Merge pull request #5 from reugn/develop

v0.4.0

.golangci.yml

@@ -1,6 +1,6 @@
 run:
   skip-dirs:
-    - generic
+    - benchmarks
 
 linters:
   disable-all: true
@@ -15,20 +15,14 @@ linters:
     - gocyclo
     - gofmt
     - goimports
-    - gosimple
     - govet
     - ineffassign
     - lll
     - misspell
     - prealloc
     - revive
-    - staticcheck
-    - structcheck
-    - stylecheck
     - typecheck
     - unconvert
-    - unparam
-    - unused
     - varcheck
 
 issues:
@@ -37,4 +31,3 @@ issues:
     - path: _test\.go
       linters:
         - errcheck
-        - unparam

README.md

@@ -13,12 +13,10 @@ The implemented patterns were taken from Scala and Java.
 ## Overview
 * **Future** - A placeholder object for a value that may not yet exist.
 * **Promise** - While futures are defined as a type of read-only placeholder object created for a result which doesn’t yet exist, a promise can be thought of as a writable, single-assignment container, which completes a future.
+* **Task** - A data type for controlling possibly lazy and asynchronous computations.
 * **Reentrant Lock** - Mutex that allows goroutines to enter into the lock on a resource more than once.
 * **Optimistic Lock** - Mutex that allows optimistic reading. Could be retried or switched to RLock in case of failure. Significantly improves performance in case of frequent reads and short writes. See [benchmarks](./benchmarks/README.md).
 
-### [Generic types](./generic)
-* **Task** - A data type for controlling possibly lazy and asynchronous computations.
-
 ## Examples
 Can be found in the examples directory/tests.
 

examples/future/main.go

@@ -1,23 +1,27 @@
 package main
 
 import (
-	"fmt"
+	"log"
 	"time"
 
 	"github.com/reugn/async"
 )
 
 func main() {
 	future := asyncAction()
-	rt, _ := future.Get()
-	fmt.Println(rt)
+	result, err := future.Get()
+	if err != nil {
+		log.Fatal(err)
+	}
+	log.Print(result)
 }
 
-func asyncAction() async.Future {
-	promise := async.NewPromise()
+func asyncAction() async.Future[string] {
+	promise := async.NewPromise[string]()
 	go func() {
 		time.Sleep(time.Second)
 		promise.Success("OK")
 	}()
+
 	return promise.Future()
 }

future.go

@@ -4,66 +4,70 @@ import "sync"
 
 // Future represents a value which may or may not currently be available,
 // but will be available at some point, or an error if that value could not be made available.
-type Future interface {
+type Future[T any] interface {
 
 	// Map creates a new Future by applying a function to the successful result of this Future.
-	Map(func(interface{}) (interface{}, error)) Future
+	Map(func(T) (T, error)) Future[T]
 
 	// FlatMap creates a new Future by applying a function to the successful result of
 	// this Future.
-	FlatMap(func(interface{}) (Future, error)) Future
+	FlatMap(func(T) (Future[T], error)) Future[T]
 
 	// Get blocks until the Future is completed and returns either a result or an error.
-	Get() (interface{}, error)
+	Get() (T, error)
 
 	// Recover handles any error that this Future might contain using a resolver function.
-	Recover(func() (interface{}, error)) Future
+	Recover(func() (T, error)) Future[T]
 
 	// RecoverWith handles any error that this Future might contain using another Future.
-	RecoverWith(Future) Future
+	RecoverWith(Future[T]) Future[T]
 
 	// complete completes the Future with either a value or an error.
 	// Is used by Promise internally.
-	complete(interface{}, error)
+	complete(T, error)
 }
 
 // FutureImpl implements the Future interface.
-type FutureImpl struct {
-	acc   sync.Once
-	compl sync.Once
-	done  chan interface{}
-	value interface{}
-	err   error
+type FutureImpl[T any] struct {
+	acceptOnce   sync.Once
+	completeOnce sync.Once
+	done         chan interface{}
+	value        T
+	err          error
 }
 
+// Verify FutureImpl satisfies the Future interface.
+var _ Future[any] = (*FutureImpl[any])(nil)
+
 // NewFuture returns a new Future.
-func NewFuture() Future {
-	return &FutureImpl{
+func NewFuture[T any]() Future[T] {
+	return &FutureImpl[T]{
 		done: make(chan interface{}),
 	}
 }
 
 // accept blocks once, until the Future result is available.
-func (fut *FutureImpl) accept() {
-	fut.acc.Do(func() {
+func (fut *FutureImpl[T]) accept() {
+	fut.acceptOnce.Do(func() {
 		sig := <-fut.done
 		switch v := sig.(type) {
 		case error:
 			fut.err = v
 		default:
-			fut.value = v
+			fut.value = v.(T)
 		}
 	})
 }
 
 // Map creates a new Future by applying a function to the successful result of this Future
 // and returns the result of the function as a new Future.
-func (fut *FutureImpl) Map(f func(interface{}) (interface{}, error)) Future {
-	next := NewFuture()
+func (fut *FutureImpl[T]) Map(f func(T) (T, error)) Future[T] {
+	next := NewFuture[T]()
 	go func() {
 		fut.accept()
 		if fut.err != nil {
-			next.complete(nil, fut.err)
+			var nilT T
+			next.complete(nilT, fut.err)
 		} else {
 			next.complete(f(fut.value))
 		}
@@ -73,16 +77,18 @@ func (fut *FutureImpl) Map(f func(interface{}) (interface{}, error)) Future {
 
 // FlatMap creates a new Future by applying a function to the successful result of
 // this Future and returns the result of the function as a new Future.
-func (fut *FutureImpl) FlatMap(f func(interface{}) (Future, error)) Future {
-	next := NewFuture()
+func (fut *FutureImpl[T]) FlatMap(f func(T) (Future[T], error)) Future[T] {
+	next := NewFuture[T]()
 	go func() {
 		fut.accept()
 		if fut.err != nil {
-			next.complete(nil, fut.err)
+			var nilT T
+			next.complete(nilT, fut.err)
 		} else {
 			tfut, terr := f(fut.value)
 			if terr != nil {
-				next.complete(nil, terr)
+				var nilT T
+				next.complete(nilT, terr)
 			} else {
 				next.complete(tfut.Get())
 			}
@@ -92,15 +98,15 @@ func (fut *FutureImpl) FlatMap(f func(interface{}) (Future, error)) Future {
 }
 
 // Get blocks until the Future is completed and returns either a result or an error.
-func (fut *FutureImpl) Get() (interface{}, error) {
+func (fut *FutureImpl[T]) Get() (T, error) {
 	fut.accept()
 	return fut.value, fut.err
 }
 
 // Recover handles any error that this Future might contain using a given resolver function.
 // Returns the result as a new Future.
-func (fut *FutureImpl) Recover(f func() (interface{}, error)) Future {
-	next := NewFuture()
+func (fut *FutureImpl[T]) Recover(f func() (T, error)) Future[T] {
+	next := NewFuture[T]()
 	go func() {
 		fut.accept()
 		if fut.err != nil {
@@ -114,8 +120,8 @@ func (fut *FutureImpl) Recover(f func() (interface{}, error)) Future {
 
 // RecoverWith handles any error that this Future might contain using another Future.
 // Returns the result as a new Future.
-func (fut *FutureImpl) RecoverWith(rf Future) Future {
-	next := NewFuture()
+func (fut *FutureImpl[T]) RecoverWith(rf Future[T]) Future[T] {
+	next := NewFuture[T]()
 	go func() {
 		fut.accept()
 		if fut.err != nil {
@@ -128,13 +134,13 @@ func (fut *FutureImpl) RecoverWith(rf Future) Future {
 }
 
 // complete completes the Future with either a value or an error.
-func (fut *FutureImpl) complete(v interface{}, e error) {
-	fut.compl.Do(func() {
+func (fut *FutureImpl[T]) complete(value T, err error) {
+	fut.completeOnce.Do(func() {
 		go func() {
-			if e != nil {
-				fut.done <- e
+			if err != nil {
+				fut.done <- err
 			} else {
-				fut.done <- v
+				fut.done <- value
 			}
 		}()
 	})

future_test.go

@@ -9,20 +9,21 @@ import (
 )
 
 func TestFuture(t *testing.T) {
-	p := NewPromise()
+	p := NewPromise[bool]()
 	go func() {
 		time.Sleep(time.Millisecond * 100)
 		p.Success(true)
 	}()
 	v, e := p.Future().Get()
-	internal.AssertEqual(t, v.(bool), true)
+
+	internal.AssertEqual(t, v, true)
 	internal.AssertEqual(t, e, nil)
 }
 
 func TestFutureUtils(t *testing.T) {
-	p1 := NewPromise()
-	p2 := NewPromise()
-	p3 := NewPromise()
+	p1 := NewPromise[int]()
+	p2 := NewPromise[int]()
+	p3 := NewPromise[int]()
 	go func() {
 		time.Sleep(time.Millisecond * 100)
 		p1.Success(1)
@@ -31,54 +32,58 @@ func TestFutureUtils(t *testing.T) {
 		time.Sleep(time.Millisecond * 300)
 		p3.Success(3)
 	}()
-	arr := []Future{p1.Future(), p2.Future(), p3.Future()}
+	arr := []Future[int]{p1.Future(), p2.Future(), p3.Future()}
 	res := []interface{}{1, 2, 3}
 	futRes, _ := FutureSeq(arr).Get()
+
 	internal.AssertEqual(t, res, futRes)
 }
 
 func TestFutureFirstCompleted(t *testing.T) {
-	p := NewPromise()
+	p := NewPromise[bool]()
 	go func() {
 		time.Sleep(time.Millisecond * 1000)
 		p.Success(true)
 	}()
-	timeout := FutureTimer(time.Millisecond * 100)
+	timeout := FutureTimer[bool](time.Millisecond * 100)
 	futRes, futErr := FutureFirstCompletedOf(p.Future(), timeout).Get()
-	internal.AssertEqual(t, nil, futRes)
+
+	internal.AssertEqual(t, false, futRes)
 	if futErr == nil {
 		t.Fatalf("futErr is nil")
 	}
 }
 
 func TestFutureTransform(t *testing.T) {
-	p1 := NewPromise()
+	p1 := NewPromise[int]()
 	go func() {
 		time.Sleep(time.Millisecond * 100)
 		p1.Success(1)
 	}()
-	res, _ := p1.Future().Map(func(v interface{}) (interface{}, error) {
-		return v.(int) + 1, nil
-	}).FlatMap(func(v interface{}) (Future, error) {
-		nv := v.(int) + 1
-		p2 := NewPromise()
+	res, _ := p1.Future().Map(func(v int) (int, error) {
+		return v + 1, nil
+	}).FlatMap(func(v int) (Future[int], error) {
+		nv := v + 1
+		p2 := NewPromise[int]()
 		p2.Success(nv)
 		return p2.Future(), nil
-	}).Recover(func() (interface{}, error) {
+	}).Recover(func() (int, error) {
 		return 5, nil
 	}).Get()
+
 	internal.AssertEqual(t, 3, res)
 }
 
 func TestFutureFailure(t *testing.T) {
-	p1 := NewPromise()
-	p2 := NewPromise()
+	p1 := NewPromise[int]()
+	p2 := NewPromise[int]()
 	go func() {
 		time.Sleep(time.Millisecond * 100)
 		p1.Failure(errors.New("Future error"))
 		time.Sleep(time.Millisecond * 200)
 		p2.Success(2)
 	}()
 	res, _ := p1.Future().RecoverWith(p2.Future()).Get()
+
 	internal.AssertEqual(t, 2, res)
 }

future_utils.go

@@ -5,9 +5,9 @@ import (
 	"time"
 )
 
-// FutureSeq reduces many Futures into a single Future
-func FutureSeq(futures []Future) Future {
-	next := NewFuture()
+// FutureSeq reduces many Futures into a single Future.
+func FutureSeq[T any](futures []Future[T]) Future[[]interface{}] {
+	next := NewFuture[[]interface{}]()
 	go func() {
 		seq := make([]interface{}, len(futures))
 		for i, f := range futures {
@@ -25,26 +25,27 @@ func FutureSeq(futures []Future) Future {
 
 // FutureFirstCompletedOf asynchronously returns a new Future to the result of the first Future
 // in the list that is completed. This means no matter if it is completed as a success or as a failure.
-func FutureFirstCompletedOf(futures ...Future) Future {
-	next := NewFuture()
+func FutureFirstCompletedOf[T any](futures ...Future[T]) Future[T] {
+	next := NewFuture[T]()
 	go func() {
 		for _, f := range futures {
-			go func(future Future) {
+			go func(future Future[T]) {
 				next.complete(future.Get())
 			}(f)
 		}
 	}()
 	return next
 }
 
-// FutureTimer returns Future that will have been resolved after given duration
-// useful for FutureFirstCompletedOf for timeout purposes
-func FutureTimer(d time.Duration) Future {
-	next := NewFuture()
+// FutureTimer returns Future that will have been resolved after given duration;
+// useful for FutureFirstCompletedOf for timeout purposes.
+func FutureTimer[T any](d time.Duration) Future[T] {
+	next := NewFuture[T]()
 	go func() {
 		timer := time.NewTimer(d)
 		<-timer.C
-		next.complete(nil, fmt.Errorf("FutureTimer %v timeout", d))
+		var nilT T
+		next.complete(nilT, fmt.Errorf("FutureTimer %v timeout", d))
 	}()
 	return next
 }