Fix: Read browser memory in place in the tab strip, app window and browser readers

rivet/runtime/windows/src/browser/chromium.rs

@@ -104,6 +104,10 @@ impl TabMoves for Chromium {
 fn read_word(address: usize) -> Option<usize> {
     use windows_sys::Win32::System::Diagnostics::Debug::ReadProcessMemory;
     use windows_sys::Win32::System::Threading::GetCurrentProcess;
+    // A word known readable is read in place, without a system call.
+    if let Some(value) = crate::chromium::memory::read_word(address) {
+        return Some(value);
+    }
     let mut value = 0usize;
     let mut done = 0usize;
     // ReadProcessMemory fails, instead of faulting, on an address that is not mapped.

rivet/runtime/windows/src/features/app_window.rs

@@ -402,6 +402,9 @@ pub(crate) unsafe fn flip_new_tab(window: HWND, offsets: &[usize]) -> bool {
 unsafe fn safe_word(address: usize) -> Option<usize> {
     use windows_sys::Win32::System::Diagnostics::Debug::ReadProcessMemory;
     use windows_sys::Win32::System::Threading::GetCurrentProcess;
+    if let Some(value) = crate::chromium::memory::read_word(address) {
+        return Some(value);
+    }
     let mut value = 0usize;
     let mut done = 0usize;
     let ok = ReadProcessMemory(

rivet/runtime/windows/src/features/tab_strip.rs

@@ -147,6 +147,11 @@ const BOUNDS: usize = 0x1C0;
 /// A word of memory that may not belong to a view, read so that a wrong guess cannot fault.
 unsafe fn read(address: usize, bytes: usize, out: *mut u8) -> bool {
     use windows_sys::Win32::System::Diagnostics::Debug::ReadProcessMemory;
+    // Memory known readable is copied in place, without a system call for every word.
+    if address > 0x10000 && crate::chromium::memory::readable(address, bytes) {
+        std::ptr::copy_nonoverlapping(address as *const u8, out, bytes);
+        return true;
+    }
     address > 0x10000
         && ReadProcessMemory(
             windows_sys::Win32::System::Threading::GetCurrentProcess(),

rivet/runtime/windows/src/frame.rs

@@ -3125,19 +3125,25 @@ pub(crate) unsafe fn update_top_bar(window: HWND) {
     if crate::features::address_bar::busy() {
         return;
     }
+    let mut laps = Laps::start();
     let dpi = layout_dpi(window);
     let top_bar = if framed(window) {
         crate::features::address_bar::view(window)
     } else {
         None
     };
+    laps.mark("view");
     APPBARS.with(|appbars| {
         if let Some(appbar) = appbars.borrow_mut().get_mut(&(window as isize)) {
             if let Err(error) = appbar.update_address(window as isize, top_bar.as_ref(), dpi) {
                 log(&format!("rivet: could not draw the top bar: {error}"));
             }
         }
     });
+    laps.mark("paint");
+    if laps.total_us() >= SLOW_UPDATE_US && crate::trace::tracing() {
+        crate::trace::trace(&laps.line().replacen("appbar:", "top bar:", 1));
+    }
 }
 
 /// The steps of one surface update and how long each took, in microseconds.