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package storage
type NeedleValue struct {
Key Key
Offset uint32 `comment:"Volume offset"` //since aligned to 8 bytes, range is 4G*8=32G
Size uint32 `comment:"Size of the data portion"`
}
const (
batch = 100000
)
type Key uint64
type CompactSection struct {
values []NeedleValue
overflow map[Key]NeedleValue
start Key
end Key
counter int
}
func NewCompactSection(start Key) *CompactSection {
return &CompactSection{
values: make([]NeedleValue, batch),
overflow: make(map[Key]NeedleValue),
start: start,
}
}
//return old entry size
func (cs *CompactSection) Set(key Key, offset uint32, size uint32) uint32 {
ret := uint32(0)
if key > cs.end {
cs.end = key
}
if i := cs.binarySearchValues(key); i >= 0 {
ret = cs.values[i].Size
//println("key", key, "old size", ret)
cs.values[i].Offset, cs.values[i].Size = offset, size
} else {
needOverflow := cs.counter >= batch
needOverflow = needOverflow || cs.counter > 0 && cs.values[cs.counter-1].Key > key
if needOverflow {
//println("start", cs.start, "counter", cs.counter, "key", key)
if oldValue, found := cs.overflow[key]; found {
ret = oldValue.Size
}
cs.overflow[key] = NeedleValue{Key: key, Offset: offset, Size: size}
} else {
p := &cs.values[cs.counter]
p.Key, p.Offset, p.Size = key, offset, size
//println("added index", cs.counter, "key", key, cs.values[cs.counter].Key)
cs.counter++
}
}
return ret
}
//return old entry size
func (cs *CompactSection) Delete(key Key) uint32 {
ret := uint32(0)
if i := cs.binarySearchValues(key); i >= 0 {
if cs.values[i].Size > 0 {
ret = cs.values[i].Size
cs.values[i].Size = 0
}
}
if v, found := cs.overflow[key]; found {
delete(cs.overflow, key)
ret = v.Size
}
return ret
}
func (cs *CompactSection) Get(key Key) (*NeedleValue, bool) {
if v, ok := cs.overflow[key]; ok {
return &v, true
}
if i := cs.binarySearchValues(key); i >= 0 {
return &cs.values[i], true
}
return nil, false
}
func (cs *CompactSection) binarySearchValues(key Key) int {
l, h := 0, cs.counter-1
if h >= 0 && cs.values[h].Key < key {
return -2
}
//println("looking for key", key)
for l <= h {
m := (l + h) / 2
//println("mid", m, "key", cs.values[m].Key, cs.values[m].Offset, cs.values[m].Size)
if cs.values[m].Key < key {
l = m + 1
} else if key < cs.values[m].Key {
h = m - 1
} else {
//println("found", m)
return m
}
}
return -1
}
//This map assumes mostly inserting increasing keys
type CompactMap struct {
list []*CompactSection
}
func NewCompactMap() CompactMap {
return CompactMap{}
}
func (cm *CompactMap) Set(key Key, offset uint32, size uint32) uint32 {
x := cm.binarySearchCompactSection(key)
if x < 0 {
//println(x, "creating", len(cm.list), "section, starting", key)
cm.list = append(cm.list, NewCompactSection(key))
x = len(cm.list) - 1
//keep compact section sorted by start
for x > 0 {
if cm.list[x-1].start > cm.list[x].start {
cm.list[x-1], cm.list[x] = cm.list[x], cm.list[x-1]
x = x - 1
} else {
break
}
}
}
return cm.list[x].Set(key, offset, size)
}
func (cm *CompactMap) Delete(key Key) uint32 {
x := cm.binarySearchCompactSection(key)
if x < 0 {
return uint32(0)
}
return cm.list[x].Delete(key)
}
func (cm *CompactMap) Get(key Key) (*NeedleValue, bool) {
x := cm.binarySearchCompactSection(key)
if x < 0 {
return nil, false
}
return cm.list[x].Get(key)
}
func (cm *CompactMap) binarySearchCompactSection(key Key) int {
l, h := 0, len(cm.list)-1
if h < 0 {
return -5
}
if cm.list[h].start <= key {
if cm.list[h].counter < batch || key <= cm.list[h].end {
return h
}
return -4
}
for l <= h {
m := (l + h) / 2
if key < cm.list[m].start {
h = m - 1
} else { // cm.list[m].start <= key
if cm.list[m+1].start <= key {
l = m + 1
} else {
return m
}
}
}
return -3
}
func (cm *CompactMap) Visit(visit func(NeedleValue) error) error {
for _, cs := range cm.list {
for _, v := range cs.overflow {
if err := visit(v); err != nil {
return err
}
}
for _, v := range cs.values {
if _, found := cs.overflow[v.Key]; !found {
if err := visit(v); err != nil {
return err
}
}
}
}
return nil
}
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