66ece494

renderer: reorder resetFences after acquire, add errdefer re-signal

a73x 2026-04-18 12:35

Commit message

renderer: reorder resetFences after acquire, add errdefer re-signal

Preparatory refactor for bounded acquire timeouts. When acquireNextImageKHR
gains a finite timeout (next commit), the existing ordering (reset → acquire)
would leave in_flight_fence unsignaled with no submit pending on a timeout,
deadlocking future waits. Reorder to (acquire → reset) and add a private
resignalFence helper that the errdefer path uses to cover the tiny
post-reset / pre-submit failure window.

Part of issue ab6c92f0.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/renderer.zig

Old		New
@@ -1267,15 +1267,31 @@ pub const Context = struct {
1267	self.instance_capacity = new_capacity;	1267	self.instance_capacity = new_capacity;
1268	}	1268	}
1269		1269
		1270	/// Submit an empty command batch that signals `fence`. Used as an
		1271	/// errdefer recovery path when acquire has succeeded, resetFences has
		1272	/// run, but we failed before queueSubmit — we need to put the fence
		1273	/// back in the signaled state so the next frame's wait succeeds.
		1274	fn resignalFence(self: *Context, fence: vk.Fence) void {
		1275	const submit_info = vk.SubmitInfo{};
		1276	_ = self.vkd.queueSubmit(
		1277	self.graphics_queue,
		1278	1,
		1279	@ptrCast(&submit_info),
		1280	fence,
		1281	) catch \|err\| {
		1282	std.log.warn("resignalFence: {s}", .{@errorName(err)});
		1283	};
		1284	}
		1285
1270	/// Record a command buffer that begins the render pass with the given clear color and presents.	1286	/// Record a command buffer that begins the render pass with the given clear color and presents.
1271	/// Does not bind the pipeline or draw — just clear + present.	1287	/// Does not bind the pipeline or draw — just clear + present.
1272	/// Blocks until the previous frame's fence signals.	1288	/// Blocks until the previous frame's fence signals.
1273	pub fn drawClear(self: *Context, clear_color: [4]f32) !void {	1289	pub fn drawClear(self: *Context, clear_color: [4]f32) !void {
1274	// Wait for previous frame to finish	1290	// Wait for previous frame to finish
1275	_ = try self.vkd.waitForFences(self.device, 1, @ptrCast(&self.in_flight_fence), .true, std.math.maxInt(u64));	1291	_ = try self.vkd.waitForFences(self.device, 1, @ptrCast(&self.in_flight_fence), .true, std.math.maxInt(u64));
1276	try self.vkd.resetFences(self.device, 1, @ptrCast(&self.in_flight_fence));
1277		1292
1278	// Acquire next image	1293	// Acquire next image BEFORE reset, so an acquire failure leaves the
		1294	// fence in a safe state (signaled from the prior frame).
1279	const acquire = self.vkd.acquireNextImageKHR(	1295	const acquire = self.vkd.acquireNextImageKHR(
1280	self.device,	1296	self.device,
1281	self.swapchain,	1297	self.swapchain,
@@ -1289,6 +1305,9 @@ pub const Context = struct {
1289	if (swapchainNeedsRebuild(acquire.result)) return error.OutOfDateKHR;	1305	if (swapchainNeedsRebuild(acquire.result)) return error.OutOfDateKHR;
1290	const image_index = acquire.image_index;	1306	const image_index = acquire.image_index;
1291		1307
		1308	try self.vkd.resetFences(self.device, 1, @ptrCast(&self.in_flight_fence));
		1309	errdefer self.resignalFence(self.in_flight_fence);
		1310
1292	// Record command buffer	1311	// Record command buffer
1293	try self.vkd.resetCommandBuffer(self.command_buffer, .{});	1312	try self.vkd.resetCommandBuffer(self.command_buffer, .{});
1294	try self.vkd.beginCommandBuffer(self.command_buffer, &vk.CommandBufferBeginInfo{	1313	try self.vkd.beginCommandBuffer(self.command_buffer, &vk.CommandBufferBeginInfo{
@@ -1708,13 +1727,13 @@ pub const Context = struct {
1708		1727
1709	// Wait for previous frame to finish	1728	// Wait for previous frame to finish
1710	_ = try self.vkd.waitForFences(self.device, 1, @ptrCast(&self.in_flight_fence), .true, std.math.maxInt(u64));	1729	_ = try self.vkd.waitForFences(self.device, 1, @ptrCast(&self.in_flight_fence), .true, std.math.maxInt(u64));
1711	try self.vkd.resetFences(self.device, 1, @ptrCast(&self.in_flight_fence));
1712	if (timing_out) \|t\| {	1730	if (timing_out) \|t\| {
1713	t.wait_fences_us = readTimer(&timer);	1731	t.wait_fences_us = readTimer(&timer);
1714	timer.reset();	1732	timer.reset();
1715	}	1733	}
1716		1734
1717	// Acquire next image	1735	// Acquire next image BEFORE reset, so an acquire failure leaves the
		1736	// fence in a safe state (signaled from the prior frame).
1718	const acquire = self.vkd.acquireNextImageKHR(	1737	const acquire = self.vkd.acquireNextImageKHR(
1719	self.device,	1738	self.device,
1720	self.swapchain,	1739	self.swapchain,
@@ -1732,6 +1751,9 @@ pub const Context = struct {
1732	timer.reset();	1751	timer.reset();
1733	}	1752	}
1734		1753
		1754	try self.vkd.resetFences(self.device, 1, @ptrCast(&self.in_flight_fence));
		1755	errdefer self.resignalFence(self.in_flight_fence);
		1756
1735	// Record command buffer	1757	// Record command buffer
1736	try self.vkd.resetCommandBuffer(self.command_buffer, .{});	1758	try self.vkd.resetCommandBuffer(self.command_buffer, .{});
1737	try self.vkd.beginCommandBuffer(self.command_buffer, &vk.CommandBufferBeginInfo{	1759	try self.vkd.beginCommandBuffer(self.command_buffer, &vk.CommandBufferBeginInfo{