rnd(M03): extract render budget scheduler

src/render/streaming/render_budget_scheduler.gd

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+## Issues bounded, per-frame permits for renderer main-thread operation lanes.
+##
+## The scheduler owns counters only. Queue contents, operation ordering and the
+## side effects performed after a permit remain owned by the caller. One instance
+## belongs to one renderer lifecycle and must only be used on the main thread.
+class_name RenderBudgetScheduler
+extends RefCounted
+
+const TILE_FINALIZE: StringName = &"tile_finalize"
+const TERRAIN_UPGRADE_FINALIZE: StringName = &"terrain_upgrade_finalize"
+const TERRAIN_CONTROL_SPLAT_FINALIZE: StringName = &"terrain_control_splat_finalize"
+const TERRAIN_SPLAT_CACHE_FINALIZE: StringName = &"terrain_splat_cache_finalize"
+const TERRAIN_SPLAT_BUILD: StringName = &"terrain_splat_build"
+const WATER_FINALIZE: StringName = &"water_finalize"
+const CHUNK_GEOMETRY: StringName = &"chunk_geometry"
+const TILE_LOAD_START: StringName = &"tile_load_start"
+const TILE_LOD_CREATE: StringName = &"tile_lod_create"
+const TILE_LOD_REMOVE: StringName = &"tile_lod_remove"
+const M2_ANIMATION_FINALIZE: StringName = &"m2_animation_finalize"
+const M2_MESH_FINALIZE: StringName = &"m2_mesh_finalize"
+const M2_BUILD: StringName = &"m2_build"
+const WMO_BUILD: StringName = &"wmo_build"
+const WMO_RENDER_GROUP_BUILD: StringName = &"wmo_render_group_build"
+const DETAIL_ASSET_SYNC: StringName = &"detail_asset_sync"
+
+var _remaining_permits_by_lane: Dictionary = {}
+var _consumed_permits_by_lane: Dictionary = {}
+var _is_cancelled := false
+
+
+## Replaces all lane limits for a new frame. Negative limits are treated as zero.
+## Calling this after [method cancel] leaves the scheduler cancelled.
+func begin_frame(operation_limits_by_lane: Dictionary) -> void:
+	_remaining_permits_by_lane.clear()
+	_consumed_permits_by_lane.clear()
+	if _is_cancelled:
+		return
+
+	for lane_variant in operation_limits_by_lane:
+		var lane := StringName(lane_variant)
+		_remaining_permits_by_lane[lane] = maxi(0, int(operation_limits_by_lane[lane_variant]))
+		_consumed_permits_by_lane[lane] = 0
+
+
+## Returns whether a lane can issue another permit without consuming it.
+## Unknown lanes and cancelled schedulers return false.
+func has_remaining_permit(lane: StringName) -> bool:
+	if _is_cancelled:
+		return false
+	return int(_remaining_permits_by_lane.get(lane, 0)) > 0
+
+
+## Consumes one permit from [param lane] and returns true when it was granted.
+## Unknown, exhausted or cancelled lanes return false without changing state.
+func try_consume_permit(lane: StringName) -> bool:
+	if not has_remaining_permit(lane):
+		return false
+	_remaining_permits_by_lane[lane] = int(_remaining_permits_by_lane[lane]) - 1
+	_consumed_permits_by_lane[lane] = int(_consumed_permits_by_lane.get(lane, 0)) + 1
+	return true
+
+
+## Returns the unconsumed permit count for one lane.
+func remaining_permits(lane: StringName) -> int:
+	if _is_cancelled:
+		return 0
+	return int(_remaining_permits_by_lane.get(lane, 0))
+
+
+## Returns a detached diagnostic snapshot of permits consumed in this frame.
+func consumed_permits_snapshot() -> Dictionary:
+	return _consumed_permits_by_lane.duplicate()
+
+
+## Permanently rejects new permits for this scheduler instance and clears limits.
+## In-flight work remains the caller's responsibility and is not interrupted.
+func cancel() -> void:
+	_is_cancelled = true
+	_remaining_permits_by_lane.clear()
+
+
+## Returns whether [method cancel] ended this scheduler lifecycle.
+func is_cancelled() -> bool:
+	return _is_cancelled

src/render/streaming/render_budget_scheduler.gd.uid

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+uid://byaii7lec82i6