shortest subtask time to finish for scheduler

main.odin

@@ -1,6 +1,7 @@
 package rune
 
 import "core:fmt"
+import "core:time"
 
 test_task :: proc(subtask: int, user_data: rawptr) {
 	fmt.printfln("test task %v", subtask)
@@ -13,9 +14,13 @@ test_finished :: proc(user_data: rawptr) {
 main :: proc() {
 	init_scheduler(100, 1000)
 	add_worker({.General, .Streaming, .Physics, .Rendering})
-	add_worker({.General, .Streaming, .Physics, .Rendering})
-	add_worker({.General, .Streaming, .Physics, .Rendering})
-	add_worker({.General, .Streaming, .Physics, .Rendering})
+	//add_worker({.General, .Streaming, .Physics, .Rendering})
+	//add_worker({.General, .Streaming, .Physics, .Rendering})
+	//add_worker({.General, .Streaming, .Physics, .Rendering})
+
+	queue_task(test_task, test_finished, nil, 10)
+
+	time.sleep(1 * time.Second)
 
 	queue_task(test_task, test_finished, nil, 10)
 

task.odin

@@ -1,9 +1,12 @@
 package rune
 
 import "core:container/queue"
+import "core:hash"
 import "core:mem"
+import "core:slice"
 import "core:sync"
 import "core:thread"
+import "core:time"
 
 Task_Error :: enum {
 	None,
@@ -56,27 +59,32 @@ Worker :: struct {
 @(private = "file")
 Scheduler :: struct {
 	// Order of subtasks to execute. Highest priority is at index 0
-	schedule_storage:   []int,
-	schedule:           queue.Queue(int),
+	schedule_storage:    []int,
+	schedule:            queue.Queue(int),
 
 	// List of tasks. We don't move these to avoid expensive
 	// copies when the schedule changes.
-	tasks:              []Task,
-	subtasks:           []Sub_Task,
-	first_free_task:    int,
-	first_free_subtask: int,
-	free_subtasks:      int,
+	tasks:               []Task,
+	subtasks:            []Sub_Task,
+	first_free_task:     int,
+	first_free_subtask:  int,
+	free_subtasks:       int,
 
 	// Used when adding or removing tasks from the list,
 	// otherwise tasks are read-only (except for the remaining subtask counter, which is atomic)
-	task_list_mutex:    sync.Mutex,
-	subtask_list_mutex: sync.Mutex,
-	schedule_mutex:     sync.Mutex,
+	task_list_mutex:     sync.Mutex,
+	subtask_list_mutex:  sync.Mutex,
+	schedule_mutex:      sync.Mutex,
+	subtask_times_mutex: sync.Mutex,
+
+	// Keeps track of how long subtasks (hash of function + subtask idx) ran in the past.
+	// We keep the last runtime and use it when scheduling subtasks.
+	subtask_times:       map[u64]f64,
 
 	// List of workers. We allow the user to dynamically add or remove workers.
-	workers:            [dynamic]^Worker,
-	workers_mutex:      sync.Mutex,
-	allocator:          mem.Allocator,
+	workers:             [dynamic]^Worker,
+	workers_mutex:       sync.Mutex,
+	allocator:           mem.Allocator,
 }
 
 @(private = "file")
@@ -100,10 +108,24 @@ init_scheduler :: proc(
 		_scheduler.subtasks[i].next_free = i + 1
 	}
 	_scheduler.free_subtasks = max_subtasks_per_task * max_tasks
+	_scheduler.subtask_times = make(map[u64]f64, allocator)
 	_scheduler.workers = make([dynamic]^Worker, allocator)
 	_scheduler.allocator = allocator
 }
 
+shutdown_scheduler :: proc() {
+	for &worker in _scheduler.workers {
+		worker.run = false
+		thread.destroy(worker.thread)
+		free(worker, _scheduler.allocator)
+	}
+	delete(_scheduler.workers)
+	delete(_scheduler.subtask_times)
+	delete(_scheduler.schedule_storage, _scheduler.allocator)
+	delete(_scheduler.tasks, _scheduler.allocator)
+	delete(_scheduler.subtasks, _scheduler.allocator)
+}
+
 add_worker :: proc(task_types: bit_set[Task_Type]) -> (int, Task_Error) {
 	sync.lock(&_scheduler.workers_mutex)
 	defer sync.unlock(&_scheduler.workers_mutex)
@@ -139,6 +161,17 @@ remove_worker :: proc(idx: int) {
 	unordered_remove(&_scheduler.workers, idx)
 }
 
+
+Subtask_Timing :: struct {
+	slot: int,
+	time: f64,
+}
+
+@(private = "file")
+sort_subtask_timings :: proc(lhs: Subtask_Timing, rhs: Subtask_Timing) -> bool {
+	return lhs.time < rhs.time
+}
+
 queue_task :: proc(
 	entry: Task_Proc,
 	finished: Task_Finished_Proc,
@@ -177,6 +210,10 @@ queue_task :: proc(
 		return .Too_Many_Tasks
 	}
 	_scheduler.free_subtasks -= subtask_count
+
+	subtask_timings := make([]Subtask_Timing, subtask_count)
+	task_hash := u64(uintptr(&task.entry))
+
 	for i := 0; i < subtask_count; i += 1 {
 		subtask_slot := _scheduler.first_free_subtask
 		assert(subtask_slot < len(_scheduler.subtasks))
@@ -186,13 +223,36 @@ queue_task :: proc(
 		subtask.task = slot
 		subtask.idx = i
 
+
+		subtask_id: [1]int = {i}
+		subtask_hash := hash.fnv64a(slice.to_bytes(subtask_id[:]))
+		final_hash := task_hash ~ subtask_hash
+
+		subtask_timings[i].slot = i
+		if final_hash in _scheduler.subtask_times {
+			sync.lock(&_scheduler.subtask_times_mutex)
+			subtask_timings[i].time = _scheduler.subtask_times[final_hash]
+			sync.unlock(&_scheduler.subtask_times_mutex)
+		} else {
+			subtask_timings[i].time = 0.0
+		}
+
+		/*
 		sync.lock(&_scheduler.schedule_mutex)
 		// Add to schedule. This is FIFO. We could be more clever (for example use shortest time to finish)
 		queue.push_back(&_scheduler.schedule, subtask_slot)
 		sync.unlock(&_scheduler.schedule_mutex)
+		*/
 	}
 	sync.unlock(&_scheduler.subtask_list_mutex)
 
+	slice.sort_by(subtask_timings, sort_subtask_timings)
+
+	sync.lock(&_scheduler.schedule_mutex)
+	for i := 0; i < subtask_count; i += 1 {
+		queue.push_back(&_scheduler.schedule, subtask_timings[i].slot)
+	}
+	sync.unlock(&_scheduler.schedule_mutex)
 
 	return .None
 }
@@ -219,7 +279,20 @@ worker_proc :: proc(t: ^thread.Thread) {
 		task := &_scheduler.tasks[taskidx]
 
 		if task.type in task_types {
+			start := time.tick_now()
 			task.entry(subtask.idx, task.user_data)
+			end := time.tick_now()
+			duration := time.tick_diff(start, end)
+
+			// Compute a hash that identifies this subtask.
+			// We just treat the (64bit) entry address as a hash
+			task_hash := u64(uintptr(&task.entry))
+			subtask_id: [1]int = {subtask.idx}
+			subtask_hash := hash.fnv64a(slice.to_bytes(subtask_id[:]))
+			final_hash := task_hash ~ subtask_hash
+			sync.lock(&_scheduler.subtask_times_mutex)
+			_scheduler.subtask_times[final_hash] = time.duration_microseconds(duration)
+			sync.unlock(&_scheduler.subtask_times_mutex)
 
 			sync.lock(&_scheduler.subtask_list_mutex)
 			subtask.next_free = _scheduler.first_free_subtask