renderer mailbox, focus message

src/Window.zig

@@ -394,7 +394,6 @@ pub fn create(alloc: Allocator, loop: libuv.Loop, config: *const Config) !*Windo
         .renderer_thread = render_thread,
         .renderer_state = .{
             .mutex = mutex,
-            .focused = true,
             .resize_screen = screen_size,
             .cursor = .{
                 .style = .blinking_block,
@@ -917,6 +916,11 @@ fn focusCallback(window: glfw.Window, focused: bool) void {
 
     const win = window.getUserPointer(Window) orelse return;
 
+    // Notify our render thread of the new state
+    _ = win.renderer_thread.mailbox.push(.{
+        .focus = focused,
+    }, .{ .forever = {} });
+
     // We have to schedule a render because no matter what we're changing
     // the cursor. If we're focused its reappearing, if we're not then
     // its changing to hollow and not blinking.
@@ -926,11 +930,6 @@ fn focusCallback(window: glfw.Window, focused: bool) void {
         win.terminal_cursor.startTimer() catch unreachable
     else
         win.terminal_cursor.stopTimer() catch unreachable;
-
-    // We are modifying renderer state from here on out
-    win.renderer_state.mutex.lock();
-    defer win.renderer_state.mutex.unlock();
-    win.renderer_state.focused = focused;
 }
 
 fn refreshCallback(window: glfw.Window) void {

src/renderer.zig

@@ -10,6 +10,7 @@
 const builtin = @import("builtin");
 
 pub usingnamespace @import("renderer/cursor.zig");
+pub usingnamespace @import("renderer/message.zig");
 pub usingnamespace @import("renderer/size.zig");
 pub const Metal = @import("renderer/Metal.zig");
 pub const OpenGL = @import("renderer/OpenGL.zig");

src/renderer/Metal.zig

@@ -33,6 +33,9 @@ alloc: std.mem.Allocator,
 /// Current cell dimensions for this grid.
 cell_size: renderer.CellSize,
 
+/// True if the window is focused
+focused: bool,
+
 /// Whether the cursor is visible or not. This is used to control cursor
 /// blinking.
 cursor_visible: bool,
@@ -205,6 +208,7 @@ pub fn init(alloc: Allocator, font_group: *font.GroupCache) !Metal {
         .cell_size = .{ .width = metrics.cell_width, .height = metrics.cell_height },
         .background = .{ .r = 0, .g = 0, .b = 0 },
         .foreground = .{ .r = 255, .g = 255, .b = 255 },
+        .focused = true,
         .cursor_visible = true,
         .cursor_style = .box,
 
@@ -290,6 +294,11 @@ pub fn threadExit(self: *const Metal) void {
     // Metal requires no per-thread state.
 }
 
+/// Callback when the focus changes for the terminal this is rendering.
+pub fn setFocus(self: *Metal, focus: bool) !void {
+    self.focused = focus;
+}
+
 /// The primary render callback that is completely thread-safe.
 pub fn render(
     self: *Metal,
@@ -315,7 +324,7 @@ pub fn render(
         defer state.resize_screen = null;
 
         // Setup our cursor state
-        if (state.focused) {
+        if (self.focused) {
             self.cursor_visible = state.cursor.visible and !state.cursor.blink;
             self.cursor_style = renderer.CursorStyle.fromTerminal(state.cursor.style) orelse .box;
         } else {

src/renderer/OpenGL.zig

@@ -74,6 +74,9 @@ foreground: terminal.color.RGB,
 /// Default background color
 background: terminal.color.RGB,
 
+/// True if the window is focused
+focused: bool,
+
 /// The raw structure that maps directly to the buffer sent to the vertex shader.
 /// This must be "extern" so that the field order is not reordered by the
 /// Zig compiler.
@@ -292,6 +295,7 @@ pub fn init(alloc: Allocator, font_group: *font.GroupCache) !OpenGL {
         .cursor_style = .box,
         .background = .{ .r = 0, .g = 0, .b = 0 },
         .foreground = .{ .r = 255, .g = 255, .b = 255 },
+        .focused = true,
     };
 }
 
@@ -432,6 +436,11 @@ pub fn threadExit(self: *const OpenGL) void {
     glfw.makeContextCurrent(null) catch {};
 }
 
+/// Callback when the focus changes for the terminal this is rendering.
+pub fn setFocus(self: *OpenGL, focus: bool) !void {
+    self.focused = focus;
+}
+
 /// The primary render callback that is completely thread-safe.
 pub fn render(
     self: *OpenGL,
@@ -455,7 +464,7 @@ pub fn render(
         defer state.resize_screen = null;
 
         // Setup our cursor state
-        if (state.focused) {
+        if (self.focused) {
             self.cursor_visible = state.cursor.visible and !state.cursor.blink;
             self.cursor_style = renderer.CursorStyle.fromTerminal(state.cursor.style) orelse .box;
         } else {

src/renderer/State.zig

@@ -12,9 +12,6 @@ const renderer = @import("../renderer.zig");
 /// state (i.e. the terminal, devmode, etc. values).
 mutex: *std.Thread.Mutex,
 
-/// True if the window is focused
-focused: bool,
-
 /// A new screen size if the screen was resized.
 resize_screen: ?renderer.ScreenSize,
 

src/renderer/Thread.zig

@@ -7,11 +7,16 @@ const builtin = @import("builtin");
 const glfw = @import("glfw");
 const libuv = @import("libuv");
 const renderer = @import("../renderer.zig");
-const gl = @import("../opengl.zig");
+const BlockingQueue = @import("../blocking_queue.zig").BlockingQueue;
 
 const Allocator = std.mem.Allocator;
 const log = std.log.scoped(.renderer_thread);
 
+/// The type used for sending messages to the IO thread. For now this is
+/// hardcoded with a capacity. We can make this a comptime parameter in
+/// the future if we want it configurable.
+const Mailbox = BlockingQueue(renderer.Message, 64);
+
 /// The main event loop for the application. The user data of this loop
 /// is always the allocator used to create the loop. This is a convenience
 /// so that users of the loop always have an allocator.
@@ -36,6 +41,10 @@ renderer: *renderer.Renderer,
 /// Pointer to the shared state that is used to generate the final render.
 state: *renderer.State,
 
+/// The mailbox that can be used to send this thread messages. Note
+/// this is a blocking queue so if it is full you will get errors (or block).
+mailbox: *Mailbox,
+
 /// Initialize the thread. This does not START the thread. This only sets
 /// up all the internal state necessary prior to starting the thread. It
 /// is up to the caller to start the thread with the threadMain entrypoint.
@@ -83,6 +92,10 @@ pub fn init(
         }
     }).callback);
 
+    // The mailbox for messaging this thread
+    var mailbox = try Mailbox.create(alloc);
+    errdefer mailbox.destroy(alloc);
+
     return Thread{
         .loop = loop,
         .wakeup = wakeup_h,
@@ -91,6 +104,7 @@ pub fn init(
         .window = window,
         .renderer = renderer_impl,
         .state = state,
+        .mailbox = mailbox,
     };
 }
 
@@ -127,6 +141,9 @@ pub fn deinit(self: *Thread) void {
     _ = self.loop.run(.default) catch |err|
         log.err("error finalizing event loop: {}", .{err});
 
+    // Nothing can possibly access the mailbox anymore, destroy it.
+    self.mailbox.destroy(alloc);
+
     // Dealloc our allocator copy
     alloc.destroy(alloc_ptr);
 
@@ -164,6 +181,23 @@ fn threadMain_(self: *Thread) !void {
     _ = try self.loop.run(.default);
 }
 
+/// Drain the mailbox.
+fn drainMailbox(self: *Thread) !void {
+    // This holds the mailbox lock for the duration of the drain. The
+    // expectation is that all our message handlers will be non-blocking
+    // ENOUGH to not mess up throughput on producers.
+
+    var drain = self.mailbox.drain();
+    defer drain.deinit();
+
+    while (drain.next()) |message| {
+        log.debug("mailbox message={}", .{message});
+        switch (message) {
+            .focus => |v| try self.renderer.setFocus(v),
+        }
+    }
+}
+
 fn wakeupCallback(h: *libuv.Async) void {
     const t = h.getData(Thread) orelse {
         // This shouldn't happen so we log it.
@@ -171,6 +205,11 @@ fn wakeupCallback(h: *libuv.Async) void {
         return;
     };
 
+    // When we wake up, we check the mailbox. Mailbox producers should
+    // wake up our thread after publishing.
+    t.drainMailbox() catch |err|
+        log.err("error draining mailbox err={}", .{err});
+
     // If the timer is already active then we don't have to do anything.
     const active = t.render_h.isActive() catch true;
     if (active) return;

src/renderer/message.zig

@@ -0,0 +1,11 @@
+const std = @import("std");
+const assert = std.debug.assert;
+const Allocator = std.mem.Allocator;
+
+/// The messages that can be sent to a renderer thread.
+pub const Message = union(enum) {
+    /// A change in state in the window focus that this renderer is
+    /// rendering within. This is only sent when a change is detected so
+    /// the renderer is expected to handle all of these.
+    focus: bool,
+};