }
    return false;
}

Status VTableFunctionNode::prepare(RuntimeState* state) {
    SCOPED_TIMER(_runtime_profile->total_time_counter());
    RETURN_IF_ERROR(ExecNode::prepare(state));

    _num_rows_filtered_counter = ADD_COUNTER(_runtime_profile, "RowsFiltered", TUnit::UNIT);
    for (auto fn : _fns) {
        RETURN_IF_ERROR(fn->prepare());
    }
    RETURN_IF_ERROR(VExpr::prepare(_vfn_ctxs, state, _row_descriptor));

    // get current all output slots
    for (const auto& tuple_desc : this->_row_descriptor.tuple_descriptors()) {
        for (const auto& slot_desc : tuple_desc->slots()) {
            _output_slots.push_back(slot_desc);
        }
    }

    // get all input slots
    for (const auto& child_tuple_desc : child(0)->row_desc().tuple_descriptors()) {
        for (const auto& child_slot_desc : child_tuple_desc->slots()) {
            _child_slots.push_back(child_slot_desc);
        }
    }

    _cur_child_offset = -1;

    return Status::OK();
}

Status VTableFunctionNode::get_next(RuntimeState* state, Block* block, bool* eos) {
    INIT_AND_SCOPE_GET_NEXT_SPAN(state->get_tracer(), _get_next_span,
                                 "VTableFunctionNode::get_next");
    SCOPED_TIMER(_runtime_profile->total_time_counter());

    RETURN_IF_CANCELLED(state);

    // if child_block is empty, get data from child.
    while (need_more_input_data()) {
        RETURN_IF_ERROR_AND_CHECK_SPAN(
                child(0)->get_next_after_projects(
                        state, &_child_block, &_child_eos,
                        std::bind((Status(ExecNode::*)(RuntimeState*, vectorized::Block*, bool*)) &
                                          ExecNode::get_next,
                                  _children[0], std::placeholders::_1, std::placeholders::_2,
                                  std::placeholders::_3)),
                child(0)->get_next_span(), _child_eos);

        RETURN_IF_ERROR(push(state, &_child_block, _child_eos));
    }

    return pull(state, block, eos);
}

Status VTableFunctionNode::get_expanded_block(RuntimeState* state, Block* output_block, bool* eos) {
    size_t column_size = _output_slots.size();
    bool mem_reuse = output_block->mem_reuse();

    std::vector<vectorized::MutableColumnPtr> columns(column_size);
    for (size_t i = 0; i < column_size; i++) {
        if (mem_reuse) {
            columns[i] = std::move(*output_block->get_by_position(i).column).mutate();
        } else {
            columns[i] = _output_slots[i]->get_empty_mutable_column();
        }
    }

    while (columns[_child_slots.size()]->size() < state->batch_size()) {
        RETURN_IF_CANCELLED(state);
        RETURN_IF_ERROR(state->check_query_state("VTableFunctionNode, while getting next batch."));

        if (_child_block.rows() == 0) {
            break;
        }

        bool skip_child_row = false;
        while (columns[_child_slots.size()]->size() < state->batch_size()) {
            int idx = _find_last_fn_eos_idx();
            if (idx == 0 || skip_child_row) {
                // all table functions' results are exhausted, process next child row.
                RETURN_IF_ERROR(_process_next_child_row());
                if (_cur_child_offset == -1) {
                    break;
                }
            } else if (idx < _fn_num && idx != -1) {
                // some of table functions' results are exhausted.
                if (!_roll_table_functions(idx)) {
                    // continue to process next child row.
                    continue;
                }
            }

            // if any table function is not outer and has empty result, go to next child row
            if (skip_child_row = _is_inner_and_empty(); skip_child_row) {
                continue;
            }

            // get slots from every table function.
            // notice that _fn_values[i] may be null if the table function has empty result set.
            for (int i = 0; i < _fn_num; i++) {
                RETURN_IF_ERROR(_fns[i]->get_value(&_fn_values[i]));
                RETURN_IF_ERROR(_fns[i]->get_value_length(&_fn_value_lengths[i]));
            }

            // The tuples order in parent row batch should be
            //      child1, child2, tf1, tf2, ...

            // 1. copy data from child_block.
            for (int i = 0; i < _child_slots.size(); i++) {
                if (!slot_need_copy(i)) {
                    columns[i]->insert_default();
                    continue;
                }
                auto src_column = _child_block.get_by_position(i).column;
                columns[i]->insert_from(*src_column, _cur_child_offset);
            }

            // 2. copy function result
            for (int i = 0; i < _fns.size(); i++) {
                int output_slot_idx = i + _child_slots.size();
                if (_fn_values[i] == nullptr) {
                    columns[output_slot_idx]->insert_default();
                } else {
                    columns[output_slot_idx]->insert_data(reinterpret_cast<char*>(_fn_values[i]),
                                                          _fn_value_lengths[i]);
                }
            }

            bool tmp = false;
            _fns[_fn_num - 1]->forward(&tmp);
        }
    }

    if (!columns.empty() && !columns[0]->empty()) {
        auto n_columns = 0;
        if (!mem_reuse) {
            for (const auto slot_desc : _output_slots) {
                output_block->insert(ColumnWithTypeAndName(std::move(columns[n_columns++]),
                                                           slot_desc->get_data_type_ptr(),
                                                           slot_desc->col_name()));
            }
        } else {
            columns.clear();
        }
    }

    // 3. eval conjuncts
    RETURN_IF_ERROR(
            VExprContext::filter_block(_vconjunct_ctx_ptr, output_block, output_block->columns()));

    *eos = _child_eos && _cur_child_offset == -1;
    return Status::OK();
}

Status VTableFunctionNode::_process_next_child_row() {
    _cur_child_offset++;

    if (_cur_child_offset >= _child_block.rows()) {
        // release block use count.
        for (TableFunction* fn : _fns) {
            RETURN_IF_ERROR(fn->process_close());
        }

        release_block_memory(_child_block);
        _cur_child_offset = -1;
        return Status::OK();
    }

    for (TableFunction* fn : _fns) {
        RETURN_IF_ERROR(fn->process_row(_cur_child_offset));
    }

    return Status::OK();
}

// Returns the index of fn of the last eos counted from back to front
// eg: there are 3 functions in `_fns`
//      eos:    false, true, true
//      return: 1
//
//      eos:    false, false, true
//      return: 2
//
//      eos:    false, false, false
//      return: -1
//
//      eos:    true, true, true
//      return: 0
//
// return:
//  0: all fns are eos
// -1: all fns are not eos
// >0: some of fns are eos
int VTableFunctionNode::_find_last_fn_eos_idx() {
    for (int i = _fn_num - 1; i >= 0; --i) {
        if (!_fns[i]->eos()) {
            if (i == _fn_num - 1) {
                return -1;
            } else {
                return i + 1;
            }
        }
    }
    // all eos
    return 0;
}

// Roll to reset the table function.
// Eg:
//  There are 3 functions f1, f2 and f3 in `_fns`.
//  If `last_eos_idx` is 1, which means f2 and f3 are eos.
//  So we need to forward f1, and reset f2 and f3.
bool VTableFunctionNode::_roll_table_functions(int last_eos_idx) {
    bool fn_eos = false;
    int i = last_eos_idx - 1;
    for (; i >= 0; --i) {
        _fns[i]->forward(&fn_eos);
        if (!fn_eos) {
            break;
        }
    }
    if (i == -1) {
        // after forward, all functions are eos.
        // we should process next child row to get more table function results.
        return false;
    }

    for (int j = i + 1; j < _fn_num; ++j) {
        _fns[j]->reset();
    }

    return true;
}

} // namespace doris::vectorized