github.com/matrixorigin/matrixone@v0.7.0/pkg/sql/colexec/mergeoffset/offset.go (about)

     1  // Copyright 2021 Matrix Origin
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //      http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package mergeoffset
    16  
    17  import (
    18  	"bytes"
    19  	"fmt"
    20  	"reflect"
    21  	"time"
    22  
    23  	"github.com/matrixorigin/matrixone/pkg/common/moerr"
    24  	"github.com/matrixorigin/matrixone/pkg/container/batch"
    25  	"github.com/matrixorigin/matrixone/pkg/vm/process"
    26  )
    27  
    28  func String(arg interface{}, buf *bytes.Buffer) {
    29  	ap := arg.(*Argument)
    30  	buf.WriteString(fmt.Sprintf("mergeOffset(%d)", ap.Offset))
    31  }
    32  
    33  func Prepare(proc *process.Process, arg interface{}) error {
    34  	ap := arg.(*Argument)
    35  	ap.ctr = new(container)
    36  	ap.ctr.seen = 0
    37  
    38  	ap.ctr.receiverListener = make([]reflect.SelectCase, len(proc.Reg.MergeReceivers))
    39  	for i, mr := range proc.Reg.MergeReceivers {
    40  		ap.ctr.receiverListener[i] = reflect.SelectCase{
    41  			Dir:  reflect.SelectRecv,
    42  			Chan: reflect.ValueOf(mr.Ch),
    43  		}
    44  	}
    45  	ap.ctr.aliveMergeReceiver = len(proc.Reg.MergeReceivers)
    46  	return nil
    47  }
    48  
    49  func Call(idx int, proc *process.Process, arg interface{}, isFirst bool, isLast bool) (bool, error) {
    50  	ap := arg.(*Argument)
    51  	anal := proc.GetAnalyze(idx)
    52  	anal.Start()
    53  	defer anal.Stop()
    54  	ctr := ap.ctr
    55  
    56  	for {
    57  		if ctr.aliveMergeReceiver == 0 {
    58  			proc.SetInputBatch(nil)
    59  			ap.Free(proc, false)
    60  			return true, nil
    61  		}
    62  
    63  		start := time.Now()
    64  		chosen, value, ok := reflect.Select(ctr.receiverListener)
    65  		if !ok {
    66  			return false, moerr.NewInternalError(proc.Ctx, "pipeline closed unexpectedly")
    67  		}
    68  		anal.WaitStop(start)
    69  
    70  		pointer := value.UnsafePointer()
    71  		bat := (*batch.Batch)(pointer)
    72  		if bat == nil {
    73  			ctr.receiverListener = append(ctr.receiverListener[:chosen], ctr.receiverListener[chosen+1:]...)
    74  			ctr.aliveMergeReceiver--
    75  			continue
    76  		}
    77  
    78  		if bat.Length() == 0 {
    79  			continue
    80  		}
    81  
    82  		anal.Input(bat, isFirst)
    83  		if ap.ctr.seen > ap.Offset {
    84  			anal.Output(bat, isLast)
    85  			proc.SetInputBatch(bat)
    86  			return false, nil
    87  		}
    88  		length := len(bat.Zs)
    89  		// bat = PartOne + PartTwo, and PartTwo is required.
    90  		if ap.ctr.seen+uint64(length) > ap.Offset {
    91  			sels := newSels(int64(ap.Offset-ap.ctr.seen), int64(length)-int64(ap.Offset-ap.ctr.seen), proc)
    92  			ap.ctr.seen += uint64(length)
    93  			bat.Shrink(sels)
    94  			proc.Mp().PutSels(sels)
    95  			anal.Output(bat, isLast)
    96  			proc.SetInputBatch(bat)
    97  			return false, nil
    98  		}
    99  		ap.ctr.seen += uint64(length)
   100  		bat.Clean(proc.Mp())
   101  	}
   102  }
   103  
   104  func newSels(start, count int64, proc *process.Process) []int64 {
   105  	sels := proc.Mp().GetSels()
   106  	for i := int64(0); i < count; i++ {
   107  		sels = append(sels, start+i)
   108  	}
   109  	return sels[:count]
   110  }