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#ifndef PRIO_QUEUE_H |
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#define PRIO_QUEUE_H |
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/* |
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* A priority queue implementation, primarily for keeping track of |
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* commits in the 'date-order' so that we process them from new to old |
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* as they are discovered, but can be used to hold any pointer to |
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* struct. The caller is responsible for supplying a function to |
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* compare two "things". |
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* |
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* Alternatively, this data structure can also be used as a LIFO stack |
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* by specifying NULL as the comparison function. |
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*/ |
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/* |
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* Compare two "things", one and two; the third parameter is cb_data |
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* in the prio_queue structure. The result is returned as a sign of |
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* the return value, being the same as the sign of the result of |
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* subtracting "two" from "one" (i.e. negative if "one" sorts earlier |
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* than "two"). |
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*/ |
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typedef int (*prio_queue_compare_fn)(const void *one, const void *two, void *cb_data); |
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struct prio_queue_entry { |
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unsigned ctr; |
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void *data; |
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}; |
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struct prio_queue { |
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prio_queue_compare_fn compare; |
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unsigned insertion_ctr; |
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void *cb_data; |
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int alloc, nr; |
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struct prio_queue_entry *array; |
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}; |
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/* |
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* Add the "thing" to the queue. |
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*/ |
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extern void prio_queue_put(struct prio_queue *, void *thing); |
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/* |
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* Extract the "thing" that compares the smallest out of the queue, |
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* or NULL. If compare function is NULL, the queue acts as a LIFO |
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* stack. |
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*/ |
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extern void *prio_queue_get(struct prio_queue *); |
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extern void clear_prio_queue(struct prio_queue *); |
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/* Reverse the LIFO elements */ |
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extern void prio_queue_reverse(struct prio_queue *); |
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#endif /* PRIO_QUEUE_H */ |
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