feat(broadcast): add unbounded policy

CHANGELOG.md

@@ -8,6 +8,7 @@ All notable changes to this project will be documented in this file.
 
 ### New features
 
+* Implement `broadcast::unbounded`, an unbounded broadcast channel that retains messages until all active receivers consume them or are dropped.
 * Add an opt-in `asyncband::blocking::FutureExt` bridge with `block_on` and `wait_timeout` methods for waiting on runtime-agnostic futures from synchronous code.
 
 ### Breaking changes

README.md

@@ -32,24 +32,25 @@ Asyncband is a runtime-agnostic library providing essential synchronization prim
 
 The crate enables no primitives by default. Categories describe each primitive's primary purpose and do not add another module level, so public paths remain concise, such as `asyncband::mutex` and `asyncband::once::OnceCell`.
 
-| Category                | Primitive                                                                            | Feature        | Purpose                                                                 |
-| ----------------------- | ------------------------------------------------------------------------------------ | -------------- | ----------------------------------------------------------------------- |
-| Shared state            | [`Mutex`](https://docs.rs/asyncband/*/asyncband/mutex/struct.Mutex.html)             | `mutex`        | Protect shared data with asynchronous mutual exclusion.                 |
-|                         | [`RwLock`](https://docs.rs/asyncband/*/asyncband/rwlock/struct.RwLock.html)          | `rwlock`       | Allow multiple readers or one writer.                                   |
-|                         | [`Condvar`](https://docs.rs/asyncband/*/asyncband/condvar/struct.Condvar.html)       | `condvar`      | Wait for notifications while releasing a mutex.                         |
-| One-time initialization | [`Once`](https://docs.rs/asyncband/*/asyncband/once/struct.Once.html)                | `once`         | Run asynchronous initialization exactly once.                           |
-|                         | [`OnceCell`](https://docs.rs/asyncband/*/asyncband/once/struct.OnceCell.html)        | `once-cell`    | Initialize and store one asynchronous value.                            |
-|                         | [`OnceMap`](https://docs.rs/asyncband/*/asyncband/once/struct.OnceMap.html)          | `once-map`     | Initialize and store one value per key.                                 |
-| Task coordination       | [`Barrier`](https://docs.rs/asyncband/*/asyncband/barrier/struct.Barrier.html)       | `barrier`      | Wait until all participants reach a synchronization point.              |
-|                         | [`Latch`](https://docs.rs/asyncband/*/asyncband/latch/struct.Latch.html)             | `latch`        | Wait until a one-way countdown completes.                               |
-|                         | [`WaitGroup`](https://docs.rs/asyncband/*/asyncband/waitgroup/struct.WaitGroup.html) | `waitgroup`    | Wait for a dynamic group of tasks to finish.                            |
-|                         | [`shutdown`](https://docs.rs/asyncband/*/asyncband/shutdown/)                        | `shutdown`     | Coordinate shutdown signals and completion.                             |
-| Channels                | [`oneshot::channel`](https://docs.rs/asyncband/*/asyncband/oneshot/fn.channel.html)  | `oneshot`      | Send one value between two tasks.                                       |
-|                         | [`mpsc::bounded`](https://docs.rs/asyncband/*/asyncband/mpsc/fn.bounded.html)        | `mpsc`         | Send values from multiple producers through a bounded channel.          |
-|                         | [`mpsc::unbounded`](https://docs.rs/asyncband/*/asyncband/mpsc/fn.unbounded.html)    | `mpsc`         | Send values from multiple producers through an unbounded channel.       |
-|                         | [`broadcast::overflow`](https://docs.rs/asyncband/*/asyncband/broadcast/overflow/)   | `broadcast`    | Broadcast values and report when slow receivers miss overwritten items. |
-| Workload control        | [`Semaphore`](https://docs.rs/asyncband/*/asyncband/semaphore/struct.Semaphore.html) | `semaphore`    | Control concurrent access with permits.                                 |
-|                         | [`Group`](https://docs.rs/asyncband/*/asyncband/singleflight/struct.Group.html)      | `singleflight` | Coalesce concurrent calls for the same key.                             |
+| Category                | Primitive                                                                            | Feature        | Purpose                                                                     |
+| ----------------------- | ------------------------------------------------------------------------------------ | -------------- | --------------------------------------------------------------------------- |
+| Shared state            | [`Mutex`](https://docs.rs/asyncband/*/asyncband/mutex/struct.Mutex.html)             | `mutex`        | Protect shared data with asynchronous mutual exclusion.                     |
+|                         | [`RwLock`](https://docs.rs/asyncband/*/asyncband/rwlock/struct.RwLock.html)          | `rwlock`       | Allow multiple readers or one writer.                                       |
+|                         | [`Condvar`](https://docs.rs/asyncband/*/asyncband/condvar/struct.Condvar.html)       | `condvar`      | Wait for notifications while releasing a mutex.                             |
+| One-time initialization | [`Once`](https://docs.rs/asyncband/*/asyncband/once/struct.Once.html)                | `once`         | Run asynchronous initialization exactly once.                               |
+|                         | [`OnceCell`](https://docs.rs/asyncband/*/asyncband/once/struct.OnceCell.html)        | `once-cell`    | Initialize and store one asynchronous value.                                |
+|                         | [`OnceMap`](https://docs.rs/asyncband/*/asyncband/once/struct.OnceMap.html)          | `once-map`     | Initialize and store one value per key.                                     |
+| Task coordination       | [`Barrier`](https://docs.rs/asyncband/*/asyncband/barrier/struct.Barrier.html)       | `barrier`      | Wait until all participants reach a synchronization point.                  |
+|                         | [`Latch`](https://docs.rs/asyncband/*/asyncband/latch/struct.Latch.html)             | `latch`        | Wait until a one-way countdown completes.                                   |
+|                         | [`WaitGroup`](https://docs.rs/asyncband/*/asyncband/waitgroup/struct.WaitGroup.html) | `waitgroup`    | Wait for a dynamic group of tasks to finish.                                |
+|                         | [`shutdown`](https://docs.rs/asyncband/*/asyncband/shutdown/)                        | `shutdown`     | Coordinate shutdown signals and completion.                                 |
+| Channels                | [`oneshot::channel`](https://docs.rs/asyncband/*/asyncband/oneshot/fn.channel.html)  | `oneshot`      | Send one value between two tasks.                                           |
+|                         | [`mpsc::bounded`](https://docs.rs/asyncband/*/asyncband/mpsc/fn.bounded.html)        | `mpsc`         | Send values from multiple producers through a bounded channel.              |
+|                         | [`mpsc::unbounded`](https://docs.rs/asyncband/*/asyncband/mpsc/fn.unbounded.html)    | `mpsc`         | Send values from multiple producers through an unbounded channel.           |
+|                         | [`broadcast::overflow`](https://docs.rs/asyncband/*/asyncband/broadcast/overflow/)   | `broadcast`    | Broadcast values and report when slow receivers miss overwritten items.     |
+|                         | [`broadcast::unbounded`](https://docs.rs/asyncband/*/asyncband/broadcast/unbounded/) | `broadcast`    | Broadcast values and retain them until every active receiver consumes them. |
+| Workload control        | [`Semaphore`](https://docs.rs/asyncband/*/asyncband/semaphore/struct.Semaphore.html) | `semaphore`    | Control concurrent access with permits.                                     |
+|                         | [`Group`](https://docs.rs/asyncband/*/asyncband/singleflight/struct.Group.html)      | `singleflight` | Coalesce concurrent calls for the same key.                                 |
 
 ## Installation
 

asyncband/src/broadcast/mod.rs

@@ -20,5 +20,7 @@
 //! This module provides broadcast channels in one of the following policies:
 //!
 //! * [`overflow`]: when the channel is full, the oldest messages are overwritten.
+//! * [`unbounded`]: messages are retained until every active receiver consumes them or is dropped.
 
 pub mod overflow;
+pub mod unbounded;