From 817d818d4c807cd1848872f762f315b1dd0d6edd Mon Sep 17 00:00:00 2001
From: Yves Biener <yves.biener@gmx.de>
Date: Sat, 9 Nov 2024 01:17:09 +0100
Subject: [PATCH] feat(benchmark): add benchmark build (with build option) to
 test frame rate

---
 README.md    |  8 ++++----
 build.zig    |  9 +++++++++
 src/main.zig | 42 ++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 53 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index a0ae101..3e13cdf 100644
--- a/README.md
+++ b/README.md
@@ -16,11 +16,11 @@ It contains information about me and my projects as well as blog entries about s
 
 - [ ] How can I support to run a sub-process inside of a given pane / layout?
 - [ ] Create demo gifs using [vhs](https://github.com/charmbracelet/vhs)
-- [ ] How would I measure my FPS?
-- [ ] Could I simulate a corresponding event loop?
-  - empty user event
-  - emmit as many as possible through another thread (until the event queue is full?)
+
+- [x] Could I simulate a corresponding event loop?
+  - emmit as many as possible through another thread (until the event queue is full?) [1023]
   - see how fast the application can render each frame and measure the necessary time for each _frame_?
   -> determine statistics like, min, max, median, mean, etc.
   -> Or buffered writer to the `std.posix.STDOUT_FILENO`?
   -> I could use this to see if it makes sense to implement a buffered version using a screen buffer (to only render the differences?)
+  - seems pretty good (with some exceptions)
diff --git a/build.zig b/build.zig
index 6fac23a..f05cf3a 100644
--- a/build.zig
+++ b/build.zig
@@ -15,6 +15,14 @@ pub fn build(b: *std.Build) void {
     // set a preferred release mode, allowing the user to decide how to optimize.
     const optimize = b.standardOptimizeOption(.{});
 
+    // build options to customize the log message formatting
+    const benchmark = b.option(bool, "benchmark", "Create a benchmark build (default: false)") orelse false;
+
+    const options = b.addOptions();
+    options.addOption(bool, "benchmark", benchmark);
+
+    const options_module = options.createModule();
+
     // Dependencies
     const vaxis_dep = b.dependency("vaxis", .{
         .optimize = optimize,
@@ -37,6 +45,7 @@ pub fn build(b: *std.Build) void {
         .target = target,
         .optimize = optimize,
     });
+    exe.root_module.addImport("build_options", options_module);
     exe.root_module.addImport("vaxis", vaxis_dep.module("vaxis"));
     exe.root_module.addImport("zlog", zlog_dep.module("zlog"));
     exe.root_module.addImport("zmd", zmd_dep.module("zmd"));
diff --git a/src/main.zig b/src/main.zig
index f950a39..6a5f95d 100644
--- a/src/main.zig
+++ b/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 {