github.com/matrixorigin/matrixone@v1.2.0/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  
    21  	"github.com/matrixorigin/matrixone/pkg/vm"
    22  	"github.com/matrixorigin/matrixone/pkg/vm/process"
    23  )
    24  
    25  const argName = "merge_offset"
    26  
    27  func (arg *Argument) String(buf *bytes.Buffer) {
    28  	buf.WriteString(argName)
    29  	buf.WriteString(fmt.Sprintf("mergeOffset(%d)", arg.Offset))
    30  }
    31  
    32  func (arg *Argument) Prepare(proc *process.Process) error {
    33  	ap := arg
    34  	ap.ctr = new(container)
    35  	ap.ctr.InitReceiver(proc, true)
    36  	ap.ctr.seen = 0
    37  	return nil
    38  }
    39  
    40  func (arg *Argument) Call(proc *process.Process) (vm.CallResult, error) {
    41  	if err, isCancel := vm.CancelCheck(proc); isCancel {
    42  		return vm.CancelResult, err
    43  	}
    44  
    45  	anal := proc.GetAnalyze(arg.GetIdx(), arg.GetParallelIdx(), arg.GetParallelMajor())
    46  	anal.Start()
    47  	defer anal.Stop()
    48  
    49  	result := vm.NewCallResult()
    50  	var end bool
    51  	var err error
    52  	if arg.buf != nil {
    53  		proc.PutBatch(arg.buf)
    54  		arg.buf = nil
    55  	}
    56  
    57  	for {
    58  		arg.buf, end, err = arg.ctr.ReceiveFromAllRegs(anal)
    59  		if err != nil {
    60  			// WTF, nil?
    61  			result.Status = vm.ExecStop
    62  			return result, nil
    63  		}
    64  
    65  		if end {
    66  			result.Batch = nil
    67  			result.Status = vm.ExecStop
    68  			return result, nil
    69  		}
    70  
    71  		anal.Input(arg.buf, arg.GetIsFirst())
    72  		if arg.ctr.seen > arg.Offset {
    73  			anal.Output(arg.buf, arg.GetIsLast())
    74  			result.Batch = arg.buf
    75  			return result, nil
    76  		}
    77  		length := arg.buf.RowCount()
    78  		// bat = PartOne + PartTwo, and PartTwo is required.
    79  		if arg.ctr.seen+uint64(length) > arg.Offset {
    80  			sels := newSels(int64(arg.Offset-arg.ctr.seen), int64(length)-int64(arg.Offset-arg.ctr.seen), proc)
    81  			arg.ctr.seen += uint64(length)
    82  			arg.buf.Shrink(sels, false)
    83  			proc.Mp().PutSels(sels)
    84  			anal.Output(arg.buf, arg.GetIsLast())
    85  			result.Batch = arg.buf
    86  			return result, nil
    87  		}
    88  		arg.ctr.seen += uint64(length)
    89  		proc.PutBatch(arg.buf)
    90  	}
    91  }
    92  
    93  func newSels(start, count int64, proc *process.Process) []int64 {
    94  	sels := proc.Mp().GetSels()
    95  	for i := int64(0); i < count; i++ {
    96  		sels = append(sels, start+i)
    97  	}
    98  	return sels[:count]
    99  }