github.com/m3db/m3@v1.5.0/src/query/util/memset.go (about)

     1  // Copyright (c) 2018 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 util
    22  
    23  // Memset is a faster way to initialize a float64 array.
    24  // NB: Inspired from https://github.com/tmthrgd/go-memset, which works
    25  // directly on the byte interface. The 0 case is optimized due to
    26  // https://github.com/golang/go/issues/5373 but for non the zero case,
    27  // we use the copy() optimization.
    28  // BenchmarkMemsetZeroValues-4    1000000   1344 ns/op
    29  // BenchmarkLoopZeroValues-4       500000   3217 ns/op
    30  // BenchmarkMemsetNonZeroValues-4 1000000   1537 ns/op
    31  // BenchmarkLoopNonZeroValues-4    500000   3236 ns/op
    32  func Memset(data []float64, value float64) {
    33  	if value == 0 {
    34  		for i := range data {
    35  			data[i] = 0
    36  		}
    37  	} else if len(data) != 0 {
    38  		data[0] = value
    39  
    40  		for i := 1; i < len(data); i *= 2 {
    41  			copy(data[i:], data[:i])
    42  		}
    43  	}
    44  }
    45  
    46  // MemsetInt is a faster way to initialize an int array.
    47  func MemsetInt(data []int, value int) {
    48  	if value == 0 {
    49  		for i := range data {
    50  			data[i] = 0
    51  		}
    52  	} else if len(data) != 0 {
    53  		data[0] = value
    54  
    55  		for i := 1; i < len(data); i *= 2 {
    56  			copy(data[i:], data[:i])
    57  		}
    58  	}
    59  }