func New(r *rand.Rand) *Simplex {
var s Simplex
perm := r.Perm(256)
copy(s[:256], perm)
copy(s[256:], perm)
return &s
}
// Shuffle a slice of strings.
func shuffleStrings(strings []string, rng *rand.Rand) []string {
var shuffled = make([]string, len(strings))
for i, j := range rng.Perm(len(strings)) {
shuffled[j] = strings[i]
}
return shuffled
}
// DepthFirstRandom traverses a graph depth first, but following arcs in
// random order among arcs from a single node.
//
// If Rand r is nil, the method creates a new source and generator for
// one-time use.
//
// Usage is otherwise like the DepthFirst method. See DepthFirst.
//
// There are equivalent labeled and unlabeled versions of this method.
func (g AdjacencyList) DepthFirstRandom(start NI, bm *Bits, v OkNodeVisitor, r *rand.Rand) (ok bool) {
if bm == nil {
if v == nil {
return false
}
bm = &Bits{}
}
if r == nil {
r = rand.New(rand.NewSource(time.Now().UnixNano()))
}
var df func(n NI) bool
df = func(n NI) bool {
if bm.Bit(n) == 1 {
return true
}
bm.SetBit(n, 1)
if v != nil && !v(n) {
return false
}
to := g[n]
for _, i := range r.Perm(len(to)) {
if !df(to[i]) {
return false
}
}
return true
}
return df(start)
}
func generateInput(rnd *rand.Rand, size int) []byte {
permutations := rnd.Perm(size)
data := make([]byte, size)
for i, p := range permutations {
data[i] = letters[p%len(letters)]
}
return data
}
func shuffleEndpoints(r *rand.Rand, eps []url.URL) []url.URL {
p := r.Perm(len(eps))
neps := make([]url.URL, len(eps))
for i, k := range p {
neps[i] = eps[k]
}
return neps
}
func (collection *exampleCollection) shuffle(r *rand.Rand) {
sort.Sort(collection)
permutation := r.Perm(len(collection.examples))
shuffledExamples := make([]*example, len(collection.examples))
for i, j := range permutation {
shuffledExamples[i] = collection.examples[j]
}
collection.examples = shuffledExamples
}
func (e *Specs) Shuffle(r *rand.Rand) {
sort.Sort(e)
permutation := r.Perm(len(e.specs))
shuffledSpecs := make([]*Spec, len(e.specs))
for i, j := range permutation {
shuffledSpecs[i] = e.specs[j]
}
e.specs = shuffledSpecs
}
func (container *containerNode) shuffle(r *rand.Rand) {
sort.Sort(container)
permutation := r.Perm(len(container.subjectAndContainerNodes))
shuffledNodes := make([]node, len(container.subjectAndContainerNodes))
for i, j := range permutation {
shuffledNodes[i] = container.subjectAndContainerNodes[j]
}
container.subjectAndContainerNodes = shuffledNodes
}
// Sample n unique individuals from a slice of individuals
func (indis Individuals) sample(n int, generator *rand.Rand) ([]int, Individuals) {
var (
sample = make(Individuals, n)
indexes = generator.Perm(len(indis))[:n]
)
for i, j := range indexes {
sample[i] = indis[j]
}
return indexes, sample
}
func ShuffledIndex(rnd *rand.Rand, n, round int, fn func(i int)) {
if rnd == nil {
rnd = NewRand()
}
for x := 0; x < round; x++ {
for _, i := range rnd.Perm(n) {
fn(i)
}
}
return
}
// BreadthFirst traverses a directed or undirected graph in breadth first order.
//
// Argument start is the start node for the traversal. If r is nil, nodes are
// visited in deterministic order. If a random number generator is supplied,
// nodes at each level are visited in random order.
//
// Argument f can be nil if you have no interest in the FromList path result.
// If FromList f is non-nil, the method populates f.Paths and sets f.MaxLen.
// It does not set f.Leaves. For convenience argument f can be a zero value
// FromList. If f.Paths is nil, the FromList is initialized first. If f.Paths
// is non-nil however, the FromList is used as is. The method uses a value of
// PathEnd.Len == 0 to indentify unvisited nodes. Existing non-zero values
// will limit the traversal.
//
// Traversal calls the visitor function v for each node starting with node
// start. If v returns true, traversal continues. If v returns false, the
// traversal terminates immediately. PathEnd Len and From values are updated
// before calling the visitor function.
//
// On return f.Paths and f.MaxLen are set but not f.Leaves.
//
// Returned is the number of nodes visited and ok = true if the traversal
// ran to completion or ok = false if it was terminated by the visitor
// function returning false.
//
// There are equivalent labeled and unlabeled versions of this method.
func (g AdjacencyList) BreadthFirst(start NI, r *rand.Rand, f *FromList, v OkNodeVisitor) (visited int, ok bool) {
switch {
case f == nil:
e := NewFromList(len(g))
f = &e
case f.Paths == nil:
*f = NewFromList(len(g))
}
rp := f.Paths
// the frontier consists of nodes all at the same level
frontier := []NI{start}
level := 1
// assign path when node is put on frontier,
rp[start] = PathEnd{Len: level, From: -1}
for {
f.MaxLen = level
level++
var next []NI
if r == nil {
for _, n := range frontier {
visited++
if !v(n) { // visit nodes as they come off frontier
return
}
for _, nb := range g[n] {
if rp[nb].Len == 0 {
next = append(next, nb)
rp[nb] = PathEnd{From: n, Len: level}
}
}
}
} else { // take nodes off frontier at random
for _, i := range r.Perm(len(frontier)) {
n := frontier[i]
// remainder of block same as above
visited++
if !v(n) {
return
}
for _, nb := range g[n] {
if rp[nb].Len == 0 {
next = append(next, nb)
rp[nb] = PathEnd{From: n, Len: level}
}
}
}
}
if len(next) == 0 {
break
}
frontier = next
}
return visited, true
}
// Apply permutation mutation.
func (mut MutPermute) Apply(indi *Individual, generator *rand.Rand) {
for i := 0; i <= generator.Intn(mut.Max); i++ {
// Choose two points on the genome
var (
points = generator.Perm(len(indi.Genome))[:2]
i = points[0]
j = points[1]
)
// Permute the genes
indi.Genome[i], indi.Genome[j] = indi.Genome[j], indi.Genome[i]
}
}
// genValues creates a slice containing a random number of random values
// that when scaled by adding minValue will fall into [min, max].
func (w *WeightedDist) genValues(rng *rand.Rand) {
nValues := (w.maxValue + 1) - w.minValue
values := rng.Perm(nValues)
if nValues < minValues {
nValues = minValues
}
if nValues > maxValues {
nValues = maxValues
}
nValues = rng.Intn(nValues) + 1
w.values = values[:nValues]
}
// selectRandom chooses up to count random store descriptors from the given
// store list.
func selectRandom(randGen *rand.Rand, count int, sl StoreList) []*roachpb.StoreDescriptor {
var descs []*roachpb.StoreDescriptor
// Randomly permute available stores matching the required attributes.
for _, idx := range randGen.Perm(len(sl.stores)) {
// Add this store; exit loop if we've satisfied count.
descs = append(descs, sl.stores[idx])
if len(descs) >= count {
break
}
}
if len(descs) == 0 {
return nil
}
return descs
}
func (h *dbCorruptHarness) buildShuffled(n int, rnd *rand.Rand) {
p := &h.dbHarness
t := p.t
db := p.db
batch := new(Batch)
for i := range rnd.Perm(n) {
batch.Reset()
batch.Put(tkey(i), tval(i, ctValSize))
err := db.Write(batch, p.wo)
if err != nil {
t.Fatal("write error: ", err)
}
}
}
// LatinHypercube generates len(batch) samples using Latin hypercube sampling
// from the given distribution. If src != nil, it will be used to generate
// random numbers, otherwise rand.Float64 will be used.
//
// Latin hypercube sampling divides the cumulative distribution function into equally
// spaced bins and guarantees that one sample is generated per bin. Within each bin,
// the location is randomly sampled. The distuv.UnitNormal variable can be used
// for easy generation from the unit interval.
func LatinHypercube(batch []float64, q distuv.Quantiler, src *rand.Rand) {
n := len(batch)
var perm []int
var f64 func() float64
if src != nil {
f64 = src.Float64
perm = src.Perm(n)
} else {
f64 = rand.Float64
perm = rand.Perm(n)
}
for i := range batch {
v := f64()/float64(n) + float64(i)/float64(n)
batch[perm[i]] = q.Quantile(v)
}
}
// LatinHypercube generates len(samples) samples using Latin hypercube sampling
// from the given distribution. If src != nil, it will be used to generate
// random numbers, otherwise rand.Float64 will be used.
//
// Latin hypercube sampling divides the cumulative distribution function into equally
// spaced bins and guarantees that one sample is generated per bin. Within each bin,
// the location is randomly sampled. The dist.UnitNormal variable can be used
// for easy generation from the unit interval.
func LatinHypercube(samples []float64, q dist.Quantiler, src *rand.Rand) {
n := len(samples)
var perm []int
var f64 func() float64
if src != nil {
f64 = src.Float64
perm = src.Perm(n)
} else {
f64 = rand.Float64
perm = rand.Perm(n)
}
for i := range samples {
v := f64()/float64(n) + float64(i)/float64(n)
samples[perm[i]] = q.Quantile(v)
}
}
func (d *Director) randomPartition(rng *rand.Rand) []*network.Link {
count := state.NodeCount()
// If there are fewer than three nodes, netsplits are pretty
// boring
if count < 3 {
return []*network.Link{d.net.Links()[0]}
}
perm := rng.Perm(count)
splitPoint := rng.Intn(count-2) + 1
split := make([]uint, 0)
for i := 0; i < splitPoint; i++ {
split = append(split, uint(perm[i]))
}
log.Debugf("Made a netsplit: %v", split)
return d.net.FindPerimeter(split)
}
func NewRandomSimilarityProvider(r *rand.Rand) *RandomSimilarityProvider {
sims := make([]Similarity, len(allSims))
for i, v := range r.Perm(len(allSims)) {
sims[i] = allSims[v]
assert(sims[i] != nil)
}
ans := &RandomSimilarityProvider{
Locker: &sync.Mutex{},
defaultSim: NewDefaultSimilarity(),
previousMappings: make(map[string]Similarity),
perFieldSeed: r.Int(),
coordType: r.Intn(3),
shouldQueryNorm: r.Intn(2) == 0,
knownSims: sims,
}
ans.PerFieldSimilarityWrapper = NewPerFieldSimilarityWrapper(ans)
return ans
}
func NewRandomSimilarityProvider(r *rand.Rand) *RandomSimilarityProvider {
sims := make([]Similarity, len(allSims))
for i, v := range r.Perm(len(allSims)) {
sims[i] = allSims[v]
}
return &RandomSimilarityProvider{
PerFieldSimilarityWrapper: NewPerFieldSimilarityWrapper(func(name string) Similarity {
panic("not implemented yet")
}),
Locker: &sync.Mutex{},
defaultSim: NewDefaultSimilarity(),
previousMappings: make(map[string]Similarity),
perFieldSeed: r.Int(),
coordType: r.Intn(3),
shouldQueryNorm: r.Intn(2) == 0,
knownSims: sims,
}
}
// SpofMonkey detects single points of failure by netsplitting one node at a
// time away from the rest of the cluster and ensuring that the cluster
// continues to make progress.
func (d *Director) SpofMonkey(rng *rand.Rand, intensity float64) bool {
if spofIndex >= state.NodeCount() {
return false
} else if len(spofOrder) != state.NodeCount() {
// Unfortunately we can't do this in an init() because we defer
// the parsing of flag arguments until later.
spofOrder = rng.Perm(state.NodeCount())
}
i := spofOrder[spofIndex]
log.Printf("[monkey] Testing if %v is a single point of failure",
d.agents[i])
netsplit := d.net.FindPerimeter([]uint{uint(i)})
spofIndex++
d.agents[i].Freeze()
for _, target := range netsplit {
target.GoodbyeForever()
}
// We need to make sure that the cluster is capable of servicing
// requests that no member of the cluster has ever seen before in order
// to ensure that the cluster is making progress. To do this, we
// determine the request ID of the last request that has been created,
// and make sure that we see a request that was created *after* that
// (any requests generated after targetRequestId were necessarily
// generated after the actions above).
targetRequestId := state.LastGeneratedRequest()
for <-state.GotRequest() <= targetRequestId {
}
log.Printf("[monkey] %v is (probably) not a single point of failure!",
d.agents[i])
for _, target := range netsplit {
target.WhyHelloThere()
}
d.agents[i].Thaw()
return true
}
// Choose random connections such that each node has a connection in the
// returned list.
func (d *Director) randomNeighborLinks(rng *rand.Rand) []*network.Link {
links := d.net.Links()
perm := rng.Perm(len(links))
cover := make(map[uint]bool, state.NodeCount())
for i := 0; i < state.NodeCount(); i++ {
cover[uint(i)] = false
}
out := make([]*network.Link, 0, (state.NodeCount()+1)/2)
for _, i := range perm {
link := links[i]
a1, a2 := link.Agents()
if !cover[a1] || !cover[a2] {
out = append(out, link)
cover[a1] = true
cover[a2] = true
}
}
return out
}
func makeRoutes(ps []place, r *rand.Rand) {
for i := range ps {
p := &ps[i]
others := r.Perm(len(ps))
percentageToConnectTo := r.Float32()
next := i + 1
if next == len(ps) {
next = 0
}
p.neighbours = append(p.neighbours, dist{to: int32(next), cost: calcDist(p, &ps[next])})
for _, o := range others {
var newNeighbour dist
if r.Float32() < percentageToConnectTo && o != next && o != i {
newNeighbour = dist{to: int32(o), cost: calcDist(p, &ps[o])}
} else {
newNeighbour = dist{-1, -1}
}
p.neighbours = append(p.neighbours, newNeighbour)
}
}
}
// selectRandom chooses up to count random store descriptors from the given
// store list.
func selectRandom(randGen *rand.Rand, count int, sl StoreList,
excluded nodeIDSet) []*roachpb.StoreDescriptor {
var descs []*roachpb.StoreDescriptor
// Randomly permute available stores matching the required attributes.
for _, idx := range randGen.Perm(len(sl.stores)) {
desc := sl.stores[idx]
// Skip if store is in excluded set.
if _, ok := excluded[desc.Node.NodeID]; ok {
continue
}
// Add this store; exit loop if we've satisfied count.
descs = append(descs, sl.stores[idx])
if len(descs) >= count {
break
}
}
if len(descs) == 0 {
return nil
}
return descs
}
// SampleGen has a parametric type:
//
// func SampleGen(population []A, n int, rng *rand.Rand) []A
//
// SampleGen returns a random sample of size `n` from a list
// `population` using a given random number generator `rng`.
// All elements in `population` have an equal chance of being selected.
// If `n` is greater than the size of `population`, then `n` is set to
// the size of the population.
func SampleGen(population interface{}, n int, rng *rand.Rand) interface{} {
chk := ty.Check(
new(func([]ty.A, int, *rand.Rand) []ty.A),
population, n, rng)
rpop, tsamp := chk.Args[0], chk.Returns[0]
popLen := rpop.Len()
if n == 0 {
return reflect.MakeSlice(tsamp, 0, 0).Interface()
}
if n > popLen {
n = popLen
}
// TODO(burntsushi): Implement an algorithm that doesn't depend on
// the size of the population.
rsamp := reflect.MakeSlice(tsamp, n, n)
choices := rng.Perm(popLen)
for i := 0; i < n; i++ {
rsamp.Index(i).Set(rpop.Index(choices[i]))
}
return rsamp.Interface()
}
// Styled after the Graph500 example code. Not well tested currently.
// Graph500 example generates undirected only. No idea if the directed variant
// here is meaningful or not.
//
// note mma returns arc size ma for dir=true, but returns size m for dir=false
func kronecker(scale uint, edgeFactor float64, dir bool, r *rand.Rand) (g AdjacencyList, mma int) {
if r == nil {
r = rand.New(rand.NewSource(time.Now().UnixNano()))
}
N := NI(1 << scale) // node extent
M := int(edgeFactor*float64(N) + .5) // number of arcs/edges to generate
a, b, c := 0.57, 0.19, 0.19 // initiator probabilities
ab := a + b
cNorm := c / (1 - ab)
aNorm := a / ab
ij := make([][2]NI, M)
var bm Bits
var nNodes int
for k := range ij {
var i, j NI
for b := NI(1); b < N; b <<= 1 {
if r.Float64() > ab {
i |= b
if r.Float64() > cNorm {
j |= b
}
} else if r.Float64() > aNorm {
j |= b
}
}
if bm.Bit(i) == 0 {
bm.SetBit(i, 1)
nNodes++
}
if bm.Bit(j) == 0 {
bm.SetBit(j, 1)
nNodes++
}
r := r.Intn(k + 1) // shuffle edges as they are generated
ij[k] = ij[r]
ij[r] = [2]NI{i, j}
}
p := r.Perm(nNodes) // mapping to shuffle IDs of non-isolated nodes
px := 0
rn := make([]NI, N)
for i := range rn {
if bm.Bit(NI(i)) == 1 {
rn[i] = NI(p[px]) // fill lookup table
px++
}
}
g = make(AdjacencyList, nNodes)
ij:
for _, e := range ij {
if e[0] == e[1] {
continue // skip loops
}
ri, rj := rn[e[0]], rn[e[1]]
for _, nb := range g[ri] {
if nb == rj {
continue ij // skip parallel edges
}
}
g[ri] = append(g[ri], rj)
mma++
if !dir {
g[rj] = append(g[rj], ri)
}
}
return
}
func RandPortMap(r *rand.Rand) PortMap {
return PortMap(r.Perm(Nhost))
}
