feat(benchmark): add benchmark build (with build option) to test frame rate

src/main.zig

@@ -1,3 +1,4 @@
+const build_options = @import("build_options");
 const std = @import("std");
 const terminal = @import("terminal.zig");
 const zlog = @import("zlog");
@@ -38,6 +39,14 @@ pub fn main() !void {
     try app.start();
     defer app.stop() catch unreachable;
 
+    // Benchmarking
+    var instants: std.ArrayList(u64) = undefined;
+    var benchmark_thread: std.Thread = undefined;
+    if (comptime build_options.benchmark) {
+        instants = try std.ArrayList(u64).initCapacity(allocator, 512);
+        benchmark_thread = try std.Thread.spawn(.{}, benchmark, .{&app});
+    }
+
     // App.Event loop
     while (true) {
         const event = app.nextEvent();
@@ -68,15 +77,44 @@ pub fn main() !void {
             },
             else => {},
         }
+
+        var start_instant: std.time.Instant = undefined;
+        if (comptime build_options.benchmark) {
+            start_instant = try std.time.Instant.now();
+        }
+
         // NOTE: this currently re-renders the screen for every key-press -> which might be a bit of an overkill
         const events = try layout.handle(event);
         for (events.items) |e| {
             app.postEvent(e);
         }
         try renderer.render(try layout.content());
+
+        if (comptime build_options.benchmark) {
+            const end_instant = try std.time.Instant.now();
+            try instants.append(end_instant.since(start_instant));
+        }
     }
-    // TODO: I could use the ascii codes in vaxis
-    // - see https://gist.github.com/ConnerWill/d4b6c776b509add763e17f9f113fd25b
+
+    if (comptime build_options.benchmark) {
+        benchmark_thread.join();
+        // print benchmark results
+        for (instants.items, 1..) |epoch, i| {
+            _ = i;
+            const epoch_float: f64 = @floatFromInt(epoch);
+            std.log.info("{d:.3}", .{epoch_float / std.time.ns_per_ms});
+        }
+        instants.deinit();
+    }
+}
+
+fn benchmark(app: *App) void {
+    std.time.sleep(1 * std.time.ns_per_s);
+    for (0..511) |_| {
+        app.postEvent(.{ .key = .{ .cp = 'j' } });
+        app.postEvent(.{ .key = .{ .cp = 'k' } });
+    }
+    app.quit();
 }
 
 test {