// Copyright 2018 yuzu emulator team
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#pragma once
#include <mutex>
#include <vector>
#include "common/common_types.h"
#include "common/multi_level_queue.h"
#include "core/hle/kernel/object.h"
#include "core/hle/kernel/thread.h"
namespace Core {
class ARM_Interface;
class System;
} // namespace Core
namespace Kernel {
class Process;
class Scheduler final {
public:
explicit Scheduler(Core::System& system, Core::ARM_Interface& cpu_core);
~Scheduler();
/// Returns whether there are any threads that are ready to run.
bool HaveReadyThreads() const;
/// Reschedules to the next available thread (call after current thread is suspended)
void Reschedule();
/// Gets the current running thread
Thread* GetCurrentThread() const;
/// Gets the timestamp for the last context switch in ticks.
u64 GetLastContextSwitchTicks() const;
/// Adds a new thread to the scheduler
void AddThread(SharedPtr<Thread> thread);
/// Removes a thread from the scheduler
void RemoveThread(Thread* thread);
/// Schedules a thread that has become "ready"
void ScheduleThread(Thread* thread, u32 priority);
/// Unschedules a thread that was already scheduled
void UnscheduleThread(Thread* thread, u32 priority);
/// Sets the priority of a thread in the scheduler
void SetThreadPriority(Thread* thread, u32 priority);
/// Gets the next suggested thread for load balancing
Thread* GetNextSuggestedThread(u32 core, u32 minimum_priority) const;
/**
* YieldWithoutLoadBalancing -- analogous to normal yield on a system
* Moves the thread to the end of the ready queue for its priority, and then reschedules the
* system to the new head of the queue.
*
* Example (Single Core -- but can be extrapolated to multi):
* ready_queue[prio=0]: ThreadA, ThreadB, ThreadC (->exec order->)
* Currently Running: ThreadR
*
* ThreadR calls YieldWithoutLoadBalancing
*
* ThreadR is moved to the end of ready_queue[prio=0]:
* ready_queue[prio=0]: ThreadA, ThreadB, ThreadC, ThreadR (->exec order->)
* Currently Running: Nothing
*
* System is rescheduled (ThreadA is popped off of queue):
* ready_queue[prio=0]: ThreadB, ThreadC, ThreadR (->exec order->)
* Currently Running: ThreadA
*
* If the queue is empty at time of call, no yielding occurs. This does not cross between cores
* or priorities at all.
*/
void YieldWithoutLoadBalancing(Thread* thread);
/**
* YieldWithLoadBalancing -- yield but with better selection of the new running thread
* Moves the current thread to the end of the ready queue for its priority, then selects a
* 'suggested thread' (a thread on a different core that could run on this core) from the
* scheduler, changes its core, and reschedules the current core to that thread.
*
* Example (Dual Core -- can be extrapolated to Quad Core, this is just normal yield if it were
* single core):
* ready_queue[core=0][prio=0]: ThreadA, ThreadB (affinities not pictured as irrelevant
* ready_queue[core=1][prio=0]: ThreadC[affinity=both], ThreadD[affinity=core1only]
* Currently Running: ThreadQ on Core 0 || ThreadP on Core 1
*
* ThreadQ calls YieldWithLoadBalancing
*
* ThreadQ is moved to the end of ready_queue[core=0][prio=0]:
* ready_queue[core=0][prio=0]: ThreadA, ThreadB
* ready_queue[core=1][prio=0]: ThreadC[affinity=both], ThreadD[affinity=core1only]
* Currently Running: ThreadQ on Core 0 || ThreadP on Core 1
*
* A list of suggested threads for each core is compiled
* Suggested Threads: {ThreadC on Core 1}
* If this were quad core (as the switch is), there could be between 0 and 3 threads in this
* list. If there are more than one, the thread is selected by highest prio.
*
* ThreadC is core changed to Core 0:
* ready_queue[core=0][prio=0]: ThreadC, ThreadA, ThreadB, ThreadQ
* ready_queue[core=1][prio=0]: ThreadD
* Currently Running: None on Core 0 || ThreadP on Core 1
*
* System is rescheduled (ThreadC is popped off of queue):
* ready_queue[core=0][prio=0]: ThreadA, ThreadB, ThreadQ
* ready_queue[core=1][prio=0]: ThreadD
* Currently Running: ThreadC on Core 0 || ThreadP on Core 1
*
* If no suggested threads can be found this will behave just as normal yield. If there are
* multiple candidates for the suggested thread on a core, the highest prio is taken.
*/
void YieldWithLoadBalancing(Thread* thread);
/// Currently unknown -- asserts as unimplemented on call
void YieldAndWaitForLoadBalancing(Thread* thread);
/// Returns a list of all threads managed by the scheduler
const std::vector<SharedPtr<Thread>>& GetThreadList() const {
return thread_list;
}
private:
/**
* Pops and returns the next thread from the thread queue
* @return A pointer to the next ready thread
*/
Thread* PopNextReadyThread();
/**
* Switches the CPU's active thread context to that of the specified thread
* @param new_thread The thread to switch to
*/
void SwitchContext(Thread* new_thread);
/**
* Called on every context switch to update the internal timestamp
* This also updates the running time ticks for the given thread and
* process using the following difference:
*
* ticks += most_recent_ticks - last_context_switch_ticks
*
* The internal tick timestamp for the scheduler is simply the
* most recent tick count retrieved. No special arithmetic is
* applied to it.
*/
void UpdateLastContextSwitchTime(Thread* thread, Process* process);
/// Lists all thread ids that aren't deleted/etc.
std::vector<SharedPtr<Thread>> thread_list;
/// Lists only ready thread ids.
Common::MultiLevelQueue<Thread*, THREADPRIO_LOWEST + 1> ready_queue;
SharedPtr<Thread> current_thread = nullptr;
Core::ARM_Interface& cpu_core;
u64 last_context_switch_time = 0;
Core::System& system;
static std::mutex scheduler_mutex;
};
} // namespace Kernel
