github.com/leanovate/gopter@v0.2.9/locked_source.go (about)

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  // Taken from golang lockedSource implementation https://github.com/golang/go/blob/master/src/math/rand/rand.go#L371-L410
     5  
     6  package gopter
     7  
     8  import (
     9  	"math/rand"
    10  	"sync"
    11  )
    12  
    13  type lockedSource struct {
    14  	lk  sync.Mutex
    15  	src rand.Source64
    16  }
    17  
    18  // NewLockedSource takes a seed and returns a new
    19  // lockedSource for use with rand.New
    20  func NewLockedSource(seed int64) *lockedSource {
    21  	return &lockedSource{
    22  		src: rand.NewSource(seed).(rand.Source64),
    23  	}
    24  }
    25  
    26  func (r *lockedSource) Int63() (n int64) {
    27  	r.lk.Lock()
    28  	n = r.src.Int63()
    29  	r.lk.Unlock()
    30  	return
    31  }
    32  
    33  func (r *lockedSource) Uint64() (n uint64) {
    34  	r.lk.Lock()
    35  	n = r.src.Uint64()
    36  	r.lk.Unlock()
    37  	return
    38  }
    39  
    40  func (r *lockedSource) Seed(seed int64) {
    41  	r.lk.Lock()
    42  	r.src.Seed(seed)
    43  	r.lk.Unlock()
    44  }
    45  
    46  // seedPos implements Seed for a lockedSource without a race condition.
    47  func (r *lockedSource) seedPos(seed int64, readPos *int8) {
    48  	r.lk.Lock()
    49  	r.src.Seed(seed)
    50  	*readPos = 0
    51  	r.lk.Unlock()
    52  }
    53  
    54  // read implements Read for a lockedSource without a race condition.
    55  func (r *lockedSource) read(p []byte, readVal *int64, readPos *int8) (n int, err error) {
    56  	r.lk.Lock()
    57  	n, err = read(p, r.src.Int63, readVal, readPos)
    58  	r.lk.Unlock()
    59  	return
    60  }
    61  
    62  func read(p []byte, int63 func() int64, readVal *int64, readPos *int8) (n int, err error) {
    63  	pos := *readPos
    64  	val := *readVal
    65  	for n = 0; n < len(p); n++ {
    66  		if pos == 0 {
    67  			val = int63()
    68  			pos = 7
    69  		}
    70  		p[n] = byte(val)
    71  		val >>= 8
    72  		pos--
    73  	}
    74  	*readPos = pos
    75  	*readVal = val
    76  	return
    77  }