Merging
Signed-off-by: Rémi Rativel <remi.rativel@etudiant.univ-rennes1.fr>
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//! # Thread manager
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//!
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//!
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//! This module describes the data structure and the methods used for thread scheduling
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//! in the BurritOS operating system. A struct named `ThreadManager` holds the list of
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//! all existing threads and synchronization objects, such as `Locks`, `Semaphores` and
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//! `Conditions`.
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//!
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//!
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//! ## Purpose
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//!
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//!
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//! `ThreadManager` holds the state of the system processes using the following subcomponents:
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//!
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//!
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//! ### Two lists of threads
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//!
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//!
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//! - **ready_list**: The list of threads ready to be executed
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//! - **g_alive**: The list of currently executing threads
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//!
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//!
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//! The difference between the two above lists lies in the state of the threads in question.
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//! Ready threads have just been enqueued. They are not being executed yet. The second list is
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//! needed because many threads may be executing at a given time. However, only a single thread
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//! can be handled by the machine at a time. The system thus needs to keep in memory the alive
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//! threads in case the currently running thread finishes or gets rescheduled.
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//!
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//!
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//! ### A list of synchronization objects
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//!
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//!
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//! Locks, Semaphores and Conditions allow resource sharing among running threads. Since resources
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//! can only be accessed by a single thread at a time, we need data structures to signal other
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//! threads that a resource may be busy or unavailable; say for example that thread **A** wants to
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//! write to a file while **B** is currently reading said file. Thread **A** mutating the state of
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//! the file could cause issues for **B**. Therefore **B** needs to lock the file in question to
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//! avoid such issues. Thread **A** will have to wait for **B** to finish reading the file.
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//!
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//!
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//! These synchronization objects are held in an instance of the ObjAddr structure held by
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//! ThreadManager. Their state is mutated depending on the actions of the currently running thread
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//! through methods such as `ThreadManager::sem_p`.
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//!
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//! through methods such as `ThreadManager::sem_p`.
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//!
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//! ## Usage
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//!
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//!
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//! `ThreadManager` is thought as a subcomponent of the `System` struct. Instanciating
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//! `System` will automatically instanciate a `ThreadManager`
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//!
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//!
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//! Manually loading a Thread into ThreadManager to execute a program with BurritOS could look like
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//! this:
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//!
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//!
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//! ```
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//! fn load_thread_manually(args: ...) {
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//! let mut system = System::new(args.debug);
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//!
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//!
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//! let thread_exec = Thread::new(args.executable.as_str());
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//! let thread_exec = Rc::new(RefCell::new(thread_exec));
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//! system.get_thread_manager().get_g_alive().push(Rc::clone(&thread_exec));
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//!
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//!
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//! let owner1 = Process { num_thread: 0 };
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//! let owner1 = Rc::new(RefCell::new(owner1));
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//! system.get_thread_manager().start_thread(Rc::clone(&thread_exec), owner1, loader.elf_header.entrypoint, ptr, -1);
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//!
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//!
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//! let to_run = system.get_thread_manager().find_next_to_run().unwrap();
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//! system.get_thread_manager().switch_to(&mut machine, Rc::clone(&to_run));
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//!
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//!
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//! machine.run(&mut system);
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//! }
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//! ```
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//!
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//!
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//! ## Imports
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//!
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//!
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//! The `List` and `ObjAddr` submodules used in this module are defined in the utility
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//! module. The source code of ObjAddr has been decoupled from thread_manager in an effort
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//! to keep this module concise.
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@ -448,12 +448,14 @@ mod test {
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let lock = Lock::new();
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let lock_id = thread_manager.get_obj_addrs().add_lock(lock);
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let thread = Rc::new(RefCell::new(Thread::new("test_lock")));
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let thread_test = thread.clone();
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thread_manager.ready_to_run(Rc::clone(&thread));
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thread_manager.set_g_current_thread(Some(thread));
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thread_manager.lock_acquire(lock_id, &mut machine).expect("lock acquire return an error: ");
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{
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let lock = thread_manager.get_obj_addrs().search_lock(lock_id).unwrap();
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assert_eq!(lock.owner,Some(thread_test));
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assert!(!lock.free);
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assert!(lock.waiting_queue.is_empty());
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}
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@ -461,6 +463,7 @@ mod test {
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thread_manager.lock_release(lock_id, &mut machine).expect("lock release return an error: ");
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{
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let lock = thread_manager.get_obj_addrs().search_lock(lock_id).unwrap();
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assert_eq!(lock.owner, None);
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assert!(!lock.free);
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assert!(lock.waiting_queue.is_empty());
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}
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