OSX/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 #if (defined(__ppc64__) || defined(__i386__) || defined(__x86_64__))
  42 #define _HAVE_64BIT_ATOMIC 1
  43 #else
  44 #define _HAVE_64BIT_ATOMIC 0
  45 #endif
  46
  47
  48 //
  49 // The AtomicTypes class is an implementation detail.
  50 // Do not use it.
  51 //
  52 template <unsigned wordsize>
  53 struct AtomicTypes {
  54         // unsupported word size (this will cause compilation errors if used)
  55 };
  56
  57 template <>
  58 struct AtomicTypes<32> {
  59         typedef int32_t Integer;
  60
  61         static Integer add(int delta, Integer &base)
  62         { return OSAtomicAdd32(delta, &base); }
  63         static Integer addb(int delta, Integer &base) { return OSAtomicAdd32Barrier(delta, &base); }
  64
  65         static bool cas(Integer oldValue, Integer newValue, Integer &base)
  66         { return OSAtomicCompareAndSwap32(oldValue, newValue, &base); }
  67         static bool casb(Integer oldValue, Integer newValue, Integer &base)
  68         { return OSAtomicCompareAndSwap32Barrier(oldValue, newValue, &base); }
  69 };
  70
  71 #if _HAVE_64BIT_ATOMIC
  72
  73 template <>
  74 struct AtomicTypes<64> {
  75         typedef int64_t Integer;
  76
  77         static Integer add(int delta, Integer &base) { return OSAtomicAdd64(delta, &base); }
  78         static Integer addb(int delta, Integer &base) { return OSAtomicAdd64Barrier(delta, &base); }
  79
  80         static bool cas(Integer oldValue, Integer newValue, Integer &base)
  81         { return OSAtomicCompareAndSwap64(oldValue, newValue, &base); }
  82         static bool casb(Integer oldValue, Integer newValue, Integer &base)
  83         { return OSAtomicCompareAndSwap64Barrier(oldValue, newValue, &base); }
  84 };
  85
  86 #endif //_HAVE_64BIT_ATOMIC
  87
  88
  89 //
  90 // Atomic<Type> is a set of (static) operations that can atomically access memory.
  91 // This is not a wrapper object. Think of it as a generator class that produces
  92 // the proper atomic memory operations for arbitrary data types.
  93 // If the underlying system does not support atomicity for a particular type
  94 // (e.g. 64 bits on ppc, or 16 bits anywhere), you will get compilation errors.
  95 //
  96 template <class Type>
  97 class Atomic {
  98         typedef AtomicTypes<sizeof(Type) * 8> _Ops;
  99         typedef typename _Ops::Integer _Type;
 100
 101 public:
 102         static Type add(int delta, Type &store)
 103         { return Type(_Ops::add(delta, (_Type &)store)); }
 104         static Type addb(int delta, Type &store)
 105         { return Type(_Ops::addb(delta, (_Type &)store)); }
 106
 107         static bool cas(Type oldValue, Type newValue, Type &store)
 108         { return _Ops::cas(_Type(oldValue), _Type(newValue), (_Type &)store); }
 109         static bool casb(Type oldValue, Type newValue, Type &store)
 110         { return _Ops::casb(_Type(oldValue), _Type(newValue), (_Type &)store); }
 111
 112         static void barrier() { OSMemoryBarrier(); }
 113         static void readBarrier() { OSMemoryBarrier(); }
 114         static void writeBarrier() { OSMemoryBarrier(); }
 115
 116         // convenience additions (expressed in terms above)
 117
 118         static Type increment(Type &store) { return add(1, store); }
 119         static Type decrement(Type &store) { return add(-1, store); }
 120
 121         static Type load(const Type &store) { readBarrier(); return store; }
 122         static Type store(Type value, Type &store)
 123         { while (!casb(store, value, store)) {}; return value; }
 124 };
 125
 126
 127 } // end namespace Security
 128
 129 #endif //_H_THREADING_INTERNAL