github.com/matrixorigin/matrixone@v1.2.0/pkg/sql/colexec/mergelimit/limit.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 mergelimit
    16  
    17  import (
    18  	"bytes"
    19  	"fmt"
    20  
    21  	"github.com/matrixorigin/matrixone/pkg/container/batch"
    22  	"github.com/matrixorigin/matrixone/pkg/vm"
    23  	"github.com/matrixorigin/matrixone/pkg/vm/process"
    24  )
    25  
    26  const argName = "merge_limit"
    27  
    28  func (arg *Argument) String(buf *bytes.Buffer) {
    29  	buf.WriteString(argName)
    30  	ap := arg
    31  	buf.WriteString(fmt.Sprintf("mergeLimit(%d)", ap.Limit))
    32  }
    33  
    34  func (arg *Argument) Prepare(proc *process.Process) error {
    35  	ap := arg
    36  	ap.ctr = new(container)
    37  	ap.ctr.seen = 0
    38  	ap.ctr.InitReceiver(proc, true)
    39  	return nil
    40  }
    41  
    42  func (arg *Argument) Call(proc *process.Process) (vm.CallResult, error) {
    43  	if err, isCancel := vm.CancelCheck(proc); isCancel {
    44  		return vm.CancelResult, err
    45  	}
    46  
    47  	anal := proc.GetAnalyze(arg.GetIdx(), arg.GetParallelIdx(), arg.GetParallelMajor())
    48  	anal.Start()
    49  	defer anal.Stop()
    50  
    51  	result := vm.NewCallResult()
    52  	var end bool
    53  	var err error
    54  	if arg.buf != nil {
    55  		proc.PutBatch(arg.buf)
    56  		arg.buf = nil
    57  	}
    58  
    59  	for {
    60  		arg.buf, end, err = arg.ctr.ReceiveFromAllRegs(anal)
    61  		if err != nil {
    62  			result.Status = vm.ExecStop
    63  			return result, nil
    64  		}
    65  		if end {
    66  			result.Batch = nil
    67  			result.Status = vm.ExecStop
    68  			return result, nil
    69  		}
    70  		if arg.buf.Last() {
    71  			result.Batch = arg.buf
    72  			return result, nil
    73  		}
    74  
    75  		anal.Input(arg.buf, arg.GetIsFirst())
    76  		if arg.ctr.seen >= arg.Limit {
    77  			proc.PutBatch(arg.buf)
    78  			continue
    79  		}
    80  		newSeen := arg.ctr.seen + uint64(arg.buf.RowCount())
    81  		if newSeen < arg.Limit {
    82  			arg.ctr.seen = newSeen
    83  			anal.Output(arg.buf, arg.GetIsLast())
    84  			result.Batch = arg.buf
    85  			return result, nil
    86  		} else {
    87  			num := int(newSeen - arg.Limit)
    88  			batch.SetLength(arg.buf, arg.buf.RowCount()-num)
    89  			arg.ctr.seen = newSeen
    90  			anal.Output(arg.buf, arg.GetIsLast())
    91  			result.Batch = arg.buf
    92  			return result, nil
    93  		}
    94  	}
    95  }