Understanding the internal of Flow, StateFlow, and SharedFlow
Blog post from RevenueCat
Kotlin Coroutines' Flow, StateFlow, and SharedFlow are introduced as advanced asynchronous data stream mechanisms that improve upon traditional Android development practices. Flow is highlighted for its ability to maintain context preservation and exception transparency, ensuring safe and predictable emissions. The AbstractFlow implementation uses a SafeCollector to enforce these properties, preventing context leaks during data emission. SharedFlow, in contrast, operates as a hot flow, broadcasting values to multiple collectors and using a sophisticated circular buffer system for efficient data management. StateFlow is a specialized SharedFlow that focuses on maintaining a single, conflated state with equality-based updates, employing a flat combining technique for synchronization. Both SharedFlow and StateFlow are designed with performance optimizations, such as minimizing allocations and using lock-based synchronization, to efficiently handle typical use cases with relatively few collectors. These reactive stream solutions offer flexible and performant options for developers working with coroutine-based workflows in Kotlin.