Security/libsecurity_utilities/lib/threading_internal.h

   1 /*
   2  * Copyright (c) 2000-2001,2003-2004,2011,2013-2014 Apple Inc. All Rights Reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24
  25 //
  26 // threading_internal - internal support classes and functions for threading implementation
  27 //
  28 #ifndef _H_THREADING_INTERNAL
  29 #define _H_THREADING_INTERNAL
  30
  31 #include <security_utilities/utilities.h>
  32 #include <libkern/OSAtomic.h>
  33
  34
  35 namespace Security {
  36
  37
  38 //
  39 // Do we have 64-bit atomic operations?
  40 //
  41 #define _HAVE_64BIT_ATOMIC (defined(__ppc64__) || defined(__i386__) || defined(__x86_64__))
  42
  43
  44 //
  45 // The AtomicTypes class is an implementation detail.
  46 // Do not use it.
  47 //
  48 template <unsigned wordsize>
  49 struct AtomicTypes {
  50         // unsupported word size (this will cause compilation errors if used)
  51 };
  52
  53 template <>
  54 struct AtomicTypes<32> {
  55         typedef int32_t Integer;
  56
  57         static Integer add(int delta, Integer &base)
  58         { return OSAtomicAdd32(delta, &base); }
  59         static Integer addb(int delta, Integer &base) { return OSAtomicAdd32Barrier(delta, &base); }
  60
  61         static bool cas(Integer oldValue, Integer newValue, Integer &base)
  62         { return OSAtomicCompareAndSwap32(oldValue, newValue, &base); }
  63         static bool casb(Integer oldValue, Integer newValue, Integer &base)
  64         { return OSAtomicCompareAndSwap32Barrier(oldValue, newValue, &base); }
  65 };
  66
  67 #if _HAVE_64BIT_ATOMIC
  68
  69 template <>
  70 struct AtomicTypes<64> {
  71         typedef int64_t Integer;
  72
  73         static Integer add(int delta, Integer &base) { return OSAtomicAdd64(delta, &base); }
  74         static Integer addb(int delta, Integer &base) { return OSAtomicAdd64Barrier(delta, &base); }
  75
  76         static bool cas(Integer oldValue, Integer newValue, Integer &base)
  77         { return OSAtomicCompareAndSwap64(oldValue, newValue, &base); }
  78         static bool casb(Integer oldValue, Integer newValue, Integer &base)
  79         { return OSAtomicCompareAndSwap64Barrier(oldValue, newValue, &base); }
  80 };
  81
  82 #endif //_HAVE_64BIT_ATOMIC
  83
  84
  85 //
  86 // Atomic<Type> is a set of (static) operations that can atomically access memory.
  87 // This is not a wrapper object. Think of it as a generator class that produces
  88 // the proper atomic memory operations for arbitrary data types.
  89 // If the underlying system does not support atomicity for a particular type
  90 // (e.g. 64 bits on ppc, or 16 bits anywhere), you will get compilation errors.
  91 //
  92 template <class Type>
  93 class Atomic {
  94         typedef AtomicTypes<sizeof(Type) * 8> _Ops;
  95         typedef typename _Ops::Integer _Type;
  96
  97 public:
  98         static Type add(int delta, Type &store)
  99         { return Type(_Ops::add(delta, (_Type &)store)); }
 100         static Type addb(int delta, Type &store)
 101         { return Type(_Ops::addb(delta, (_Type &)store)); }
 102
 103         static bool cas(Type oldValue, Type newValue, Type &store)
 104         { return _Ops::cas(_Type(oldValue), _Type(newValue), (_Type &)store); }
 105         static bool casb(Type oldValue, Type newValue, Type &store)
 106         { return _Ops::casb(_Type(oldValue), _Type(newValue), (_Type &)store); }
 107
 108         static void barrier() { OSMemoryBarrier(); }
 109         static void readBarrier() { OSMemoryBarrier(); }
 110         static void writeBarrier() { OSMemoryBarrier(); }
 111
 112         // convenience additions (expressed in terms above)
 113
 114         static Type increment(Type &store) { return add(1, store); }
 115         static Type decrement(Type &store) { return add(-1, store); }
 116
 117         static Type load(const Type &store) { readBarrier(); return store; }
 118         static Type store(Type value, Type &store)
 119         { while (!casb(store, value, store)) {}; return value; }
 120 };
 121
 122
 123 } // end namespace Security
 124
 125 #endif //_H_THREADING_INTERNAL