Alexandre Lision | ddd731e | 2014-01-31 11:50:08 -0500 | [diff] [blame^] | 1 | // Copyright (C) 2006-2010 David Sugar, Tycho Softworks. |
| 2 | // |
| 3 | // This file is part of GNU uCommon C++. |
| 4 | // |
| 5 | // GNU uCommon C++ is free software: you can redistribute it and/or modify |
| 6 | // it under the terms of the GNU Lesser General Public License as published |
| 7 | // by the Free Software Foundation, either version 3 of the License, or |
| 8 | // (at your option) any later version. |
| 9 | // |
| 10 | // GNU uCommon C++ is distributed in the hope that it will be useful, |
| 11 | // but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 13 | // GNU Lesser General Public License for more details. |
| 14 | // |
| 15 | // You should have received a copy of the GNU Lesser General Public License |
| 16 | // along with GNU uCommon C++. If not, see <http://www.gnu.org/licenses/>. |
| 17 | |
| 18 | /** |
| 19 | * Atomic pointers and locks. These are meant to use atomic CPU operations |
| 20 | * and hence offer maximum performance. |
| 21 | * @file ucommon/atomic.h |
| 22 | * @author David Sugar <dyfet@gnutelephony.org> |
| 23 | */ |
| 24 | |
| 25 | #ifndef _UCOMMON_ATOMIC_H_ |
| 26 | #define _UCOMMON_ATOMIC_H_ |
| 27 | |
| 28 | #ifndef _UCOMMON_CONFIG_H_ |
| 29 | #include <ucommon/platform.h> |
| 30 | #endif |
| 31 | |
| 32 | NAMESPACE_UCOMMON |
| 33 | |
| 34 | /** |
| 35 | * Generic atomic class for referencing atomic objects and static functions. |
| 36 | * We have an atomic counter and spinlock, and in the future we may add |
| 37 | * other atomic classes and atomic manipulations needed to create lockfree |
| 38 | * data structures. The atomic classes use mutexes if no suitable atomic |
| 39 | * code is available. |
| 40 | * @author David Sugar <dyfet@gnutelephony.org> |
| 41 | */ |
| 42 | class __EXPORT atomic |
| 43 | { |
| 44 | public: |
| 45 | /** |
| 46 | * Set to true if atomics have to be simulated with mutexes. |
| 47 | */ |
| 48 | static const bool simulated; |
| 49 | |
| 50 | /** |
| 51 | * Atomic counter class. Can be used to manipulate value of an |
| 52 | * atomic counter without requiring explicit thread locking. |
| 53 | * @author David Sugar <dyfet@gnutelephony.org> |
| 54 | */ |
| 55 | class __EXPORT counter |
| 56 | { |
| 57 | private: |
| 58 | volatile long value; |
| 59 | |
| 60 | public: |
| 61 | counter(long initial = 0); |
| 62 | |
| 63 | long operator++(); |
| 64 | long operator--(); |
| 65 | long operator+=(long offset); |
| 66 | long operator-=(long offset); |
| 67 | |
| 68 | inline operator long() |
| 69 | {return (long)(value);}; |
| 70 | |
| 71 | inline long operator*() |
| 72 | {return value;}; |
| 73 | }; |
| 74 | |
| 75 | /** |
| 76 | * Atomic spinlock class. Used as high-performance sync lock between |
| 77 | * threads. |
| 78 | * @author David Sugar <dyfet@gnutelephony.org> |
| 79 | */ |
| 80 | class __EXPORT spinlock |
| 81 | { |
| 82 | private: |
| 83 | volatile long value; |
| 84 | |
| 85 | public: |
| 86 | /** |
| 87 | * Construct and initialize spinlock. |
| 88 | */ |
| 89 | spinlock(); |
| 90 | |
| 91 | /** |
| 92 | * Acquire the lock. If the lock is not acquired, one "spins" |
| 93 | * by doing something else. One suggestion is using thread::yield. |
| 94 | * @return true if acquired. |
| 95 | */ |
| 96 | bool acquire(void); |
| 97 | |
| 98 | /** |
| 99 | * Release an acquired spinlock. |
| 100 | */ |
| 101 | void release(void); |
| 102 | }; |
| 103 | }; |
| 104 | |
| 105 | END_NAMESPACE |
| 106 | |
| 107 | #endif |