block.cpp

//
// Created by Max Tyson on 19/01/2026.
//
 
#include <processes/block.h>
#include <processes/scheduler.h>
 
using namespace MaxOS;
using namespace MaxOS::processes;
using namespace MaxOS::hardwarecommunication;
using namespace MaxOS::system;
 
BlockingLock::BlockingLock() = default;
BlockingLock::~BlockingLock() = default;
 
bool BlockingLock::must_spin() {
    return GlobalScheduler::is_active();
}
 
void BlockingLock::lock() {
    acquire();
}
 
void BlockingLock::unlock() {
    release();
}
 
bool BlockingLock::is_locked() const {
    return m_locked;
}
 
void BlockingLock::acquire() {
 
    // Try to get the lock
    for (int i = 0; (i < BLOCKING_FAST_TRY_LIMIT || must_spin()); ++i)
        if(!__atomic_test_and_set(&m_locked, __ATOMIC_ACQUIRE))
            return;
 
    // Add to the queue
    auto thread = GlobalScheduler::current_thread();
    thread->thread_state = ThreadState::WAITING;
    m_queue.push_back(thread->tid);
 
    // Scheduler will awake when the process that holds this lock marks this thread as READY
    thread->yield();
}
 
void BlockingLock::release() {
 
    // Next thread can be run
    if(!m_queue.empty())
        GlobalScheduler::get_thread(m_queue.pop_front())->thread_state = ThreadState::READY;
 
    __atomic_clear(&m_locked, __ATOMIC_RELEASE);
}