66 lines
1.7 KiB
Go
66 lines
1.7 KiB
Go
// Copyright 2016 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package executor
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import (
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"github.com/cznic/mathutil"
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"github.com/pingcap/tidb/types"
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"github.com/pingcap/tidb/util/chunk"
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goctx "golang.org/x/net/context"
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)
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// ExplainExec represents an explain executor.
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type ExplainExec struct {
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baseExecutor
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rows [][]string
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cursor int
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}
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// Next implements Execution Next interface.
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func (e *ExplainExec) Next(goCtx goctx.Context) (Row, error) {
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if e.cursor >= len(e.rows) {
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return nil, nil
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}
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resultRow := make([]types.Datum, 0, len(e.rows[0]))
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for i := range e.rows[e.cursor] {
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resultRow = append(resultRow, types.NewStringDatum(e.rows[e.cursor][i]))
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}
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e.cursor++
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return resultRow, nil
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}
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// Close implements the Executor Close interface.
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func (e *ExplainExec) Close() error {
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e.rows = nil
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return nil
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}
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// NextChunk implements the Executor NextChunk interface.
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func (e *ExplainExec) NextChunk(goCtx goctx.Context, chk *chunk.Chunk) error {
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chk.Reset()
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if e.cursor >= len(e.rows) {
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return nil
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}
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numCurRows := mathutil.Min(e.maxChunkSize, len(e.rows)-e.cursor)
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for i := e.cursor; i < e.cursor+numCurRows; i++ {
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for j := range e.rows[i] {
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chk.AppendString(j, e.rows[i][j])
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}
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}
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e.cursor += numCurRows
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return nil
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}
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