github.com/m3db/m3@v1.5.0/src/x/test/file.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 test
    22  
    23  import (
    24  	"math"
    25  	"math/rand"
    26  
    27  	"github.com/m3db/m3/src/x/os"
    28  )
    29  
    30  // corruptingFile implements the xos.File interface and can corrupt all writes issued
    31  // to it based on a configurable probability.
    32  type corruptingFile struct {
    33  	fd                    xos.File
    34  	corruptionProbability float64
    35  	rng                   *rand.Rand
    36  }
    37  
    38  // NewCorruptingFile creates a new corrupting file.
    39  func NewCorruptingFile(
    40  	fd xos.File,
    41  	corruptionProbability float64,
    42  	seed int64,
    43  ) xos.File {
    44  	return &corruptingFile{
    45  		fd: fd,
    46  		corruptionProbability: corruptionProbability,
    47  		rng: rand.New(rand.NewSource(seed)),
    48  	}
    49  }
    50  
    51  // Write to the underlying file with a chance of corrupting it.
    52  func (c *corruptingFile) Write(p []byte) (int, error) {
    53  	threshold := uint64(c.corruptionProbability * float64(math.MaxUint64))
    54  	if c.rng.Uint64() <= threshold {
    55  		var (
    56  			byteStart  int
    57  			byteOffset int
    58  		)
    59  		if len(p) > 1 {
    60  			byteStart = rand.Intn(len(p) - 1)
    61  			byteOffset = rand.Intn(len(p) - 1 - byteStart)
    62  		}
    63  
    64  		if byteStart >= 0 && byteStart+byteOffset < len(p) {
    65  			copy(p[byteStart:byteStart+byteOffset], make([]byte, byteOffset))
    66  		}
    67  	}
    68  	return c.fd.Write(p)
    69  }
    70  
    71  // Sync fsyncs the underlying file.
    72  func (c *corruptingFile) Sync() error {
    73  	return c.fd.Sync()
    74  }
    75  
    76  // Close the underlying file.
    77  func (c *corruptingFile) Close() error {
    78  	return c.fd.Close()
    79  }