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435 lines (381 loc) · 13.5 KB
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// Copyright 2025 samber.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://github.com/samber/ro/blob/main/licenses/LICENSE.apache.md
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package ro
import (
"context"
"sync/atomic"
"time"
)
// Catch catches errors on the observable to be handled by returning a new observable
// or throwing an error.
// Play: https://go.dev/play/p/0pVlxwjhdMT
func Catch[T any](finally func(err error) Observable[T]) func(Observable[T]) Observable[T] {
return func(source Observable[T]) Observable[T] {
return NewUnsafeObservableWithContext(func(subscriberCtx context.Context, destination Observer[T]) Teardown {
subscriptions := NewSubscription(nil)
subscriptions.AddUnsubscribable(
source.SubscribeWithContext(
subscriberCtx,
NewObserverWithContext(
destination.NextWithContext,
func(ctx context.Context, err error) {
subscriptions.AddUnsubscribable(
finally(err).SubscribeWithContext(ctx, destination),
)
},
destination.CompleteWithContext,
),
),
)
return subscriptions.Unsubscribe
})
}
}
// OnErrorResumeNextWith instructs an Observable to begin emitting a second
// Observable sequence if it encounters an error or completes. It immediately
// subscribes to the next one that was passed.
// Play: https://go.dev/play/p/9XLTAOginbK
func OnErrorResumeNextWith[T any](finally ...Observable[T]) func(Observable[T]) Observable[T] {
return func(source Observable[T]) Observable[T] {
if len(finally) == 0 {
return source
}
finally = append([]Observable[T]{source}, finally...)
return NewUnsafeObservableWithContext(func(subscriberCtx context.Context, destination Observer[T]) Teardown {
subscriptions := NewSubscription(nil)
var lastCtx context.Context
var err error
for i := range finally {
if subscriptions.IsClosed() {
break
}
err = nil
sub := finally[i].SubscribeWithContext(
subscriberCtx,
NewObserverWithContext(
destination.NextWithContext,
func(ctx context.Context, e error) {
err = e
lastCtx = ctx
},
func(ctx context.Context) {
lastCtx = ctx
},
),
)
// `subscriptions` cancels `sub` when it unsubscribes
// but `sub` cannot unsubscribe `subscriptions`
subscriptions.AddUnsubscribable(sub)
sub.Wait()
}
if err != nil {
destination.ErrorWithContext(lastCtx, err)
} else {
destination.CompleteWithContext(lastCtx)
}
return subscriptions.Unsubscribe
})
}
}
// OnErrorReturn instructs an Observable to emit a particular item when it
// encounters an error. It will then complete the sequence.
// Play: https://go.dev/play/p/d_9xe1oedjU
func OnErrorReturn[T any](finally T) func(Observable[T]) Observable[T] {
return func(source Observable[T]) Observable[T] {
return NewUnsafeObservableWithContext(func(subscriberCtx context.Context, destination Observer[T]) Teardown {
sub := source.SubscribeWithContext(
subscriberCtx,
NewObserverWithContext(
destination.NextWithContext,
func(ctx context.Context, err error) {
destination.NextWithContext(ctx, finally)
destination.CompleteWithContext(ctx)
},
destination.CompleteWithContext,
),
)
return sub.Unsubscribe
})
}
}
// Retry resubscribes to the source observable when it encounters an error.
// It will retry infinitely. If you want to limit the number of retries, use
// RetryWithConfig.
// Play: https://go.dev/play/p/Llj9dT9Y3Z2
func Retry[T any]() func(Observable[T]) Observable[T] {
return RetryWithConfig[T](RetryConfig{
MaxRetries: 0, // unlimited
Delay: 0, // disabled
ResetOnSuccess: false, // disabled because it retries infinitely
})
}
// RetryConfig is the configuration for the Retry operator.
type RetryConfig struct {
MaxRetries uint64
Delay time.Duration
ResetOnSuccess bool
}
// RetryWithConfig resubscribes to the source observable when it encounters
// an error. If a max number of retries is set, it will retry until the max
// number of retries is reached. If a delay is set, it will wait before retrying.
// If resetOnSuccess is set, it will reset the number of retries when a value is
// emitted.
// Play: https://go.dev/play/p/GilWi5xG0lr
func RetryWithConfig[T any](opts RetryConfig) func(Observable[T]) Observable[T] {
return func(source Observable[T]) Observable[T] {
return NewUnsafeObservableWithContext(func(subscriberCtx context.Context, destination Observer[T]) Teardown {
subscriptions := NewSubscription(nil)
retries := uint64(0)
for !subscriptions.IsClosed() {
// Check for context cancellation before retrying
select {
case <-subscriberCtx.Done():
destination.ErrorWithContext(subscriberCtx, subscriberCtx.Err())
return subscriptions.Unsubscribe
default:
}
var shouldRetry bool
var lastErr error
sub := source.SubscribeWithContext(
subscriberCtx,
NewObserverWithContext(
func(ctx context.Context, value T) {
if opts.ResetOnSuccess {
retries = 0
}
destination.NextWithContext(ctx, value)
},
func(ctx context.Context, err error) {
lastErr = err
retries++
shouldRetry = opts.MaxRetries == 0 || retries <= opts.MaxRetries
},
func(ctx context.Context) {
destination.CompleteWithContext(ctx)
},
),
)
subscriptions.AddUnsubscribable(sub)
sub.Wait()
if lastErr != nil {
if shouldRetry {
if opts.Delay > 0 {
// Use context-aware sleep that can be cancelled
select {
case <-time.After(opts.Delay):
// Continue to next iteration
case <-subscriberCtx.Done():
destination.ErrorWithContext(subscriberCtx, subscriberCtx.Err())
return subscriptions.Unsubscribe
}
}
// Continue to next iteration
continue
}
destination.ErrorWithContext(subscriberCtx, lastErr)
}
break
}
return subscriptions.Unsubscribe
})
}
}
// ThrowIfEmpty throws an error if the source observable is empty. It will
// throw the error returned by the throw function. If the source observable
// emits a value, it will complete. If the source observable emits an error,
// it will propagate the error.
// Play: https://go.dev/play/p/mLCaC7p_6p4
func ThrowIfEmpty[T any](throw func() error) func(Observable[T]) Observable[T] {
return func(source Observable[T]) Observable[T] {
return NewUnsafeObservableWithContext(func(subscriberCtx context.Context, destination Observer[T]) Teardown {
count := uint64(0)
sub := source.SubscribeWithContext(
subscriberCtx,
NewObserverWithContext(
func(ctx context.Context, value T) {
atomic.AddUint64(&count, 1)
destination.NextWithContext(ctx, value)
},
destination.ErrorWithContext,
func(ctx context.Context) {
if atomic.LoadUint64(&count) == 0 {
destination.ErrorWithContext(ctx, throw())
} else {
destination.CompleteWithContext(ctx)
}
},
),
)
return sub.Unsubscribe
})
}
}
// DoWhile repeats the source observable while the condition is true. It will
// complete when the condition is false. It will not emit any values if the
// source observable is empty. It will not emit any values if the source observable
// emits an error.
// Play: https://go.dev/play/p/nEWabaItDpn
func DoWhile[T any](condition func() bool) func(Observable[T]) Observable[T] {
return DoWhileI[T](func(_ int64) bool {
return condition()
})
}
// DoWhileWithContext repeats the source observable while the condition is true. It will
// complete when the condition is false. It will not emit any values if the
// source observable is empty. It will not emit any values if the source observable
// emits an error.
func DoWhileWithContext[T any](condition func(ctx context.Context) (context.Context, bool)) func(Observable[T]) Observable[T] {
return DoWhileIWithContext[T](func(ctx context.Context, _ int64) (context.Context, bool) {
return condition(ctx)
})
}
// DoWhileI repeats the source observable while the condition is true. It will
// complete when the condition is false. It will not emit any values if the
// source observable is empty. It will not emit any values if the source observable
// emits an error.
// Play: https://go.dev/play/p/cxOA9gimkCq
func DoWhileI[T any](condition func(index int64) bool) func(Observable[T]) Observable[T] {
return DoWhileIWithContext[T](func(ctx context.Context, index int64) (context.Context, bool) {
return ctx, condition(index)
})
}
// DoWhileIWithContext repeats the source observable while the condition is true. It will
// complete when the condition is false. It will not emit any values if the
// source observable is empty. It will not emit any values if the source observable
// emits an error.
// Play: https://go.dev/play/p/yMoCCnnvRRH
func DoWhileIWithContext[T any](condition func(ctx context.Context, index int64) (context.Context, bool)) func(Observable[T]) Observable[T] {
return func(source Observable[T]) Observable[T] {
return NewUnsafeObservableWithContext(func(subscriberCtx context.Context, destination Observer[T]) Teardown {
i := int64(0)
subscriptions := NewSubscription(nil)
currentCtx := subscriberCtx
shouldContinue := true
var lastErr error
for shouldContinue {
if subscriptions.IsClosed() {
break
}
var completed bool
sub := source.SubscribeWithContext(
currentCtx,
NewObserverWithContext(
destination.NextWithContext,
func(ctx context.Context, err error) {
lastErr = err
destination.ErrorWithContext(ctx, err)
},
func(ctx context.Context) {
currentCtx, shouldContinue = condition(ctx, i)
completed = true
i++
},
),
)
subscriptions.AddUnsubscribable(sub)
sub.Wait()
if lastErr != nil {
// Source emitted an error, stop the loop
break
}
if completed && !shouldContinue {
// Condition is false, stop the loop
break
}
}
if lastErr == nil {
destination.CompleteWithContext(currentCtx)
}
return subscriptions.Unsubscribe
})
}
}
// While repeats the source observable while the condition is true. It will
// complete when the condition is false. It will not emit any values if the
// source observable is empty. It will not emit any values if the source observable
// emits an error.
// Play: https://go.dev/play/p/hMj3DBVtp73
func While[T any](condition func() bool) func(Observable[T]) Observable[T] {
return WhileIWithContext[T](func(ctx context.Context, _ int64) (context.Context, bool) {
return ctx, condition()
})
}
// WhileWithContext repeats the source observable while the condition is true. It will
// complete when the condition is false. It will not emit any values if the
// source observable is empty. It will not emit any values if the source observable
// emits an error.
func WhileWithContext[T any](condition func(ctx context.Context) (context.Context, bool)) func(Observable[T]) Observable[T] {
return WhileIWithContext[T](func(ctx context.Context, _ int64) (context.Context, bool) {
return condition(ctx)
})
}
// WhileI repeats the source observable while the condition is true. It will
// complete when the condition is false. It will not emit any values if the
// source observable is empty. It will not emit any values if the source observable
// emits an error.
// Play: https://go.dev/play/p/9aAuzAspyMc
func WhileI[T any](condition func(index int64) bool) func(Observable[T]) Observable[T] {
return WhileIWithContext[T](func(ctx context.Context, index int64) (context.Context, bool) {
return ctx, condition(index)
})
}
// WhileIWithContext repeats the source observable while the condition is true. It will
// complete when the condition is false. It will not emit any values if the
// source observable is empty. It will not emit any values if the source observable
// emits an error.
// Play: https://go.dev/play/p/xTpqdGSxOxw
func WhileIWithContext[T any](condition func(ctx context.Context, index int64) (context.Context, bool)) func(Observable[T]) Observable[T] {
return func(source Observable[T]) Observable[T] {
return NewUnsafeObservableWithContext(func(subscriberCtx context.Context, destination Observer[T]) Teardown {
i := int64(0)
subscriptions := NewSubscription(nil)
currentCtx := subscriberCtx
var lastErr error
for !subscriptions.IsClosed() {
var nextCtx context.Context
var shouldContinue bool
nextCtx, shouldContinue = condition(currentCtx, i)
if !shouldContinue {
// Condition is false, stop the loop
break
}
i++
sub := source.SubscribeWithContext(
nextCtx,
NewObserverWithContext(
destination.NextWithContext,
func(ctx context.Context, err error) {
lastErr = err
destination.ErrorWithContext(ctx, err)
},
func(ctx context.Context) {
// Source completed normally
},
),
)
subscriptions.AddUnsubscribable(sub)
sub.Wait()
if lastErr != nil {
// Source emitted an error, stop the loop
break
}
currentCtx = nextCtx
}
if lastErr == nil {
destination.CompleteWithContext(currentCtx)
}
return subscriptions.Unsubscribe
})
}
}