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forgejo/vendor/github.com/RoaringBitmap/roaring/roaringarray.go
2018-05-19 20:49:46 +08:00

893 lines
23 KiB
Go

package roaring
import (
"bytes"
"encoding/binary"
"fmt"
"io"
"io/ioutil"
snappy "github.com/glycerine/go-unsnap-stream"
"github.com/tinylib/msgp/msgp"
)
//go:generate msgp -unexported
type container interface {
clone() container
and(container) container
andCardinality(container) int
iand(container) container // i stands for inplace
andNot(container) container
iandNot(container) container // i stands for inplace
getCardinality() int
// rank returns the number of integers that are
// smaller or equal to x. rank(infinity) would be getCardinality().
rank(uint16) int
iadd(x uint16) bool // inplace, returns true if x was new.
iaddReturnMinimized(uint16) container // may change return type to minimize storage.
//addRange(start, final int) container // range is [firstOfRange,lastOfRange) (unused)
iaddRange(start, endx int) container // i stands for inplace, range is [firstOfRange,endx)
iremove(x uint16) bool // inplace, returns true if x was present.
iremoveReturnMinimized(uint16) container // may change return type to minimize storage.
not(start, final int) container // range is [firstOfRange,lastOfRange)
inot(firstOfRange, endx int) container // i stands for inplace, range is [firstOfRange,endx)
xor(r container) container
getShortIterator() shortIterable
getManyIterator() manyIterable
contains(i uint16) bool
maximum() uint16
minimum() uint16
// equals is now logical equals; it does not require the
// same underlying container types, but compares across
// any of the implementations.
equals(r container) bool
fillLeastSignificant16bits(array []uint32, i int, mask uint32)
or(r container) container
orCardinality(r container) int
isFull() bool
ior(r container) container // i stands for inplace
intersects(r container) bool // whether the two containers intersect
lazyOR(r container) container
lazyIOR(r container) container
getSizeInBytes() int
//removeRange(start, final int) container // range is [firstOfRange,lastOfRange) (unused)
iremoveRange(start, final int) container // i stands for inplace, range is [firstOfRange,lastOfRange)
selectInt(x uint16) int // selectInt returns the xth integer in the container
serializedSizeInBytes() int
readFrom(io.Reader) (int, error)
writeTo(io.Writer) (int, error)
numberOfRuns() int
toEfficientContainer() container
String() string
containerType() contype
}
type contype uint8
const (
bitmapContype contype = iota
arrayContype
run16Contype
run32Contype
)
// careful: range is [firstOfRange,lastOfRange]
func rangeOfOnes(start, last int) container {
if start > MaxUint16 {
panic("rangeOfOnes called with start > MaxUint16")
}
if last > MaxUint16 {
panic("rangeOfOnes called with last > MaxUint16")
}
if start < 0 {
panic("rangeOfOnes called with start < 0")
}
if last < 0 {
panic("rangeOfOnes called with last < 0")
}
return newRunContainer16Range(uint16(start), uint16(last))
}
type roaringArray struct {
keys []uint16
containers []container `msg:"-"` // don't try to serialize directly.
needCopyOnWrite []bool
copyOnWrite bool
// conserz is used at serialization time
// to serialize containers. Otherwise empty.
conserz []containerSerz
}
// containerSerz facilitates serializing container (tricky to
// serialize because it is an interface) by providing a
// light wrapper with a type identifier.
type containerSerz struct {
t contype `msg:"t"` // type
r msgp.Raw `msg:"r"` // Raw msgpack of the actual container type
}
func newRoaringArray() *roaringArray {
return &roaringArray{}
}
// runOptimize compresses the element containers to minimize space consumed.
// Q: how does this interact with copyOnWrite and needCopyOnWrite?
// A: since we aren't changing the logical content, just the representation,
// we don't bother to check the needCopyOnWrite bits. We replace
// (possibly all) elements of ra.containers in-place with space
// optimized versions.
func (ra *roaringArray) runOptimize() {
for i := range ra.containers {
ra.containers[i] = ra.containers[i].toEfficientContainer()
}
}
func (ra *roaringArray) appendContainer(key uint16, value container, mustCopyOnWrite bool) {
ra.keys = append(ra.keys, key)
ra.containers = append(ra.containers, value)
ra.needCopyOnWrite = append(ra.needCopyOnWrite, mustCopyOnWrite)
}
func (ra *roaringArray) appendWithoutCopy(sa roaringArray, startingindex int) {
mustCopyOnWrite := sa.needCopyOnWrite[startingindex]
ra.appendContainer(sa.keys[startingindex], sa.containers[startingindex], mustCopyOnWrite)
}
func (ra *roaringArray) appendCopy(sa roaringArray, startingindex int) {
// cow only if the two request it, or if we already have a lightweight copy
copyonwrite := (ra.copyOnWrite && sa.copyOnWrite) || sa.needsCopyOnWrite(startingindex)
if !copyonwrite {
// since there is no copy-on-write, we need to clone the container (this is important)
ra.appendContainer(sa.keys[startingindex], sa.containers[startingindex].clone(), copyonwrite)
} else {
ra.appendContainer(sa.keys[startingindex], sa.containers[startingindex], copyonwrite)
if !sa.needsCopyOnWrite(startingindex) {
sa.setNeedsCopyOnWrite(startingindex)
}
}
}
func (ra *roaringArray) appendWithoutCopyMany(sa roaringArray, startingindex, end int) {
for i := startingindex; i < end; i++ {
ra.appendWithoutCopy(sa, i)
}
}
func (ra *roaringArray) appendCopyMany(sa roaringArray, startingindex, end int) {
for i := startingindex; i < end; i++ {
ra.appendCopy(sa, i)
}
}
func (ra *roaringArray) appendCopiesUntil(sa roaringArray, stoppingKey uint16) {
// cow only if the two request it, or if we already have a lightweight copy
copyonwrite := ra.copyOnWrite && sa.copyOnWrite
for i := 0; i < sa.size(); i++ {
if sa.keys[i] >= stoppingKey {
break
}
thiscopyonewrite := copyonwrite || sa.needsCopyOnWrite(i)
if thiscopyonewrite {
ra.appendContainer(sa.keys[i], sa.containers[i], thiscopyonewrite)
if !sa.needsCopyOnWrite(i) {
sa.setNeedsCopyOnWrite(i)
}
} else {
// since there is no copy-on-write, we need to clone the container (this is important)
ra.appendContainer(sa.keys[i], sa.containers[i].clone(), thiscopyonewrite)
}
}
}
func (ra *roaringArray) appendCopiesAfter(sa roaringArray, beforeStart uint16) {
// cow only if the two request it, or if we already have a lightweight copy
copyonwrite := ra.copyOnWrite && sa.copyOnWrite
startLocation := sa.getIndex(beforeStart)
if startLocation >= 0 {
startLocation++
} else {
startLocation = -startLocation - 1
}
for i := startLocation; i < sa.size(); i++ {
thiscopyonewrite := copyonwrite || sa.needsCopyOnWrite(i)
if thiscopyonewrite {
ra.appendContainer(sa.keys[i], sa.containers[i], thiscopyonewrite)
if !sa.needsCopyOnWrite(i) {
sa.setNeedsCopyOnWrite(i)
}
} else {
// since there is no copy-on-write, we need to clone the container (this is important)
ra.appendContainer(sa.keys[i], sa.containers[i].clone(), thiscopyonewrite)
}
}
}
func (ra *roaringArray) removeIndexRange(begin, end int) {
if end <= begin {
return
}
r := end - begin
copy(ra.keys[begin:], ra.keys[end:])
copy(ra.containers[begin:], ra.containers[end:])
copy(ra.needCopyOnWrite[begin:], ra.needCopyOnWrite[end:])
ra.resize(len(ra.keys) - r)
}
func (ra *roaringArray) resize(newsize int) {
for k := newsize; k < len(ra.containers); k++ {
ra.containers[k] = nil
}
ra.keys = ra.keys[:newsize]
ra.containers = ra.containers[:newsize]
ra.needCopyOnWrite = ra.needCopyOnWrite[:newsize]
}
func (ra *roaringArray) clear() {
ra.resize(0)
ra.copyOnWrite = false
ra.conserz = nil
}
func (ra *roaringArray) clone() *roaringArray {
sa := roaringArray{}
sa.copyOnWrite = ra.copyOnWrite
// this is where copyOnWrite is used.
if ra.copyOnWrite {
sa.keys = make([]uint16, len(ra.keys))
copy(sa.keys, ra.keys)
sa.containers = make([]container, len(ra.containers))
copy(sa.containers, ra.containers)
sa.needCopyOnWrite = make([]bool, len(ra.needCopyOnWrite))
ra.markAllAsNeedingCopyOnWrite()
sa.markAllAsNeedingCopyOnWrite()
// sa.needCopyOnWrite is shared
} else {
// make a full copy
sa.keys = make([]uint16, len(ra.keys))
copy(sa.keys, ra.keys)
sa.containers = make([]container, len(ra.containers))
for i := range sa.containers {
sa.containers[i] = ra.containers[i].clone()
}
sa.needCopyOnWrite = make([]bool, len(ra.needCopyOnWrite))
}
return &sa
}
// unused function:
//func (ra *roaringArray) containsKey(x uint16) bool {
// return (ra.binarySearch(0, int64(len(ra.keys)), x) >= 0)
//}
func (ra *roaringArray) getContainer(x uint16) container {
i := ra.binarySearch(0, int64(len(ra.keys)), x)
if i < 0 {
return nil
}
return ra.containers[i]
}
func (ra *roaringArray) getContainerAtIndex(i int) container {
return ra.containers[i]
}
func (ra *roaringArray) getFastContainerAtIndex(i int, needsWriteable bool) container {
c := ra.getContainerAtIndex(i)
switch t := c.(type) {
case *arrayContainer:
c = t.toBitmapContainer()
case *runContainer16:
if !t.isFull() {
c = t.toBitmapContainer()
}
case *bitmapContainer:
if needsWriteable && ra.needCopyOnWrite[i] {
c = ra.containers[i].clone()
}
}
return c
}
func (ra *roaringArray) getWritableContainerAtIndex(i int) container {
if ra.needCopyOnWrite[i] {
ra.containers[i] = ra.containers[i].clone()
ra.needCopyOnWrite[i] = false
}
return ra.containers[i]
}
func (ra *roaringArray) getIndex(x uint16) int {
// before the binary search, we optimize for frequent cases
size := len(ra.keys)
if (size == 0) || (ra.keys[size-1] == x) {
return size - 1
}
return ra.binarySearch(0, int64(size), x)
}
func (ra *roaringArray) getKeyAtIndex(i int) uint16 {
return ra.keys[i]
}
func (ra *roaringArray) insertNewKeyValueAt(i int, key uint16, value container) {
ra.keys = append(ra.keys, 0)
ra.containers = append(ra.containers, nil)
copy(ra.keys[i+1:], ra.keys[i:])
copy(ra.containers[i+1:], ra.containers[i:])
ra.keys[i] = key
ra.containers[i] = value
ra.needCopyOnWrite = append(ra.needCopyOnWrite, false)
copy(ra.needCopyOnWrite[i+1:], ra.needCopyOnWrite[i:])
ra.needCopyOnWrite[i] = false
}
func (ra *roaringArray) remove(key uint16) bool {
i := ra.binarySearch(0, int64(len(ra.keys)), key)
if i >= 0 { // if a new key
ra.removeAtIndex(i)
return true
}
return false
}
func (ra *roaringArray) removeAtIndex(i int) {
copy(ra.keys[i:], ra.keys[i+1:])
copy(ra.containers[i:], ra.containers[i+1:])
copy(ra.needCopyOnWrite[i:], ra.needCopyOnWrite[i+1:])
ra.resize(len(ra.keys) - 1)
}
func (ra *roaringArray) setContainerAtIndex(i int, c container) {
ra.containers[i] = c
}
func (ra *roaringArray) replaceKeyAndContainerAtIndex(i int, key uint16, c container, mustCopyOnWrite bool) {
ra.keys[i] = key
ra.containers[i] = c
ra.needCopyOnWrite[i] = mustCopyOnWrite
}
func (ra *roaringArray) size() int {
return len(ra.keys)
}
func (ra *roaringArray) binarySearch(begin, end int64, ikey uint16) int {
low := begin
high := end - 1
for low+16 <= high {
middleIndex := low + (high-low)/2 // avoid overflow
middleValue := ra.keys[middleIndex]
if middleValue < ikey {
low = middleIndex + 1
} else if middleValue > ikey {
high = middleIndex - 1
} else {
return int(middleIndex)
}
}
for ; low <= high; low++ {
val := ra.keys[low]
if val >= ikey {
if val == ikey {
return int(low)
}
break
}
}
return -int(low + 1)
}
func (ra *roaringArray) equals(o interface{}) bool {
srb, ok := o.(roaringArray)
if ok {
if srb.size() != ra.size() {
return false
}
for i, k := range ra.keys {
if k != srb.keys[i] {
return false
}
}
for i, c := range ra.containers {
if !c.equals(srb.containers[i]) {
return false
}
}
return true
}
return false
}
func (ra *roaringArray) headerSize() uint64 {
size := uint64(len(ra.keys))
if ra.hasRunCompression() {
if size < noOffsetThreshold { // for small bitmaps, we omit the offsets
return 4 + (size+7)/8 + 4*size
}
return 4 + (size+7)/8 + 8*size // - 4 because we pack the size with the cookie
}
return 4 + 4 + 8*size
}
// should be dirt cheap
func (ra *roaringArray) serializedSizeInBytes() uint64 {
answer := ra.headerSize()
for _, c := range ra.containers {
answer += uint64(c.serializedSizeInBytes())
}
return answer
}
//
// spec: https://github.com/RoaringBitmap/RoaringFormatSpec
//
func (ra *roaringArray) toBytes() ([]byte, error) {
stream := &bytes.Buffer{}
hasRun := ra.hasRunCompression()
isRunSizeInBytes := 0
cookieSize := 8
if hasRun {
cookieSize = 4
isRunSizeInBytes = (len(ra.keys) + 7) / 8
}
descriptiveHeaderSize := 4 * len(ra.keys)
preambleSize := cookieSize + isRunSizeInBytes + descriptiveHeaderSize
buf := make([]byte, preambleSize+4*len(ra.keys))
nw := 0
if hasRun {
binary.LittleEndian.PutUint16(buf[0:], uint16(serialCookie))
nw += 2
binary.LittleEndian.PutUint16(buf[2:], uint16(len(ra.keys)-1))
nw += 2
// compute isRun bitmap
var ir []byte
isRun := newBitmapContainer()
for i, c := range ra.containers {
switch c.(type) {
case *runContainer16:
isRun.iadd(uint16(i))
}
}
// convert to little endian
ir = isRun.asLittleEndianByteSlice()[:isRunSizeInBytes]
nw += copy(buf[nw:], ir)
} else {
binary.LittleEndian.PutUint32(buf[0:], uint32(serialCookieNoRunContainer))
nw += 4
binary.LittleEndian.PutUint32(buf[4:], uint32(len(ra.keys)))
nw += 4
}
// descriptive header
for i, key := range ra.keys {
binary.LittleEndian.PutUint16(buf[nw:], key)
nw += 2
c := ra.containers[i]
binary.LittleEndian.PutUint16(buf[nw:], uint16(c.getCardinality()-1))
nw += 2
}
startOffset := int64(preambleSize + 4*len(ra.keys))
if !hasRun || (len(ra.keys) >= noOffsetThreshold) {
// offset header
for _, c := range ra.containers {
binary.LittleEndian.PutUint32(buf[nw:], uint32(startOffset))
nw += 4
switch rc := c.(type) {
case *runContainer16:
startOffset += 2 + int64(len(rc.iv))*4
default:
startOffset += int64(getSizeInBytesFromCardinality(c.getCardinality()))
}
}
}
_, err := stream.Write(buf[:nw])
if err != nil {
return nil, err
}
for i, c := range ra.containers {
_ = i
_, err := c.writeTo(stream)
if err != nil {
return nil, err
}
}
return stream.Bytes(), nil
}
//
// spec: https://github.com/RoaringBitmap/RoaringFormatSpec
//
func (ra *roaringArray) writeTo(out io.Writer) (int64, error) {
by, err := ra.toBytes()
if err != nil {
return 0, err
}
n, err := out.Write(by)
if err == nil && n < len(by) {
err = io.ErrShortWrite
}
return int64(n), err
}
func (ra *roaringArray) fromBuffer(buf []byte) (int64, error) {
pos := 0
if len(buf) < 8 {
return 0, fmt.Errorf("buffer too small, expecting at least 8 bytes, was %d", len(buf))
}
cookie := binary.LittleEndian.Uint32(buf)
pos += 4
var size uint32 // number of containers
haveRunContainers := false
var isRunBitmap []byte
// cookie header
if cookie&0x0000FFFF == serialCookie {
haveRunContainers = true
size = uint32(uint16(cookie>>16) + 1) // number of containers
// create is-run-container bitmap
isRunBitmapSize := (int(size) + 7) / 8
if pos+isRunBitmapSize > len(buf) {
return 0, fmt.Errorf("malformed bitmap, is-run bitmap overruns buffer at %d", pos+isRunBitmapSize)
}
isRunBitmap = buf[pos : pos+isRunBitmapSize]
pos += isRunBitmapSize
} else if cookie == serialCookieNoRunContainer {
size = binary.LittleEndian.Uint32(buf[pos:])
pos += 4
} else {
return 0, fmt.Errorf("error in roaringArray.readFrom: did not find expected serialCookie in header")
}
if size > (1 << 16) {
return 0, fmt.Errorf("It is logically impossible to have more than (1<<16) containers.")
}
// descriptive header
// keycard - is {key, cardinality} tuple slice
if pos+2*2*int(size) > len(buf) {
return 0, fmt.Errorf("malfomred bitmap, key-cardinality slice overruns buffer at %d", pos+2*2*int(size))
}
keycard := byteSliceAsUint16Slice(buf[pos : pos+2*2*int(size)])
pos += 2 * 2 * int(size)
if !haveRunContainers || size >= noOffsetThreshold {
pos += 4 * int(size)
}
// Allocate slices upfront as number of containers is known
if cap(ra.containers) >= int(size) {
ra.containers = ra.containers[:size]
} else {
ra.containers = make([]container, size)
}
if cap(ra.keys) >= int(size) {
ra.keys = ra.keys[:size]
} else {
ra.keys = make([]uint16, size)
}
if cap(ra.needCopyOnWrite) >= int(size) {
ra.needCopyOnWrite = ra.needCopyOnWrite[:size]
} else {
ra.needCopyOnWrite = make([]bool, size)
}
for i := uint32(0); i < size; i++ {
key := uint16(keycard[2*i])
card := int(keycard[2*i+1]) + 1
ra.keys[i] = key
ra.needCopyOnWrite[i] = true
if haveRunContainers && isRunBitmap[i/8]&(1<<(i%8)) != 0 {
// run container
nr := binary.LittleEndian.Uint16(buf[pos:])
pos += 2
if pos+int(nr)*4 > len(buf) {
return 0, fmt.Errorf("malformed bitmap, a run container overruns buffer at %d:%d", pos, pos+int(nr)*4)
}
nb := runContainer16{
iv: byteSliceAsInterval16Slice(buf[pos : pos+int(nr)*4]),
card: int64(card),
}
pos += int(nr) * 4
ra.containers[i] = &nb
} else if card > arrayDefaultMaxSize {
// bitmap container
nb := bitmapContainer{
cardinality: card,
bitmap: byteSliceAsUint64Slice(buf[pos : pos+arrayDefaultMaxSize*2]),
}
pos += arrayDefaultMaxSize * 2
ra.containers[i] = &nb
} else {
// array container
nb := arrayContainer{
byteSliceAsUint16Slice(buf[pos : pos+card*2]),
}
pos += card * 2
ra.containers[i] = &nb
}
}
return int64(pos), nil
}
func (ra *roaringArray) readFrom(stream io.Reader) (int64, error) {
pos := 0
var cookie uint32
err := binary.Read(stream, binary.LittleEndian, &cookie)
if err != nil {
return 0, fmt.Errorf("error in roaringArray.readFrom: could not read initial cookie: %s", err)
}
pos += 4
var size uint32
haveRunContainers := false
var isRun *bitmapContainer
if cookie&0x0000FFFF == serialCookie {
haveRunContainers = true
size = uint32(uint16(cookie>>16) + 1)
bytesToRead := (int(size) + 7) / 8
numwords := (bytesToRead + 7) / 8
by := make([]byte, bytesToRead, numwords*8)
nr, err := io.ReadFull(stream, by)
if err != nil {
return 8 + int64(nr), fmt.Errorf("error in readFrom: could not read the "+
"runContainer bit flags of length %v bytes: %v", bytesToRead, err)
}
pos += bytesToRead
by = by[:cap(by)]
isRun = newBitmapContainer()
for i := 0; i < numwords; i++ {
isRun.bitmap[i] = binary.LittleEndian.Uint64(by)
by = by[8:]
}
} else if cookie == serialCookieNoRunContainer {
err = binary.Read(stream, binary.LittleEndian, &size)
if err != nil {
return 0, fmt.Errorf("error in roaringArray.readFrom: when reading size, got: %s", err)
}
pos += 4
} else {
return 0, fmt.Errorf("error in roaringArray.readFrom: did not find expected serialCookie in header")
}
if size > (1 << 16) {
return 0, fmt.Errorf("It is logically impossible to have more than (1<<16) containers.")
}
// descriptive header
keycard := make([]uint16, 2*size, 2*size)
err = binary.Read(stream, binary.LittleEndian, keycard)
if err != nil {
return 0, err
}
pos += 2 * 2 * int(size)
// offset header
if !haveRunContainers || size >= noOffsetThreshold {
io.CopyN(ioutil.Discard, stream, 4*int64(size)) // we never skip ahead so this data can be ignored
pos += 4 * int(size)
}
for i := uint32(0); i < size; i++ {
key := int(keycard[2*i])
card := int(keycard[2*i+1]) + 1
if haveRunContainers && isRun.contains(uint16(i)) {
nb := newRunContainer16()
nr, err := nb.readFrom(stream)
if err != nil {
return 0, err
}
pos += nr
ra.appendContainer(uint16(key), nb, false)
} else if card > arrayDefaultMaxSize {
nb := newBitmapContainer()
nr, err := nb.readFrom(stream)
if err != nil {
return 0, err
}
nb.cardinality = card
pos += nr
ra.appendContainer(keycard[2*i], nb, false)
} else {
nb := newArrayContainerSize(card)
nr, err := nb.readFrom(stream)
if err != nil {
return 0, err
}
pos += nr
ra.appendContainer(keycard[2*i], nb, false)
}
}
return int64(pos), nil
}
func (ra *roaringArray) hasRunCompression() bool {
for _, c := range ra.containers {
switch c.(type) {
case *runContainer16:
return true
}
}
return false
}
func (ra *roaringArray) writeToMsgpack(stream io.Writer) error {
ra.conserz = make([]containerSerz, len(ra.containers))
for i, v := range ra.containers {
switch cn := v.(type) {
case *bitmapContainer:
bts, err := cn.MarshalMsg(nil)
if err != nil {
return err
}
ra.conserz[i].t = bitmapContype
ra.conserz[i].r = bts
case *arrayContainer:
bts, err := cn.MarshalMsg(nil)
if err != nil {
return err
}
ra.conserz[i].t = arrayContype
ra.conserz[i].r = bts
case *runContainer16:
bts, err := cn.MarshalMsg(nil)
if err != nil {
return err
}
ra.conserz[i].t = run16Contype
ra.conserz[i].r = bts
default:
panic(fmt.Errorf("Unrecognized container implementation: %T", cn))
}
}
w := snappy.NewWriter(stream)
err := msgp.Encode(w, ra)
ra.conserz = nil
return err
}
func (ra *roaringArray) readFromMsgpack(stream io.Reader) error {
r := snappy.NewReader(stream)
err := msgp.Decode(r, ra)
if err != nil {
return err
}
if len(ra.containers) != len(ra.keys) {
ra.containers = make([]container, len(ra.keys))
}
for i, v := range ra.conserz {
switch v.t {
case bitmapContype:
c := &bitmapContainer{}
_, err = c.UnmarshalMsg(v.r)
if err != nil {
return err
}
ra.containers[i] = c
case arrayContype:
c := &arrayContainer{}
_, err = c.UnmarshalMsg(v.r)
if err != nil {
return err
}
ra.containers[i] = c
case run16Contype:
c := &runContainer16{}
_, err = c.UnmarshalMsg(v.r)
if err != nil {
return err
}
ra.containers[i] = c
default:
return fmt.Errorf("unrecognized contype serialization code: '%v'", v.t)
}
}
ra.conserz = nil
return nil
}
func (ra *roaringArray) advanceUntil(min uint16, pos int) int {
lower := pos + 1
if lower >= len(ra.keys) || ra.keys[lower] >= min {
return lower
}
spansize := 1
for lower+spansize < len(ra.keys) && ra.keys[lower+spansize] < min {
spansize *= 2
}
var upper int
if lower+spansize < len(ra.keys) {
upper = lower + spansize
} else {
upper = len(ra.keys) - 1
}
if ra.keys[upper] == min {
return upper
}
if ra.keys[upper] < min {
// means
// array
// has no
// item
// >= min
// pos = array.length;
return len(ra.keys)
}
// we know that the next-smallest span was too small
lower += (spansize >> 1)
mid := 0
for lower+1 != upper {
mid = (lower + upper) >> 1
if ra.keys[mid] == min {
return mid
} else if ra.keys[mid] < min {
lower = mid
} else {
upper = mid
}
}
return upper
}
func (ra *roaringArray) markAllAsNeedingCopyOnWrite() {
for i := range ra.needCopyOnWrite {
ra.needCopyOnWrite[i] = true
}
}
func (ra *roaringArray) needsCopyOnWrite(i int) bool {
return ra.needCopyOnWrite[i]
}
func (ra *roaringArray) setNeedsCopyOnWrite(i int) {
ra.needCopyOnWrite[i] = true
}