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fn.go
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fn.go
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package fx
import (
"sort"
"sync"
"github.com/tal-tech/go-zero/core/collection"
"github.com/tal-tech/go-zero/core/lang"
"github.com/tal-tech/go-zero/core/threading"
)
const (
defaultWorkers = 16
minWorkers = 1
)
type (
rxOptions struct {
unlimitedWorkers bool
workers int
}
FilterFunc func(item interface{}) bool
ForAllFunc func(pipe <-chan interface{})
ForEachFunc func(item interface{})
GenerateFunc func(source chan<- interface{})
KeyFunc func(item interface{}) interface{}
LessFunc func(a, b interface{}) bool
MapFunc func(item interface{}) interface{}
Option func(opts *rxOptions)
ParallelFunc func(item interface{})
ReduceFunc func(pipe <-chan interface{}) (interface{}, error)
WalkFunc func(item interface{}, pipe chan<- interface{})
Stream struct {
source <-chan interface{}
}
)
// From constructs a Stream from the given GenerateFunc.
func From(generate GenerateFunc) Stream {
source := make(chan interface{})
threading.GoSafe(func() {
defer close(source)
generate(source)
})
return Range(source)
}
// Just converts the given arbitrary items to a Stream.
func Just(items ...interface{}) Stream {
source := make(chan interface{}, len(items))
for _, item := range items {
source <- item
}
close(source)
return Range(source)
}
// Range converts the given channel to a Stream.
func Range(source <-chan interface{}) Stream {
return Stream{
source: source,
}
}
// Buffer buffers the items into a queue with size n.
// It can balance the producer and the consumer if their processing throughput don't match.
func (p Stream) Buffer(n int) Stream {
if n < 0 {
n = 0
}
source := make(chan interface{}, n)
go func() {
for item := range p.source {
source <- item
}
close(source)
}()
return Range(source)
}
// Count counts the number of elements in the result.
func (p Stream) Count() (count int) {
for range p.source {
count++
}
return
}
// Distinct removes the duplicated items base on the given KeyFunc.
func (p Stream) Distinct(fn KeyFunc) Stream {
source := make(chan interface{})
threading.GoSafe(func() {
defer close(source)
keys := make(map[interface{}]lang.PlaceholderType)
for item := range p.source {
key := fn(item)
if _, ok := keys[key]; !ok {
source <- item
keys[key] = lang.Placeholder
}
}
})
return Range(source)
}
// Done waits all upstreaming operations to be done.
func (p Stream) Done() {
for range p.source {
}
}
// Filter filters the items by the given FilterFunc.
func (p Stream) Filter(fn FilterFunc, opts ...Option) Stream {
return p.Walk(func(item interface{}, pipe chan<- interface{}) {
if fn(item) {
pipe <- item
}
}, opts...)
}
// ForAll handles the streaming elements from the source and no later streams.
func (p Stream) ForAll(fn ForAllFunc) {
fn(p.source)
}
// ForEach seals the Stream with the ForEachFunc on each item, no successive operations.
func (p Stream) ForEach(fn ForEachFunc) {
for item := range p.source {
fn(item)
}
}
// Group groups the elements into different groups based on their keys.
func (p Stream) Group(fn KeyFunc) Stream {
groups := make(map[interface{}][]interface{})
for item := range p.source {
key := fn(item)
groups[key] = append(groups[key], item)
}
source := make(chan interface{})
go func() {
for _, group := range groups {
source <- group
}
close(source)
}()
return Range(source)
}
func (p Stream) Head(n int64) Stream {
if n < 1 {
panic("n must be greater than 0")
}
source := make(chan interface{})
go func() {
for item := range p.source {
n--
if n >= 0 {
source <- item
}
if n == 0 {
// let successive method go ASAP even we have more items to skip
// why we don't just break the loop, because if break,
// this former goroutine will block forever, which will cause goroutine leak.
close(source)
}
}
if n > 0 {
close(source)
}
}()
return Range(source)
}
// Maps converts each item to another corresponding item, which means it's a 1:1 model.
func (p Stream) Map(fn MapFunc, opts ...Option) Stream {
return p.Walk(func(item interface{}, pipe chan<- interface{}) {
pipe <- fn(item)
}, opts...)
}
// Merge merges all the items into a slice and generates a new stream.
func (p Stream) Merge() Stream {
var items []interface{}
for item := range p.source {
items = append(items, item)
}
source := make(chan interface{}, 1)
source <- items
close(source)
return Range(source)
}
// Parallel applies the given ParallelFunc to each item concurrently with given number of workers.
func (p Stream) Parallel(fn ParallelFunc, opts ...Option) {
p.Walk(func(item interface{}, pipe chan<- interface{}) {
fn(item)
}, opts...).Done()
}
// Reduce is a utility method to let the caller deal with the underlying channel.
func (p Stream) Reduce(fn ReduceFunc) (interface{}, error) {
return fn(p.source)
}
// Reverse reverses the elements in the stream.
func (p Stream) Reverse() Stream {
var items []interface{}
for item := range p.source {
items = append(items, item)
}
// reverse, official method
for i := len(items)/2 - 1; i >= 0; i-- {
opp := len(items) - 1 - i
items[i], items[opp] = items[opp], items[i]
}
return Just(items...)
}
// Sort sorts the items from the underlying source.
func (p Stream) Sort(less LessFunc) Stream {
var items []interface{}
for item := range p.source {
items = append(items, item)
}
sort.Slice(items, func(i, j int) bool {
return less(items[i], items[j])
})
return Just(items...)
}
// Split splits the elements into chunk with size up to n,
// might be less than n on tailing elements.
func (p Stream) Split(n int) Stream {
if n < 1 {
panic("n should be greater than 0")
}
source := make(chan interface{})
go func() {
var chunk []interface{}
for item := range p.source {
chunk = append(chunk, item)
if len(chunk) == n {
source <- chunk
chunk = nil
}
}
if chunk != nil {
source <- chunk
}
close(source)
}()
return Range(source)
}
func (p Stream) Tail(n int64) Stream {
if n < 1 {
panic("n should be greater than 0")
}
source := make(chan interface{})
go func() {
ring := collection.NewRing(int(n))
for item := range p.source {
ring.Add(item)
}
for _, item := range ring.Take() {
source <- item
}
close(source)
}()
return Range(source)
}
// Walk lets the callers handle each item, the caller may write zero, one or more items base on the given item.
func (p Stream) Walk(fn WalkFunc, opts ...Option) Stream {
option := buildOptions(opts...)
if option.unlimitedWorkers {
return p.walkUnlimited(fn, option)
} else {
return p.walkLimited(fn, option)
}
}
func (p Stream) walkLimited(fn WalkFunc, option *rxOptions) Stream {
pipe := make(chan interface{}, option.workers)
go func() {
var wg sync.WaitGroup
pool := make(chan lang.PlaceholderType, option.workers)
for {
pool <- lang.Placeholder
item, ok := <-p.source
if !ok {
<-pool
break
}
wg.Add(1)
// better to safely run caller defined method
threading.GoSafe(func() {
defer func() {
wg.Done()
<-pool
}()
fn(item, pipe)
})
}
wg.Wait()
close(pipe)
}()
return Range(pipe)
}
func (p Stream) walkUnlimited(fn WalkFunc, option *rxOptions) Stream {
pipe := make(chan interface{}, defaultWorkers)
go func() {
var wg sync.WaitGroup
for {
item, ok := <-p.source
if !ok {
break
}
wg.Add(1)
// better to safely run caller defined method
threading.GoSafe(func() {
defer wg.Done()
fn(item, pipe)
})
}
wg.Wait()
close(pipe)
}()
return Range(pipe)
}
// UnlimitedWorkers lets the caller to use as many workers as the tasks.
func UnlimitedWorkers() Option {
return func(opts *rxOptions) {
opts.unlimitedWorkers = true
}
}
// WithWorkers lets the caller to customize the concurrent workers.
func WithWorkers(workers int) Option {
return func(opts *rxOptions) {
if workers < minWorkers {
opts.workers = minWorkers
} else {
opts.workers = workers
}
}
}
func buildOptions(opts ...Option) *rxOptions {
options := newOptions()
for _, opt := range opts {
opt(options)
}
return options
}
func newOptions() *rxOptions {
return &rxOptions{
workers: defaultWorkers,
}
}