# steady.ludic - render3d allocates nothing in its steady state: a buffer released and made again
# (what a streamed or grown buffer does every few frames) and a whole frame, drawn over and over,
# leave malloc's live bytes where they were. Prints STEADY OK. The heap is read on the Mac
# (Vk.heap_bytes) once the device is idle; elsewhere it reads 0 and the check passes on the run alone.
#
#   bin/ludic build examples/rendering/steady.ludic --headless && ./build/steady_headless
program Steady {
  numbers float
  import "ludic.render3d/r3d.ludic"

  property Marker { on: int = 1 }
  model Anchor { Marker }

  function scene_draw(render3d_st: mut Render3dState) -> void { actor_draw(render3d_st) }
  function scene_draw_casters(render3d_st: mut Render3dState, light_vp: floats) -> void { }
  # a chunk of 20 to 51 instances, different for every cell
  function stream_fill(render3d_st: mut Render3dState, s: Stream, cx: int, cz: int, band: int) -> void {
    let n = 20 + ((cx * 7 + cz * 13 + band) & 31)
    for i in 0 .. n { stream_emit(render3d_st, s, float(cx) * 32.0 + float(i), 0.0, float(cz) * 32.0, 1.0, 0.0, 0.5, 0.0) }
  }

  # The heap once the device is idle and MoltenVK's completion handlers, which release a finished
  # command buffer on their own thread, have caught up: two reads 20 ms apart that agree. Read at
  # once, a machine busy with other work showed ~80 KB of buffers still being handed back.
  function settled(render3d_st: Render3dState) -> long {
    Vk.device_wait_idle(render3d_st.gvk_dev)
    var last = Vk.heap_bytes()
    for k in 0 .. 100 {
      Time.sleep_us(20000)
      let now = Vk.heap_bytes()
      if now == last { return now }
      last = now
    }
    return last
  }

  # bytes gained by the heap over n rounds of the buffer path, after a warm-up of its own
  function buffer_rounds(render3d_st: mut Render3dState, b: int, n: int) -> long {
    let before = settled(render3d_st)
    for i in 0 .. n {
      gpu_buffer_upload(render3d_st, b, 4096 + (i % 16) * 4096, null, GPU_DYNAMIC)
      gpu_buffer_free(render3d_st, b)
    }
    return settled(render3d_st) - before
  }
  function frame_rounds(render3d_st: mut Render3dState, n: int) -> long {
    let before = settled(render3d_st)
    for i in 0 .. n {
      r3d_frame(render3d_st, float(i) / 60.0)
      r3d_present(render3d_st)
    }
    return settled(render3d_st) - before
  }

  # bytes gained over n loads and releases of one model: its parse, its meshes and its textures
  function model_rounds(render3d_st: mut Render3dState, n: int) -> long {
    let before = settled(render3d_st)
    for i in 0 .. n {
      let m = gltf_load(render3d_st, "packages/ludic.lab/plate", "plate.gltf", "plate")
      model_release(render3d_st, m)
    }
    return settled(render3d_st) - before
  }

  # bytes gained over n actors placed and released (actor_release): the records come round again
  function actor_rounds(render3d_st: mut Render3dState, m: Model, n: int) -> long {
    let before = settled(render3d_st)
    for i in 0 .. n {
      let a = actor_new(render3d_st, m)
      actor_place(a, float(i % 7), 0.0, 0.0, 0.0)
      actor_hide_part(a, "none", true)
      actor_release(render3d_st, a)
    }
    return settled(render3d_st) - before
  }

  # bytes gained while a frame draws more and more: 20 actors to 200, 30 frames at each count.
  # MoltenVK's command pooling kept every command a frame had recorded (~650 bytes a draw more).
  function ramp_rounds(render3d_st: mut Render3dState, m: Model) -> long {
    let acts = new []Actor
    for i in 0 .. 200 {
      let a = actor_new(render3d_st, m)
      a.cull = 0.0
      a.visible = false
      actor_place(a, float(i % 20) - 10.0, 0.0, -float(i / 20), 0.0)
      push(acts, a)
    }
    for i in 0 .. 20 { acts[i].visible = true }
    frame_rounds(render3d_st, 30)
    let before = settled(render3d_st)
    for k in 2 .. 11 {
      for i in 0 .. k * 20 { acts[i].visible = true }
      frame_rounds(render3d_st, 30)
    }
    let grew = settled(render3d_st) - before
    for i in 0 .. 200 { actor_release(render3d_st, acts[i]) }
    return grew
  }

  # bytes gained while the camera crosses new ground for 300 cells: a streamed layer's cache holds
  # at most 256 chunks, so it fills, evicts and compacts on the way. Each chunk once brought its
  # own record and copy, made as the ground was found.
  function stream_rounds(render3d_st: mut Render3dState, m: Model) -> long {
    render3d_st.STREAM_MAX_CHUNKS = 256
    let l = layer_new(render3d_st, m, 20000, false, 0.0, 0.0, 400.0)
    let st = stream_new(render3d_st, l, 32.0, 96.0, 32.0, 64.0, 80.0, 96.0)
    cam_set(render3d_st, 0.0, 3.0, 0.0, 0.0, -10.0)
    frame_rounds(render3d_st, 10)
    let before = settled(render3d_st)
    for step in 1 .. 301 {
      cam_set(render3d_st, float(step) * 32.0, 3.0, float(step % 7) * 32.0, 0.0, -10.0)
      frame_rounds(render3d_st, 2)
    }
    let grew = settled(render3d_st) - before
    # every chunk kept, after all that evicting and compacting, still holds its own cell's instances
    var wrong = 0
    for i in 0 .. st.n {
      let c = st.chunks[i]
      let cx = c.key / 4 / 8192 - 4096
      if c.count < 20 or float_from_bits(st.arena[c.off]) != float(cx) * 32.0 { wrong += 1 }
    }
    if wrong > 0 or st.n == 0 or l.count == 0 {
      print(`steady: FAILED - {wrong} of {st.n} kept chunks hold another cell's instances ({l.count} drawn)`)
      return 1000000
    }
    return grew
  }

  # bytes gained over n parses of a glTF document, each freed whole (Json.free_all): strings too
  function parse_rounds(render3d_st: Render3dState, text: string, n: int) -> long {
    let before = settled(render3d_st)
    for i in 0 .. n {
      let doc = Json.parse(text)
      Json.free_all(doc)
    }
    return settled(render3d_st) - before
  }

  handler Boot(render3d_st: mut Render3dState) phase Start {
    spawn Anchor {}
    r3d_on_draw(render3d_st, fn scene_draw)
    r3d_on_casters(render3d_st, fn scene_draw_casters)
    r3d_on_stream_fill(render3d_st, fn stream_fill)
    r3d_plate_mode(render3d_st, true)
    render3d_st.r3d_sky_path = "packages/ludic.lab/plate/sky.hdr"
    if not r3d_init(render3d_st, 320, 180, "Steady") {
      quit()
      return
    }
    let b = gpu_buffer_new(render3d_st)
    buffer_rounds(render3d_st, b, 500)
    let grew_b = buffer_rounds(render3d_st, b, 5000)
    frame_rounds(render3d_st, 120)
    # the least of three windows: a leak grows in every one, while a busy GPU's lag (a valley
    # self-test beside it once read 87 KB) does not repeat three times
    var grew_f = frame_rounds(render3d_st, 600)
    for w in 0 .. 2 {
      let g = frame_rounds(render3d_st, 600)
      if g < grew_f { grew_f = g }
    }
    model_rounds(render3d_st, 20)
    let grew_m = model_rounds(render3d_st, 200)
    let am = gltf_load(render3d_st, "packages/ludic.lab/plate", "plate.gltf", "plate")
    actor_rounds(render3d_st, am, 20)
    let grew_a = actor_rounds(render3d_st, am, 2000)
    let grew_r = ramp_rounds(render3d_st, am)
    let grew_s = stream_rounds(render3d_st, am)
    let text = Fs.read_text("packages/ludic.lab/plate/plate.gltf")
    parse_rounds(render3d_st, text, 20)
    let grew_p = parse_rounds(render3d_st, text, 200)
    print(`steady: the buffer path gained {grew_b} bytes over 5000 rounds, the frame {grew_f} over 600, a glTF parsed and freed {grew_p} over 200, a model loaded and let go {grew_m} over 200, an actor placed and released {grew_a} over 2000, a frame drawing 20 to 200 actors {grew_r}, a stream over 300 new cells {grew_s}`)
    # a few KB of slack for what the system's own libraries keep (Metal's caches, the allocator)
    var ok = grew_b < 16384
    if not ok { print("steady: FAILED - releasing and making a buffer again leaves memory behind") }
    if grew_f >= 4096 {
      ok = false
      print("steady: FAILED - a frame leaves memory behind")
    }
    if grew_p >= 16384 {
      ok = false
      print("steady: FAILED - a parsed document freed whole leaves memory behind")
    }
    # a load and a release leave nothing: 0 over 200 (a document's strings were ~640 KB a model, a
    # texture's create infos and its .dds path ~700 bytes a round)
    if grew_m >= 4096 {
      ok = false
      print("steady: FAILED - a model loaded and let go leaves memory behind")
    }
    if grew_a >= 4096 {
      ok = false
      print("steady: FAILED - an actor placed and released leaves memory behind")
    }
    if grew_r >= 16384 {
      ok = false
      print("steady: FAILED - a frame drawing more than before leaves memory behind")
    }
    if grew_s >= 4096 {
      ok = false
      print("steady: FAILED - streaming new ground leaves memory behind")
    }
    if ok { print("STEADY OK") } else { print("STEADY FAILED") }
    quit()
  }

  handler Present(render3d_st: mut Render3dState) phase Render {
    r3d_present(render3d_st)
  }
}