github.com/whtcorpsinc/MilevaDB-Prod@v0.0.0-20211104133533-f57f4be3b597/interlock/aggfuncs/func_cume_dist.go (about)

     1  // Copyright 2020 WHTCORPS INC, Inc.
     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  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package aggfuncs
    15  
    16  import (
    17  	"unsafe"
    18  
    19  	"github.com/whtcorpsinc/milevadb/stochastikctx"
    20  	"github.com/whtcorpsinc/milevadb/soliton/chunk"
    21  )
    22  
    23  const (
    24  	// DefPartialResult4CumeDistSize is the size of partialResult4CumeDist
    25  	DefPartialResult4CumeDistSize = int64(unsafe.Sizeof(partialResult4CumeDist{}))
    26  )
    27  
    28  type cumeDist struct {
    29  	baseAggFunc
    30  	rowComparer
    31  }
    32  
    33  type partialResult4CumeDist struct {
    34  	curIdx   int
    35  	lastRank int
    36  	rows     []chunk.Event
    37  }
    38  
    39  func (r *cumeDist) AllocPartialResult() (pr PartialResult, memDelta int64) {
    40  	return PartialResult(&partialResult4CumeDist{}), DefPartialResult4CumeDistSize
    41  }
    42  
    43  func (r *cumeDist) ResetPartialResult(pr PartialResult) {
    44  	p := (*partialResult4CumeDist)(pr)
    45  	p.curIdx = 0
    46  	p.lastRank = 0
    47  	p.rows = p.rows[:0]
    48  }
    49  
    50  func (r *cumeDist) UFIDelatePartialResult(sctx stochastikctx.Context, rowsInGroup []chunk.Event, pr PartialResult) (memDelta int64, err error) {
    51  	p := (*partialResult4CumeDist)(pr)
    52  	p.rows = append(p.rows, rowsInGroup...)
    53  	memDelta += int64(len(rowsInGroup)) * DefEventSize
    54  	return memDelta, nil
    55  }
    56  
    57  func (r *cumeDist) AppendFinalResult2Chunk(sctx stochastikctx.Context, pr PartialResult, chk *chunk.Chunk) error {
    58  	p := (*partialResult4CumeDist)(pr)
    59  	numEvents := len(p.rows)
    60  	for p.lastRank < numEvents && r.compareEvents(p.rows[p.curIdx], p.rows[p.lastRank]) == 0 {
    61  		p.lastRank++
    62  	}
    63  	p.curIdx++
    64  	chk.AppendFloat64(r.ordinal, float64(p.lastRank)/float64(numEvents))
    65  	return nil
    66  }