Skip to content

ChannelIterator: add an example #4539

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 4 commits into
base: master
Choose a base branch
from
Open

ChannelIterator: add an example #4539

Changes from 2 commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
88a2ec3
add an example, stress that different coroutines *can* iterate over t…
murfel Oct 9, 2025
4ac5121
add "created"
murfel Oct 9, 2025
9d2c273
fix
murfel Nov 7, 2025
742262d
add wording on hasNext/next
murfel Nov 7, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
31 changes: 30 additions & 1 deletion kotlinx-coroutines-core/common/src/channels/Channel.kt
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1050,7 +1050,36 @@ public inline fun <T> ChannelResult<T>.onClosed(action: (exception: Throwable?)

/**
* Iterator for a [ReceiveChannel].
* Instances of this interface are *not thread-safe* and shall not be used from concurrent coroutines.
* Instances of this interface are *not thread-safe*.
* Each iterator instance should be created and used by a single coroutine.
*
* An example usage:
Copy link
Collaborator

@dkhalanskyjb dkhalanskyjb Oct 9, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Could you describe the sequence of events where this sample would answer a question a user may realistically have? It neither explains the next()/hasNext() interplay useful in deeply technical cases where you'd manipulate ChannelIterator manually, nor does it spell out "hey, this is not the class that you need to use manually, just write for (... in ...) instead" if that was the intention.

Copy link
Contributor Author

@murfel murfel Nov 7, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I'm addressing my own confusion with the original wording - it primed me to think that only one coroutine is allowed to create instances of the iterator.

Copy link
Contributor Author

@murfel murfel Nov 7, 2025 •
edited
Loading

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Added wording on "don't use directly" and "next/hasNext"

*
* ```
* val channel = Channel<Int>()
* launch {
* channel.send(1)
* channel.send(2)
* channel.send(3)
* channel.close() // NB: must close for iterators to finish
* }
* launch {
* for (element in channel) {
* println("Consumer A got $element")
* }
* }
* launch {
* for (element in channel) {
* println("Consumer B got $element")
* }
* }
* ```
* Possible output:
* ```text
* Consumer A got 1
* Consumer A got 2
* Consumer B got 3
* ```
*/
public interface ChannelIterator<out E> {
/**
Expand Down