LCOV - code coverage report
Current view: directory - ipc/chromium/src/base - atomic_ref_count.h (source / functions) Found Hit Coverage
Test: app.info Lines: 12 12 100.0 %
Date: 2012-06-02 Functions: 5 5 100.0 %

       1                 : // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
       2                 : // Use of this source code is governed by a BSD-style license that can be
       3                 : // found in the LICENSE file.
       4                 : 
       5                 : // This is a low level implementation of atomic semantics for reference
       6                 : // counting.  Please use base/ref_counted.h directly instead.
       7                 : 
       8                 : #ifndef BASE_ATOMIC_REF_COUNT_H_
       9                 : #define BASE_ATOMIC_REF_COUNT_H_
      10                 : 
      11                 : #include "base/atomicops.h"
      12                 : 
      13                 : namespace base {
      14                 : 
      15                 : typedef subtle::Atomic32 AtomicRefCount;
      16                 : 
      17                 : // Increment a reference count by "increment", which must exceed 0.
      18            8564 : inline void AtomicRefCountIncN(volatile AtomicRefCount *ptr,
      19                 :                                AtomicRefCount increment) {
      20            8564 :   subtle::NoBarrier_AtomicIncrement(ptr, increment);
      21            8564 : }
      22                 : 
      23                 : // Decrement a reference count by "decrement", which must exceed 0,
      24                 : // and return whether the result is non-zero.
      25                 : // Insert barriers to ensure that state written before the reference count
      26                 : // became zero will be visible to a thread that has just made the count zero.
      27            7096 : inline bool AtomicRefCountDecN(volatile AtomicRefCount *ptr,
      28                 :                                AtomicRefCount decrement) {
      29            7096 :   return subtle::Barrier_AtomicIncrement(ptr, -decrement) != 0;
      30                 : }
      31                 : 
      32                 : // Increment a reference count by 1.
      33            8564 : inline void AtomicRefCountInc(volatile AtomicRefCount *ptr) {
      34            8564 :   base::AtomicRefCountIncN(ptr, 1);
      35            8564 : }
      36                 : 
      37                 : // Decrement a reference count by 1 and return whether the result is non-zero.
      38                 : // Insert barriers to ensure that state written before the reference count
      39                 : // became zero will be visible to a thread that has just made the count zero.
      40            7096 : inline bool AtomicRefCountDec(volatile AtomicRefCount *ptr) {
      41            7096 :   return base::AtomicRefCountDecN(ptr, 1);
      42                 : }
      43                 : 
      44                 : // Return whether the reference count is one.  If the reference count is used
      45                 : // in the conventional way, a refrerence count of 1 implies that the current
      46                 : // thread owns the reference and no other thread shares it.  This call performs
      47                 : // the test for a reference count of one, and performs the memory barrier
      48                 : // needed for the owning thread to act on the object, knowing that it has
      49                 : // exclusive access to the object.
      50                 : inline bool AtomicRefCountIsOne(volatile AtomicRefCount *ptr) {
      51                 :   return subtle::Acquire_Load(ptr) == 1;
      52                 : }
      53                 : 
      54                 : // Return whether the reference count is zero.  With conventional object
      55                 : // referencing counting, the object will be destroyed, so the reference count
      56                 : // should never be zero.  Hence this is generally used for a debug check.
      57            7096 : inline bool AtomicRefCountIsZero(volatile AtomicRefCount *ptr) {
      58            7096 :   return subtle::Acquire_Load(ptr) == 0;
      59                 : }
      60                 : 
      61                 : }  // namespace base
      62                 : 
      63                 : #endif  // BASE_ATOMIC_REF_COUNT_H_

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