Add libdom RSS and v8 total_physical_size to testing --json output

https://github.com/lightpanda-io/browser/issues/1057

src/browser/mimalloc.zig

@@ -40,6 +40,45 @@ pub fn destroy() void {
     heap = null;
 }
 
+pub fn getRSS() i64 {
+    if (@import("builtin").mode != .Debug) {
+        // just don't trust my implementation, plus a caller might not know
+        // that this requires parsing some unstructured data
+        @compileError("Only available in debug builds");
+    }
+    var buf: [4096]u8 = undefined;
+    var fba = std.heap.FixedBufferAllocator.init(&buf);
+    var writer = std.Io.Writer.Allocating.init(fba.allocator());
+
+    c.mi_stats_print_out(struct {
+        fn print(msg: [*c]const u8, data: ?*anyopaque) callconv(.c) void {
+            const w: *std.Io.Writer = @ptrCast(@alignCast(data.?));
+            w.writeAll(std.mem.span(msg)) catch |err| {
+                std.debug.print("Failed to write mimalloc data: {}", .{err});
+            };
+        }
+    }.print, &writer.writer);
+
+    const data = writer.written();
+    const index = std.mem.indexOf(u8, data, "rss: ") orelse return -1;
+    const sep = std.mem.indexOfScalarPos(u8, data, index + 5, ' ') orelse return -2;
+    const value = std.fmt.parseFloat(f64, data[index+5..sep]) catch return -3;
+    const unit = data[sep+1..];
+    if (std.mem.startsWith(u8, unit, "KiB,")) {
+        return @as(i64, @intFromFloat(value)) * 1024;
+    }
+
+    if (std.mem.startsWith(u8, unit, "MiB,")) {
+        return @as(i64, @intFromFloat(value)) * 1024 * 1024;
+    }
+
+    if (std.mem.startsWith(u8, unit, "GiB,")) {
+        return @as(i64, @intFromFloat(value)) * 1024 * 1024 * 1024;
+    }
+
+    return -4;
+}
+
 pub export fn m_alloc(size: usize) callconv(.c) ?*anyopaque {
     std.debug.assert(heap != null);
     return c.mi_heap_malloc(heap.?, size);

src/test_runner.zig

@@ -35,6 +35,8 @@ pub const std_options = std.Options{
 };
 
 pub var js_runner_duration: usize = 0;
+pub var v8_peak_memory: usize = 0;
+pub var libdom_memory: i64 = 0;
 pub var tracking_allocator: Allocator = undefined;
 
 pub fn main() !void {
@@ -194,13 +196,13 @@ pub fn main() !void {
                 .duration = js_runner_duration,
                 .alloc_nb = 0,
                 .realloc_nb = 0,
-                .alloc_size = 0,
+                .alloc_size = libdom_memory,
             } },
             .{ .name = "v8", .bench = .{
                 .duration = js_runner_duration,
                 .alloc_nb = 0,
                 .realloc_nb = 0,
-                .alloc_size = 0,
+                .alloc_size = v8_peak_memory,
             } },
             .{ .name = "main", .bench = .{
                 .duration = js_runner_duration,

src/testing.zig

@@ -379,6 +379,8 @@ pub fn setup() !void {
     test_session = try test_browser.newSession();
 }
 pub fn shutdown() void {
+    @import("root").v8_peak_memory = test_browser.env.isolate.getHeapStatistics().total_physical_size;
+    @import("root").libdom_memory = @import("browser/mimalloc.zig").getRSS();
     test_browser.deinit();
     test_app.deinit();
 }