github.com/xg0n/routine@v0.0.0-20240119033701-c364deb94aee/thread_local_map.go (about)

     1  package routine
     2  
     3  var unset entry = &object{}
     4  
     5  type object struct {
     6  	none bool //nolint:unused
     7  }
     8  
     9  type threadLocalMap struct {
    10  	table []entry
    11  }
    12  
    13  func (mp *threadLocalMap) get(index int) entry {
    14  	lookup := mp.table
    15  	if index < len(lookup) {
    16  		return lookup[index]
    17  	}
    18  	return unset
    19  }
    20  
    21  func (mp *threadLocalMap) set(index int, value entry) {
    22  	lookup := mp.table
    23  	if index < len(lookup) {
    24  		lookup[index] = value
    25  		return
    26  	}
    27  	mp.expandAndSet(index, value)
    28  }
    29  
    30  func (mp *threadLocalMap) remove(index int) {
    31  	lookup := mp.table
    32  	if index < len(lookup) {
    33  		lookup[index] = unset
    34  	}
    35  }
    36  
    37  func (mp *threadLocalMap) expandAndSet(index int, value entry) {
    38  	oldArray := mp.table
    39  	oldCapacity := len(oldArray)
    40  	newCapacity := index
    41  	newCapacity |= newCapacity >> 1
    42  	newCapacity |= newCapacity >> 2
    43  	newCapacity |= newCapacity >> 4
    44  	newCapacity |= newCapacity >> 8
    45  	newCapacity |= newCapacity >> 16
    46  	newCapacity++
    47  
    48  	newArray := make([]entry, newCapacity)
    49  	copy(newArray, oldArray)
    50  	fill(newArray, oldCapacity, newCapacity, unset)
    51  	newArray[index] = value
    52  	mp.table = newArray
    53  }
    54  
    55  func createInheritedMap() *threadLocalMap {
    56  	parent := currentThread(false)
    57  	if parent == nil {
    58  		return nil
    59  	}
    60  	parentMap := parent.inheritableThreadLocals
    61  	if parentMap == nil {
    62  		return nil
    63  	}
    64  	lookup := parentMap.table
    65  	if lookup == nil {
    66  		return nil
    67  	}
    68  	table := make([]entry, len(lookup))
    69  	copy(table, lookup)
    70  	for i := 0; i < len(table); i++ {
    71  		if c, ok := entryAssert[Cloneable](table[i]); ok {
    72  			table[i] = entry(c.Clone())
    73  		}
    74  	}
    75  	return &threadLocalMap{table: table}
    76  }
    77  
    78  func fill[T any](a []T, fromIndex int, toIndex int, val T) {
    79  	for i := fromIndex; i < toIndex; i++ {
    80  		a[i] = val
    81  	}
    82  }