Crate thread 

Available on crate feature threading only.

Multi-threading for Ariel OS.

Implements a scheduler based on fixed priorities and preemption. Within one priority level, threads are scheduled cooperatively. This means that there is no time slicing that would equally distribute CPU time among same-priority threads. Instead, you need to use yield_same() to explicitly yield to another thread with the same priority. If no thread is ready, the core is prompted to enter deep sleep until a next thread is ready.

Threads should be implemented using the ariel_os_macros::thread proc macro, which takes care of calling the necessary initialization methods and linking the thread function element it into the binary. A ThreadId between 0 and THREAD_COUNT is assigned to each thread in the order in which the threads are declared.

Optionally, the stacksize and a priority between 1 and SCHED_PRIO_LEVELS can be configured. By default, the stack size is 2048 bytes and priority is 1.

Synchronization

The threading module supports three basic synchronization primitives:

• Channel: synchronous (blocking) channel for sending data between threads
• Lock: basic locking object
• thread_flags: thread-flag implementation for signaling between threads

Modules

sync

Synchronization primitives.

thread_flags

Thread flags.

Structs

CoreAffinitycore-affinity

Affinity mask that defines on what cores a thread can be scheduled.

CoreId

ID of a physical core.

RunqueueId

Runqueue number.

ThreadId

Identifier of a thread.

Constants

CORE_COUNT

Number of processor cores.

IDLE_THREAD_STACK_SIZEmulti-core

Stack size of the idle threads (in bytes).

SCHED_PRIO_LEVELS

The number of possible priority levels.

THREAD_COUNT

The maximum number of concurrent threads that can be created.

Traits

Arguable

Trait for types that can be used as argument for threads.

Functions

block_on

Runs a future to completion.

core_id

Returns the id of the CPU that this thread is running on.

create

Low-level function to create a thread that runs func with arg.

create_noarg

Low-level function to create a thread without argument.

current_stack_limits

Returns the current thread’s stack limits (lowest, highest).

current_tid

Returns the ThreadId of the currently active thread.

get_priority

Returns the priority of a thread.

is_valid_tid

Checks if a given ThreadId is valid.

isr_stack_core1_get_limits

Returns the isr stack limits for the second core as (lowest, highest).

park

Suspends/ pauses the current thread’s execution.

set_priority

Changes the priority of a thread.

unpark

Wakes up a thread and adds it to the runqueue.

yield_sameNon-infini-core

“Yields” to another thread with the same priority.