Files
rust-based-os-comp2022/os5-ref/src/task/mod.rs

100 lines
3.1 KiB
Rust

//! Implementation of process management mechanism
//!
//! Here is the entry for process scheduling required by other modules
//! (such as syscall or clock interrupt).
//! By suspending or exiting the current process, you can
//! modify the process state, manage the process queue through TASK_MANAGER,
//! and switch the control flow through PROCESSOR.
//!
//! Be careful when you see [`__switch`]. Control flow around this function
//! might not be what you expect.
mod context;
mod manager;
mod pid;
mod processor;
mod switch;
#[allow(clippy::module_inception)]
mod task;
use crate::loader::get_app_data_by_name;
use alloc::sync::Arc;
use lazy_static::*;
use manager::fetch_task;
use switch::__switch;
pub use task::{TaskControlBlock, TaskStatus};
pub use context::TaskContext;
pub use manager::add_task;
pub use pid::{pid_alloc, KernelStack, PidHandle};
pub use processor::{
current_task, current_trap_cx, current_user_token, run_tasks, schedule, take_current_task,
};
/// Make current task suspended and switch to the next task
pub fn suspend_current_and_run_next() {
// There must be an application running.
let task = take_current_task().unwrap();
// ---- access current TCB exclusively
let mut task_inner = task.inner_exclusive_access();
let task_cx_ptr = &mut task_inner.task_cx as *mut TaskContext;
// Change status to Ready
task_inner.task_status = TaskStatus::Ready;
drop(task_inner);
// ---- release current PCB
// push back to ready queue.
add_task(task);
// jump to scheduling cycle
schedule(task_cx_ptr);
}
/// Exit current task, recycle process resources and switch to the next task
pub fn exit_current_and_run_next(exit_code: i32) {
// take from Processor
let task = take_current_task().unwrap();
// **** access current TCB exclusively
let mut inner = task.inner_exclusive_access();
// Change status to Zombie
inner.task_status = TaskStatus::Zombie;
// Record exit code
inner.exit_code = exit_code;
// do not move to its parent but under initproc
// ++++++ access initproc TCB exclusively
{
let mut initproc_inner = INITPROC.inner_exclusive_access();
for child in inner.children.iter() {
child.inner_exclusive_access().parent = Some(Arc::downgrade(&INITPROC));
initproc_inner.children.push(child.clone());
}
}
// ++++++ release parent PCB
inner.children.clear();
// deallocate user space
inner.memory_set.recycle_data_pages();
drop(inner);
// **** release current PCB
// drop task manually to maintain rc correctly
drop(task);
// we do not have to save task context
let mut _unused = TaskContext::zero_init();
schedule(&mut _unused as *mut _);
}
lazy_static! {
/// Creation of initial process
///
/// the name "initproc" may be changed to any other app name like "usertests",
/// but we have user_shell, so we don't need to change it.
pub static ref INITPROC: Arc<TaskControlBlock> = Arc::new(TaskControlBlock::new(
get_app_data_by_name("ch5b_initproc").unwrap()
));
}
pub fn add_initproc() {
add_task(INITPROC.clone());
}