mirror of
https://github.com/git/git.git
synced 2025-12-05 18:47:16 -06:00
3d5091d232
Add a function to replace the top element of the queue that basically does the same as prio_queue_get() followed by prio_queue_put(), but without the work by prio_queue_get() to rebalance the heap. It can be used to optimize loops that get one element and then immediately add another one. That's common e.g., with commit history traversal, where we get out a commit and then put in its parents. Signed-off-by: René Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
69 lines
1.9 KiB
C
69 lines
1.9 KiB
C
#ifndef PRIO_QUEUE_H
|
|
#define PRIO_QUEUE_H
|
|
|
|
/*
|
|
* A priority queue implementation, primarily for keeping track of
|
|
* commits in the 'date-order' so that we process them from new to old
|
|
* as they are discovered, but can be used to hold any pointer to
|
|
* struct. The caller is responsible for supplying a function to
|
|
* compare two "things".
|
|
*
|
|
* Alternatively, this data structure can also be used as a LIFO stack
|
|
* by specifying NULL as the comparison function.
|
|
*/
|
|
|
|
/*
|
|
* Compare two "things", one and two; the third parameter is cb_data
|
|
* in the prio_queue structure. The result is returned as a sign of
|
|
* the return value, being the same as the sign of the result of
|
|
* subtracting "two" from "one" (i.e. negative if "one" sorts earlier
|
|
* than "two").
|
|
*/
|
|
typedef int (*prio_queue_compare_fn)(const void *one, const void *two, void *cb_data);
|
|
|
|
struct prio_queue_entry {
|
|
size_t ctr;
|
|
void *data;
|
|
};
|
|
|
|
struct prio_queue {
|
|
prio_queue_compare_fn compare;
|
|
size_t insertion_ctr;
|
|
void *cb_data;
|
|
size_t alloc, nr;
|
|
struct prio_queue_entry *array;
|
|
};
|
|
|
|
/*
|
|
* Add the "thing" to the queue.
|
|
*/
|
|
void prio_queue_put(struct prio_queue *, void *thing);
|
|
|
|
/*
|
|
* Extract the "thing" that compares the smallest out of the queue,
|
|
* or NULL. If compare function is NULL, the queue acts as a LIFO
|
|
* stack.
|
|
*/
|
|
void *prio_queue_get(struct prio_queue *);
|
|
|
|
/*
|
|
* Gain access to the "thing" that would be returned by
|
|
* prio_queue_get, but do not remove it from the queue.
|
|
*/
|
|
void *prio_queue_peek(struct prio_queue *);
|
|
|
|
/*
|
|
* Replace the "thing" that compares the smallest with a new "thing",
|
|
* like prio_queue_get()+prio_queue_put() would do, but in a more
|
|
* efficient way. Does the same as prio_queue_put() if the queue is
|
|
* empty.
|
|
*/
|
|
void prio_queue_replace(struct prio_queue *queue, void *thing);
|
|
|
|
void clear_prio_queue(struct prio_queue *);
|
|
|
|
/* Reverse the LIFO elements */
|
|
void prio_queue_reverse(struct prio_queue *);
|
|
|
|
#endif /* PRIO_QUEUE_H */
|