path: root/src/core/hle/kernel/mutex.cpp

// Copyright 2014 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.

#include <map>
#include <vector>
#include <boost/range/algorithm_ext/erase.hpp>
#include "common/assert.h"
#include "core/core.h"
#include "core/hle/kernel/handle_table.h"
#include "core/hle/kernel/kernel.h"
#include "core/hle/kernel/mutex.h"
#include "core/hle/kernel/object_address_table.h"
#include "core/hle/kernel/thread.h"

namespace Kernel {

void ReleaseThreadMutexes(Thread* thread) {
    for (auto& mtx : thread->held_mutexes) {
        mtx->SetHasWaiters(false);
        mtx->SetHoldingThread(nullptr);
        mtx->WakeupAllWaitingThreads();
    }
    thread->held_mutexes.clear();
}

Mutex::Mutex() {}
Mutex::~Mutex() {}

SharedPtr<Mutex> Mutex::Create(SharedPtr<Kernel::Thread> holding_thread, VAddr guest_addr,
                               std::string name) {
    SharedPtr<Mutex> mutex(new Mutex);

    mutex->guest_addr = guest_addr;
    mutex->name = std::move(name);

    // If mutex was initialized with a holding thread, acquire it by the holding thread
    if (holding_thread) {
        mutex->Acquire(holding_thread.get());
    }

    // Mutexes are referenced by guest address, so track this in the kernel
    g_object_address_table.Insert(guest_addr, mutex);

    return mutex;
}

bool Mutex::ShouldWait(Thread* thread) const {
    auto holding_thread = GetHoldingThread();
    return holding_thread != nullptr && thread != holding_thread;
}

void Mutex::Acquire(Thread* thread) {
    ASSERT_MSG(!ShouldWait(thread), "object unavailable!");

    priority = thread->current_priority;
    thread->held_mutexes.insert(this);
    SetHoldingThread(thread);
    thread->UpdatePriority();
    Core::System::GetInstance().PrepareReschedule();
}

ResultCode Mutex::Release(Thread* thread) {
    auto holding_thread = GetHoldingThread();
    ASSERT(holding_thread);

    // We can only release the mutex if it's held by the calling thread.
    ASSERT(thread == holding_thread);

    holding_thread->held_mutexes.erase(this);
    holding_thread->UpdatePriority();
    SetHoldingThread(nullptr);
    SetHasWaiters(!GetWaitingThreads().empty());
    WakeupAllWaitingThreads();
    Core::System::GetInstance().PrepareReschedule();

    return RESULT_SUCCESS;
}

void Mutex::AddWaitingThread(SharedPtr<Thread> thread) {
    WaitObject::AddWaitingThread(thread);
    thread->pending_mutexes.insert(this);
    SetHasWaiters(true);
    UpdatePriority();
}

void Mutex::RemoveWaitingThread(Thread* thread) {
    WaitObject::RemoveWaitingThread(thread);
    thread->pending_mutexes.erase(this);
    if (!GetHasWaiters())
        SetHasWaiters(!GetWaitingThreads().empty());
    UpdatePriority();
}

void Mutex::UpdatePriority() {
    if (!GetHoldingThread())
        return;

    u32 best_priority = THREADPRIO_LOWEST;
    for (auto& waiter : GetWaitingThreads()) {
        if (waiter->current_priority < best_priority)
            best_priority = waiter->current_priority;
    }

    if (best_priority != priority) {
        priority = best_priority;
        GetHoldingThread()->UpdatePriority();
    }
}

Handle Mutex::GetOwnerHandle() const {
    GuestState guest_state{Memory::Read32(guest_addr)};
    return guest_state.holding_thread_handle;
}

SharedPtr<Thread> Mutex::GetHoldingThread() const {
    GuestState guest_state{Memory::Read32(guest_addr)};
    return g_handle_table.Get<Thread>(guest_state.holding_thread_handle);
}

void Mutex::SetHoldingThread(SharedPtr<Thread> thread) {
    GuestState guest_state{Memory::Read32(guest_addr)};
    guest_state.holding_thread_handle.Assign(thread ? thread->guest_handle : 0);
    Memory::Write32(guest_addr, guest_state.raw);
}

bool Mutex::GetHasWaiters() const {
    GuestState guest_state{Memory::Read32(guest_addr)};
    return guest_state.has_waiters != 0;
}

void Mutex::SetHasWaiters(bool has_waiters) {
    GuestState guest_state{Memory::Read32(guest_addr)};
    guest_state.has_waiters.Assign(has_waiters ? 1 : 0);
    Memory::Write32(guest_addr, guest_state.raw);
}

} // namespace Kernel