/usr/include/ucommon/atomic.h is in libucommon-dev 6.4.4-2ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 | // Copyright (C) 2006-2014 David Sugar, Tycho Softworks.
// Copyright (C) 2015 Cherokees of Idaho.
//
// This file is part of GNU uCommon C++.
//
// GNU uCommon C++ is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published
// by the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// GNU uCommon C++ is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with GNU uCommon C++. If not, see <http://www.gnu.org/licenses/>.
/**
* Atomic pointers and locks. These are meant to use atomic CPU operations
* and hence offer maximum performance.
* @file ucommon/atomic.h
* @author David Sugar <dyfet@gnutelephony.org>
*/
#ifndef _UCOMMON_ATOMIC_H_
#define _UCOMMON_ATOMIC_H_
#ifndef _UCOMMON_CONFIG_H_
#include <ucommon/platform.h>
#endif
#ifdef _MSWINDOWS_
typedef LONG atomic_t;
#else
typedef int atomic_t;
#endif
namespace ucommon {
/**
* Generic atomic class for referencing atomic objects and static functions.
* We have an atomic counter and spinlock, and in the future we may add
* other atomic classes and atomic manipulations needed to create lockfree
* data structures. The atomic classes use mutexes if no suitable atomic
* code is available.
* @author David Sugar <dyfet@gnutelephony.org>
*/
class __EXPORT atomic
{
public:
/**
* Set to true if atomics have to be simulated with mutexes.
*/
static const bool simulated;
/**
* Atomic counter class. Can be used to manipulate value of an
* atomic counter without requiring explicit thread locking.
* @author David Sugar <dyfet@gnutelephony.org>
*/
class __EXPORT counter
{
private:
mutable volatile atomic_t value;
public:
counter(atomic_t initial = 0);
// fetch add/sub optimized semantics
atomic_t fetch_add(atomic_t offset = 1) volatile;
atomic_t fetch_sub(atomic_t offset = 1) volatile;
atomic_t operator++() volatile;
atomic_t operator--() volatile;
atomic_t operator+=(atomic_t offset) volatile;
atomic_t operator-=(atomic_t offset) volatile;
atomic_t get() volatile;
void clear() volatile;
inline operator atomic_t() volatile {
return get();
}
inline atomic_t operator*() volatile {
return get();
}
};
/**
* Atomic spinlock class. Used as high-performance sync lock between
* threads.
* @author David Sugar <dyfet@gnutelephony.org>
*/
class __EXPORT spinlock
{
private:
#ifdef __GNUC__
mutable volatile atomic_t value __attribute__ ((aligned(16)));
#else
mutable volatile atomic_t value;
#endif
public:
/**
* Construct and initialize spinlock.
*/
spinlock();
/**NAMESPACE_UCOMMON
* Acquire the lock. If the lock is not acquired, one "spins"
* by doing something else. One suggestion is using thread::yield.
* @return true if acquired.
*/
bool acquire(void) volatile;
/**
* Wait for and aquire spinlock.
*/
void wait(void) volatile;
/**
* Release an acquired spinlock.
*/
void release(void) volatile;
};
/**
* Atomically aligned heap alloc function.
* @param size of memory to allocate.
* @return pointer or NULL if cannot alloc.
*/
static void *alloc(size_t size);
};
// for abi7
typedef atomic Atomic;
} // namespace ucommon
#endif
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