counter.c

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/* ==================================================================== 
 * The Kannel Software License, Version 1.0 
 * 
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 * Copyright (c) 1998-2001 WapIT Ltd.   
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 *    if any, must include the following acknowledgment: 
 *       "This product includes software developed by the 
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 * Portions of this software are based upon software originally written at  
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 */ 

/*
 * gwlib/counter.c - a counter object
 *
 * This file implements the Counter objects declared in counter.h.
 *
 * Lars Wirzenius.
 *
 * Changed the counter type 'long' into 'unsigned long' so it wraps 
 * by itself. Just keep increasing it.
 * Also added a counter_increase_with function.
 * harrie@lisanza.net
 */

#include <limits.h>

#include "gwlib.h"

struct Counter
{
#ifdef HAVE_PTHREAD_SPINLOCK_T
    pthread_spinlock_t lock;
#else
    Mutex *lock;
#endif
    unsigned long n;
};


#ifdef HAVE_PTHREAD_SPINLOCK_T
#define lock(c) pthread_spin_lock(&c->lock)
#define unlock(c) pthread_spin_unlock(&c->lock)
#else
#define lock(c) mutex_lock(c->lock)
#define unlock(c) mutex_unlock(c->lock)
#endif


Counter *counter_create(void)
{
    Counter *counter;

    counter = gw_malloc(sizeof(Counter));
#ifdef HAVE_PTHREAD_SPINLOCK_T
    pthread_spin_init(&counter->lock, 0);
#else
    counter->lock = mutex_create();
#endif

    counter->n = 0;
    return counter;
}


void counter_destroy(Counter *counter)
{
    if (counter == NULL)
        return;

#ifdef HAVE_PTHREAD_SPINLOCK_T
    pthread_spin_destroy(&counter->lock);
#else
    mutex_destroy(counter->lock);
#endif
    gw_free(counter);
}

unsigned long counter_increase(Counter *counter)
{
    unsigned long ret;

    lock(counter);
    ret = counter->n;
    ++counter->n;
    unlock(counter);
    return ret;
}

unsigned long counter_increase_with(Counter *counter, unsigned long value)
{
    unsigned long ret;

    lock(counter);
    ret = counter->n;
    counter->n += value;
    unlock(counter);
    return ret;
}

unsigned long counter_value(Counter *counter)
{
    unsigned long ret;

    lock(counter);
    ret = counter->n;
    unlock(counter);
    return ret;
}

unsigned long counter_decrease(Counter *counter)
{
    unsigned long ret;

    lock(counter);
    ret = counter->n;
    if (counter->n > 0)
        --counter->n;
    unlock(counter);
    return ret;
}

unsigned long counter_set(Counter *counter, unsigned long n)
{
    unsigned long ret;

    lock(counter);
    ret = counter->n;
    counter->n = n;
    unlock(counter);
    return ret;
}