100 lines
2.4 KiB
C
100 lines
2.4 KiB
C
/*
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* File : rw.c
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*
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* Title : Demo Readers/Writer.
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*
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* Short : A solution to the multi-reader's, one writer problem.
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*
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* Long :
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*
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* Author : Andrae Muys
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*
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* Date : 18 September 1997
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*
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* Revised : 4-7-04 Shamelessly stolen and adapted by Rusty Sears.
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* Found the code at this url:
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* http://www.cs.nmsu.edu/~jcook/Tools/pthreads/rw.c
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*/
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#ifndef __LIBDFA_RW_H
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#define __LIBDFA_RW_H
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#include <stasis/common.h>
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#include <pthread.h>
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#include <stdio.h>
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BEGIN_C_DECLS
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#define HAVE_PTHREAD_RWLOCK
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#ifdef HAVE_PTHREAD_RWLOCK
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typedef pthread_rwlock_t rwl;
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static inline rwl* initlock(void) {
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rwl* ret = (rwl*)malloc(sizeof(*ret));
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int err = pthread_rwlock_init(ret, 0);
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if(err) { perror("couldn't init rwlock"); abort(); }
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return ret;
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}
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static inline void readlock(rwl *lock, int d) {
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pthread_rwlock_rdlock(lock);
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}
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static inline int tryreadlock(rwl *lock, int d) {
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return 0 == pthread_rwlock_tryrdlock(lock);
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}
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static inline void writelock(rwl *lock, int d) {
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pthread_rwlock_wrlock(lock);
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}
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static inline int trywritelock(rwl *lock, int d) {
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return 0 == pthread_rwlock_trywrlock(lock);
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}
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static inline void assertlocked(rwl * lock) { }
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static inline void assertunlocked(rwl * lock) { }
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static inline void unlock(rwl *lock) {
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pthread_rwlock_unlock(lock);
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}
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static inline void readunlock(rwl *lock) { unlock(lock); }
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static inline void writeunlock(rwl *lock) { unlock(lock); }
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static inline void deletelock(rwl *lock) {
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pthread_rwlock_destroy(lock);
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free(lock);
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}
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#else
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typedef struct {
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pthread_mutex_t *mut;
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int writers;
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int readers;
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int waiting;
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pthread_cond_t *writeOK, *readOK;
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} rwl;
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rwl *initlock (void);
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void readlock (rwl *lock, int d);
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int tryreadlock(rwl *lock, int d);
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void writelock (rwl *lock, int d);
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int trywritelock(rwl *lock, int d);
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/** aborts if called when no thread holds this latch. */
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void assertlocked(rwl *lock);
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/** aborts if called when a thread holds this latch. */
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void assertunlocked(rwl *lock);
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void downgradelock(rwl * lock);
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void unlock(rwl * lock);
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/** @deprecated in favor of unlock() */
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void readunlock (rwl *lock);
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/** @deprecated in favor of unlock() */
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void writeunlock (rwl *lock);
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void deletelock (rwl *lock);
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/*
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typedef struct {
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rwl *lock;
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int id;
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long delay;
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} rwargs;
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rwargs *newRWargs (rwl *l, int i, long d);
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void *reader (void *args);
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void *writer (void *args);
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*/
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#endif
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END_C_DECLS
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#endif /* rw.h */
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