Bug 1633410 - Back out bug 1631721.

Rebased and squashed.

Differential Revision: https://phabricator.services.mozilla.com/D78174

Cargo.lock

@@ -1275,7 +1275,7 @@ checksum = "e88a8acf291dafb59c2d96e8f59828f3838bb1a70398823ade51a84de6a6deed"
 name = "fallible"
 version = "0.0.1"
 dependencies = [
- "hashbrown",
+ "hashglobe",
  "smallvec",
 ]
 
@@ -2064,6 +2064,13 @@ dependencies = [
  "autocfg 1.0.0",
 ]
 
+[[package]]
+name = "hashglobe"
+version = "0.1.0"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "hawk"
 version = "3.1.1"
@@ -2709,7 +2716,7 @@ dependencies = [
  "app_units",
  "cssparser",
  "euclid",
- "hashbrown",
+ "hashglobe",
  "selectors",
  "servo_arc",
  "smallbitvec",
@@ -4529,6 +4536,7 @@ dependencies = [
  "fallible",
  "fxhash",
  "hashbrown",
+ "hashglobe",
  "indexmap",
  "itertools",
  "itoa",

servo/components/fallible/Cargo.toml

@@ -10,5 +10,16 @@ name = "fallible"
 path = "lib.rs"
 
 [dependencies]
-hashbrown = "0.7"
+hashglobe = { path = "../hashglobe" }
 smallvec = "1.0"
+
+# This crate effectively does nothing except if the `known_system_malloc`
+# feature is specified.
+#
+# In that case, we actually call the system malloc functions to reserve space,
+# otherwise we just let rust do its thing (aborting on OOM).
+#
+# This is effectively a stop-gap measure until we can do this properly in
+# stable rust.
+[features]
+known_system_malloc = []

servo/components/fallible/lib.rs

@@ -2,61 +2,20 @@
  * 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/. */
 
-extern crate hashbrown;
+extern crate hashglobe;
 extern crate smallvec;
 
-use hashbrown::hash_map::Entry;
-use hashbrown::CollectionAllocErr;
+#[cfg(feature = "known_system_malloc")]
+use hashglobe::alloc;
+use hashglobe::FailedAllocationError;
 use smallvec::Array;
 use smallvec::SmallVec;
-use std::alloc::{self, Layout};
-use std::mem;
-use std::ptr::copy_nonoverlapping;
 use std::vec::Vec;
 
 pub trait FallibleVec<T> {
     /// Append |val| to the end of |vec|.  Returns Ok(()) on success,
     /// Err(reason) if it fails, with |reason| describing the failure.
-    fn try_push(&mut self, value: T) -> Result<(), CollectionAllocErr>;
-}
-
-pub trait FallibleHashMap<K, V, H> {
-    fn try_insert(&mut self, k: K, v: V) -> Result<Option<V>, CollectionAllocErr>;
-    fn try_entry(&mut self, k: K) -> Result<Entry<K, V, H>, CollectionAllocErr>;
-}
-
-pub trait FallibleHashSet<T, H> {
-    fn try_insert(&mut self, x: T) -> Result<bool, CollectionAllocErr>;
-}
-
-impl<K, V, H> FallibleHashMap<K, V, H> for hashbrown::HashMap<K, V, H>
-where
-    K: Eq + std::hash::Hash,
-    H: std::hash::BuildHasher,
-{
-    #[inline]
-    fn try_insert(&mut self, k: K, v: V) -> Result<Option<V>, CollectionAllocErr> {
-        self.try_reserve(1)?;
-        Ok(self.insert(k, v))
-    }
-
-    #[inline]
-    fn try_entry(&mut self, k: K) -> Result<Entry<K, V, H>, CollectionAllocErr> {
-        self.try_reserve(1)?;
-        Ok(self.entry(k))
-    }
-}
-
-impl<T, H> FallibleHashSet<T, H> for hashbrown::HashSet<T, H>
-where
-    T: Eq + std::hash::Hash,
-    H: std::hash::BuildHasher,
-{
-    #[inline]
-    fn try_insert(&mut self, x: T) -> Result<bool, CollectionAllocErr> {
-        self.try_reserve(1)?;
-        Ok(self.insert(x))
-    }
+    fn try_push(&mut self, value: T) -> Result<(), FailedAllocationError>;
 }
 
 /////////////////////////////////////////////////////////////////
@@ -64,30 +23,26 @@ where
 
 impl<T> FallibleVec<T> for Vec<T> {
     #[inline(always)]
-    fn try_push(&mut self, val: T) -> Result<(), CollectionAllocErr> {
-        if self.capacity() == self.len() {
-            try_double_vec(self)?;
-            debug_assert!(self.capacity() > self.len());
+    fn try_push(&mut self, val: T) -> Result<(), FailedAllocationError> {
+        #[cfg(feature = "known_system_malloc")]
+        {
+            if self.capacity() == self.len() {
+                try_double_vec(self)?;
+                debug_assert!(self.capacity() > self.len());
+            }
         }
         self.push(val);
         Ok(())
     }
 }
 
-/// FIXME: use `Layout::array` when it’s stable https://github.com/rust-lang/rust/issues/55724
-fn layout_array<T>(n: usize) -> Result<Layout, CollectionAllocErr> {
-    let size = n.checked_mul(mem::size_of::<T>())
-        .ok_or(CollectionAllocErr::CapacityOverflow)?;
-    let align = std::mem::align_of::<T>();
-    Layout::from_size_align(size, align)
-        .map_err(|_| CollectionAllocErr::CapacityOverflow)
-}
-
 // Double the capacity of |vec|, or fail to do so due to lack of memory.
 // Returns Ok(()) on success, Err(..) on failure.
+#[cfg(feature = "known_system_malloc")]
 #[inline(never)]
 #[cold]
-fn try_double_vec<T>(vec: &mut Vec<T>) -> Result<(), CollectionAllocErr> {
+fn try_double_vec<T>(vec: &mut Vec<T>) -> Result<(), FailedAllocationError> {
+    use std::mem;
 
     let old_ptr = vec.as_mut_ptr();
     let old_len = vec.len();
@@ -98,22 +53,25 @@ fn try_double_vec<T>(vec: &mut Vec<T>) -> Result<(), CollectionAllocErr> {
     } else {
         old_cap
             .checked_mul(2)
-            .ok_or(CollectionAllocErr::CapacityOverflow)?
+            .ok_or(FailedAllocationError::new("capacity overflow for Vec"))?
     };
 
-    let old_layout = layout_array::<T>(old_cap)?;
-    let new_layout = layout_array::<T>(new_cap)?;
+    let new_size_bytes = new_cap
+        .checked_mul(mem::size_of::<T>())
+        .ok_or(FailedAllocationError::new("capacity overflow for Vec"))?;
 
     let new_ptr = unsafe {
         if old_cap == 0 {
-            alloc::alloc(new_layout)
+            alloc::alloc(new_size_bytes, 0)
         } else {
-            alloc::realloc(old_ptr as *mut u8, old_layout, new_layout.size())
+            alloc::realloc(old_ptr as *mut u8, new_size_bytes)
         }
     };
 
     if new_ptr.is_null() {
-        return Err(CollectionAllocErr::AllocErr { layout: new_layout });
+        return Err(FailedAllocationError::new(
+            "out of memory when allocating Vec",
+        ));
     }
 
     let new_vec = unsafe { Vec::from_raw_parts(new_ptr as *mut T, old_len, new_cap) };
@@ -127,10 +85,13 @@ fn try_double_vec<T>(vec: &mut Vec<T>) -> Result<(), CollectionAllocErr> {
 
 impl<T: Array> FallibleVec<T::Item> for SmallVec<T> {
     #[inline(always)]
-    fn try_push(&mut self, val: T::Item) -> Result<(), CollectionAllocErr> {
-        if self.capacity() == self.len() {
-            try_double_small_vec(self)?;
-            debug_assert!(self.capacity() > self.len());
+    fn try_push(&mut self, val: T::Item) -> Result<(), FailedAllocationError> {
+        #[cfg(feature = "known_system_malloc")]
+        {
+            if self.capacity() == self.len() {
+                try_double_small_vec(self)?;
+                debug_assert!(self.capacity() > self.len());
+            }
         }
         self.push(val);
         Ok(())
@@ -139,12 +100,16 @@ impl<T: Array> FallibleVec<T::Item> for SmallVec<T> {
 
 // Double the capacity of |svec|, or fail to do so due to lack of memory.
 // Returns Ok(()) on success, Err(..) on failure.
+#[cfg(feature = "known_system_malloc")]
 #[inline(never)]
 #[cold]
-fn try_double_small_vec<T>(svec: &mut SmallVec<T>) -> Result<(), CollectionAllocErr>
+fn try_double_small_vec<T>(svec: &mut SmallVec<T>) -> Result<(), FailedAllocationError>
 where
     T: Array,
 {
+    use std::mem;
+    use std::ptr::copy_nonoverlapping;
+
     let old_ptr = svec.as_mut_ptr();
     let old_len = svec.len();
 
@@ -154,33 +119,40 @@ where
     } else {
         old_cap
             .checked_mul(2)
-            .ok_or(CollectionAllocErr::CapacityOverflow)?
+            .ok_or(FailedAllocationError::new("capacity overflow for SmallVec"))?
     };
 
     // This surely shouldn't fail, if |old_cap| was previously accepted as a
     // valid value.  But err on the side of caution.
-    let old_layout = layout_array::<T>(old_cap)?;
-    let new_layout = layout_array::<T>(new_cap)?;
+    let old_size_bytes = old_cap
+        .checked_mul(mem::size_of::<T>())
+        .ok_or(FailedAllocationError::new("capacity overflow for SmallVec"))?;
+
+    let new_size_bytes = new_cap
+        .checked_mul(mem::size_of::<T>())
+        .ok_or(FailedAllocationError::new("capacity overflow for SmallVec"))?;
 
     let new_ptr;
     if svec.spilled() {
         // There's an old block to free, and, presumably, old contents to
         // copy.  realloc takes care of both aspects.
         unsafe {
-            new_ptr = alloc::realloc(old_ptr as *mut u8, old_layout, new_layout.size());
+            new_ptr = alloc::realloc(old_ptr as *mut u8, new_size_bytes);
         }
     } else {
         // There's no old block to free.  There may be old contents to copy.
         unsafe {
-            new_ptr = alloc::alloc(new_layout);
-            if !new_ptr.is_null() && old_layout.size() > 0 {
-                copy_nonoverlapping(old_ptr as *const u8, new_ptr as *mut u8, old_layout.size());
+            new_ptr = alloc::alloc(new_size_bytes, 0);
+            if !new_ptr.is_null() && old_size_bytes > 0 {
+                copy_nonoverlapping(old_ptr as *const u8, new_ptr as *mut u8, old_size_bytes);
             }
         }
     }
 
     if new_ptr.is_null() {
-        return Err(CollectionAllocErr::AllocErr { layout: new_layout });
+        return Err(FailedAllocationError::new(
+            "out of memory when allocating SmallVec",
+        ));
     }
 
     let new_vec = unsafe { Vec::from_raw_parts(new_ptr as *mut T::Item, old_len, new_cap) };

servo/components/hashglobe/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "hashglobe"
+version = "0.1.0"
+authors = ["The Rust Project Developers", "Manish Goregaokar <manishsmail@gmail.com>"]
+license = "MIT/Apache-2.0"
+description = "Fork of std::HashMap with stable fallible allocation."
+documentation = "https://docs.rs/hashglobe"
+repository = "https://github.com/Manishearth/hashglobe"
+
+readme = "README.md"
+
+[dependencies]
+libc = "0.2"
+
+[dev-dependencies]
+rand = "0.7"

servo/components/hashglobe/LICENSE-APACHE

@@ -0,0 +1,201 @@
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servo/components/hashglobe/LICENSE-MIT

@@ -0,0 +1,23 @@
+Permission is hereby granted, free of charge, to any
+person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the
+Software without restriction, including without
+limitation the rights to use, copy, modify, merge,
+publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software
+is furnished to do so, subject to the following
+conditions:
+
+The above copyright notice and this permission notice
+shall be included in all copies or substantial portions
+of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.

servo/components/hashglobe/README.md

@@ -0,0 +1,17 @@
+hashglobe
+========
+
+
+This is a fork of Rust's `std::HashMap`. It works on stable out of the stdlib and has fallible APIs.
+
+We intend to diverge as little as possible from the original hashmap.
+
+
+Dual licensed Apache/MIT, the same as the stdlib.
+
+
+## Should I use this?
+
+No.
+
+Wait for https://github.com/rust-lang/rfcs/pull/2116 instead.

servo/components/hashglobe/src/alloc.rs

@@ -0,0 +1,161 @@
+// FORK NOTE: Copied from liballoc_system, removed unnecessary APIs,
+// APIs take size/align directly instead of Layout
+
+// The minimum alignment guaranteed by the architecture. This value is used to
+// add fast paths for low alignment values. In practice, the alignment is a
+// constant at the call site and the branch will be optimized out.
+#[cfg(all(any(
+    target_arch = "x86",
+    target_arch = "arm",
+    target_arch = "mips",
+    target_arch = "powerpc",
+    target_arch = "powerpc64",
+    target_arch = "asmjs",
+    target_arch = "wasm32"
+)))]
+const MIN_ALIGN: usize = 8;
+#[cfg(all(any(
+    target_arch = "x86_64",
+    target_arch = "aarch64",
+    target_arch = "mips64",
+    target_arch = "s390x",
+    target_arch = "sparc64"
+)))]
+const MIN_ALIGN: usize = 16;
+
+pub use self::platform::{alloc, dealloc, realloc};
+
+#[cfg(any(unix, target_os = "redox"))]
+mod platform {
+    extern crate libc;
+
+    #[cfg(not(any(target_os = "android")))]
+    use std::ptr;
+
+    use super::MIN_ALIGN;
+
+    #[inline]
+    pub unsafe fn alloc(size: usize, align: usize) -> *mut u8 {
+        let ptr = if align <= MIN_ALIGN {
+            libc::malloc(size) as *mut u8
+        } else {
+            aligned_malloc(size, align)
+        };
+        ptr
+    }
+
+    #[inline]
+    pub unsafe fn dealloc(ptr: *mut u8, _align: usize) {
+        libc::free(ptr as *mut libc::c_void)
+    }
+
+    #[inline]
+    pub unsafe fn realloc(ptr: *mut u8, new_size: usize) -> *mut u8 {
+        libc::realloc(ptr as *mut libc::c_void, new_size) as *mut u8
+    }
+
+    #[cfg(any(target_os = "android", target_os = "redox"))]
+    #[inline]
+    unsafe fn aligned_malloc(size: usize, align: usize) -> *mut u8 {
+        // On android we currently target API level 9 which unfortunately
+        // doesn't have the `posix_memalign` API used below. Instead we use
+        // `memalign`, but this unfortunately has the property on some systems
+        // where the memory returned cannot be deallocated by `free`!
+        //
+        // Upon closer inspection, however, this appears to work just fine with
+        // Android, so for this platform we should be fine to call `memalign`
+        // (which is present in API level 9). Some helpful references could
+        // possibly be chromium using memalign [1], attempts at documenting that
+        // memalign + free is ok [2] [3], or the current source of chromium
+        // which still uses memalign on android [4].
+        //
+        // [1]: https://codereview.chromium.org/10796020/
+        // [2]: https://code.google.com/p/android/issues/detail?id=35391
+        // [3]: https://bugs.chromium.org/p/chromium/issues/detail?id=138579
+        // [4]: https://chromium.googlesource.com/chromium/src/base/+/master/
+        //                                       /memory/aligned_memory.cc
+        libc::memalign(align, size) as *mut u8
+    }
+
+    #[cfg(not(any(target_os = "android", target_os = "redox")))]
+    #[inline]
+    unsafe fn aligned_malloc(size: usize, align: usize) -> *mut u8 {
+        let mut out = ptr::null_mut();
+        let ret = libc::posix_memalign(&mut out, align, size);
+        if ret != 0 {
+            ptr::null_mut()
+        } else {
+            out as *mut u8
+        }
+    }
+}
+
+#[cfg(windows)]
+#[allow(bad_style)]
+mod platform {
+
+    use super::MIN_ALIGN;
+    type LPVOID = *mut u8;
+    type HANDLE = LPVOID;
+    type SIZE_T = usize;
+    type DWORD = u32;
+    type BOOL = i32;
+
+    extern "system" {
+        fn GetProcessHeap() -> HANDLE;
+        fn HeapAlloc(hHeap: HANDLE, dwFlags: DWORD, dwBytes: SIZE_T) -> LPVOID;
+        fn HeapReAlloc(hHeap: HANDLE, dwFlags: DWORD, lpMem: LPVOID, dwBytes: SIZE_T) -> LPVOID;
+        fn HeapFree(hHeap: HANDLE, dwFlags: DWORD, lpMem: LPVOID) -> BOOL;
+        fn GetLastError() -> DWORD;
+    }
+
+    #[repr(C)]
+    struct Header(*mut u8);
+
+    unsafe fn get_header<'a>(ptr: *mut u8) -> &'a mut Header {
+        &mut *(ptr as *mut Header).offset(-1)
+    }
+
+    unsafe fn align_ptr(ptr: *mut u8, align: usize) -> *mut u8 {
+        let aligned = ptr.offset((align - (ptr as usize & (align - 1))) as isize);
+        *get_header(aligned) = Header(ptr);
+        aligned
+    }
+
+    #[inline]
+    unsafe fn allocate_with_flags(size: usize, align: usize, flags: DWORD) -> *mut u8 {
+        if align <= MIN_ALIGN {
+            HeapAlloc(GetProcessHeap(), flags, size)
+        } else {
+            let size = size + align;
+            let ptr = HeapAlloc(GetProcessHeap(), flags, size);
+            if ptr.is_null() {
+                ptr
+            } else {
+                align_ptr(ptr, align)
+            }
+        }
+    }
+
+    #[inline]
+    pub unsafe fn alloc(size: usize, align: usize) -> *mut u8 {
+        allocate_with_flags(size, align, 0)
+    }
+
+    #[inline]
+    pub unsafe fn dealloc(ptr: *mut u8, align: usize) {
+        if align <= MIN_ALIGN {
+            let err = HeapFree(GetProcessHeap(), 0, ptr as LPVOID);
+            debug_assert!(err != 0, "Failed to free heap memory: {}", GetLastError());
+        } else {
+            let header = get_header(ptr);
+            let err = HeapFree(GetProcessHeap(), 0, header.0 as LPVOID);
+            debug_assert!(err != 0, "Failed to free heap memory: {}", GetLastError());
+        }
+    }
+
+    #[inline]
+    pub unsafe fn realloc(ptr: *mut u8, new_size: usize) -> *mut u8 {
+        HeapReAlloc(GetProcessHeap(), 0, ptr as LPVOID, new_size) as *mut u8
+    }
+}

servo/components/hashglobe/src/fake.rs

@@ -0,0 +1,269 @@
+// Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! This module contains shims around the stdlib HashMap
+//! that add fallible methods
+//!
+//! These methods are a lie. They are not actually fallible. This is just to make
+//! it smooth to switch between hashmap impls in a codebase.
+
+use std::collections::HashMap as StdMap;
+use std::collections::HashSet as StdSet;
+use std::fmt;
+use std::hash::{BuildHasher, Hash};
+use std::ops::{Deref, DerefMut};
+
+pub use std::collections::hash_map::{Entry, Iter as MapIter, IterMut as MapIterMut, RandomState};
+pub use std::collections::hash_set::{IntoIter as SetIntoIter, Iter as SetIter};
+
+#[derive(Clone)]
+pub struct HashMap<K, V, S = RandomState>(StdMap<K, V, S>);
+
+use crate::FailedAllocationError;
+
+impl<K, V, S> Deref for HashMap<K, V, S> {
+    type Target = StdMap<K, V, S>;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<K, V, S> DerefMut for HashMap<K, V, S> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+impl<K, V, S> HashMap<K, V, S>
+where
+    K: Eq + Hash,
+    S: BuildHasher,
+{
+    #[inline]
+    pub fn try_with_hasher(hash_builder: S) -> Result<HashMap<K, V, S>, FailedAllocationError> {
+        Ok(HashMap(StdMap::with_hasher(hash_builder)))
+    }
+
+    #[inline]
+    pub fn try_with_capacity_and_hasher(
+        capacity: usize,
+        hash_builder: S,
+    ) -> Result<HashMap<K, V, S>, FailedAllocationError> {
+        Ok(HashMap(StdMap::with_capacity_and_hasher(
+            capacity,
+            hash_builder,
+        )))
+    }
+
+    pub fn with_capacity_and_hasher(capacity: usize, hash_builder: S) -> HashMap<K, V, S> {
+        HashMap(StdMap::with_capacity_and_hasher(capacity, hash_builder))
+    }
+
+    #[inline]
+    pub fn try_reserve(&mut self, additional: usize) -> Result<(), FailedAllocationError> {
+        Ok(self.reserve(additional))
+    }
+
+    pub fn try_shrink_to_fit(&mut self) -> Result<(), FailedAllocationError> {
+        Ok(self.shrink_to_fit())
+    }
+
+    pub fn try_entry(&mut self, key: K) -> Result<Entry<K, V>, FailedAllocationError> {
+        Ok(self.entry(key))
+    }
+
+    #[inline]
+    pub fn try_insert(&mut self, k: K, v: V) -> Result<Option<V>, FailedAllocationError> {
+        Ok(self.insert(k, v))
+    }
+}
+
+#[derive(Clone)]
+pub struct HashSet<T, S = RandomState>(StdSet<T, S>);
+
+impl<T, S> Deref for HashSet<T, S> {
+    type Target = StdSet<T, S>;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<T, S> DerefMut for HashSet<T, S> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+impl<T: Hash + Eq> HashSet<T, RandomState> {
+    #[inline]
+    pub fn new() -> HashSet<T, RandomState> {
+        HashSet(StdSet::new())
+    }
+
+    #[inline]
+    pub fn with_capacity(capacity: usize) -> HashSet<T, RandomState> {
+        HashSet(StdSet::with_capacity(capacity))
+    }
+}
+
+impl<T, S> HashSet<T, S>
+where
+    T: Eq + Hash,
+    S: BuildHasher,
+{
+    #[inline]
+    pub fn with_hasher(hasher: S) -> HashSet<T, S> {
+        HashSet(StdSet::with_hasher(hasher))
+    }
+
+    #[inline]
+    pub fn with_capacity_and_hasher(capacity: usize, hasher: S) -> HashSet<T, S> {
+        HashSet(StdSet::with_capacity_and_hasher(capacity, hasher))
+    }
+
+    #[inline]
+    pub fn try_reserve(&mut self, additional: usize) -> Result<(), FailedAllocationError> {
+        Ok(self.reserve(additional))
+    }
+
+    #[inline]
+    pub fn try_shrink_to_fit(&mut self) -> Result<(), FailedAllocationError> {
+        Ok(self.shrink_to_fit())
+    }
+
+    #[inline]
+    pub fn try_insert(&mut self, value: T) -> Result<bool, FailedAllocationError> {
+        Ok(self.insert(value))
+    }
+}
+
+// Pass through trait impls
+// We can't derive these since the bounds are not obvious to the derive macro
+
+impl<K: Hash + Eq, V, S: BuildHasher + Default> Default for HashMap<K, V, S> {
+    fn default() -> Self {
+        HashMap(Default::default())
+    }
+}
+
+impl<K, V, S> fmt::Debug for HashMap<K, V, S>
+where
+    K: Eq + Hash + fmt::Debug,
+    V: fmt::Debug,
+    S: BuildHasher,
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+impl<K, V, S> PartialEq for HashMap<K, V, S>
+where
+    K: Eq + Hash,
+    V: PartialEq,
+    S: BuildHasher,
+{
+    fn eq(&self, other: &HashMap<K, V, S>) -> bool {
+        self.0.eq(&other.0)
+    }
+}
+
+impl<K, V, S> Eq for HashMap<K, V, S>
+where
+    K: Eq + Hash,
+    V: Eq,
+    S: BuildHasher,
+{
+}
+
+impl<'a, K, V, S> IntoIterator for &'a HashMap<K, V, S>
+where
+    K: Eq + Hash,
+    S: BuildHasher,
+{
+    type Item = (&'a K, &'a V);
+    type IntoIter = MapIter<'a, K, V>;
+
+    fn into_iter(self) -> MapIter<'a, K, V> {
+        self.0.iter()
+    }
+}
+
+impl<'a, K, V, S> IntoIterator for &'a mut HashMap<K, V, S>
+where
+    K: Eq + Hash,
+    S: BuildHasher,
+{
+    type Item = (&'a K, &'a mut V);
+    type IntoIter = MapIterMut<'a, K, V>;
+
+    fn into_iter(self) -> MapIterMut<'a, K, V> {
+        self.0.iter_mut()
+    }
+}
+
+impl<T: Eq + Hash, S: BuildHasher + Default> Default for HashSet<T, S> {
+    fn default() -> Self {
+        HashSet(Default::default())
+    }
+}
+
+impl<T, S> fmt::Debug for HashSet<T, S>
+where
+    T: Eq + Hash + fmt::Debug,
+    S: BuildHasher,
+{
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+impl<T, S> PartialEq for HashSet<T, S>
+where
+    T: Eq + Hash,
+    S: BuildHasher,
+{
+    fn eq(&self, other: &HashSet<T, S>) -> bool {
+        self.0.eq(&other.0)
+    }
+}
+
+impl<T, S> Eq for HashSet<T, S>
+where
+    T: Eq + Hash,
+    S: BuildHasher,
+{
+}
+
+impl<'a, T, S> IntoIterator for &'a HashSet<T, S>
+where
+    T: Eq + Hash,
+    S: BuildHasher,
+{
+    type Item = &'a T;
+    type IntoIter = SetIter<'a, T>;
+
+    fn into_iter(self) -> SetIter<'a, T> {
+        self.0.iter()
+    }
+}
+
+impl<T, S> IntoIterator for HashSet<T, S>
+where
+    T: Eq + Hash,
+    S: BuildHasher,
+{
+    type Item = T;
+    type IntoIter = SetIntoIter<T>;
+
+    fn into_iter(self) -> SetIntoIter<T> {
+        self.0.into_iter()
+    }
+}

servo/components/hashglobe/src/lib.rs

@@ -0,0 +1,71 @@
+// Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+pub mod alloc;
+pub mod hash_map;
+pub mod hash_set;
+mod shim;
+mod table;
+
+pub mod fake;
+
+use std::{error, fmt};
+
+trait Recover<Q: ?Sized> {
+    type Key;
+
+    fn get(&self, key: &Q) -> Option<&Self::Key>;
+    fn take(&mut self, key: &Q) -> Option<Self::Key>;
+    fn replace(&mut self, key: Self::Key) -> Option<Self::Key>;
+}
+
+#[derive(Debug)]
+pub struct AllocationInfo {
+    /// The size we are requesting.
+    size: usize,
+    /// The alignment we are requesting.
+    alignment: usize,
+}
+
+#[derive(Debug)]
+pub struct FailedAllocationError {
+    reason: &'static str,
+    /// The allocation info we are requesting, if needed.
+    allocation_info: Option<AllocationInfo>,
+}
+
+impl FailedAllocationError {
+    #[inline]
+    pub fn new(reason: &'static str) -> Self {
+        Self {
+            reason,
+            allocation_info: None,
+        }
+    }
+}
+
+impl error::Error for FailedAllocationError {
+    fn description(&self) -> &str {
+        self.reason
+    }
+}
+
+impl fmt::Display for FailedAllocationError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self.allocation_info {
+            Some(ref info) => write!(
+                f,
+                "{}, allocation: (size: {}, alignment: {})",
+                self.reason, info.size, info.alignment
+            ),
+            None => self.reason.fmt(f),
+        }
+    }
+}

servo/components/hashglobe/src/shim.rs

@@ -0,0 +1,61 @@
+use std::marker::PhantomData;
+
+// FIXME: remove this and use std::ptr::NonNull when Firefox requires Rust 1.25+
+pub struct NonZeroPtr<T: 'static>(&'static T);
+
+impl<T: 'static> NonZeroPtr<T> {
+    pub unsafe fn new_unchecked(ptr: *mut T) -> Self {
+        NonZeroPtr(&*ptr)
+    }
+    pub fn as_ptr(&self) -> *mut T {
+        self.0 as *const T as *mut T
+    }
+}
+
+pub struct Unique<T: 'static> {
+    ptr: NonZeroPtr<T>,
+    _marker: PhantomData<T>,
+}
+
+impl<T: 'static> Unique<T> {
+    pub unsafe fn new_unchecked(ptr: *mut T) -> Self {
+        Unique {
+            ptr: NonZeroPtr::new_unchecked(ptr),
+            _marker: PhantomData,
+        }
+    }
+    pub fn as_ptr(&self) -> *mut T {
+        self.ptr.as_ptr()
+    }
+}
+
+unsafe impl<T: Send + 'static> Send for Unique<T> {}
+
+unsafe impl<T: Sync + 'static> Sync for Unique<T> {}
+
+pub struct Shared<T: 'static> {
+    ptr: NonZeroPtr<T>,
+    _marker: PhantomData<T>,
+    // force it to be !Send/!Sync
+    _marker2: PhantomData<*const u8>,
+}
+
+impl<T: 'static> Shared<T> {
+    pub unsafe fn new_unchecked(ptr: *mut T) -> Self {
+        Shared {
+            ptr: NonZeroPtr::new_unchecked(ptr),
+            _marker: PhantomData,
+            _marker2: PhantomData,
+        }
+    }
+
+    pub unsafe fn as_mut(&self) -> &mut T {
+        &mut *self.ptr.as_ptr()
+    }
+}
+
+impl<'a, T> From<&'a mut T> for Shared<T> {
+    fn from(reference: &'a mut T) -> Self {
+        unsafe { Shared::new_unchecked(reference) }
+    }
+}

servo/components/malloc_size_of/Cargo.toml

@@ -33,7 +33,7 @@ content-security-policy = { version = "0.4.0", features = ["serde"], optional =
 crossbeam-channel = { version = "0.4", optional = true }
 cssparser = "0.27"
 euclid = "0.20"
-hashbrown = "0.7"
+hashglobe = { path = "../hashglobe" }
 hyper = { version = "0.12", optional = true }
 hyper_serde = { version = "0.11", optional = true }
 keyboard-types = { version = "0.4.3", optional = true }

servo/components/malloc_size_of/lib.rs

@@ -55,7 +55,7 @@ extern crate content_security_policy;
 extern crate crossbeam_channel;
 extern crate cssparser;
 extern crate euclid;
-extern crate hashbrown;
+extern crate hashglobe;
 #[cfg(feature = "servo")]
 extern crate hyper;
 #[cfg(feature = "servo")]
@@ -487,7 +487,8 @@ macro_rules! malloc_size_of_hash_set {
 }
 
 malloc_size_of_hash_set!(std::collections::HashSet<T, S>);
-malloc_size_of_hash_set!(hashbrown::HashSet<T, S>);
+malloc_size_of_hash_set!(hashglobe::hash_set::HashSet<T, S>);
+malloc_size_of_hash_set!(hashglobe::fake::HashSet<T, S>);
 
 macro_rules! malloc_size_of_hash_map {
     ($ty:ty) => {
@@ -527,7 +528,8 @@ macro_rules! malloc_size_of_hash_map {
 }
 
 malloc_size_of_hash_map!(std::collections::HashMap<K, V, S>);
-malloc_size_of_hash_map!(hashbrown::HashMap<K, V, S>);
+malloc_size_of_hash_map!(hashglobe::hash_map::HashMap<K, V, S>);
+malloc_size_of_hash_map!(hashglobe::fake::HashMap<K, V, S>);
 
 impl<K, V> MallocShallowSizeOf for std::collections::BTreeMap<K, V>
 where

servo/components/style/Cargo.toml

@@ -17,7 +17,7 @@ path = "lib.rs"
 doctest = false
 
 [features]
-gecko = ["nsstring", "serde", "style_traits/gecko", "bindgen", "regex", "toml"]
+gecko = ["nsstring", "serde", "style_traits/gecko", "fallible/known_system_malloc", "bindgen", "regex", "toml"]
 servo = ["serde", "style_traits/servo", "servo_atoms", "servo_config", "html5ever",
          "cssparser/serde", "encoding_rs", "malloc_size_of/servo", "arrayvec/use_union",
          "servo_url", "string_cache", "to_shmem/servo", "servo_arc/servo"]
@@ -41,6 +41,7 @@ euclid = "0.20"
 fallible = { path = "../fallible" }
 fxhash = "0.2"
 hashbrown = "0.7"
+hashglobe = { path = "../hashglobe" }
 html5ever = {version = "0.24", optional = true}
 indexmap = "1.0"
 itertools = "0.8"

servo/components/style/hash.rs

@@ -2,11 +2,28 @@
  * 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/. */
 
-//! Reexports of hashbrown, without and with FxHash
+//! Reexports of hashglobe types in Gecko mode, and stdlib hashmap shims in Servo mode
+//!
+//! Can go away when the stdlib gets fallible collections
+//! https://github.com/rust-lang/rfcs/pull/2116
 
 use fxhash;
 
-pub use hashbrown::{hash_map as map, HashMap, HashSet};
+#[cfg(feature = "gecko")]
+pub use hashglobe::hash_map::HashMap;
+#[cfg(feature = "gecko")]
+pub use hashglobe::hash_set::HashSet;
+
+#[cfg(feature = "servo")]
+pub use hashglobe::fake::{HashMap, HashSet};
+
+/// Appropriate reexports of hash_map types
+pub mod map {
+    #[cfg(feature = "gecko")]
+    pub use hashglobe::hash_map::{Entry, Iter};
+    #[cfg(feature = "servo")]
+    pub use std::collections::hash_map::{Entry, Iter};
+}
 
 /// Hash map that uses the Fx hasher
 pub type FxHashMap<K, V> = HashMap<K, V, fxhash::FxBuildHasher>;

servo/components/style/invalidation/element/invalidation_map.rs

@@ -11,8 +11,8 @@ use crate::selector_map::{
 };
 use crate::selector_parser::SelectorImpl;
 use crate::{Atom, LocalName, Namespace};
-use fallible::{FallibleHashMap, FallibleVec};
-use hashbrown::CollectionAllocErr;
+use fallible::FallibleVec;
+use hashglobe::FailedAllocationError;
 use selectors::attr::NamespaceConstraint;
 use selectors::parser::{Combinator, Component};
 use selectors::parser::{Selector, SelectorIter};
@@ -35,7 +35,7 @@ use smallvec::SmallVec;
 /// We generate a Dependency for both |a _ b:X _| and |a _ b:X _ c _ d:Y _|,
 /// even though those selectors may not appear on their own in any stylesheet.
 /// This allows us to quickly scan through the dependency sites of all style
-/// rules and determine the maximum effect that a given state or attribute
+/// rules and determine the maximum effect that a given state or attributef
 /// change may have on the style of elements in the document.
 #[derive(Clone, Debug, MallocSizeOf)]
 pub struct Dependency {
@@ -244,7 +244,7 @@ impl InvalidationMap {
         &mut self,
         selector: &Selector<SelectorImpl>,
         quirks_mode: QuirksMode,
-    ) -> Result<(), CollectionAllocErr> {
+    ) -> Result<(), FailedAllocationError> {
         debug!("InvalidationMap::note_selector({:?})", selector);
 
         let mut document_state = DocumentState::empty();
@@ -325,7 +325,7 @@ struct SelectorDependencyCollector<'a> {
     compound_state: PerCompoundState,
 
     /// The allocation error, if we OOM.
-    alloc_error: &'a mut Option<CollectionAllocErr>,
+    alloc_error: &'a mut Option<FailedAllocationError>,
 }
 
 impl<'a> SelectorDependencyCollector<'a> {

servo/components/style/invalidation/stylesheets.rs

@@ -18,7 +18,6 @@ use crate::stylesheets::{CssRule, StylesheetInDocument};
 use crate::Atom;
 use crate::CaseSensitivityExt;
 use crate::LocalName as SelectorLocalName;
-use fallible::FallibleHashSet;
 use fxhash::FxHasher;
 use selectors::attr::CaseSensitivity;
 use selectors::parser::{Component, LocalName, Selector};

servo/components/style/lib.rs

@@ -44,7 +44,7 @@ extern crate fxhash;
 #[cfg(feature = "gecko")]
 #[macro_use]
 pub mod gecko_string_cache;
-extern crate hashbrown;
+extern crate hashglobe;
 #[cfg(feature = "servo")]
 #[macro_use]
 extern crate html5ever;

servo/components/style/selector_map.rs

@@ -14,8 +14,8 @@ use crate::rule_tree::CascadeLevel;
 use crate::selector_parser::SelectorImpl;
 use crate::stylist::Rule;
 use crate::{Atom, LocalName, Namespace, WeakAtom};
-use fallible::{FallibleHashMap, FallibleVec};
-use hashbrown::CollectionAllocErr;
+use fallible::FallibleVec;
+use hashglobe::FailedAllocationError;
 use precomputed_hash::PrecomputedHash;
 use selectors::matching::{matches_selector, ElementSelectorFlags, MatchingContext};
 use selectors::parser::{Combinator, Component, SelectorIter};
@@ -95,7 +95,7 @@ pub trait SelectorMapEntry: Sized + Clone {
 ///
 /// TODO: Tune the initial capacity of the HashMap
 #[derive(Debug, MallocSizeOf)]
-pub struct SelectorMap<T> {
+pub struct SelectorMap<T: 'static> {
     /// Rules that have `:root` selectors.
     pub root: SmallVec<[T; 1]>,
     /// A hash from an ID to rules which contain that ID selector.
@@ -112,14 +112,17 @@ pub struct SelectorMap<T> {
     pub count: usize,
 }
 
-impl<T> Default for SelectorMap<T> {
+impl<T: 'static> Default for SelectorMap<T> {
     #[inline]
     fn default() -> Self {
         Self::new()
     }
 }
 
-impl<T> SelectorMap<T> {
+// FIXME(Manishearth) the 'static bound can be removed when
+// our HashMap fork (hashglobe) is able to use NonZero,
+// or when stdlib gets fallible collections
+impl<T: 'static> SelectorMap<T> {
     /// Trivially constructs an empty `SelectorMap`.
     pub fn new() -> Self {
         SelectorMap {
@@ -276,7 +279,11 @@ impl SelectorMap<Rule> {
 
 impl<T: SelectorMapEntry> SelectorMap<T> {
     /// Inserts an entry into the correct bucket(s).
-    pub fn insert(&mut self, entry: T, quirks_mode: QuirksMode) -> Result<(), CollectionAllocErr> {
+    pub fn insert(
+        &mut self,
+        entry: T,
+        quirks_mode: QuirksMode,
+    ) -> Result<(), FailedAllocationError> {
         self.count += 1;
 
         // NOTE(emilio): It'd be nice for this to be a separate function, but
@@ -609,9 +616,14 @@ fn find_bucket<'a>(
 
 /// Wrapper for PrecomputedHashMap that does ASCII-case-insensitive lookup in quirks mode.
 #[derive(Debug, MallocSizeOf)]
-pub struct MaybeCaseInsensitiveHashMap<K: PrecomputedHash + Hash + Eq, V>(PrecomputedHashMap<K, V>);
+pub struct MaybeCaseInsensitiveHashMap<K: PrecomputedHash + Hash + Eq, V: 'static>(
+    PrecomputedHashMap<K, V>,
+);
 
-impl<V> MaybeCaseInsensitiveHashMap<Atom, V> {
+// FIXME(Manishearth) the 'static bound can be removed when
+// our HashMap fork (hashglobe) is able to use NonZero,
+// or when stdlib gets fallible collections
+impl<V: 'static> MaybeCaseInsensitiveHashMap<Atom, V> {
     /// Empty map
     pub fn new() -> Self {
         MaybeCaseInsensitiveHashMap(PrecomputedHashMap::default())
@@ -622,8 +634,7 @@ impl<V> MaybeCaseInsensitiveHashMap<Atom, V> {
         &mut self,
         mut key: Atom,
         quirks_mode: QuirksMode,
-    ) -> Result<hash_map::Entry<Atom, V, BuildHasherDefault<PrecomputedHasher>>, CollectionAllocErr>
-    {
+    ) -> Result<hash_map::Entry<Atom, V>, FailedAllocationError> {
         if quirks_mode == QuirksMode::Quirks {
             key = key.to_ascii_lowercase()
         }

servo/components/style/stylist.rs

@@ -33,8 +33,8 @@ use crate::stylesheets::{CounterStyleRule, FontFaceRule, FontFeatureValuesRule,
 use crate::stylesheets::{CssRule, Origin, OriginSet, PerOrigin, PerOriginIter};
 use crate::thread_state::{self, ThreadState};
 use crate::{Atom, LocalName, Namespace, WeakAtom};
-use fallible::{FallibleHashMap, FallibleVec};
-use hashbrown::CollectionAllocErr;
+use fallible::FallibleVec;
+use hashglobe::FailedAllocationError;
 use malloc_size_of::MallocSizeOf;
 #[cfg(feature = "gecko")]
 use malloc_size_of::{MallocShallowSizeOf, MallocSizeOfOps, MallocUnconditionalShallowSizeOf};
@@ -88,7 +88,7 @@ impl UserAgentCascadeDataCache {
         device: &Device,
         quirks_mode: QuirksMode,
         guard: &SharedRwLockReadGuard,
-    ) -> Result<Arc<UserAgentCascadeData>, CollectionAllocErr>
+    ) -> Result<Arc<UserAgentCascadeData>, FailedAllocationError>
     where
         I: Iterator<Item = &'a S> + Clone,
         S: StylesheetInDocument + ToMediaListKey + PartialEq + 'static,
@@ -260,7 +260,7 @@ impl DocumentCascadeData {
         quirks_mode: QuirksMode,
         mut flusher: DocumentStylesheetFlusher<'a, S>,
         guards: &StylesheetGuards,
-    ) -> Result<(), CollectionAllocErr>
+    ) -> Result<(), FailedAllocationError>
     where
         S: StylesheetInDocument + ToMediaListKey + PartialEq + 'static,
     {
@@ -1835,7 +1835,7 @@ impl CascadeData {
         quirks_mode: QuirksMode,
         collection: SheetCollectionFlusher<S>,
         guard: &SharedRwLockReadGuard,
-    ) -> Result<(), CollectionAllocErr>
+    ) -> Result<(), FailedAllocationError>
     where
         S: StylesheetInDocument + ToMediaListKey + PartialEq + 'static,
     {
@@ -1972,7 +1972,7 @@ impl CascadeData {
         guard: &SharedRwLockReadGuard,
         rebuild_kind: SheetRebuildKind,
         mut precomputed_pseudo_element_decls: Option<&mut PrecomputedPseudoElementDeclarations>,
-    ) -> Result<(), CollectionAllocErr>
+    ) -> Result<(), FailedAllocationError>
     where
         S: StylesheetInDocument + ToMediaListKey + 'static,
     {

tools/lint/clippy.yml

@@ -94,6 +94,7 @@ clippy:
         - media/audioipc/audioipc/
         - media/audioipc/server/
         - tools/lint/test/files/clippy/
+        - servo/components/hashglobe/
         - servo/ports/geckolib/
         - servo/ports/geckolib/tests/
         - servo/tests/unit/malloc_size_of/

tools/lint/license.yml

@@ -46,6 +46,8 @@ license:
         - security/mac/hardenedruntime/plugin-container.developer.entitlements.xml
         - security/mac/hardenedruntime/plugin-container.production.entitlements.xml
         - security/mac/hardenedruntime/production.entitlements.xml
+        - servo/components/hashglobe/src/alloc.rs
+        - servo/components/hashglobe/src/shim.rs
         - toolkit/components/reputationservice/chromium/chrome/common/safe_browsing/csd.pb.cc
         - toolkit/components/reputationservice/chromium/chrome/common/safe_browsing/csd.pb.h
         - toolkit/mozapps/update/updater/crctable.h