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Revision e88aab917e0dc3e99af8fb0f3ecbef66ac3e49b6 authored by Derrick Stolee on 24 October 2019, 13:40:41 UTC, committed by Junio C Hamano on 25 October 2019, 02:19:14 UTC 
t5510-fetch.sh: demonstrate fetch.writeCommitGraph bug
 
While dogfooding, Johannes found a bug in the fetch.writeCommitGraph
config behavior. His example initially happened during a clone with
--recurse-submodules, we found that this happens with the first fetch
after cloning a repository that contains a submodule:

	$ git clone <url> test
	$ cd test
	$ git -c fetch.writeCommitGraph=true fetch origin
	Computing commit graph generation numbers: 100% (12/12), done.
	BUG: commit-graph.c:886: missing parent <hash1> for commit <hash2>
	Aborted (core dumped)

In the repo I had cloned, there were really 60 commits to scan, but
only 12 were in the list to write when calling
compute_generation_numbers(). A commit in the list expects to see a
parent, but that parent is not in the list.

A follow-up will fix the bug, but first we create a test that
demonstrates the problem. This test must be careful about an existing
commit-graph file, since GIT_TEST_COMMIT_GRAPH=1 will cause the repo we
are cloning to already have one. This then prevents the incremtnal
commit-graph write during the first 'git fetch'.

Helped-by: Jeff King <peff@peff.net>
Helped-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Helped-by: Szeder Gábor <szeder.dev@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent 50f26bd
Raw File
prio-queue.c 
#include "cache.h"
#include "prio-queue.h"

static inline int compare(struct prio_queue *queue, int i, int j)
{
	int cmp = queue->compare(queue->array[i].data, queue->array[j].data,
				 queue->cb_data);
	if (!cmp)
		cmp = queue->array[i].ctr - queue->array[j].ctr;
	return cmp;
}

static inline void swap(struct prio_queue *queue, int i, int j)
{
	SWAP(queue->array[i], queue->array[j]);
}

void prio_queue_reverse(struct prio_queue *queue)
{
	int i, j;

	if (queue->compare != NULL)
		BUG("prio_queue_reverse() on non-LIFO queue");
	for (i = 0; i < (j = (queue->nr - 1) - i); i++)
		swap(queue, i, j);
}

void clear_prio_queue(struct prio_queue *queue)
{
	FREE_AND_NULL(queue->array);
	queue->nr = 0;
	queue->alloc = 0;
	queue->insertion_ctr = 0;
}

void prio_queue_put(struct prio_queue *queue, void *thing)
{
	int ix, parent;

	/* Append at the end */
	ALLOC_GROW(queue->array, queue->nr + 1, queue->alloc);
	queue->array[queue->nr].ctr = queue->insertion_ctr++;
	queue->array[queue->nr].data = thing;
	queue->nr++;
	if (!queue->compare)
		return; /* LIFO */

	/* Bubble up the new one */
	for (ix = queue->nr - 1; ix; ix = parent) {
		parent = (ix - 1) / 2;
		if (compare(queue, parent, ix) <= 0)
			break;

		swap(queue, parent, ix);
	}
}

void *prio_queue_get(struct prio_queue *queue)
{
	void *result;
	int ix, child;

	if (!queue->nr)
		return NULL;
	if (!queue->compare)
		return queue->array[--queue->nr].data; /* LIFO */

	result = queue->array[0].data;
	if (!--queue->nr)
		return result;

	queue->array[0] = queue->array[queue->nr];

	/* Push down the one at the root */
	for (ix = 0; ix * 2 + 1 < queue->nr; ix = child) {
		child = ix * 2 + 1; /* left */
		if (child + 1 < queue->nr &&
		    compare(queue, child, child + 1) >= 0)
			child++; /* use right child */

		if (compare(queue, ix, child) <= 0)
			break;

		swap(queue, child, ix);
	}
	return result;
}

void *prio_queue_peek(struct prio_queue *queue)
{
	if (!queue->nr)
		return NULL;
	if (!queue->compare)
		return queue->array[queue->nr - 1].data;
	return queue->array[0].data;
}
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