github.com/m3db/m3@v1.5.0/src/aggregator/aggregation/quantile/cm/heap_pool.go (about)

     1  // Copyright (c) 2021 Uber Technologies, Inc.
     2  //
     3  // Permission is hereby granted, free of charge, to any person obtaining a copy
     4  // of this software and associated documentation files (the "Software"), to deal
     5  // in the Software without restriction, including without limitation the rights
     6  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
     7  // copies of the Software, and to permit persons to whom the Software is
     8  // furnished to do so, subject to the following conditions:
     9  //
    10  // The above copyright notice and this permission notice shall be included in
    11  // all copies or substantial portions of the Software.
    12  //
    13  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    14  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    15  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    16  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    17  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    18  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    19  // THE SOFTWARE.
    20  
    21  package cm
    22  
    23  import (
    24  	"sync"
    25  )
    26  
    27  const (
    28  	// create buckets of 64, 256, 1024, 4096, 16484, 65536 floats
    29  	_initialHeapBucketSize      = 64
    30  	_heapSizeBuckets            = 6
    31  	_heapSizeBucketGrowthFactor = 4
    32  )
    33  
    34  var sharedHeapPool heapPool
    35  
    36  type heapPool struct {
    37  	pools []*sync.Pool
    38  	sizes []int
    39  }
    40  
    41  func newHeapPool() heapPool {
    42  	var (
    43  		p = heapPool{
    44  			pools: make([]*sync.Pool, _heapSizeBuckets),
    45  			sizes: make([]int, _heapSizeBuckets),
    46  		}
    47  		sz = _initialHeapBucketSize
    48  	)
    49  
    50  	for i := 0; i < _heapSizeBuckets; i++ {
    51  		size := sz
    52  
    53  		p.sizes[i] = size
    54  		p.pools[i] = &sync.Pool{
    55  			New: func() interface{} {
    56  				buf := make(minHeap, 0, size)
    57  				return &buf
    58  			},
    59  		}
    60  
    61  		sz *= _heapSizeBucketGrowthFactor
    62  	}
    63  
    64  	return p
    65  }
    66  
    67  func (p heapPool) Get(size int) *minHeap {
    68  	for i := range p.sizes {
    69  		if p.sizes[i] < size {
    70  			continue
    71  		}
    72  
    73  		v, ok := p.pools[i].Get().(*minHeap)
    74  		if !ok { // should never happen
    75  			goto makeNew
    76  		}
    77  
    78  		*v = (*v)[:0]
    79  		return v
    80  	}
    81  makeNew:
    82  	newVal := make(minHeap, 0, size)
    83  
    84  	return &newVal
    85  }
    86  
    87  func (p heapPool) Put(value minHeap) {
    88  	size := cap(value)
    89  	for i := 0; i < len(p.sizes); i++ {
    90  		if p.sizes[i] < size {
    91  			continue
    92  		}
    93  		pool := p.pools[i]
    94  		value = value[:0]
    95  		pool.Put(&value)
    96  		return
    97  	}
    98  }
    99  
   100  func init() {
   101  	sharedHeapPool = newHeapPool()
   102  }