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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Taken from golang lockedSource implementation https://github.com/golang/go/blob/master/src/math/rand/rand.go#L371-L410
package gopter
import (
"math/rand"
"sync"
)
type lockedSource struct {
lk sync.Mutex
src rand.Source64
}
// NewLockedSource takes a seed and returns a new
// lockedSource for use with rand.New
func NewLockedSource(seed int64) *lockedSource {
return &lockedSource{
src: rand.NewSource(seed).(rand.Source64),
}
}
func (r *lockedSource) Int63() (n int64) {
r.lk.Lock()
n = r.src.Int63()
r.lk.Unlock()
return
}
func (r *lockedSource) Uint64() (n uint64) {
r.lk.Lock()
n = r.src.Uint64()
r.lk.Unlock()
return
}
func (r *lockedSource) Seed(seed int64) {
r.lk.Lock()
r.src.Seed(seed)
r.lk.Unlock()
}
// seedPos implements Seed for a lockedSource without a race condition.
func (r *lockedSource) seedPos(seed int64, readPos *int8) {
r.lk.Lock()
r.src.Seed(seed)
*readPos = 0
r.lk.Unlock()
}
// read implements Read for a lockedSource without a race condition.
func (r *lockedSource) read(p []byte, readVal *int64, readPos *int8) (n int, err error) {
r.lk.Lock()
n, err = read(p, r.src.Int63, readVal, readPos)
r.lk.Unlock()
return
}
func read(p []byte, int63 func() int64, readVal *int64, readPos *int8) (n int, err error) {
pos := *readPos
val := *readVal
for n = 0; n < len(p); n++ {
if pos == 0 {
val = int63()
pos = 7
}
p[n] = byte(val)
val >>= 8
pos--
}
*readPos = pos
*readVal = val
return
}
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