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diff --git a/third_party/rust/want/README.md b/third_party/rust/want/README.md new file mode 100644 index 0000000000..bd71b52b69 --- /dev/null +++ b/third_party/rust/want/README.md @@ -0,0 +1,24 @@ +# Want + +- [Crates.io](https://crates.io/crates/want) +- [Docs](https://docs.rs/want) + +A `Future`s channel-like utility to signal when a value is wanted. + +Futures are supposed to be lazy, and only starting work if `Future::poll` +is called. The same is true of `Stream`s, but when using a channel as +a `Stream`, it can be hard to know if the receiver is ready for the next +value. + +Put another way, given a `(tx, rx)` from `futures::sync::mpsc::channel()`, +how can the sender (`tx`) know when the receiver (`rx`) actually wants more +work to be produced? Just because there is room in the channel buffer +doesn't mean the work would be used by the receiver. + +This is where something like `want` comes in. Added to a channel, you can +make sure that the `tx` only creates the message and sends it when the `rx` +has `poll()` for it, and the buffer was empty. + +## License + +`want` is provided under the MIT license. See [LICENSE](LICENSE). |