// Lookup a cell based on a uint64 key value. Returns nil if key not found.
func (t *HashTableSomeStruct) Lookup(key uint64) *CellSomeStruct {
var cell *CellSomeStruct
if key == 0 {
if t.zero().unHashedKey == 1 {
return t.zero()
}
return nil
}
h := util.IntegerHash(uint64(key)) % t.ArraySize
for {
cell = t.cellAt(h)
if cell.unHashedKey == key {
return cell
}
if cell.unHashedKey == 0 {
return nil
}
h++
if h == t.ArraySize {
h = 0
}
}
}
func (t *HashTableSomeStruct) Insert(key uint64) (*CellSomeStruct, bool) {
var cell *CellSomeStruct
if key == 0 {
zc := t.zero()
// inuse
isNew := zc.unHashedKey == 0
if isNew {
t.Population++
zc.unHashedKey = 1
}
return zc, isNew
}
// if key != 0 {
for {
h := util.IntegerHash(uint64(key)) % t.ArraySize
for {
cell = t.cellAt(h)
if cell.unHashedKey == key {
// already exists
return cell, false
}
if cell.unHashedKey == 0 {
if (t.Population+1)*4 >= t.ArraySize*3 {
t.Repopulate(t.ArraySize * 2)
// resized, so start all over
break
}
t.Population++
cell.unHashedKey = key
return cell, true
}
h++
if h == t.ArraySize {
h = 0
}
}
}
}
// DeleteCellSomeStruct deletes the cell pointed to by cell.
func (t *HashTableSomeStruct) DeleteCellSomeStruct(cell *CellSomeStruct) {
pos := uint64((uintptr(unsafe.Pointer(cell)) - uintptr(unsafe.Pointer(t.cells))) / uintptr(unsafe.Sizeof(CellSomeStruct{})))
// Delete from regular cells
if pos < 0 || pos >= t.ArraySize {
panic(fmt.Sprintf("cell out of bounds: pos %v was < 0 or >= t.ArraySize == %v", pos, t.ArraySize))
}
if t.cellAt(pos).unHashedKey == 0 {
panic("zero unHashedKey in non-zero CellSomeStruct!")
}
// Remove this cell by shuffling neighboring cells so there are no gaps in anyone's probe chain
nei := pos + 1
if nei >= t.ArraySize {
nei = 0
}
var neighbor *CellSomeStruct
var circular_offset_ideal_pos int64
var circular_offset_ideal_nei int64
var cellPos *CellSomeStruct
for {
neighbor = t.cellAt(nei)
if neighbor.unHashedKey == 0 {
// There's nobody to swap with. Go ahead and clear this cell, then return
cellPos = t.cellAt(pos)
cellPos.unHashedKey = 0
cellPos.ZeroValue()
t.Population--
return
}
ideal := util.IntegerHash(neighbor.unHashedKey) % t.ArraySize
if pos >= ideal {
circular_offset_ideal_pos = int64(pos) - int64(ideal)
} else {
// pos < ideal, so pos - ideal is negative, wrap-around has happened.
circular_offset_ideal_pos = int64(t.ArraySize) - int64(ideal) + int64(pos)
}
if nei >= ideal {
circular_offset_ideal_nei = int64(nei) - int64(ideal)
} else {
// nei < ideal, so nei - ideal is negative, wrap-around has happened.
circular_offset_ideal_nei = int64(t.ArraySize) - int64(ideal) + int64(nei)
}
if circular_offset_ideal_pos < circular_offset_ideal_nei {
// Swap with neighbor, then make neighbor the new cell to remove.
*t.cellAt(pos) = *neighbor
pos = nei
}
nei++
if nei >= t.ArraySize {
nei = 0
}
}
}
