App prepare for multi-window

src/App.zig

@@ -9,46 +9,111 @@ const glfw = @import("glfw");
 const Window = @import("Window.zig");
 const tracy = @import("tracy");
 const Config = @import("config.zig").Config;
+const BlockingQueue = @import("./blocking_queue.zig").BlockingQueue;
 
 const log = std.log.scoped(.app);
 
+const WindowList = std.ArrayListUnmanaged(*Window);
+
+/// The type used for sending messages to the app thread.
+pub const Mailbox = BlockingQueue(Message, 64);
+
 /// General purpose allocator
 alloc: Allocator,
 
-/// The primary window for the application. We currently support only
-/// single window operations.
-window: *Window,
+/// The list of windows that are currently open
+windows: WindowList,
 
 // The configuration for the app.
 config: *const Config,
 
+/// 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 main app instance. This creates the main window, sets
 /// up the renderer state, compiles the shaders, etc. This is the primary
 /// "startup" logic.
 pub fn init(alloc: Allocator, config: *const Config) !App {
-    // Create the window
+    // The mailbox for messaging this thread
+    var mailbox = try Mailbox.create(alloc);
+    errdefer mailbox.destroy(alloc);
+
+    // Create the first window
     var window = try Window.create(alloc, config);
     errdefer window.destroy();
 
+    // Create our windows list and add our initial window.
+    var windows: WindowList = .{};
+    errdefer windows.deinit(alloc);
+    try windows.append(alloc, window);
+
     return App{
         .alloc = alloc,
-        .window = window,
+        .windows = windows,
         .config = config,
+        .mailbox = mailbox,
     };
 }
 
 pub fn deinit(self: *App) void {
-    self.window.destroy();
+    // Clean up all our windows
+    for (self.windows.items) |window| window.destroy();
+    self.windows.deinit(self.alloc);
+    self.mailbox.destroy(self.alloc);
     self.* = undefined;
 }
 
-pub fn run(self: App) !void {
-    while (!self.window.shouldClose()) {
-        // Block for any glfw events. This may also be an "empty" event
-        // posted by the libuv watcher so that we trigger a libuv loop tick.
+/// Wake up the app event loop. This should be called after any messages
+/// are sent to the mailbox.
+pub fn wakeup(self: App) void {
+    _ = self;
+    glfw.postEmptyEvent() catch {};
+}
+
+/// Run the main event loop for the application. This blocks until the
+/// application quits or every window is closed.
+pub fn run(self: *App) !void {
+    while (self.windows.items.len > 0) {
+        // Block for any glfw events.
         try glfw.waitEvents();
 
         // Mark this so we're in a totally different "frame"
         tracy.frameMark();
+
+        // If any windows are closing, destroy them
+        var i: usize = 0;
+        while (i < self.windows.items.len) {
+            const window = self.windows.items[i];
+            if (window.shouldClose()) {
+                window.destroy();
+                _ = self.windows.swapRemove(i);
+                continue;
+            }
+
+            i += 1;
+        }
+
+        // Drain our mailbox
+        try self.drainMailbox();
     }
 }
+
+/// Drain the mailbox.
+fn drainMailbox(self: *App) !void {
+    var drain = self.mailbox.drain();
+    defer drain.deinit();
+
+    while (drain.next()) |message| {
+        log.debug("mailbox message={}", .{message});
+        switch (message) {
+            .new_window => unreachable,
+        }
+    }
+}
+
+/// The message types that can be sent to the app thread.
+pub const Message = union(enum) {
+    /// Create a new terminal window.
+    new_window: void,
+};

src/Window.zig

@@ -136,6 +136,10 @@ pub fn create(alloc: Allocator, config: *const Config) !*Window {
     };
 
     // Find all the fonts for this window
+    //
+    // Future: we can share the font group amongst all windows to save
+    // some new window init time and some memory. This will require making
+    // thread-safe changes to font structs.
     var font_lib = try font.Library.init();
     errdefer font_lib.deinit();
     var font_group = try alloc.create(font.GroupCache);