yew/platform.rs
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48
//! Yew's compatibility between JavaScript Runtime and Native Runtimes.
//!
//! This module is also published under the name [tokise] on crates.io.
//!
//! # Rationale
//!
//! When designing components and libraries that works on both WebAssembly targets backed by
//! JavaScript Runtime and non-WebAssembly targets with Native Runtimes. Developers usually face
//! challenges that requires applying multiple feature flags throughout their application:
//!
//! 1. Select I/O and timers that works with the target runtime.
//! 2. Native Runtimes usually require `Send` futures and WebAssembly types are usually `!Send`.
//!
//! # Implementation
//!
//! To alleviate these issues, Yew implements a single-threaded runtime that executes `?Send`
//! (`Send` or `!Send`) futures.
//!
//! On platforms with multi-threading support, Yew spawns multiple independent runtimes
//! proportional to the CPU core number. When tasks are spawned with a runtime handle, it will
//! randomly select a worker thread from the internal pool. All tasks spawned with `spawn_local`
//! will run on the same thread as the thread the task was running. When the runtime runs in a
//! WebAssembly target, all tasks will be scheduled on the main thread.
//!
//! This runtime is designed in favour of IO-bounded workload with similar runtime cost.
//! When running I/O workloads, it would produce a slightly better performance as tasks are
//! never moved to another thread. However, If a worker thread is busy,
//! other threads will not be able to steal tasks scheduled on the busy thread.
//! When you have a CPU-bounded task where CPU time is significantly
//! more expensive, it should be spawned with a dedicated thread (or Web Worker) and communicates
//! with the application using channels.
//!
//! Yew platform provides the following components:
//!
//! 1. A Task Scheduler that is capable of running non-Send tasks.
//! 2. A Timer that is compatible with the scheduler backend.
//! 3. Task Synchronisation Mechanisms.
//!
//! # Runtime Backend
//!
//! The Yew runtime is implemented with different runtimes depending on the target platform and can
//! use all features (timers / IO / task synchronisation) from the selected native runtime:
//!
//! - `wasm-bindgen-futures` (WebAssembly targets)
//! - `tokio` (non-WebAssembly targets)
#[doc(inline)]
pub use tokise::*;