signal bus with data

src/ecs.odin

@@ -1,19 +1,7 @@
 package shoal
 
-import "core:strings"
-import "core:thread"
-import ml "vendor:microui"
 import rl "vendor:raylib"
 
-update_pool: thread.Pool
-
-@(private)
-sparse_entity_limit: int
-
-get_entity_limit :: proc() -> int {
-	return sparse_entity_limit
-}
-
 App :: struct {
 	systems:  map[int][dynamic]proc(),
 	plugins:  [dynamic]proc(app: ^App),

src/signals.odin

@@ -1,25 +1,85 @@
 package shoal
 
+// per-type signal bus, created on first use.
+// one system writes a signal with data, any number of other systems read it
+// after. same-frame reads only work until signal_system clears the buses at
+// POST_UPDATE — see read/signal_system below for the details.
+Bus :: struct($T: typeid) {
+	pending: [dynamic]T,
+}
+
 @(private)
-signal_buffer_b: [dynamic]string
+Bus_Entry :: struct {
+	bus:   rawptr,
+	clear: proc(b: rawptr),
+}
+
 @(private)
-signal_buffer_a: [dynamic]string
+buses: map[typeid]Bus_Entry
 
-write :: proc(name: string) {
+@(private)
-	append(&signal_buffer_b, name)
+get_bus :: proc($T: typeid) -> ^Bus(T) {
+	if entry, exists := buses[T]; exists {
+		return (^Bus(T))(entry.bus)
+	}
+	bus := new(Bus(T))
+	buses[T] = {
+		bus   = bus,
+		clear = clear_bus(T),
+	}
+	return bus
 }
 
-read :: proc(name: string) -> bool {
+// called once per payload type, hands signal_system a rawptr clear for that bus
-	for s in signal_buffer_a {
+@(private)
-		if s == name {return true}
+clear_bus :: proc($T: typeid) -> proc(b: rawptr) {
+	return proc(b: rawptr) {
+			bus := (^Bus(T))(b)
+			clear(&bus.pending)
 		}
-	for s in signal_buffer_b {
-		if s == name {return true}
-	}
-	return false
 }
 
+// queue a signal, readable until signal_system clears it at POST_UPDATE.
+// note POST_UPDATE runs before PRE_DRAW/DRAW, so a reader sees exactly what's
+// been written since the last POST_UPDATE: UPDATE systems see same-frame
+// writes, but a DRAW system only sees writes made after this frame's
+// POST_UPDATE (by PRE_DRAW or earlier DRAW systems)
+// queue an empty payload by passing the bare type: write(MySignal)
+write :: proc {
+	write_empty,
+	write_with_data,
+}
+
+write_empty :: proc($T: typeid) {
+	bus := get_bus(T)
+	append(&bus.pending, T{})
+}
+
+write_with_data :: proc(data: $T) {
+	bus := get_bus(T)
+	append(&bus.pending, data)
+}
+
+// every signal of type T written since the last POST_UPDATE, non-consuming,
+// empty if none. iterate it: for s in read(MySignal)
+// copied into context.temp_allocator so write() during iteration can't
+// reallocate the pending buffer out from under you — but that means the result
+// dies with the frame's temp arena, don't hold onto it past that
+read :: proc($T: typeid) -> []T {
+	bus := get_bus(T)
+	if len(bus.pending) == 0 {return nil}
+	result := make([]T, len(bus.pending), context.temp_allocator)
+	copy(result, bus.pending[:])
+	return result
+}
+
+// runs at POST_UPDATE, clears every bus so the next frame starts fresh.
+// writes made after it (e.g. in DRAW) survive until the *next* frame's
+// POST_UPDATE, so the rest of this frame and the next frame's
+// PRE_UPDATE/UPDATE systems still read them — but the next frame's DRAW
+// never does, POST_UPDATE gets there first
 signal_system :: proc() {
-	signal_buffer_a = signal_buffer_b
+	for _, e in buses {
-	clear(&signal_buffer_b)
+		e.clear(e.bus)
+	}
 }

src/systems.odin

@@ -6,7 +6,7 @@ import rl "vendor:raylib"
 DefaultPlugin :: proc(app: ^App) {
 	add_system(app, STARTUP, startup_window)
 	add_system(app, DRAW, draw_sprite)
-	add_system(app, UPDATE, signal_system)
+	add_system(app, POST_UPDATE, signal_system)
 	add_system(app, UPDATE, run_timers)
 	add_system(app, UPDATE, update_cursor_position)
 	add_system(app, PRE_DRAW, proc() {rl.BeginDrawing()