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concurrent_stream.go
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concurrent_stream.go
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package stream
import (
"math"
"sort"
"sync"
"sync/atomic"
)
var _ Stream = (*concurrentStream)(nil)
type concurrentStream struct {
source <-chan any
parallelism uint
}
// WithSync returns an option that sets the sync of the stream
func WithSync() func(Stream) {
return WithParallelism(1)
}
// WithParallelism returns an option that sets the parallelism of the stream
func WithParallelism(parallelism uint) func(Stream) {
if parallelism == 0 {
panic("parallelism must be greater than 0")
}
return func(s Stream) {
if cs, ok := s.(*concurrentStream); ok {
cs.parallelism = parallelism
} else {
panic("stream: WithParallelism must be used with concurrentStream")
}
}
}
func (cs *concurrentStream) newStream(source <-chan any) *concurrentStream {
return &concurrentStream{source, cs.parallelism}
}
func (cs *concurrentStream) newStreamWithSlice(slice []any) *concurrentStream {
out := make(chan any, cs.parallelism)
go func() {
defer close(out)
for _, item := range slice {
out <- item
}
}()
return cs.newStream(out)
}
func (cs *concurrentStream) Map(mapper MapFunc, opts ...Option) Stream {
return cs.doStream(func(item any, out chan<- any) {
out <- mapper(item)
}, opts...)
}
func (cs *concurrentStream) FlatMap(mapper FlatMapFunc, opts ...Option) Stream {
return cs.doStream(func(item any, out chan<- any) {
mapper(item).ForEach(func(each any) {
out <- each
})
}, opts...)
}
func (cs *concurrentStream) Filter(filter FilterFunc, opts ...Option) Stream {
return cs.doStream(func(item any, out chan<- any) {
if filter(item) {
out <- item
}
}, opts...)
}
func (cs *concurrentStream) Concat(streams []Stream, opts ...Option) Stream {
cs.applyOptions(opts...)
concatStreams := append([]Stream{cs}, streams...)
if !cs.isParallel() {
out := make(chan any)
go func() {
defer close(out)
for _, s := range concatStreams {
s.ForEach(func(item any) {
out <- item
})
}
}()
return cs.newStream(out)
}
out := make(chan any, cs.parallelism)
go func() {
defer close(out)
semaphore := make(chan struct{}, cs.parallelism)
for _, s := range concatStreams {
semaphore <- struct{}{}
go func(s Stream) {
defer func() {
<-semaphore
}()
s.ForEach(func(item any) {
out <- item
})
}(s)
}
// wait for all goroutines to finish
for i := 0; uint(i) < cs.parallelism; i++ {
semaphore <- struct{}{}
}
}()
return cs.newStream(out)
}
func (cs *concurrentStream) Sort(less LessFunc, opts ...Option) Stream {
iface := cs.ToIfaceSlice(opts...)
sort.Slice(iface, func(i, j int) bool {
return less(iface[i], iface[j])
})
return cs.newStreamWithSlice(iface)
}
func (cs *concurrentStream) Distinct(distinct DistinctFunc, opts ...Option) Stream {
cs.applyOptions(opts...)
if !cs.isParallel() {
seen := make(map[any]struct{})
return cs.doStream(func(item any, out chan<- any) {
if _, ok := seen[item]; !ok {
seen[item] = struct{}{}
out <- item
}
})
}
seen := new(sync.Map)
return cs.doStream(func(item any, out chan<- any) {
_, loaded := seen.LoadOrStore(distinct(item), struct{}{})
if !loaded {
out <- item
}
})
}
func (cs *concurrentStream) Limit(limit int64, opts ...Option) Stream {
cs.applyOptions(opts...)
out := make(chan any, cs.parallelism)
go func() {
defer close(out)
for item := range cs.source {
if limit <= 0 {
go cs.drain()
break
}
limit--
out <- item
}
}()
return cs.newStream(out)
}
func (cs *concurrentStream) Skip(limit int64, opts ...Option) Stream {
cs.applyOptions(opts...)
out := make(chan any, cs.parallelism)
go func() {
defer close(out)
for item := range cs.source {
if limit <= 0 {
out <- item
} else {
limit--
}
}
}()
return cs.newStream(out)
}
func (cs *concurrentStream) TakeWhile(match MatchFunc, opts ...Option) Stream {
cs.applyOptions(opts...)
out := make(chan any, cs.parallelism)
go func() {
defer close(out)
for item := range cs.source {
if match(item) {
out <- item
} else {
go cs.drain()
break
}
}
}()
return cs.newStream(out)
}
func (cs *concurrentStream) DropWhile(match MatchFunc, opts ...Option) Stream {
cs.applyOptions(opts...)
out := make(chan any, cs.parallelism)
go func() {
defer close(out)
dropping := true
for item := range cs.source {
if dropping && match(item) {
continue
}
out <- item
dropping = false
}
}()
return cs.newStream(out)
}
func (cs *concurrentStream) Peek(consumer ConsumeFunc, opts ...Option) Stream {
return cs.doStream(func(item any, out chan<- any) {
consumer(item)
out <- item
}, opts...)
}
func (cs *concurrentStream) AnyMatch(match MatchFunc, opts ...Option) bool {
cs.applyOptions(opts...)
if !cs.isParallel() {
for item := range cs.source {
if match(item) {
go cs.drain()
return true
}
}
return false
}
semaphore := make(chan struct{}, cs.parallelism)
var result int32 = 0
for item := range cs.source {
semaphore <- struct{}{}
if atomic.LoadInt32(&result) == 0 {
go func(item any) {
defer func() {
<-semaphore
}()
if match(item) {
atomic.StoreInt32(&result, 1)
}
}(item)
} else {
<-semaphore
go cs.drain()
break
}
}
// wait for all goroutines to finish
for i := 0; uint(i) < cs.parallelism; i++ {
semaphore <- struct{}{}
}
return atomic.LoadInt32(&result) == 1
}
func (cs *concurrentStream) AllMatch(match MatchFunc, opts ...Option) bool {
cs.applyOptions(opts...)
if !cs.isParallel() {
for item := range cs.source {
if !match(item) {
go cs.drain()
return false
}
}
return true
}
semaphore := make(chan struct{}, cs.parallelism)
var result int32 = 1
for item := range cs.source {
semaphore <- struct{}{}
if atomic.LoadInt32(&result) == 1 {
go func(item any) {
defer func() {
<-semaphore
}()
if !match(item) {
atomic.StoreInt32(&result, 0)
}
}(item)
} else {
<-semaphore
go cs.drain()
break
}
}
return atomic.LoadInt32(&result) == 1
}
func (cs *concurrentStream) NoneMatch(match MatchFunc, opts ...Option) bool {
cs.applyOptions(opts...)
if !cs.isParallel() {
for item := range cs.source {
if match(item) {
go cs.drain()
return false
}
}
return true
}
semaphore := make(chan struct{}, cs.parallelism)
var result int32 = 1
for item := range cs.source {
semaphore <- struct{}{}
if atomic.LoadInt32(&result) == 1 {
go func(item any) {
defer func() {
<-semaphore
}()
if match(item) {
atomic.StoreInt32(&result, 0)
}
}(item)
} else {
<-semaphore
go cs.drain()
break
}
}
return atomic.LoadInt32(&result) == 1
}
func (cs *concurrentStream) FindFirst(opts ...Option) (item any, found bool) {
cs.applyOptions(opts...)
for item = range cs.source {
go cs.drain()
return item, true
}
return nil, false
}
func (cs *concurrentStream) Count(opts ...Option) int64 {
return cs.Reduce(int64(0), func(identity any, item any) any {
cnt := identity.(int64) + 1
if cnt < 0 {
cnt = math.MaxInt64
}
return cnt
},
copyAndAppend[Option](WithSync(), opts...)...,
).(int64)
}
func (cs *concurrentStream) Reduce(identity any, accumulator AccumulatorFunc, opts ...Option) any {
cs.doStreamWithTerminate(func(item any) {
identity = accumulator(identity, item)
},
opts...,
)
return identity
}
func (cs *concurrentStream) ForEach(consumer ConsumeFunc, opts ...Option) {
cs.doStreamWithTerminate(func(item any) {
consumer(item)
}, opts...)
}
func (cs *concurrentStream) ToIfaceSlice(opts ...Option) []any {
ifaces := cs.Reduce(make([]any, 0), func(identity any, item any) any {
return append(identity.([]any), item)
},
copyAndAppend[Option](WithSync(), opts...)...,
)
return ifaces.([]any)
}
func (cs *concurrentStream) ApplyOptions(opts ...Option) Stream {
cs.applyOptions(opts...)
return cs
}
func (cs *concurrentStream) Collect(
supplier func() any,
accumulator func(container, item any),
finisher func(container any) any,
) any {
container := supplier()
cs.doStreamWithTerminate(func(item any) {
accumulator(container, item)
})
return finisher(container)
}
func (cs *concurrentStream) Close() {
cs.doStreamWithTerminate(func(item any) {})
}
func (cs *concurrentStream) doStream(fn func(item any, out chan<- any), opts ...Option) *concurrentStream {
return cs.doStreamWithOption(fn, false, opts...)
}
func (cs *concurrentStream) doStreamWithTerminate(fn func(item any), opts ...Option) {
cs.doStreamWithOption(func(item any, out chan<- any) {
fn(item)
}, true, opts...)
}
// doStreamWithOption is a helper function for doStream and doStreamWithTerminate
//
// fn is the function that will be executed in parallel
//
// terminate is true if the stream should be terminated after the function is executed
func (cs *concurrentStream) doStreamWithOption(
fn func(item any, out chan<- any),
terminate bool,
opts ...Option,
) *concurrentStream {
cs.applyOptions(opts...)
if !cs.isParallel() {
return cs.doStreamWithOptionSync(fn, terminate)
}
var out chan any
var wg *sync.WaitGroup
if terminate {
wg = new(sync.WaitGroup)
wg.Add(1)
} else {
out = make(chan any, cs.parallelism)
}
go func() {
defer func() {
if terminate {
wg.Done()
} else {
close(out)
}
}()
semaphore := make(chan struct{}, cs.parallelism)
for item := range cs.source {
// acquire semaphore
semaphore <- struct{}{}
go func(item any) {
// release semaphore
defer func() { <-semaphore }()
fn(item, out)
}(item)
}
// wait for all goroutines to finish
for i := 0; uint(i) < cs.parallelism; i++ {
semaphore <- struct{}{}
}
}()
if terminate {
wg.Wait()
return nil
} else {
return cs.newStream(out)
}
}
func (cs *concurrentStream) doStreamWithOptionSync(
fn func(item any, out chan<- any),
terminate bool,
opts ...Option,
) *concurrentStream {
cs.applyOptions(opts...)
if cs.isParallel() {
return cs.doStreamWithOption(fn, terminate)
}
var out chan any
var wg *sync.WaitGroup
if terminate {
wg = new(sync.WaitGroup)
wg.Add(1)
} else {
out = make(chan any)
}
go func() {
defer func() {
if terminate {
wg.Done()
} else {
close(out)
}
}()
for item := range cs.source {
fn(item, out)
}
}()
if terminate {
wg.Wait()
return nil
} else {
return cs.newStream(out)
}
}
func (cs *concurrentStream) isParallel() bool {
return cs.parallelism > 1
}
func (cs *concurrentStream) applyOptions(opts ...Option) {
for _, opt := range opts {
opt(cs)
}
}
// drain the source
func (cs *concurrentStream) drain() {
for range cs.source {
}
}
func copyAndAppend[T any](item T, items ...T) []T {
newItems := make([]T, len(items)+1)
copy(newItems, items)
newItems[len(items)] = item
return newItems
}