Start pulling out IO thread and IO implementation

src/Window.zig

@@ -10,6 +10,7 @@ const builtin = @import("builtin");
 const assert = std.debug.assert;
 const Allocator = std.mem.Allocator;
 const renderer = @import("renderer.zig");
+const termio = @import("termio.zig");
 const objc = @import("objc");
 const glfw = @import("glfw");
 const imgui = @import("imgui");
@@ -76,6 +77,11 @@ command: Command,
 /// Mouse state.
 mouse: Mouse,
 
+/// The terminal IO handler.
+io: termio.Impl,
+io_thread: termio.Thread,
+io_thr: std.Thread,
+
 /// The terminal emulator internal state. This is the abstract "terminal"
 /// that manages input, grid updating, etc. and is renderer-agnostic. It
 /// just stores internal state about a grid. This is connected back to
@@ -445,6 +451,18 @@ pub fn create(alloc: Allocator, loop: libuv.Loop, config: *const Config) !*Windo
     var io_arena = std.heap.ArenaAllocator.init(alloc);
     errdefer io_arena.deinit();
 
+    // Start our IO implementation
+    var io = try termio.Impl.init(alloc, .{
+        .grid_size = grid_size,
+        .screen_size = screen_size,
+        .config = config,
+    });
+    errdefer io.deinit(alloc);
+
+    // Create the IO thread
+    var io_thread = try termio.Thread.init(alloc, &self.io);
+    errdefer io_thread.deinit();
+
     // The mutex used to protect our renderer state.
     var mutex = try alloc.create(std.Thread.Mutex);
     mutex.* = .{};
@@ -484,6 +502,9 @@ pub fn create(alloc: Allocator, loop: libuv.Loop, config: *const Config) !*Windo
         .pty = pty,
         .command = cmd,
         .mouse = .{},
+        .io = io,
+        .io_thread = io_thread,
+        .io_thr = undefined,
         .terminal = term,
         .terminal_stream = .{ .handler = self },
         .terminal_cursor = .{ .timer = timer },
@@ -524,11 +545,11 @@ pub fn create(alloc: Allocator, loop: libuv.Loop, config: *const Config) !*Windo
     // Load imgui. This must be done LAST because it has to be done after
     // all our GLFW setup is complete.
     if (DevMode.enabled) {
-        const io = try imgui.IO.get();
-        io.cval().IniFilename = "ghostty_dev_mode.ini";
+        const dev_io = try imgui.IO.get();
+        dev_io.cval().IniFilename = "ghostty_dev_mode.ini";
 
         // Add our built-in fonts so it looks slightly better
-        const dev_atlas = @ptrCast(*imgui.FontAtlas, io.cval().Fonts);
+        const dev_atlas = @ptrCast(*imgui.FontAtlas, dev_io.cval().Fonts);
         dev_atlas.addFontFromMemoryTTF(
             face_ttf,
             @intToFloat(f32, font_size.pixels()),
@@ -553,6 +574,13 @@ pub fn create(alloc: Allocator, loop: libuv.Loop, config: *const Config) !*Windo
         .{&self.renderer_thread},
     );
 
+    // Start our IO thread
+    self.io_thr = try std.Thread.spawn(
+        .{},
+        termio.Thread.threadMain,
+        .{&self.io_thread},
+    );
+
     return self;
 }
 
@@ -579,6 +607,17 @@ pub fn destroy(self: *Window) void {
         self.imgui_ctx.destroy();
     }
 
+    {
+        // Stop our IO thread
+        self.io_thread.stop.send() catch |err|
+            log.err("error notifying io thread to stop, may stall err={}", .{err});
+        self.io_thr.join();
+        self.io_thread.deinit();
+
+        // Deinitialize our terminal IO
+        self.io.deinit(self.alloc);
+    }
+
     // Deinitialize the pty. This closes the pty handles. This should
     // cause a close in the our subprocess so just wait for that.
     self.pty.deinit();

src/termio.zig

@@ -0,0 +1,17 @@
+//! IO implementation and utilities. The IO implementation is responsible
+//! for taking the config, spinning up a child process, and handling IO
+//! with the termianl.
+
+pub const Exec = @import("termio/Exec.zig");
+pub const Options = @import("termio/Options.zig");
+pub const Thread = @import("termio/Thread.zig");
+
+/// The implementation to use for the IO. This is just "exec" for now but
+/// this is somewhat pluggable so that in the future we can introduce other
+/// options for other platforms (i.e. wasm) or even potentially a vtable
+/// implementation for runtime polymorphism.
+pub const Impl = Exec;
+
+test {
+    @import("std").testing.refAllDecls(@This());
+}

src/termio/Exec.zig

@@ -0,0 +1,100 @@
+//! Implementation of IO that uses child exec to talk to the child process.
+pub const Exec = @This();
+
+const std = @import("std");
+const builtin = @import("builtin");
+const Allocator = std.mem.Allocator;
+const termio = @import("../termio.zig");
+const Command = @import("../Command.zig");
+const Pty = @import("../Pty.zig");
+const terminal = @import("../terminal/main.zig");
+const libuv = @import("libuv");
+
+const log = std.log.scoped(.io_exec);
+
+/// This is the pty fd created for the subcommand.
+pty: Pty,
+
+/// This is the container for the subcommand.
+command: Command,
+
+/// The terminal emulator internal state. This is the abstract "terminal"
+/// that manages input, grid updating, etc. and is renderer-agnostic. It
+/// just stores internal state about a grid.
+terminal: terminal.Terminal,
+
+/// Initialize the exec implementation. This will also start the child
+/// process.
+pub fn init(alloc: Allocator, opts: termio.Options) !Exec {
+    // Create our pty
+    var pty = try Pty.open(.{
+        .ws_row = @intCast(u16, opts.grid_size.rows),
+        .ws_col = @intCast(u16, opts.grid_size.columns),
+        .ws_xpixel = @intCast(u16, opts.screen_size.width),
+        .ws_ypixel = @intCast(u16, opts.screen_size.height),
+    });
+    errdefer pty.deinit();
+
+    // Determine the path to the binary we're executing
+    const path = (try Command.expandPath(alloc, opts.config.command orelse "sh")) orelse
+        return error.CommandNotFound;
+    defer alloc.free(path);
+
+    // Set our env vars
+    var env = try std.process.getEnvMap(alloc);
+    defer env.deinit();
+    try env.put("TERM", "xterm-256color");
+
+    // Build our subcommand
+    var cmd: Command = .{
+        .path = path,
+        .args = &[_][]const u8{path},
+        .env = &env,
+        .cwd = opts.config.@"working-directory",
+        .pre_exec = (struct {
+            fn callback(c: *Command) void {
+                const p = c.getData(Pty) orelse unreachable;
+                p.childPreExec() catch |err|
+                    log.err("error initializing child: {}", .{err});
+            }
+        }).callback,
+        .data = &pty,
+    };
+    // note: can't set these in the struct initializer because it
+    // sets the handle to "0". Probably a stage1 zig bug.
+    cmd.stdin = std.fs.File{ .handle = pty.slave };
+    cmd.stdout = cmd.stdin;
+    cmd.stderr = cmd.stdin;
+    try cmd.start(alloc);
+    log.info("started subcommand path={s} pid={?}", .{ path, cmd.pid });
+
+    // Create our terminal
+    var term = try terminal.Terminal.init(alloc, opts.grid_size.columns, opts.grid_size.rows);
+    errdefer term.deinit(alloc);
+
+    return Exec{
+        .pty = pty,
+        .command = cmd,
+        .terminal = term,
+    };
+}
+
+pub fn deinit(self: *Exec, alloc: Allocator) void {
+    // Deinitialize the pty. This closes the pty handles. This should
+    // cause a close in the our subprocess so just wait for that.
+    self.pty.deinit();
+    _ = self.command.wait() catch |err|
+        log.err("error waiting for command to exit: {}", .{err});
+
+    // Clean up the terminal state
+    self.terminal.deinit(alloc);
+}
+
+pub fn threadEnter(self: *Exec, loop: libuv.Loop) !void {
+    _ = self;
+    _ = loop;
+}
+
+pub fn threadExit(self: *Exec) void {
+    _ = self;
+}

src/termio/Options.zig

@@ -0,0 +1,13 @@
+//! The options that are used to configure a terminal IO implementation.
+
+const renderer = @import("../renderer.zig");
+const Config = @import("../config.zig").Config;
+
+/// The size of the terminal grid.
+grid_size: renderer.GridSize,
+
+/// The size of the viewport in pixels.
+screen_size: renderer.ScreenSize,
+
+/// The app configuration.
+config: *const Config,

src/termio/Thread.zig

@@ -0,0 +1,140 @@
+//! Represents the IO thread logic. The IO thread is responsible for
+//! the child process and pty management.
+pub const Thread = @This();
+
+const std = @import("std");
+const builtin = @import("builtin");
+const libuv = @import("libuv");
+const termio = @import("../termio.zig");
+
+const Allocator = std.mem.Allocator;
+const log = std.log.scoped(.io_thread);
+
+/// The main event loop for the thread. 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.
+loop: libuv.Loop,
+
+/// This can be used to wake up the thread.
+wakeup: libuv.Async,
+
+/// This can be used to stop the thread on the next loop iteration.
+stop: libuv.Async,
+
+/// The underlying IO implementation.
+impl: *termio.Impl,
+
+/// 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.
+pub fn init(
+    alloc: Allocator,
+    impl: *termio.Impl,
+) !Thread {
+    // We always store allocator pointer on the loop data so that
+    // handles can use our global allocator.
+    const allocPtr = try alloc.create(Allocator);
+    errdefer alloc.destroy(allocPtr);
+    allocPtr.* = alloc;
+
+    // Create our event loop.
+    var loop = try libuv.Loop.init(alloc);
+    errdefer loop.deinit(alloc);
+    loop.setData(allocPtr);
+
+    // This async handle is used to "wake up" the renderer and force a render.
+    var wakeup_h = try libuv.Async.init(alloc, loop, wakeupCallback);
+    errdefer wakeup_h.close((struct {
+        fn callback(h: *libuv.Async) void {
+            const loop_alloc = h.loop().getData(Allocator).?.*;
+            h.deinit(loop_alloc);
+        }
+    }).callback);
+
+    // This async handle is used to stop the loop and force the thread to end.
+    var stop_h = try libuv.Async.init(alloc, loop, stopCallback);
+    errdefer stop_h.close((struct {
+        fn callback(h: *libuv.Async) void {
+            const loop_alloc = h.loop().getData(Allocator).?.*;
+            h.deinit(loop_alloc);
+        }
+    }).callback);
+
+    return Thread{
+        .loop = loop,
+        .wakeup = wakeup_h,
+        .stop = stop_h,
+        .impl = impl,
+    };
+}
+
+/// Clean up the thread. This is only safe to call once the thread
+/// completes executing; the caller must join prior to this.
+pub fn deinit(self: *Thread) void {
+    // Get a copy to our allocator
+    const alloc_ptr = self.loop.getData(Allocator).?;
+    const alloc = alloc_ptr.*;
+
+    // Schedule our handles to close
+    self.stop.close((struct {
+        fn callback(h: *libuv.Async) void {
+            const handle_alloc = h.loop().getData(Allocator).?.*;
+            h.deinit(handle_alloc);
+        }
+    }).callback);
+    self.wakeup.close((struct {
+        fn callback(h: *libuv.Async) void {
+            const handle_alloc = h.loop().getData(Allocator).?.*;
+            h.deinit(handle_alloc);
+        }
+    }).callback);
+
+    // Run the loop one more time, because destroying our other things
+    // like windows usually cancel all our event loop stuff and we need
+    // one more run through to finalize all the closes.
+    _ = self.loop.run(.default) catch |err|
+        log.err("error finalizing event loop: {}", .{err});
+
+    // Dealloc our allocator copy
+    alloc.destroy(alloc_ptr);
+
+    self.loop.deinit(alloc);
+}
+
+/// The main entrypoint for the thread.
+pub fn threadMain(self: *Thread) void {
+    // Call child function so we can use errors...
+    self.threadMain_() catch |err| {
+        // In the future, we should expose this on the thread struct.
+        log.warn("error in io thread err={}", .{err});
+    };
+}
+
+fn threadMain_(self: *Thread) !void {
+    // Run our thread start/end callbacks. This allows the implementation
+    // to hook into the event loop as needed.
+    try self.impl.threadEnter(self.loop);
+    defer self.impl.threadExit();
+
+    // Set up our async handler to support rendering
+    self.wakeup.setData(self);
+    defer self.wakeup.setData(null);
+
+    // Run
+    log.debug("starting IO thread", .{});
+    defer log.debug("exiting IO thread", .{});
+    _ = try self.loop.run(.default);
+}
+
+fn wakeupCallback(h: *libuv.Async) void {
+    _ = h;
+    // const t = h.getData(Thread) orelse {
+    //     // This shouldn't happen so we log it.
+    //     log.warn("render callback fired without data set", .{});
+    //     return;
+    // };
+}
+
+fn stopCallback(h: *libuv.Async) void {
+    h.loop().stop();
+}