partition_alloc: copy ref_counted and scoped_refptr to PA library.

PS1 = just copying ref_counted and scoped_refptr to PA library

Bug: 1151236
Change-Id: I0d35f6474f7f95bbf0766ba56d83aeae5b3afe1e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3637437
Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Reviewed-by: Yuki Shiino <yukishiino@chromium.org>
Reviewed-by: Bartek Nowierski <bartekn@chromium.org>
Commit-Queue: Takashi Sakamoto <tasak@google.com>
Cr-Commit-Position: refs/heads/main@{#1002492}

base/allocator/partition_allocator/BUILD.gn

@@ -74,6 +74,7 @@ target(partition_alloc_target_type, "partition_alloc") {
     "partition_alloc-inl.h",
     "partition_alloc.cc",
     "partition_alloc.h",
+    "partition_alloc_base/atomic_ref_count.h",
     "partition_alloc_base/bits.h",
     "partition_alloc_base/cpu.cc",
     "partition_alloc_base/cpu.h",
@@ -83,6 +84,9 @@ target(partition_alloc_target_type, "partition_alloc") {
     "partition_alloc_base/gtest_prod_util.h",
     "partition_alloc_base/logging.cc",
     "partition_alloc_base/logging.h",
+    "partition_alloc_base/memory/ref_counted.cc",
+    "partition_alloc_base/memory/ref_counted.h",
+    "partition_alloc_base/memory/scoped_refptr.h",
     "partition_alloc_base/migration_adapter.h",
     "partition_alloc_base/no_destructor.h",
     "partition_alloc_base/numerics/checked_math.h",

base/allocator/partition_allocator/DEPS

@@ -22,8 +22,6 @@ include_rules = [
     "+base/mac/foundation_util.h",
     "+base/mac/mac_util.h",
     "+base/mac/scoped_cftyperef.h",
-    "+base/memory/ref_counted.h",
-    "+base/memory/scoped_refptr.h",
     "+base/process/memory.h",
     "+base/strings/stringprintf.h",
     "+base/system/sys_info.h",

base/allocator/partition_allocator/partition_alloc_base/atomic_ref_count.h

@@ -0,0 +1,69 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// This is a low level implementation of atomic semantics for reference
+// counting.  Please use base/memory/ref_counted.h directly instead.
+
+#ifndef BASE_ALLOCATOR_PARTITION_ALLOCATOR_PARTITION_ALLOC_BASE_ATOMIC_REF_COUNT_H_
+#define BASE_ALLOCATOR_PARTITION_ALLOCATOR_PARTITION_ALLOC_BASE_ATOMIC_REF_COUNT_H_
+
+#include <atomic>
+
+namespace partition_alloc::internal::base {
+
+class AtomicRefCount {
+ public:
+  constexpr AtomicRefCount() : ref_count_(0) {}
+  explicit constexpr AtomicRefCount(int initial_value)
+      : ref_count_(initial_value) {}
+
+  // Increment a reference count.
+  // Returns the previous value of the count.
+  int Increment() { return Increment(1); }
+
+  // Increment a reference count by "increment", which must exceed 0.
+  // Returns the previous value of the count.
+  int Increment(int increment) {
+    return ref_count_.fetch_add(increment, std::memory_order_relaxed);
+  }
+
+  // Decrement a reference count, and return whether the result is non-zero.
+  // Insert barriers to ensure that state written before the reference count
+  // became zero will be visible to a thread that has just made the count zero.
+  bool Decrement() {
+    // TODO(jbroman): Technically this doesn't need to be an acquire operation
+    // unless the result is 1 (i.e., the ref count did indeed reach zero).
+    // However, there are toolchain issues that make that not work as well at
+    // present (notably TSAN doesn't like it).
+    return ref_count_.fetch_sub(1, std::memory_order_acq_rel) != 1;
+  }
+
+  // Return whether the reference count is one.  If the reference count is used
+  // in the conventional way, a reference count of 1 implies that the current
+  // thread owns the reference and no other thread shares it.  This call
+  // performs the test for a reference count of one, and performs the memory
+  // barrier needed for the owning thread to act on the object, knowing that it
+  // has exclusive access to the object.
+  bool IsOne() const { return ref_count_.load(std::memory_order_acquire) == 1; }
+
+  // Return whether the reference count is zero.  With conventional object
+  // referencing counting, the object will be destroyed, so the reference count
+  // should never be zero.  Hence this is generally used for a debug check.
+  bool IsZero() const {
+    return ref_count_.load(std::memory_order_acquire) == 0;
+  }
+
+  // Returns the current reference count (with no barriers). This is subtle, and
+  // should be used only for debugging.
+  int SubtleRefCountForDebug() const {
+    return ref_count_.load(std::memory_order_relaxed);
+  }
+
+ private:
+  std::atomic_int ref_count_;
+};
+
+}  // namespace partition_alloc::internal::base
+
+#endif  // BASE_ALLOCATOR_PARTITION_ALLOCATOR_PARTITION_ALLOC_BASE_ATOMIC_REF_COUNT_H_

base/allocator/partition_allocator/partition_alloc_base/memory/ref_counted.cc

@@ -0,0 +1,46 @@
+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/allocator/partition_allocator/partition_alloc_base/memory/ref_counted.h"
+
+#include <limits>
+#include <ostream>
+#include <type_traits>
+
+namespace partition_alloc::internal::base::subtle {
+
+bool RefCountedThreadSafeBase::HasOneRef() const {
+  return ref_count_.IsOne();
+}
+
+bool RefCountedThreadSafeBase::HasAtLeastOneRef() const {
+  return !ref_count_.IsZero();
+}
+
+#if DCHECK_IS_ON()
+RefCountedThreadSafeBase::~RefCountedThreadSafeBase() {
+  DCHECK(in_dtor_) << "RefCountedThreadSafe object deleted without "
+                      "calling Release()";
+}
+#endif
+
+// For security and correctness, we check the arithmetic on ref counts.
+//
+// In an attempt to avoid binary bloat (from inlining the `CHECK`), we define
+// these functions out-of-line. However, compilers are wily. Further testing may
+// show that `NOINLINE` helps or hurts.
+//
+#if !defined(ARCH_CPU_X86_FAMILY)
+bool RefCountedThreadSafeBase::Release() const {
+  return ReleaseImpl();
+}
+void RefCountedThreadSafeBase::AddRef() const {
+  AddRefImpl();
+}
+void RefCountedThreadSafeBase::AddRefWithCheck() const {
+  AddRefWithCheckImpl();
+}
+#endif
+
+}  // namespace partition_alloc::internal::base::subtle

base/allocator/partition_allocator/partition_alloc_base/memory/ref_counted.h

@@ -0,0 +1,188 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_ALLOCATOR_PARTITION_ALLOCATOR_PARTITION_ALLOC_BASE_MEMORY_REF_COUNTED_H_
+#define BASE_ALLOCATOR_PARTITION_ALLOCATOR_PARTITION_ALLOC_BASE_MEMORY_REF_COUNTED_H_
+
+#include "base/allocator/partition_allocator/partition_alloc_base/atomic_ref_count.h"
+#include "base/allocator/partition_allocator/partition_alloc_base/memory/scoped_refptr.h"
+#include "base/base_export.h"
+#include "base/check.h"
+#include "base/check_op.h"
+#include "base/compiler_specific.h"
+#include "base/dcheck_is_on.h"
+#include "build/build_config.h"
+
+namespace partition_alloc::internal::base {
+namespace subtle {
+
+class BASE_EXPORT RefCountedThreadSafeBase {
+ public:
+  RefCountedThreadSafeBase(const RefCountedThreadSafeBase&) = delete;
+  RefCountedThreadSafeBase& operator=(const RefCountedThreadSafeBase&) = delete;
+
+  bool HasOneRef() const;
+  bool HasAtLeastOneRef() const;
+
+ protected:
+  explicit constexpr RefCountedThreadSafeBase(StartRefCountFromZeroTag) {}
+  explicit constexpr RefCountedThreadSafeBase(StartRefCountFromOneTag)
+      : ref_count_(1) {
+#if DCHECK_IS_ON()
+    needs_adopt_ref_ = true;
+#endif
+  }
+
+#if DCHECK_IS_ON()
+  ~RefCountedThreadSafeBase();
+#else
+  ~RefCountedThreadSafeBase() = default;
+#endif
+
+// Release and AddRef are suitable for inlining on X86 because they generate
+// very small code sequences. On other platforms (ARM), it causes a size
+// regression and is probably not worth it.
+#if defined(ARCH_CPU_X86_FAMILY)
+  // Returns true if the object should self-delete.
+  bool Release() const { return ReleaseImpl(); }
+  void AddRef() const { AddRefImpl(); }
+  void AddRefWithCheck() const { AddRefWithCheckImpl(); }
+#else
+  // Returns true if the object should self-delete.
+  bool Release() const;
+  void AddRef() const;
+  void AddRefWithCheck() const;
+#endif
+
+ private:
+  template <typename U>
+  friend scoped_refptr<U> AdoptRef(U*);
+
+  void Adopted() const {
+#if DCHECK_IS_ON()
+    DCHECK(needs_adopt_ref_);
+    needs_adopt_ref_ = false;
+#endif
+  }
+
+  ALWAYS_INLINE void AddRefImpl() const {
+#if DCHECK_IS_ON()
+    DCHECK(!in_dtor_);
+    // This RefCounted object is created with non-zero reference count.
+    // The first reference to such a object has to be made by AdoptRef or
+    // MakeRefCounted.
+    DCHECK(!needs_adopt_ref_);
+#endif
+    ref_count_.Increment();
+  }
+
+  ALWAYS_INLINE void AddRefWithCheckImpl() const {
+#if DCHECK_IS_ON()
+    DCHECK(!in_dtor_);
+    // This RefCounted object is created with non-zero reference count.
+    // The first reference to such a object has to be made by AdoptRef or
+    // MakeRefCounted.
+    DCHECK(!needs_adopt_ref_);
+#endif
+    CHECK_GT(ref_count_.Increment(), 0);
+  }
+
+  ALWAYS_INLINE bool ReleaseImpl() const {
+#if DCHECK_IS_ON()
+    DCHECK(!in_dtor_);
+    DCHECK(!ref_count_.IsZero());
+#endif
+    if (!ref_count_.Decrement()) {
+#if DCHECK_IS_ON()
+      in_dtor_ = true;
+#endif
+      return true;
+    }
+    return false;
+  }
+
+  mutable AtomicRefCount ref_count_{0};
+#if DCHECK_IS_ON()
+  mutable bool needs_adopt_ref_ = false;
+  mutable bool in_dtor_ = false;
+#endif
+};
+
+}  // namespace subtle
+
+// Forward declaration.
+template <class T, typename Traits>
+class RefCountedThreadSafe;
+
+// Default traits for RefCountedThreadSafe<T>.  Deletes the object when its ref
+// count reaches 0.  Overload to delete it on a different thread etc.
+template <typename T>
+struct DefaultRefCountedThreadSafeTraits {
+  static void Destruct(const T* x) {
+    // Delete through RefCountedThreadSafe to make child classes only need to be
+    // friend with RefCountedThreadSafe instead of this struct, which is an
+    // implementation detail.
+    RefCountedThreadSafe<T, DefaultRefCountedThreadSafeTraits>::DeleteInternal(
+        x);
+  }
+};
+
+//
+// A thread-safe variant of RefCounted<T>
+//
+//   class MyFoo : public base::RefCountedThreadSafe<MyFoo> {
+//    ...
+//   };
+//
+// If you're using the default trait, then you should add compile time
+// asserts that no one else is deleting your object.  i.e.
+//    private:
+//     friend class base::RefCountedThreadSafe<MyFoo>;
+//     ~MyFoo();
+//
+// We can use REQUIRE_ADOPTION_FOR_REFCOUNTED_TYPE() with RefCountedThreadSafe
+// too. See the comment above the RefCounted definition for details.
+template <class T, typename Traits = DefaultRefCountedThreadSafeTraits<T>>
+class RefCountedThreadSafe : public subtle::RefCountedThreadSafeBase {
+ public:
+  static constexpr subtle::StartRefCountFromZeroTag kRefCountPreference =
+      subtle::kStartRefCountFromZeroTag;
+
+  explicit RefCountedThreadSafe()
+      : subtle::RefCountedThreadSafeBase(T::kRefCountPreference) {}
+
+  RefCountedThreadSafe(const RefCountedThreadSafe&) = delete;
+  RefCountedThreadSafe& operator=(const RefCountedThreadSafe&) = delete;
+
+  void AddRef() const { AddRefImpl(T::kRefCountPreference); }
+
+  void Release() const {
+    if (subtle::RefCountedThreadSafeBase::Release()) {
+      ANALYZER_SKIP_THIS_PATH();
+      Traits::Destruct(static_cast<const T*>(this));
+    }
+  }
+
+ protected:
+  ~RefCountedThreadSafe() = default;
+
+ private:
+  friend struct DefaultRefCountedThreadSafeTraits<T>;
+  template <typename U>
+  static void DeleteInternal(const U* x) {
+    delete x;
+  }
+
+  void AddRefImpl(subtle::StartRefCountFromZeroTag) const {
+    subtle::RefCountedThreadSafeBase::AddRef();
+  }
+
+  void AddRefImpl(subtle::StartRefCountFromOneTag) const {
+    subtle::RefCountedThreadSafeBase::AddRefWithCheck();
+  }
+};
+
+}  // namespace partition_alloc::internal::base
+
+#endif  // BASE_ALLOCATOR_PARTITION_ALLOCATOR_PARTITION_ALLOC_BASE_MEMORY_REF_COUNTED_H_