Kernel/Threads: When putting a thread to wait, specify a function to execute when it is awoken.

This change makes for a clearer (less confusing) path of execution in the scheduler, now the code to execute when a thread awakes is closer to the code that puts the thread to sleep (WaitSynch1, WaitSynchN). It also allows us to implement the special wake up behavior of ReplyAndReceive without hacking up WaitObject::WakeupAllWaitingThreads.

If savestates are desired in the future, we can change this implementation to one similar to the CoreTiming event system, where we first register the callback functions at startup and assign their identifiers to the Thread callback variable instead of directly assigning a lambda to the wake up callback variable.

src/core/hle/kernel/thread.h

@@ -41,6 +41,11 @@ enum ThreadStatus {
     THREADSTATUS_DEAD            ///< Run to completion, or forcefully terminated
 };
 
+enum class ThreadWakeupReason {
+    Signal, // The thread was woken up by WakeupAllWaitingThreads due to an object signal.
+    Timeout // The thread was woken up due to a wait timeout.
+};
+
 namespace Kernel {
 
 class Mutex;
@@ -197,14 +202,18 @@ public:
 
     VAddr wait_address; ///< If waiting on an AddressArbiter, this is the arbitration address
 
-    /// True if the WaitSynchronizationN output parameter should be set on thread wakeup.
-    bool wait_set_output;
-
     std::string name;
 
     /// Handle used as userdata to reference this object when inserting into the CoreTiming queue.
     Handle callback_handle;
 
+    using WakeupCallback = void(ThreadWakeupReason reason, SharedPtr<Thread> thread,
+                                SharedPtr<WaitObject> object);
+    // Callback that will be invoked when the thread is resumed from a waiting state. If the thread
+    // was waiting via WaitSynchronizationN then the object will be the last object that became
+    // available. In case of a timeout, the object will be nullptr.
+    std::function<WakeupCallback> wakeup_callback;
+
 private:
     Thread();
     ~Thread() override;