use golang 1.19 native atomic types

Author: alphadose

Diff for: README.md

@@ -8,7 +8,7 @@ Benchmarks to support the above claims [here](#benchmarks)
 
 ## Installation
 
-You need Golang [1.18.x](https://go.dev/dl/) or above since this package uses generics
+You need Golang [1.19.x](https://go.dev/dl/) or above
 
 ```bash
 $ go get github.com/alphadose/[email protected]
@@ -101,12 +101,12 @@ OS -> darwin
 Results were computed from [benchstat](https://pkg.go.dev/golang.org/x/perf/cmd/benchstat) of 30 cases
 ```
 name                   time/op
-UnlimitedGoroutines-8   301ms ± 4%
+UnlimitedGoroutines-8   331ms ± 4%
 ErrGroup-8              515ms ± 9%
 AntsPool-8              582ms ± 9%
 GammaZeroPool-8         740ms ±13%
 BytedanceGoPool-8       572ms ±18%
-ItogamiPool-8           331ms ± 7%
+ItogamiPool-8           337ms ± 1%
 
 name                   alloc/op
 UnlimitedGoroutines-8  96.3MB ± 0%
@@ -120,14 +120,14 @@ name                   allocs/op
 UnlimitedGoroutines-8   2.00M ± 0%
 ErrGroup-8              3.00M ± 0%
 AntsPool-8              1.10M ± 2%
-GammaZeroPool-8         1.05M ± 0%
+GammaZeroPool-8         1.08M ± 0%
 BytedanceGoPool-8       2.59M ± 1%
-ItogamiPool-8           1.05M ± 0%
+ItogamiPool-8           1.08M ± 0%
 ```
 
 The following conclusions can be drawn from the above results:-
 
-1. [Itogami](https://github.com/alphadose/itogami) is the fastest among all goroutine pool implementations and slower only than unlimited goroutines
+1. [Itogami](https://github.com/alphadose/itogami) is the fastest among all goroutine pool implementations and slightly slower than unlimited goroutines
 2. [Itogami](https://github.com/alphadose/itogami) has the least `allocs/op` and hence the memory usage scales really well with high load
 3. The memory used per operation is in the acceptable range of other pools and drastically lower than unlimited goroutines
 4. The tolerance (± %) for [Itogami](https://github.com/alphadose/itogami) is quite low for all 3 metrics indicating that the algorithm is quite stable overall

Diff for: go.mod

@@ -1,3 +1,3 @@
 module github.com/alphadose/itogami
 
-go 1.18
+go 1.19

Diff for: pool.go

@@ -19,8 +19,8 @@ type Pool struct {
 	maxSize  uint64
 	_p2      [cacheLinePadSize - unsafe.Sizeof(uint64(0))]byte
 	// using a stack keeps cpu caches warm based on FILO property
-	top unsafe.Pointer
-	_p3 [cacheLinePadSize - unsafe.Sizeof(unsafe.Pointer(nil))]byte
+	top atomic.Pointer[node]
+	_p3 [cacheLinePadSize - unsafe.Sizeof(atomic.Pointer[node]{})]byte
 }
 
 // NewPool returns a new thread pool
@@ -78,23 +78,24 @@ var (
 
 // a single node in this stack
 type node struct {
-	next  unsafe.Pointer
+	next  atomic.Pointer[node]
 	value *slot
 }
 
 // pop pops value from the top of the stack
 func (self *Pool) pop() (value *slot) {
-	var top, next unsafe.Pointer
+	var top, next *node
 	for {
-		top = atomic.LoadPointer(&self.top)
+		top = self.top.Load()
 		if top == nil {
 			return
 		}
-		next = atomic.LoadPointer(&(*node)(top).next)
-		if atomic.CompareAndSwapPointer(&self.top, top, next) {
-			value = (*node)(top).value
-			(*node)(top).next, (*node)(top).value = nil, nil
-			itemFree((*node)(top))
+		next = top.next.Load()
+		if self.top.CompareAndSwap(top, next) {
+			value = top.value
+			top.value = nil
+			top.next.Store(nil)
+			itemFree(top)
 			return
 		}
 	}
@@ -103,14 +104,14 @@ func (self *Pool) pop() (value *slot) {
 // push pushes a value on top of the stack
 func (self *Pool) push(v *slot) {
 	var (
-		top  unsafe.Pointer
+		top  *node
 		item = itemAlloc().(*node)
 	)
 	item.value = v
 	for {
-		top = atomic.LoadPointer(&self.top)
-		item.next = top
-		if atomic.CompareAndSwapPointer(&self.top, top, unsafe.Pointer(item)) {
+		top = self.top.Load()
+		item.next.Store(top)
+		if self.top.CompareAndSwap(top, item) {
 			return
 		}
 	}

Diff for: pool_func.go

@@ -6,27 +6,30 @@ import (
 	"unsafe"
 )
 
-// a single slot for a worker in PoolWithFunc
-type slotFunc[T any] struct {
-	threadPtr unsafe.Pointer
-	data      T
-}
+type (
+	// a single slot for a worker in PoolWithFunc
+	slotFunc[T any] struct {
+		threadPtr unsafe.Pointer
+		data      T
+	}
 
-// PoolWithFunc is used for spawning workers for a single pre-defined function with myriad inputs
-// useful for throughput bound cases
-// has lower memory usage and allocs per op than the default Pool
-//  ( type -> func(T) {} ) where T is a generic parameter
-type PoolWithFunc[T any] struct {
-	currSize uint64
-	_p1      [cacheLinePadSize - unsafe.Sizeof(uint64(0))]byte
-	maxSize  uint64
-	alloc    func() any
-	free     func(any)
-	task     func(T)
-	_p2      [cacheLinePadSize - unsafe.Sizeof(uint64(0)) - 3*unsafe.Sizeof(func() {})]byte
-	top      unsafe.Pointer
-	_p3      [cacheLinePadSize - unsafe.Sizeof(unsafe.Pointer(nil))]byte
-}
+	// PoolWithFunc is used for spawning workers for a single pre-defined function with myriad inputs
+	// useful for throughput bound cases
+	// has lower memory usage and allocs per op than the default Pool
+	//
+	//	( type -> func(T) {} ) where T is a generic parameter
+	PoolWithFunc[T any] struct {
+		currSize uint64
+		_p1      [cacheLinePadSize - unsafe.Sizeof(uint64(0))]byte
+		maxSize  uint64
+		alloc    func() any
+		free     func(any)
+		task     func(T)
+		_p2      [cacheLinePadSize - unsafe.Sizeof(uint64(0)) - 3*unsafe.Sizeof(func() {})]byte
+		top      atomic.Pointer[dataItem[T]]
+		_p3      [cacheLinePadSize - unsafe.Sizeof(atomic.Pointer[dataItem[T]]{})]byte
+	}
+)
 
 // NewPoolWithFunc returns a new PoolWithFunc
 func NewPoolWithFunc[T any](size uint64, task func(T)) *PoolWithFunc[T] {
@@ -68,23 +71,24 @@ func (self *PoolWithFunc[T]) loopQ(d *slotFunc[T]) {
 
 // a single node in the stack
 type dataItem[T any] struct {
-	next  unsafe.Pointer
+	next  atomic.Pointer[dataItem[T]]
 	value *slotFunc[T]
 }
 
 // pop pops value from the top of the stack
 func (self *PoolWithFunc[T]) pop() (value *slotFunc[T]) {
-	var top, next unsafe.Pointer
+	var top, next *dataItem[T]
 	for {
-		top = atomic.LoadPointer(&self.top)
+		top = self.top.Load()
 		if top == nil {
 			return
 		}
-		next = atomic.LoadPointer(&(*dataItem[T])(top).next)
-		if atomic.CompareAndSwapPointer(&self.top, top, next) {
-			value = (*dataItem[T])(top).value
-			(*dataItem[T])(top).next, (*dataItem[T])(top).value = nil, nil
-			self.free((*dataItem[T])(top))
+		next = top.next.Load()
+		if self.top.CompareAndSwap(top, next) {
+			value = top.value
+			top.value = nil
+			top.next.Store(nil)
+			self.free(top)
 			return
 		}
 	}
@@ -93,14 +97,14 @@ func (self *PoolWithFunc[T]) pop() (value *slotFunc[T]) {
 // push pushes a value on top of the stack
 func (self *PoolWithFunc[T]) push(v *slotFunc[T]) {
 	var (
-		top  unsafe.Pointer
+		top  *dataItem[T]
 		item = self.alloc().(*dataItem[T])
 	)
 	item.value = v
 	for {
-		top = atomic.LoadPointer(&self.top)
-		item.next = top
-		if atomic.CompareAndSwapPointer(&self.top, top, unsafe.Pointer(item)) {
+		top = self.top.Load()
+		item.next.Store(top)
+		if self.top.CompareAndSwap(top, item) {
 			return
 		}
 	}