Expose v8 CpuProfiler + add fast properties for some window properties

First, this exposes the v8 Profiler. Right now it's just a commented-out block
in `fetch` and meant for internal debugging.
Depends on: lightpanda-io/zig-v8-fork#105

Use postAttach on Window to attach "static" properties. This comes from
profiling (lightpanda.io) and seeing window.get_self called tens of thousands
of times.

Author: karlseguin

build.zig.zon

@@ -5,8 +5,8 @@
     .fingerprint = 0xda130f3af836cea0,
     .dependencies = .{
         .v8 = .{
-            .url = "https://github.com/lightpanda-io/zig-v8-fork/archive/5ce9ade6c6d7f7ab9ab4582a6b1b36fdc8e246e2.tar.gz",
-            .hash = "v8-0.0.0-xddH6yTGAwA__kfiDozsVXL2_jnycrtDUfR8kIADQFUz",
+            .url = "https://github.com/lightpanda-io/zig-v8-fork/archive/305bb3706716d32d59b2ffa674731556caa1002b.tar.gz",
+            .hash = "v8-0.0.0-xddH63bVAwBSEobaUok9J0er1FqsvEujCDDVy6ItqKQ5",
         },
         //.v8 = .{ .path = "../zig-v8-fork" }
     },

src/browser/html/window.zig

@@ -136,14 +136,6 @@ pub const Window = struct {
         self.onload_callback = null;
     }
 
-    pub fn get_window(self: *Window) *Window {
-        return self;
-    }
-
-    pub fn get_navigator(self: *Window) *Navigator {
-        return &self.navigator;
-    }
-
     pub fn get_location(self: *Window) *Location {
         return &self.location;
     }
@@ -152,22 +144,6 @@ pub const Window = struct {
         return page.navigateFromWebAPI(url, .{ .reason = .script });
     }
 
-    pub fn get_console(self: *Window) *Console {
-        return &self.console;
-    }
-
-    pub fn get_crypto(self: *Window) *Crypto {
-        return &self.crypto;
-    }
-
-    pub fn get_self(self: *Window) *Window {
-        return self;
-    }
-
-    pub fn get_parent(self: *Window) *Window {
-        return self;
-    }
-
     // frames return the window itself, but accessing it via a pseudo
     // array returns the Window object corresponding to the given frame or
     // iframe.
@@ -205,10 +181,6 @@ pub const Window = struct {
         return frames.get_length();
     }
 
-    pub fn get_top(self: *Window) *Window {
-        return self;
-    }
-
     pub fn get_document(self: *Window) ?*parser.DocumentHTML {
         return self.document;
     }
@@ -243,14 +215,6 @@ pub const Window = struct {
         return &self.storage_shelf.?.bucket.session;
     }
 
-    pub fn get_performance(self: *Window) *Performance {
-        return &self.performance;
-    }
-
-    pub fn get_screen(self: *Window) *Screen {
-        return &self.screen;
-    }
-
     pub fn get_CSS(self: *Window) *Css {
         return &self.css;
     }
@@ -463,6 +427,18 @@ pub const Window = struct {
         // and thus the target has already been set to the document.
         return self.base.redispatchEvent(evt);
     }
+
+    pub fn postAttach(self: *Window, js_this: js.This) !void {
+        try js_this.set("top", self, .{});
+        try js_this.set("self", self, .{});
+        try js_this.set("parent", self, .{});
+        try js_this.set("window", self, .{});
+        try js_this.set("crypto", &self.crypto, .{});
+        try js_this.set("screen", &self.screen, .{});
+        try js_this.set("console", &self.console, .{});
+        try js_this.set("navigator", &self.navigator, .{});
+        try js_this.set("performance", &self.performance, .{});
+    }
 };
 
 const TimerCallback = struct {

src/browser/js/Context.zig

@@ -29,6 +29,8 @@ isolate: v8.Isolate,
 v8_context: v8.Context,
 handle_scope: ?v8.HandleScope,
 
+cpu_profiler: ?v8.CpuProfiler = null,
+
 // references Env.templates
 templates: []v8.FunctionTemplate,
 
@@ -1819,6 +1821,11 @@ fn zigJsonToJs(isolate: v8.Isolate, v8_context: v8.Context, value: std.json.Valu
     }
 }
 
+pub fn getGlobalThis(self: *Context) js.This {
+    const js_global = self.v8_context.getGlobal();
+    return .{ .obj = .{ .js_obj = js_global, .context = self } };
+}
+
 // == Misc ==
 // An interface for types that want to have their jsDeinit function to be
 // called when the call context ends
@@ -1847,3 +1854,26 @@ const DestructorCallback = struct {
         self.destructorFn(self.ptr);
     }
 };
+
+// == Profiler ==
+pub fn startCpuProfiler(self: *Context) void {
+    if (builtin.mode != .Debug) {
+        // Still testing this out, don't have it properly exposed, so add this
+        // guard for the time being to prevent any accidental/weird prod issues.
+        @compileError("CPU Profiling is only available in debug builds");
+    }
+
+    std.debug.assert(self.cpu_profiler == null);
+    v8.CpuProfiler.useDetailedSourcePositionsForProfiling(self.isolate);
+    const cpu_profiler = v8.CpuProfiler.init(self.isolate);
+    const title = self.isolate.initStringUtf8("v8_cpu_profile");
+    cpu_profiler.startProfiling(title);
+    self.cpu_profiler = cpu_profiler;
+}
+
+pub fn stopCpuProfiler(self: *Context) ![]const u8 {
+    const title = self.isolate.initStringUtf8("v8_cpu_profile");
+    const profile = self.cpu_profiler.?.stopProfiling(title) orelse unreachable;
+    const serialized = profile.serialize(self.isolate).?;
+    return self.jsStringToZig(serialized, .{});
+}

src/browser/js/Object.zig

@@ -27,7 +27,7 @@ pub fn setIndex(self: Object, index: u32, value: anytype, opts: SetOpts) !void {
     return self.set(key, value, opts);
 }
 
-pub fn set(self: Object, key: []const u8, value: anytype, opts: SetOpts) !void {
+pub fn set(self: Object, key: []const u8, value: anytype, opts: SetOpts) error{ FailedToSet, OutOfMemory }!void {
     const context = self.context;
 
     const js_key = v8.String.initUtf8(context.isolate, key);

src/browser/page.zig

@@ -849,7 +849,7 @@ pub const Page = struct {
         _ = self.session.browser.transfer_arena.reset(.{ .retain_with_limit = 4 * 1024 });
     }
 
-    // extracted because this sis called from tests to set things up.
+    // extracted because this is called from tests to set things up.
     pub fn setDocument(self: *Page, html_doc: *parser.DocumentHTML) !void {
         const doc = parser.documentHTMLToDocument(html_doc);
         try parser.documentSetDocumentURI(doc, self.url.raw);

src/main.zig

@@ -165,6 +165,24 @@ fn run(alloc: Allocator) !void {
             // page
             const page = try session.createPage();
 
+            // // Comment this out to get a profile of the JS code in v8/profile.json.
+            // // You can open this in Chrome's profiler.
+            // // I've seen it generate invalid JSON, but I'm not sure why. It only
+            // // happens rarely, and I manually fix the file.
+            // page.js.startCpuProfiler();
+            // defer {
+            //     if (page.js.stopCpuProfiler()) |profile| {
+            //         std.fs.cwd().writeFile(.{
+            //             .sub_path = "v8/profile.json",
+            //             .data = profile,
+            //         }) catch |err| {
+            //             log.err(.app, "profile write error", .{ .err = err });
+            //         };
+            //     } else |err| {
+            //         log.err(.app, "profile error", .{ .err = err });
+            //     }
+            // }
+
             _ = page.navigate(url, .{}) catch |err| switch (err) {
                 error.UnsupportedUriScheme, error.UriMissingHost => {
                     log.fatal(.app, "invalid fetch URL", .{ .err = err, .url = url });