Move page.wait to session.wait

page.wait is the only significant difference between the "root" page and a page
for an iframe. I think it's more explicit to move this out of the page and
into the session, which was already the sole entry-point for page.wait.

src/browser/Page.zig

@@ -942,6 +942,7 @@ fn clearTransferArena(self: *Page) void {
     self.arena_pool.reset(self._session.transfer_arena, 4 * 1024);
 }
 
+<<<<<<< HEAD
 pub fn wait(self: *Page, wait_ms: u32) Session.WaitResult {
     return self._wait(wait_ms) catch |err| {
         switch (err) {
@@ -1173,6 +1174,8 @@ fn printWaitAnalysis(self: *Page) void {
     }
 }
 
+=======
+>>>>>>> 3bd80eb3 (Move page.wait to session.wait)
 pub fn isGoingAway(self: *const Page) bool {
     return self._queued_navigation != null;
 }
@@ -1565,7 +1568,7 @@ pub fn deliverSlotchangeEvents(self: *Page) void {
     }
 }
 
-fn notifyNetworkIdle(self: *Page) void {
+pub fn notifyNetworkIdle(self: *Page) void {
     lp.assert(self._notified_network_idle == .done, "Page.notifyNetworkIdle", .{});
     self._session.notification.dispatch(.page_network_idle, &.{
         .page_id = self.id,
@@ -1574,7 +1577,7 @@ fn notifyNetworkIdle(self: *Page) void {
     });
 }
 
-fn notifyNetworkAlmostIdle(self: *Page) void {
+pub fn notifyNetworkAlmostIdle(self: *Page) void {
     lp.assert(self._notified_network_almost_idle == .done, "Page.notifyNetworkAlmostIdle", .{});
     self._session.notification.dispatch(.page_network_almost_idle, &.{
         .page_id = self.id,

src/browser/Session.zig

@@ -18,6 +18,7 @@
 
 const std = @import("std");
 const lp = @import("lightpanda");
+const builtin = @import("builtin");
 
 const log = @import("../log.zig");
 
@@ -31,7 +32,7 @@ const Browser = @import("Browser.zig");
 const Notification = @import("../Notification.zig");
 
 const Allocator = std.mem.Allocator;
-const IS_DEBUG = @import("builtin").mode == .Debug;
+const IS_DEBUG = builtin.mode == .Debug;
 
 // Session is like a browser's tab.
 // It owns the js env and the loader for all the pages of the session.
@@ -176,26 +177,167 @@ pub fn findPage(self: *Session, id: u32) ?*Page {
 }
 
 pub fn wait(self: *Session, wait_ms: u32) WaitResult {
+    var page = &(self.page orelse return .no_page);
     while (true) {
-        if (self.page) |*page| {
-            switch (page.wait(wait_ms)) {
-                .done => {
-                    if (page._queued_navigation == null) {
-                        return .done;
-                    }
-                    self.processScheduledNavigation() catch return .done;
-                },
-                else => |result| return result,
+        const wait_result = self._wait(page, wait_ms) catch |err| {
+            switch (err) {
+                error.JsError => {}, // already logged (with hopefully more context)
+                else => log.err(.browser, "session wait", .{ .err = err, }),
             }
-        } else {
-            return .no_page;
+            return .done;
+        };
+
+        switch (wait_result) {
+            .done => {
+                if (page._queued_navigation == null) {
+                    return .done;
+                }
+                page = self.processScheduledNavigation() catch return .done;
+            },
+            else => |result| return result,
         }
-        // if we've successfull navigated, we'll give the new page another
-        // page.wait(wait_ms)
     }
 }
 
-fn processScheduledNavigation(self: *Session) !void {
+fn _wait(self: *Session, page: *Page, wait_ms: u32) !WaitResult {
+    var timer = try std.time.Timer.start();
+    var ms_remaining = wait_ms;
+
+    const browser = self.browser;
+    var http_client = browser.http_client;
+
+    // I'd like the page to know NOTHING about cdp_socket / CDP, but the
+    // fact is that the behavior of wait changes depending on whether or
+    // not we're using CDP.
+    // If we aren't using CDP, as soon as we think there's nothing left
+    // to do, we can exit - we'de done.
+    // But if we are using CDP, we should wait for the whole `wait_ms`
+    // because the http_click.tick() also monitors the CDP socket. And while
+    // we could let CDP poll http (like it does for HTTP requests), the fact
+    // is that we know more about the timing of stuff (e.g. how long to
+    // poll/sleep) in the page.
+    const exit_when_done = http_client.cdp_client == null;
+
+    while (true) {
+        switch (page._parse_state) {
+            .pre, .raw, .text, .image => {
+                // The main page hasn't started/finished navigating.
+                // There's no JS to run, and no reason to run the scheduler.
+                if (http_client.active == 0 and exit_when_done) {
+                    // haven't started navigating, I guess.
+                    return .done;
+                }
+                // Either we have active http connections, or we're in CDP
+                // mode with an extra socket. Either way, we're waiting
+                // for http traffic
+                if (try http_client.tick(@intCast(ms_remaining)) == .cdp_socket) {
+                    // exit_when_done is explicitly set when there isn't
+                    // an extra socket, so it should not be possibl to
+                    // get an cdp_socket message when exit_when_done
+                    // is true.
+                    if (IS_DEBUG) {
+                        std.debug.assert(exit_when_done == false);
+                    }
+
+                    // data on a socket we aren't handling, return to caller
+                    return .cdp_socket;
+                }
+            },
+            .html, .complete => {
+                if (page._queued_navigation != null) {
+                    return .done;
+                }
+
+                // The HTML page was parsed. We now either have JS scripts to
+                // download, or scheduled tasks to execute, or both.
+
+                // scheduler.run could trigger new http transfers, so do not
+                // store http_client.active BEFORE this call and then use
+                // it AFTER.
+                const ms_to_next_task = try browser.runMacrotasks();
+
+                const http_active = http_client.active;
+                const total_network_activity = http_active + http_client.intercepted;
+                if (page._notified_network_almost_idle.check(total_network_activity <= 2)) {
+                    page.notifyNetworkAlmostIdle();
+                }
+                if (page._notified_network_idle.check(total_network_activity == 0)) {
+                    page.notifyNetworkIdle();
+                }
+
+                if (http_active == 0 and exit_when_done) {
+                    // we don't need to consider http_client.intercepted here
+                    // because exit_when_done is true, and that can only be
+                    // the case when interception isn't possible.
+                    if (comptime IS_DEBUG) {
+                        std.debug.assert(http_client.intercepted == 0);
+                    }
+
+                    const ms = ms_to_next_task orelse blk: {
+                        if (wait_ms - ms_remaining < 100) {
+                            if (comptime builtin.is_test) {
+                                return .done;
+                            }
+                            // Look, we want to exit ASAP, but we don't want
+                            // to exit so fast that we've run none of the
+                            // background jobs.
+                            break :blk 50;
+                        }
+                        // No http transfers, no cdp extra socket, no
+                        // scheduled tasks, we're done.
+                        return .done;
+                    };
+
+                    if (ms > ms_remaining) {
+                        // Same as above, except we have a scheduled task,
+                        // it just happens to be too far into the future
+                        // compared to how long we were told to wait.
+                        return .done;
+                    }
+
+                    // We have a task to run in the not-so-distant future.
+                    // You might think we can just sleep until that task is
+                    // ready, but we should continue to run lowPriority tasks
+                    // in the meantime, and that could unblock things. So
+                    // we'll just sleep for a bit, and then restart our wait
+                    // loop to see if anything new can be processed.
+                    std.Thread.sleep(std.time.ns_per_ms * @as(u64, @intCast(@min(ms, 20))));
+                } else {
+                    // We're here because we either have active HTTP
+                    // connections, or exit_when_done == false (aka, there's
+                    // an cdp_socket registered with the http client).
+                    // We should continue to run lowPriority tasks, so we
+                    // minimize how long we'll poll for network I/O.
+                    const ms_to_wait = @min(200, @min(ms_remaining, ms_to_next_task orelse 200));
+                    if (try http_client.tick(ms_to_wait) == .cdp_socket) {
+                        // data on a socket we aren't handling, return to caller
+                        return .cdp_socket;
+                    }
+                }
+            },
+            .err => |err| {
+                page._parse_state = .{ .raw_done = @errorName(err) };
+                return err;
+            },
+            .raw_done => {
+                if (exit_when_done) {
+                    return .done;
+                }
+                // we _could_ http_client.tick(ms_to_wait), but this has
+                // the same result, and I feel is more correct.
+                return .no_page;
+            },
+        }
+
+        const ms_elapsed = timer.lap() / 1_000_000;
+        if (ms_elapsed >= ms_remaining) {
+            return .done;
+        }
+        ms_remaining -= @intCast(ms_elapsed);
+    }
+}
+
+fn processScheduledNavigation(self: *Session) !*Page {
     defer self.browser.arena_pool.reset(self.transfer_arena, 4 * 1024);
     const url, const opts, const page_id = blk: {
         const page = self.page.?;
@@ -226,4 +368,6 @@ fn processScheduledNavigation(self: *Session) !void {
         log.err(.browser, "queued navigation error", .{ .err = err, .url = url });
         return err;
     };
+
+    return page;
 }

src/main_wpt.zig

@@ -126,7 +126,7 @@ fn run(
     const url = try std.fmt.allocPrintSentinel(arena, "http://localhost:9582/{s}", .{test_file}, 0);
     try page.navigate(url, .{});
 
-    _ = page.wait(2000);
+    _ = session.wait(2000);
 
     var ls: lp.js.Local.Scope = undefined;
     page.js.localScope(&ls);