From 26a029d407be480d791972afb5975cf62c9360a6 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Fri, 19 Apr 2024 02:47:55 +0200 Subject: Adding upstream version 124.0.1. Signed-off-by: Daniel Baumann --- .../style/gecko_bindings/sugar/refptr.rs | 289 +++++++++++++++++++++ 1 file changed, 289 insertions(+) create mode 100644 servo/components/style/gecko_bindings/sugar/refptr.rs (limited to 'servo/components/style/gecko_bindings/sugar/refptr.rs') diff --git a/servo/components/style/gecko_bindings/sugar/refptr.rs b/servo/components/style/gecko_bindings/sugar/refptr.rs new file mode 100644 index 0000000000..c4a0479a07 --- /dev/null +++ b/servo/components/style/gecko_bindings/sugar/refptr.rs @@ -0,0 +1,289 @@ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at https://mozilla.org/MPL/2.0/. */ + +//! A rust helper to ease the use of Gecko's refcounted types. + +use crate::gecko_bindings::{bindings, structs}; +use crate::Atom; +use servo_arc::Arc; +use std::fmt::Write; +use std::marker::PhantomData; +use std::ops::Deref; +use std::{fmt, mem, ptr}; + +/// Trait for all objects that have Addref() and Release +/// methods and can be placed inside RefPtr +pub unsafe trait RefCounted { + /// Bump the reference count. + fn addref(&self); + /// Decrease the reference count. + unsafe fn release(&self); +} + +/// Trait for types which can be shared across threads in RefPtr. +pub unsafe trait ThreadSafeRefCounted: RefCounted {} + +/// A custom RefPtr implementation to take into account Drop semantics and +/// a bit less-painful memory management. +pub struct RefPtr { + ptr: *mut T, + _marker: PhantomData, +} + +impl fmt::Debug for RefPtr { + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + f.write_str("RefPtr { ")?; + self.ptr.fmt(f)?; + f.write_char('}') + } +} + +impl RefPtr { + /// Create a new RefPtr from an already addrefed pointer obtained from FFI. + /// + /// The pointer must be valid, non-null and have been addrefed. + pub unsafe fn from_addrefed(ptr: *mut T) -> Self { + debug_assert!(!ptr.is_null()); + RefPtr { + ptr, + _marker: PhantomData, + } + } + + /// Returns whether the current pointer is null. + pub fn is_null(&self) -> bool { + self.ptr.is_null() + } + + /// Returns a null pointer. + pub fn null() -> Self { + Self { + ptr: ptr::null_mut(), + _marker: PhantomData, + } + } + + /// Create a new RefPtr from a pointer obtained from FFI. + /// + /// This method calls addref() internally + pub unsafe fn new(ptr: *mut T) -> Self { + let ret = RefPtr { + ptr, + _marker: PhantomData, + }; + ret.addref(); + ret + } + + /// Produces an FFI-compatible RefPtr that can be stored in style structs. + /// + /// structs::RefPtr does not have a destructor, so this may leak + pub fn forget(self) -> structs::RefPtr { + let ret = structs::RefPtr { + mRawPtr: self.ptr, + _phantom_0: PhantomData, + }; + mem::forget(self); + ret + } + + /// Returns the raw inner pointer to be fed back into FFI. + pub fn get(&self) -> *mut T { + self.ptr + } + + /// Addref the inner data, obviously leaky on its own. + pub fn addref(&self) { + if !self.ptr.is_null() { + unsafe { + (*self.ptr).addref(); + } + } + } + + /// Release the inner data. + /// + /// Call only when the data actually needs releasing. + pub unsafe fn release(&self) { + if !self.ptr.is_null() { + (*self.ptr).release(); + } + } +} + +impl Deref for RefPtr { + type Target = T; + fn deref(&self) -> &T { + debug_assert!(!self.ptr.is_null()); + unsafe { &*self.ptr } + } +} + +impl structs::RefPtr { + /// Produces a Rust-side RefPtr from an FFI RefPtr, bumping the refcount. + /// + /// Must be called on a valid, non-null structs::RefPtr. + pub unsafe fn to_safe(&self) -> RefPtr { + let r = RefPtr { + ptr: self.mRawPtr, + _marker: PhantomData, + }; + r.addref(); + r + } + /// Produces a Rust-side RefPtr, consuming the existing one (and not bumping + /// the refcount). + pub unsafe fn into_safe(self) -> RefPtr { + debug_assert!(!self.mRawPtr.is_null()); + RefPtr { + ptr: self.mRawPtr, + _marker: PhantomData, + } + } + + /// Replace a structs::RefPtr with a different one, appropriately + /// addref/releasing. + /// + /// Both `self` and `other` must be valid, but can be null. + /// + /// Safe when called on an aliased pointer because the refcount in that case + /// needs to be at least two. + pub unsafe fn set(&mut self, other: &Self) { + self.clear(); + if !other.mRawPtr.is_null() { + *self = other.to_safe().forget(); + } + } + + /// Clear an instance of the structs::RefPtr, by releasing + /// it and setting its contents to null. + /// + /// `self` must be valid, but can be null. + pub unsafe fn clear(&mut self) { + if !self.mRawPtr.is_null() { + (*self.mRawPtr).release(); + self.mRawPtr = ptr::null_mut(); + } + } + + /// Replace a `structs::RefPtr` with a `RefPtr`, + /// consuming the `RefPtr`, and releasing the old + /// value in `self` if necessary. + /// + /// `self` must be valid, possibly null. + pub fn set_move(&mut self, other: RefPtr) { + if !self.mRawPtr.is_null() { + unsafe { + (*self.mRawPtr).release(); + } + } + *self = other.forget(); + } +} + +impl structs::RefPtr { + /// Returns a new, null refptr. + pub fn null() -> Self { + Self { + mRawPtr: ptr::null_mut(), + _phantom_0: PhantomData, + } + } + + /// Create a new RefPtr from an arc. + pub fn from_arc(s: Arc) -> Self { + Self { + mRawPtr: Arc::into_raw(s) as *mut _, + _phantom_0: PhantomData, + } + } + + /// Sets the contents to an Arc. + pub fn set_arc(&mut self, other: Arc) { + unsafe { + if !self.mRawPtr.is_null() { + let _ = Arc::from_raw(self.mRawPtr); + } + self.mRawPtr = Arc::into_raw(other) as *mut _; + } + } +} + +impl Drop for RefPtr { + fn drop(&mut self) { + unsafe { self.release() } + } +} + +impl Clone for RefPtr { + fn clone(&self) -> Self { + self.addref(); + RefPtr { + ptr: self.ptr, + _marker: PhantomData, + } + } +} + +impl PartialEq for RefPtr { + fn eq(&self, other: &Self) -> bool { + self.ptr == other.ptr + } +} + +unsafe impl Send for RefPtr {} +unsafe impl Sync for RefPtr {} + +macro_rules! impl_refcount { + ($t:ty, $addref:path, $release:path) => { + unsafe impl RefCounted for $t { + #[inline] + fn addref(&self) { + unsafe { $addref(self as *const _ as *mut _) } + } + + #[inline] + unsafe fn release(&self) { + $release(self as *const _ as *mut _) + } + } + }; +} + +// Companion of NS_DECL_THREADSAFE_FFI_REFCOUNTING. +// +// Gets you a free RefCounted impl implemented via FFI. +macro_rules! impl_threadsafe_refcount { + ($t:ty, $addref:path, $release:path) => { + impl_refcount!($t, $addref, $release); + unsafe impl ThreadSafeRefCounted for $t {} + }; +} + +impl_threadsafe_refcount!( + structs::mozilla::URLExtraData, + bindings::Gecko_AddRefURLExtraDataArbitraryThread, + bindings::Gecko_ReleaseURLExtraDataArbitraryThread +); +impl_threadsafe_refcount!( + structs::nsIURI, + bindings::Gecko_AddRefnsIURIArbitraryThread, + bindings::Gecko_ReleasensIURIArbitraryThread +); +impl_threadsafe_refcount!( + structs::SheetLoadDataHolder, + bindings::Gecko_AddRefSheetLoadDataHolderArbitraryThread, + bindings::Gecko_ReleaseSheetLoadDataHolderArbitraryThread +); + +#[inline] +unsafe fn addref_atom(atom: *mut structs::nsAtom) { + mem::forget(Atom::from_raw(atom)); +} + +#[inline] +unsafe fn release_atom(atom: *mut structs::nsAtom) { + let _ = Atom::from_addrefed(atom); +} +impl_threadsafe_refcount!(structs::nsAtom, addref_atom, release_atom); -- cgit v1.2.3