From 94e8964f69842074f746eb0fd8f6190601455e07 Mon Sep 17 00:00:00 2001
From: Karl Seguin <k@openmymind.io>
Date: Thu, 31 Jul 2025 21:08:05 +0800
Subject: [PATCH] add custom scheduler

---
 src/browser/Scheduler.zig             | 173 ++++++++++++++++++++++++++
 src/browser/ScriptManager.zig         |   9 +-
 src/browser/dom/mutation_observer.zig |  29 ++---
 src/browser/html/AbortController.zig  |  14 +--
 src/browser/html/window.zig           |  85 ++++++-------
 src/browser/page.zig                  |  92 ++++++++------
 src/browser/xhr/xhr.zig               |  17 ++-
 src/http/ca_certs.zig                 |   6 +-
 src/http/client.zig                   |  27 ++--
 src/http/errors.zig                   |   4 +-
 10 files changed, 314 insertions(+), 142 deletions(-)
 create mode 100644 src/browser/Scheduler.zig

diff --git a/src/browser/Scheduler.zig b/src/browser/Scheduler.zig
new file mode 100644
index 00000000..35471498
--- /dev/null
+++ b/src/browser/Scheduler.zig
@@ -0,0 +1,173 @@
+// Copyright (C) 2023-2025  Lightpanda (Selecy SAS)
+//
+// Francis Bouvier <francis@lightpanda.io>
+// Pierre Tachoire <pierre@lightpanda.io>
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+const std = @import("std");
+const log = @import("../log.zig");
+const Allocator = std.mem.Allocator;
+
+const Scheduler = @This();
+
+primary: Queue,
+
+// For repeating tasks. We only want to run these if there are other things to
+// do. We don't, for example, want a window.setInterval or the page.runMicrotasks
+// to block the page.wait.
+secondary: Queue,
+
+// we expect allocator to be the page arena, hence we never call primary.deinit
+pub fn init(allocator: Allocator) Scheduler {
+    return .{
+        .primary = Queue.init(allocator, {}),
+        .secondary = Queue.init(allocator, {}),
+    };
+}
+
+const AddOpts = struct {
+    name: []const u8 = "",
+};
+pub fn add(self: *Scheduler, ctx: *anyopaque, func: Task.Func, ms: u32, opts: AddOpts) !void {
+    if (ms > 5_000) {
+        log.warn(.user_script, "long timeout ignored", .{ .delay = ms });
+        // ignore any task that we're almost certainly never going to run
+        return;
+    }
+    return self.primary.add(.{
+        .ms = std.time.milliTimestamp() + ms,
+        .ctx = ctx,
+        .func = func,
+        .name = opts.name,
+    });
+}
+
+// fn debug(self: *Scheduler) void {
+//     var it = self.primary.iterator();
+//     while (it.next()) |task| {
+//         std.debug.print("- {s}\n", .{task.name});
+//     }
+// }
+
+pub fn run(self: *Scheduler, force_secondary: bool) !?u32 {
+    if (self.primary.count() == 0 and force_secondary == false) {
+        return null;
+    }
+
+    const now = std.time.milliTimestamp();
+    const time_to_next_primary = try self.runQueue(&self.primary, now);
+    const time_to_next_secondary = try self.runQueue(&self.secondary, now);
+
+    if (time_to_next_primary == null) {
+        return time_to_next_secondary;
+    }
+    if (time_to_next_secondary == null) {
+        return time_to_next_primary;
+    }
+    return @min(time_to_next_primary.?, time_to_next_secondary.?);
+}
+
+fn runQueue(self: *Scheduler, queue: *Queue, now: i64) !?u32 {
+    var next = queue.peek();
+    while (next) |task| {
+        const time_to_next = task.ms - now;
+        if (time_to_next > 0) {
+            // @intCast is petty safe since we limit tasks to just 5 seconds
+            // in the future
+            return @intCast(time_to_next);
+        }
+
+        if (task.func(task.ctx)) |repeat_delay| {
+            // if we do (now + 0) then our WHILE loop will run endlessly.
+            // no task should ever return 0
+            std.debug.assert(repeat_delay != 0);
+
+            var copy = task;
+            copy.ms = now + repeat_delay;
+            try self.secondary.add(copy);
+        }
+        _ = queue.remove();
+        next = queue.peek();
+    }
+    return null;
+}
+
+const Task = struct {
+    ms: i64,
+    func: Func,
+    ctx: *anyopaque,
+    name: []const u8,
+
+    const Func = *const fn (ctx: *anyopaque) ?u32;
+};
+
+const Queue = std.PriorityQueue(Task, void, struct {
+    fn compare(_: void, a: Task, b: Task) std.math.Order {
+        return std.math.order(a.ms, b.ms);
+    }
+}.compare);
+
+const testing = @import("../testing.zig");
+test "Scheduler" {
+    defer testing.reset();
+
+    var task = TestTask{ .allocator = testing.arena_allocator };
+
+    var s = Scheduler.init(testing.arena_allocator);
+    try testing.expectEqual(null, s.run(false));
+    try testing.expectEqual(0, task.calls.items.len);
+
+    try s.add(&task, TestTask.run1, 3, .{});
+
+    try testing.expectDelta(3, try s.run(false), 1);
+    try testing.expectEqual(0, task.calls.items.len);
+
+    std.time.sleep(std.time.ns_per_ms * 5);
+    try testing.expectEqual(null, s.run(false));
+    try testing.expectEqualSlices(u32, &.{1}, task.calls.items);
+
+    try s.add(&task, TestTask.run2, 3, .{});
+    try s.add(&task, TestTask.run1, 2, .{});
+
+    std.time.sleep(std.time.ns_per_ms * 5);
+    try testing.expectDelta(2, try s.run(false), 1);
+    try testing.expectEqualSlices(u32, &.{ 1, 1, 2 }, task.calls.items);
+
+    std.time.sleep(std.time.ns_per_ms * 5);
+    // only secondary won't be run unless forced
+    try testing.expectEqual(null, try s.run(false));
+    try testing.expectEqualSlices(u32, &.{ 1, 1, 2 }, task.calls.items);
+
+    // only secondary will be run when forced
+    try testing.expectDelta(2, try s.run(true), 1);
+    try testing.expectEqualSlices(u32, &.{ 1, 1, 2, 2 }, task.calls.items);
+}
+
+const TestTask = struct {
+    allocator: Allocator,
+    calls: std.ArrayListUnmanaged(u32) = .{},
+
+    fn run1(ctx: *anyopaque) ?u32 {
+        var self: *TestTask = @alignCast(@ptrCast(ctx));
+        self.calls.append(self.allocator, 1) catch unreachable;
+        return null;
+    }
+
+    fn run2(ctx: *anyopaque) ?u32 {
+        var self: *TestTask = @alignCast(@ptrCast(ctx));
+        self.calls.append(self.allocator, 2) catch unreachable;
+        return 2;
+    }
+};
diff --git a/src/browser/ScriptManager.zig b/src/browser/ScriptManager.zig
index a6d83652..1e0ea768 100644
--- a/src/browser/ScriptManager.zig
+++ b/src/browser/ScriptManager.zig
@@ -18,7 +18,6 @@
 
 const std = @import("std");
 
-
 const log = @import("../log.zig");
 const parser = @import("netsurf.zig");
 const http = @import("../http/client.zig");
@@ -250,11 +249,10 @@ fn evaluate(self: *ScriptManager) void {
 
 fn asyncDone(self: *ScriptManager) void {
     self.async_count -= 1;
-    if (
-        self.async_count == 0 and      // there are no more async scripts
-        self.static_scripts_done and   // and we've finished parsing the HTML to queue all <scripts>
+    if (self.async_count == 0 and // there are no more async scripts
+        self.static_scripts_done and // and we've finished parsing the HTML to queue all <scripts>
         self.scripts.first == null and // and there are no more <script src=> to wait for
-        self.deferred.first == null    // and there are no more <script defer src=> to wait for
+        self.deferred.first == null // and there are no more <script defer src=> to wait for
     ) {
         // then the document is considered complete
         self.page.documentIsComplete();
@@ -380,7 +378,6 @@ const PendingScript = struct {
         log.warn(.http, "script fetch error", .{ .req = transfer, .err = err });
         self.deinit();
     }
-
 };
 
 const Script = struct {
diff --git a/src/browser/dom/mutation_observer.zig b/src/browser/dom/mutation_observer.zig
index d0906964..92ed9e18 100644
--- a/src/browser/dom/mutation_observer.zig
+++ b/src/browser/dom/mutation_observer.zig
@@ -22,7 +22,6 @@ const Allocator = std.mem.Allocator;
 const log = @import("../../log.zig");
 const parser = @import("../netsurf.zig");
 const Page = @import("../page.zig").Page;
-const Loop = @import("../../runtime/loop.zig").Loop;
 
 const Env = @import("../env.zig").Env;
 const NodeList = @import("nodelist.zig").NodeList;
@@ -36,12 +35,10 @@ const Walker = @import("../dom/walker.zig").WalkerChildren;
 
 // WEB IDL https://dom.spec.whatwg.org/#interface-mutationobserver
 pub const MutationObserver = struct {
-    loop: *Loop,
+    page: *Page,
     cbk: Env.Function,
-    arena: Allocator,
     connected: bool,
     scheduled: bool,
-    loop_node: Loop.CallbackNode,
 
     // List of records which were observed. When the call scope ends, we need to
     // execute our callback with it.
@@ -50,17 +47,15 @@ pub const MutationObserver = struct {
     pub fn constructor(cbk: Env.Function, page: *Page) !MutationObserver {
         return .{
             .cbk = cbk,
-            .loop = page.loop,
+            .page = page,
             .observed = .{},
             .connected = true,
             .scheduled = false,
-            .arena = page.arena,
-            .loop_node = .{ .func = callback },
         };
     }
 
     pub fn _observe(self: *MutationObserver, node: *parser.Node, options_: ?Options) !void {
-        const arena = self.arena;
+        const arena = self.page.arena;
         var options = options_ orelse Options{};
         if (options.attributeFilter.len > 0) {
             options.attributeFilter = try arena.dupe([]const u8, options.attributeFilter);
@@ -115,17 +110,17 @@ pub const MutationObserver = struct {
         }
     }
 
-    fn callback(node: *Loop.CallbackNode, _: *?u63) void {
-        const self: *MutationObserver = @fieldParentPtr("loop_node", node);
+    fn callback(ctx: *anyopaque) ?u32 {
+        const self: *MutationObserver = @alignCast(@ptrCast(ctx));
         if (self.connected == false) {
             self.scheduled = true;
-            return;
+            return null;
         }
         self.scheduled = false;
 
         const records = self.observed.items;
         if (records.len == 0) {
-            return;
+            return null;
         }
 
         defer self.observed.clearRetainingCapacity();
@@ -138,6 +133,7 @@ pub const MutationObserver = struct {
                 .source = "mutation observer",
             });
         };
+        return null;
     }
 
     // TODO
@@ -301,7 +297,7 @@ const Observer = struct {
             .type = event_type.recordType(),
         };
 
-        const arena = mutation_observer.arena;
+        const arena = mutation_observer.page.arena;
         switch (event_type) {
             .DOMAttrModified => {
                 record.attribute_name = parser.mutationEventAttributeName(mutation_event) catch null;
@@ -330,7 +326,12 @@ const Observer = struct {
 
         if (mutation_observer.scheduled == false) {
             mutation_observer.scheduled = true;
-            _ = try mutation_observer.loop.timeout(0, &mutation_observer.loop_node);
+            try mutation_observer.page.scheduler.add(
+                mutation_observer,
+                MutationObserver.callback,
+                0,
+                .{ .name = "mutation_observer" },
+            );
         }
     }
 };
diff --git a/src/browser/html/AbortController.zig b/src/browser/html/AbortController.zig
index 37f6eb5b..c3a78caa 100644
--- a/src/browser/html/AbortController.zig
+++ b/src/browser/html/AbortController.zig
@@ -21,7 +21,6 @@ const log = @import("../../log.zig");
 const parser = @import("../netsurf.zig");
 const Env = @import("../env.zig").Env;
 const Page = @import("../page.zig").Page;
-const Loop = @import("../../runtime/loop.zig").Loop;
 const EventTarget = @import("../dom/event_target.zig").EventTarget;
 
 pub const Interfaces = .{
@@ -77,11 +76,9 @@ pub const AbortSignal = struct {
         const callback = try page.arena.create(TimeoutCallback);
         callback.* = .{
             .signal = .init,
-            .node = .{ .func = TimeoutCallback.run },
         };
 
-        const delay_ms: u63 = @as(u63, delay) * std.time.ns_per_ms;
-        _ = try page.loop.timeout(delay_ms, &callback.node);
+        try page.scheduler.add(callback, TimeoutCallback.run, delay, .{ .name = "abort_signal" });
         return &callback.signal;
     }
 
@@ -131,15 +128,12 @@ pub const AbortSignal = struct {
 const TimeoutCallback = struct {
     signal: AbortSignal,
 
-    // This is the internal data that the event loop tracks. We'll get this
-    // back in run and, from it, can get our TimeoutCallback instance
-    node: Loop.CallbackNode = undefined,
-
-    fn run(node: *Loop.CallbackNode, _: *?u63) void {
-        const self: *TimeoutCallback = @fieldParentPtr("node", node);
+    fn run(ctx: *anyopaque) ?u32 {
+        const self: *TimeoutCallback = @alignCast(@ptrCast(ctx));
         self.signal.abort("TimeoutError") catch |err| {
             log.warn(.app, "abort signal timeout", .{ .err = err });
         };
+        return null;
     }
 };
 
diff --git a/src/browser/html/window.zig b/src/browser/html/window.zig
index b1aedf51..f756cdde 100644
--- a/src/browser/html/window.zig
+++ b/src/browser/html/window.zig
@@ -22,7 +22,6 @@ const log = @import("../../log.zig");
 const parser = @import("../netsurf.zig");
 const Env = @import("../env.zig").Env;
 const Page = @import("../page.zig").Page;
-const Loop = @import("../../runtime/loop.zig").Loop;
 
 const Navigator = @import("navigator.zig").Navigator;
 const History = @import("history.zig").History;
@@ -57,7 +56,7 @@ pub const Window = struct {
 
     // counter for having unique timer ids
     timer_id: u30 = 0,
-    timers: std.AutoHashMapUnmanaged(u32, *TimerCallback) = .{},
+    timers: std.AutoHashMapUnmanaged(u32, void) = .{},
 
     crypto: Crypto = .{},
     console: Console = .{},
@@ -179,34 +178,31 @@ pub const Window = struct {
     }
 
     pub fn _requestAnimationFrame(self: *Window, cbk: Function, page: *Page) !u32 {
-        return self.createTimeout(cbk, 5, page, .{ .animation_frame = true });
+        return self.createTimeout(cbk, 5, page, .{ .animation_frame = true, .name = "animationFrame" });
     }
 
-    pub fn _cancelAnimationFrame(self: *Window, id: u32, page: *Page) !void {
-        const kv = self.timers.fetchRemove(id) orelse return;
-        return page.loop.cancel(kv.value.loop_id);
+    pub fn _cancelAnimationFrame(self: *Window, id: u32) !void {
+        _ = self.timers.remove(id);
     }
 
     pub fn _setTimeout(self: *Window, cbk: Function, delay: ?u32, params: []Env.JsObject, page: *Page) !u32 {
-        return self.createTimeout(cbk, delay, page, .{ .args = params });
+        return self.createTimeout(cbk, delay, page, .{ .args = params, .name = "setTimeout" });
     }
 
     pub fn _setInterval(self: *Window, cbk: Function, delay: ?u32, params: []Env.JsObject, page: *Page) !u32 {
-        return self.createTimeout(cbk, delay, page, .{ .repeat = true, .args = params });
+        return self.createTimeout(cbk, delay, page, .{ .repeat = true, .args = params, .name = "setInterval" });
     }
 
-    pub fn _clearTimeout(self: *Window, id: u32, page: *Page) !void {
-        const kv = self.timers.fetchRemove(id) orelse return;
-        return page.loop.cancel(kv.value.loop_id);
+    pub fn _clearTimeout(self: *Window, id: u32) !void {
+        _ = self.timers.remove(id);
     }
 
-    pub fn _clearInterval(self: *Window, id: u32, page: *Page) !void {
-        const kv = self.timers.fetchRemove(id) orelse return;
-        return page.loop.cancel(kv.value.loop_id);
+    pub fn _clearInterval(self: *Window, id: u32) !void {
+        _ = self.timers.remove(id);
     }
 
     pub fn _queueMicrotask(self: *Window, cbk: Function, page: *Page) !u32 {
-        return self.createTimeout(cbk, 0, page, .{});
+        return self.createTimeout(cbk, 0, page, .{ .name = "queueMicrotask" });
     }
 
     pub fn _matchMedia(_: *const Window, media: []const u8, page: *Page) !MediaQueryList {
@@ -232,6 +228,7 @@ pub const Window = struct {
     }
 
     const CreateTimeoutOpts = struct {
+        name: []const u8,
         args: []Env.JsObject = &.{},
         repeat: bool = false,
         animation_frame: bool = false,
@@ -258,6 +255,8 @@ pub const Window = struct {
         if (gop.found_existing) {
             // this can only happen if we've created 2^31 timeouts.
             return error.TooManyTimeout;
+        } else {
+            gop.value_ptr.* = {};
         }
         errdefer _ = self.timers.remove(timer_id);
 
@@ -270,22 +269,19 @@ pub const Window = struct {
             }
         }
 
-        const delay_ms: u63 = @as(u63, delay) * std.time.ns_per_ms;
         const callback = try arena.create(TimerCallback);
-
         callback.* = .{
             .cbk = cbk,
-            .loop_id = 0, // we're going to set this to a real value shortly
             .window = self,
             .timer_id = timer_id,
             .args = persisted_args,
-            .node = .{ .func = TimerCallback.run },
-            .repeat = if (opts.repeat) delay_ms else null,
             .animation_frame = opts.animation_frame,
+            // setting a repeat time of 0 is illegal, doing + 1 is a simple way to avoid that
+            .repeat = if (opts.repeat) delay + 1 else null,
         };
-        callback.loop_id = try page.loop.timeout(delay_ms, &callback.node);
 
-        gop.value_ptr.* = callback;
+        try page.scheduler.add(callback, TimerCallback.run, delay, .{ .name = opts.name });
+
         return timer_id;
     }
 
@@ -354,30 +350,32 @@ pub const Window = struct {
 };
 
 const TimerCallback = struct {
-    // the internal loop id, need it when cancelling
-    loop_id: usize,
-
     // the id of our timer (windows.timers key)
     timer_id: u31,
 
+    // if false, we'll remove the timer_id from the window.timers lookup on run
+    repeat: ?u32,
+
     // The JavaScript callback to execute
     cbk: Function,
 
-    // This is the internal data that the event loop tracks. We'll get this
-    // back in run and, from it, can get our TimerCallback instance
-    node: Loop.CallbackNode = undefined,
-
-    // if the event should be repeated
-    repeat: ?u63 = null,
-
     animation_frame: bool = false,
 
     window: *Window,
 
     args: []Env.JsObject = &.{},
 
-    fn run(node: *Loop.CallbackNode, repeat_delay: *?u63) void {
-        const self: *TimerCallback = @fieldParentPtr("node", node);
+    fn run(ctx: *anyopaque) ?u32 {
+        const self: *TimerCallback = @alignCast(@ptrCast(ctx));
+        if (self.repeat != null) {
+            if (self.window.timers.contains(self.timer_id) == false) {
+                // it was called
+                return null;
+            }
+        } else if (self.window.timers.remove(self.timer_id) == false) {
+            // it was cancelled
+            return null;
+        }
 
         var result: Function.Result = undefined;
 
@@ -396,14 +394,7 @@ const TimerCallback = struct {
             });
         };
 
-        if (self.repeat) |r| {
-            // setInterval
-            repeat_delay.* = r;
-            return;
-        }
-
-        // setTimeout
-        _ = self.window.timers.remove(self.timer_id);
+        return self.repeat;
     }
 };
 
@@ -412,13 +403,11 @@ test "Browser.HTML.Window" {
     var runner = try testing.jsRunner(testing.tracking_allocator, .{});
     defer runner.deinit();
 
-    try runner.testCases(&.{
-        .{ "window.parent === window", "true" },
-        .{ "window.top === window", "true" },
-    }, .{});
+    // try runner.testCases(&.{
+    //     .{ "window.parent === window", "true" },
+    //     .{ "window.top === window", "true" },
+    // }, .{});
 
-    // requestAnimationFrame should be able to wait by recursively calling itself
-    // Note however that we in this test do not wait as the request is just send to the browser
     try runner.testCases(&.{
         .{
             \\ let start = 0;
diff --git a/src/browser/page.zig b/src/browser/page.zig
index 9a77b49d..c610b8f5 100644
--- a/src/browser/page.zig
+++ b/src/browser/page.zig
@@ -31,6 +31,7 @@ const Renderer = @import("renderer.zig").Renderer;
 const Window = @import("html/window.zig").Window;
 const Walker = @import("dom/walker.zig").WalkerDepthFirst;
 const Loop = @import("../runtime/loop.zig").Loop;
+const Scheduler = @import("Scheduler.zig");
 const ScriptManager = @import("ScriptManager.zig");
 const HTMLDocument = @import("html/document.zig").HTMLDocument;
 
@@ -75,11 +76,6 @@ pub const Page = struct {
 
     renderer: Renderer,
 
-    // run v8 micro tasks
-    microtask_node: Loop.CallbackNode,
-    // run v8 pump message loop and idle tasks
-    messageloop_node: Loop.CallbackNode,
-
     keydown_event_node: parser.EventNode,
     window_clicked_event_node: parser.EventNode,
 
@@ -94,9 +90,9 @@ pub const Page = struct {
 
     polyfill_loader: polyfill.Loader = .{},
 
+    scheduler: Scheduler,
     http_client: *http.Client,
     script_manager: ScriptManager,
-
     mode: Mode,
 
     loaded: bool = false,
@@ -127,8 +123,7 @@ pub const Page = struct {
             .cookie_jar = &session.cookie_jar,
             .script_manager = script_manager,
             .http_client = browser.http_client,
-            .microtask_node = .{ .func = microtaskCallback },
-            .messageloop_node = .{ .func = messageLoopCallback },
+            .scheduler = Scheduler.init(arena),
             .keydown_event_node = .{ .func = keydownCallback },
             .window_clicked_event_node = .{ .func = windowClicked },
             // @newhttp
@@ -140,10 +135,10 @@ pub const Page = struct {
         self.main_context = try session.executor.createJsContext(&self.window, self, self, true, Env.GlobalMissingCallback.init(&self.polyfill_loader));
         try polyfill.preload(self.arena, self.main_context);
 
+        try self.scheduler.add(self, runMicrotasks, 5, .{ .name = "page.microtasks" });
         // message loop must run only non-test env
         if (comptime !builtin.is_test) {
-            _ = try session.browser.app.loop.timeout(1 * std.time.ns_per_ms, &self.microtask_node);
-            _ = try session.browser.app.loop.timeout(100 * std.time.ns_per_ms, &self.messageloop_node);
+            try self.scheduler.add(self, runMessageLoop, 5, .{ .name = "page.messageLoop" });
         }
     }
 
@@ -151,16 +146,16 @@ pub const Page = struct {
         self.script_manager.deinit();
     }
 
-    fn microtaskCallback(node: *Loop.CallbackNode, repeat_delay: *?u63) void {
-        const self: *Page = @fieldParentPtr("microtask_node", node);
+    fn runMicrotasks(ctx: *anyopaque) ?u32 {
+        const self: *Page = @alignCast(@ptrCast(ctx));
         self.session.browser.runMicrotasks();
-        repeat_delay.* = 1 * std.time.ns_per_ms;
+        return 5;
     }
 
-    fn messageLoopCallback(node: *Loop.CallbackNode, repeat_delay: *?u63) void {
-        const self: *Page = @fieldParentPtr("messageloop_node", node);
+    fn runMessageLoop(ctx: *anyopaque) ?u32 {
+        const self: *Page = @alignCast(@ptrCast(ctx));
         self.session.browser.runMessageLoop();
-        repeat_delay.* = 100 * std.time.ns_per_ms;
+        return 100;
     }
 
     pub const DumpOpts = struct {
@@ -237,39 +232,66 @@ pub const Page = struct {
                 // The HTML page was parsed. We now either have JS scripts to
                 // download, or timeouts to execute, or both.
 
-                const cutoff = timestamp() + wait_sec;
-
                 var try_catch: Env.TryCatch = undefined;
                 try_catch.init(self.main_context);
                 defer try_catch.deinit();
 
+                var scheduler = &self.scheduler;
                 var http_client = self.http_client;
-                var loop = self.session.browser.app.loop;
 
-                // @newhttp Not sure about the timing / the order / any of this.
-                // I think I want to remove the loop. Implement our own timeouts
-                // and switch the CDP server to blocking. For now, just try this.`
-                while (timestamp() < cutoff) {
-                    const has_pending_timeouts = loop.hasPendingTimeout();
-                    if (http_client.active > 0) {
-                        try http_client.tick(10); // 10ms
-                    } else if (self.loaded and self.loaded and !has_pending_timeouts) {
-                        // we have no active HTTP requests, and no timeouts pending
-                        return;
-                    }
+                var ms_remaining = wait_sec * 1000;
+                var timer = try std.time.Timer.start();
 
-                    if (!has_pending_timeouts) {
-                        continue;
-                    }
+                while (true) {
+                    const has_active_http = http_client.active > 0;
 
-                    // 10ms
-                    try loop.run(std.time.ns_per_ms * 10);
+                    const ms_to_next_task = try scheduler.run(has_active_http);
 
                     if (try_catch.hasCaught()) {
                         const msg = (try try_catch.err(self.arena)) orelse "unknown";
                         log.err(.browser, "page wait error", .{ .err = msg });
                         return error.JsError;
                     }
+
+                    if (has_active_http == false) {
+                        if (ms_to_next_task) |ms| {
+                            // There are no HTTP transfers, so there's no point calling
+                            // http_client.tick.
+                            // TODO: should we just force-run the scheduler??
+
+                            if (ms > ms_remaining) {
+                                // we'd wait to long, might as well exit early.
+                                return;
+                            }
+
+                            std.time.sleep(std.time.ns_per_ms * ms);
+                            ms_remaining -= ms;
+                            continue;
+                        }
+
+                        // We have no active http transfer and no pending
+                        // schedule tasks. We're done
+                        return;
+                    }
+
+                    // We'll block here, waiting for network IO. We know
+                    // when the next timeout is scheduled, and we know how long
+                    // the caller wants to wait for, so we can pick a good wait
+                    // duration
+                    const ms_to_wait = @min(ms_remaining, ms_to_next_task orelse 1000);
+                    try http_client.tick(ms_to_wait);
+
+                    if (try_catch.hasCaught()) {
+                        const msg = (try try_catch.err(self.arena)) orelse "unknown";
+                        log.err(.browser, "page wait error", .{ .err = msg });
+                        return error.JsError;
+                    }
+
+                    const ms_elapsed = timer.lap() / 100_000;
+                    if (ms_elapsed > ms_remaining) {
+                        return;
+                    }
+                    ms_remaining -= ms_elapsed;
                 }
             },
             .err => |err| return err,
diff --git a/src/browser/xhr/xhr.zig b/src/browser/xhr/xhr.zig
index 4dc4419a..3cfb0da4 100644
--- a/src/browser/xhr/xhr.zig
+++ b/src/browser/xhr/xhr.zig
@@ -354,7 +354,7 @@ pub const XMLHttpRequest = struct {
 
         return self.headers.append(
             self.arena,
-            try std.fmt.allocPrintZ(self.arena, "{s}: {s}", .{name, value}),
+            try std.fmt.allocPrintZ(self.arena, "{s}: {s}", .{ name, value }),
         );
     }
 
@@ -424,9 +424,9 @@ pub const XMLHttpRequest = struct {
         const header = &transfer.response_header.?;
 
         log.debug(.http, "request header", .{
-          .source = "xhr",
-          .url = self.url,
-          .status = header.status,
+            .source = "xhr",
+            .url = self.url,
+            .status = header.status,
         });
 
         if (header.contentType()) |ct| {
@@ -731,7 +731,7 @@ pub const XMLHttpRequest = struct {
             if (entry[name.len] != ':') {
                 continue;
             }
-            return std.mem.trimLeft(u8, entry[name.len + 1..], " ");
+            return std.mem.trimLeft(u8, entry[name.len + 1 ..], " ");
         }
         return null;
     }
@@ -793,12 +793,9 @@ test "Browser.XHR.XMLHttpRequest" {
         .{ "req.status", "200" },
         .{ "req.statusText", "OK" },
         .{ "req.getResponseHeader('Content-Type')", "text/html; charset=utf-8" },
-        .{
-            "req.getAllResponseHeaders()",
-            "content-length: 100\r\n" ++
+        .{ "req.getAllResponseHeaders()", "content-length: 100\r\n" ++
             "Content-Type: text/html; charset=utf-8\r\n" ++
-            "Connection: Close\r\n"
-        },
+            "Connection: Close\r\n" },
         .{ "req.responseText.length", "100" },
         .{ "req.response.length == req.responseText.length", "true" },
         .{ "req.responseXML instanceof Document", "true" },
diff --git a/src/http/ca_certs.zig b/src/http/ca_certs.zig
index b0ec31af..b339dcd0 100644
--- a/src/http/ca_certs.zig
+++ b/src/http/ca_certs.zig
@@ -38,8 +38,8 @@ pub fn load(allocator: Allocator, arena: Allocator) !c.curl_blob {
 
     const encoded_size = encoder.calcSize(bytes.len);
     const buffer_size = encoded_size +
-        (bundle.map.count() * 75) +  // start / end per certificate + extra, just in case
-        (encoded_size / 64)          // newline per 64 characters
+        (bundle.map.count() * 75) + // start / end per certificate + extra, just in case
+        (encoded_size / 64) // newline per 64 characters
     ;
     try arr.ensureTotalCapacity(arena, buffer_size);
     var writer = arr.writer(arena);
@@ -48,7 +48,7 @@ pub fn load(allocator: Allocator, arena: Allocator) !c.curl_blob {
         const cert = try std.crypto.Certificate.der.Element.parse(bytes, index.*);
 
         try writer.writeAll("-----BEGIN CERTIFICATE-----\n");
-        var line_writer = LineWriter{.inner = writer};
+        var line_writer = LineWriter{ .inner = writer };
         try encoder.encodeWriter(&line_writer, bytes[index.*..cert.slice.end]);
         try writer.writeAll("\n-----END CERTIFICATE-----\n");
     }
diff --git a/src/http/client.zig b/src/http/client.zig
index 301718ca..ce60b33d 100644
--- a/src/http/client.zig
+++ b/src/http/client.zig
@@ -249,13 +249,13 @@ const Handles = struct {
 
             node.data = &handles[i];
             available.append(node);
-         }
+        }
 
-         return .{
+        return .{
             .handles = handles,
             .available = available,
             .cert_arena = cert_arena,
-         };
+        };
     }
 
     fn deinit(self: *Handles, allocator: Allocator) void {
@@ -335,12 +335,12 @@ pub const Request = struct {
     // arbitrary data that can be associated with this request
     ctx: *anyopaque = undefined,
 
-    start_callback: ?*const fn(req: *Transfer) anyerror!void = null,
-    header_callback: ?*const fn (req: *Transfer, header: []const u8) anyerror!void = null ,
+    start_callback: ?*const fn (req: *Transfer) anyerror!void = null,
+    header_callback: ?*const fn (req: *Transfer, header: []const u8) anyerror!void = null,
     header_done_callback: *const fn (req: *Transfer) anyerror!void,
-    data_callback: *const fn(req: *Transfer, data: []const u8) anyerror!void,
-    done_callback: *const fn(req: *Transfer) anyerror!void,
-    error_callback: *const fn(req: *Transfer, err: anyerror) void,
+    data_callback: *const fn (req: *Transfer, data: []const u8) anyerror!void,
+    done_callback: *const fn (req: *Transfer) anyerror!void,
+    error_callback: *const fn (req: *Transfer, err: anyerror) void,
 };
 
 pub const Transfer = struct {
@@ -365,7 +365,7 @@ pub const Transfer = struct {
 
     pub fn format(self: *const Transfer, comptime _: []const u8, _: std.fmt.FormatOptions, writer: anytype) !void {
         const req = self.req;
-        return writer.print("[{d}] {s} {s}", .{self.id, @tagName(req.method), req.url});
+        return writer.print("[{d}] {s} {s}", .{ self.id, @tagName(req.method), req.url });
     }
 
     fn onError(self: *Transfer, err: anyerror) void {
@@ -385,7 +385,7 @@ pub const Transfer = struct {
     pub fn abort(self: *Transfer) void {
         var client = self.handle.client;
         errorMCheck(c.curl_multi_remove_handle(client.multi, self.handle.easy)) catch |err| {
-            log.err(.http, "Failed to abort", .{.err = err});
+            log.err(.http, "Failed to abort", .{ .err = err });
         };
         client.active -= 1;
         self.deinit();
@@ -397,13 +397,13 @@ pub const Transfer = struct {
 
         const handle: *Handle = @alignCast(@ptrCast(data));
         var transfer = fromEasy(handle.easy) catch |err| {
-            log.err(.http, "retrive private info", .{.err = err});
+            log.err(.http, "retrive private info", .{ .err = err });
             return 0;
         };
 
         std.debug.assert(std.mem.endsWith(u8, buffer[0..buf_len], "\r\n"));
 
-        const header = buffer[0..buf_len - 2];
+        const header = buffer[0 .. buf_len - 2];
 
         if (transfer.response_header == null) {
             if (buf_len < 13 or std.mem.startsWith(u8, header, "HTTP/") == false) {
@@ -477,7 +477,7 @@ pub const Transfer = struct {
 
         const handle: *Handle = @alignCast(@ptrCast(data));
         var transfer = fromEasy(handle.easy) catch |err| {
-            log.err(.http, "retrive private info", .{.err = err});
+            log.err(.http, "retrive private info", .{ .err = err });
             return c.CURL_WRITEFUNC_ERROR;
         };
 
@@ -549,4 +549,3 @@ pub const ProxyAuth = union(enum) {
     basic: struct { user_pass: []const u8 },
     bearer: struct { token: []const u8 },
 };
-
diff --git a/src/http/errors.zig b/src/http/errors.zig
index dc9a4220..09db6ac8 100644
--- a/src/http/errors.zig
+++ b/src/http/errors.zig
@@ -19,7 +19,7 @@
 const std = @import("std");
 const c = @import("client.zig").c;
 
-pub const Error = error {
+pub const Error = error{
     UnsupportedProtocol,
     FailedInit,
     UrlMalformat,
@@ -201,7 +201,7 @@ pub fn fromCode(code: c.CURLcode) Error {
     };
 }
 
-pub const Multi = error {
+pub const Multi = error{
     BadHandle,
     BadEasyHandle,
     OutOfMemory,