Merge #909

909: Split embassy-time from embassy-executor. r=Dirbaio a=Dirbaio

For now this will fail to link unless you enable `embassy-executor/integrated-timers`. i'll add an executor-independent timer queue to `embassy-time` later.

Co-authored-by: Dario Nieuwenhuis <[email protected]>

1 files changed, 11 insertions, 0 deletions

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+# embassy-executor
+
+An async/await executor designed for embedded usage.
+
+- No `alloc`, no heap needed. Task futures are statically allocated.
+- No "fixed capacity" data structures, executor works with 1 or 1000 tasks without needing config/tuning.
+- Integrated timer queue: sleeping is easy, just do `Timer::after(Duration::from_secs(1)).await;`.
+- No busy-loop polling: CPU sleeps when there's no work to do, using interrupts or `WFE/SEV`.
+- Efficient polling: a wake will only poll the woken task, not all of them.
+- Fair: a task can't monopolize CPU time even if it's constantly being woken. All other tasks get a chance to run before a given task gets polled for the second time.
+- Creating multiple executor instances is supported, to run tasks with multiple priority levels. This allows higher-priority tasks to preempt lower-priority tasks.