Staging
v0.7.0
v0.7.0
Revision cb99a34e23e32ca8e94bafaa9699cfd133a17fd3 authored by Derrick Stolee on 24 October 2019, 13:40:42 UTC, committed by Junio C Hamano on 25 October 2019, 02:19:16 UTC
The previous commit includes a failing test for an issue around fetch.writeCommitGraph and fetching in a repo with a submodule. Here, we fix that bug and set the test to "test_expect_success". The problem arises with this set of commands when the remote repo at <url> has a submodule. Note that --recurse-submodules is not needed to demonstrate the bug. $ 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) As an initial fix, I converted the code in builtin/fetch.c that calls write_commit_graph_reachable() to instead launch a "git commit-graph write --reachable --split" process. That code worked, but is not how we want the feature to work long-term. That test did demonstrate that the issue must be something to do with internal state of the 'git fetch' process. The write_commit_graph() method in commit-graph.c ensures the commits we plan to write are "closed under reachability" using close_reachable(). This method walks from the input commits, and uses the UNINTERESTING flag to mark which commits have already been visited. This allows the walk to take O(N) time, where N is the number of commits, instead of O(P) time, where P is the number of paths. (The number of paths can be exponential in the number of commits.) However, the UNINTERESTING flag is used in lots of places in the codebase. This flag usually means some barrier to stop a commit walk, such as in revision-walking to compare histories. It is not often cleared after the walk completes because the starting points of those walks do not have the UNINTERESTING flag, and clear_commit_marks() would stop immediately. This is happening during a 'git fetch' call with a remote. The fetch negotiation is comparing the remote refs with the local refs and marking some commits as UNINTERESTING. I tested running clear_commit_marks_many() to clear the UNINTERESTING flag inside close_reachable(), but the tips did not have the flag, so that did nothing. It turns out that the calculate_changed_submodule_paths() method is at fault. Thanks, Peff, for pointing out this detail! More specifically, for each submodule, the collect_changed_submodules() runs a revision walk to essentially do file-history on the list of submodules. That revision walk marks commits UNININTERESTING if they are simplified away by not changing the submodule. Instead, I finally arrived on the conclusion that I should use a flag that is not used in any other part of the code. In commit-reach.c, a number of flags were defined for commit walk algorithms. The REACHABLE flag seemed like it made the most sense, and it seems it was not actually used in the file. The REACHABLE flag was used in early versions of commit-reach.c, but was removed by 4fbcca4 (commit-reach: make can_all_from_reach... linear, 2018-07-20). Add the REACHABLE flag to commit-graph.c and use it instead of UNINTERESTING in close_reachable(). This fixes the bug in manual testing. Reported-by: Johannes Schindelin <johannes.schindelin@gmx.de> Helped-by: Jeff King <peff@peff.net> 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 e88aab9
hashmap.c
/*
* Generic implementation of hash-based key value mappings.
*/
#include "cache.h"
#include "hashmap.h"
#define FNV32_BASE ((unsigned int) 0x811c9dc5)
#define FNV32_PRIME ((unsigned int) 0x01000193)
unsigned int strhash(const char *str)
{
unsigned int c, hash = FNV32_BASE;
while ((c = (unsigned char) *str++))
hash = (hash * FNV32_PRIME) ^ c;
return hash;
}
unsigned int strihash(const char *str)
{
unsigned int c, hash = FNV32_BASE;
while ((c = (unsigned char) *str++)) {
if (c >= 'a' && c <= 'z')
c -= 'a' - 'A';
hash = (hash * FNV32_PRIME) ^ c;
}
return hash;
}
unsigned int memhash(const void *buf, size_t len)
{
unsigned int hash = FNV32_BASE;
unsigned char *ucbuf = (unsigned char *) buf;
while (len--) {
unsigned int c = *ucbuf++;
hash = (hash * FNV32_PRIME) ^ c;
}
return hash;
}
unsigned int memihash(const void *buf, size_t len)
{
unsigned int hash = FNV32_BASE;
unsigned char *ucbuf = (unsigned char *) buf;
while (len--) {
unsigned int c = *ucbuf++;
if (c >= 'a' && c <= 'z')
c -= 'a' - 'A';
hash = (hash * FNV32_PRIME) ^ c;
}
return hash;
}
/*
* Incoporate another chunk of data into a memihash
* computation.
*/
unsigned int memihash_cont(unsigned int hash_seed, const void *buf, size_t len)
{
unsigned int hash = hash_seed;
unsigned char *ucbuf = (unsigned char *) buf;
while (len--) {
unsigned int c = *ucbuf++;
if (c >= 'a' && c <= 'z')
c -= 'a' - 'A';
hash = (hash * FNV32_PRIME) ^ c;
}
return hash;
}
#define HASHMAP_INITIAL_SIZE 64
/* grow / shrink by 2^2 */
#define HASHMAP_RESIZE_BITS 2
/* load factor in percent */
#define HASHMAP_LOAD_FACTOR 80
static void alloc_table(struct hashmap *map, unsigned int size)
{
map->tablesize = size;
map->table = xcalloc(size, sizeof(struct hashmap_entry *));
/* calculate resize thresholds for new size */
map->grow_at = (unsigned int) ((uint64_t) size * HASHMAP_LOAD_FACTOR / 100);
if (size <= HASHMAP_INITIAL_SIZE)
map->shrink_at = 0;
else
/*
* The shrink-threshold must be slightly smaller than
* (grow-threshold / resize-factor) to prevent erratic resizing,
* thus we divide by (resize-factor + 1).
*/
map->shrink_at = map->grow_at / ((1 << HASHMAP_RESIZE_BITS) + 1);
}
static inline int entry_equals(const struct hashmap *map,
const struct hashmap_entry *e1, const struct hashmap_entry *e2,
const void *keydata)
{
return (e1 == e2) ||
(e1->hash == e2->hash &&
!map->cmpfn(map->cmpfn_data, e1, e2, keydata));
}
static inline unsigned int bucket(const struct hashmap *map,
const struct hashmap_entry *key)
{
return key->hash & (map->tablesize - 1);
}
int hashmap_bucket(const struct hashmap *map, unsigned int hash)
{
return hash & (map->tablesize - 1);
}
static void rehash(struct hashmap *map, unsigned int newsize)
{
unsigned int i, oldsize = map->tablesize;
struct hashmap_entry **oldtable = map->table;
alloc_table(map, newsize);
for (i = 0; i < oldsize; i++) {
struct hashmap_entry *e = oldtable[i];
while (e) {
struct hashmap_entry *next = e->next;
unsigned int b = bucket(map, e);
e->next = map->table[b];
map->table[b] = e;
e = next;
}
}
free(oldtable);
}
static inline struct hashmap_entry **find_entry_ptr(const struct hashmap *map,
const struct hashmap_entry *key, const void *keydata)
{
struct hashmap_entry **e = &map->table[bucket(map, key)];
while (*e && !entry_equals(map, *e, key, keydata))
e = &(*e)->next;
return e;
}
static int always_equal(const void *unused_cmp_data,
const void *unused1,
const void *unused2,
const void *unused_keydata)
{
return 0;
}
void hashmap_init(struct hashmap *map, hashmap_cmp_fn equals_function,
const void *cmpfn_data, size_t initial_size)
{
unsigned int size = HASHMAP_INITIAL_SIZE;
memset(map, 0, sizeof(*map));
map->cmpfn = equals_function ? equals_function : always_equal;
map->cmpfn_data = cmpfn_data;
/* calculate initial table size and allocate the table */
initial_size = (unsigned int) ((uint64_t) initial_size * 100
/ HASHMAP_LOAD_FACTOR);
while (initial_size > size)
size <<= HASHMAP_RESIZE_BITS;
alloc_table(map, size);
/*
* Keep track of the number of items in the map and
* allow the map to automatically grow as necessary.
*/
map->do_count_items = 1;
}
void hashmap_free(struct hashmap *map, int free_entries)
{
if (!map || !map->table)
return;
if (free_entries) {
struct hashmap_iter iter;
struct hashmap_entry *e;
hashmap_iter_init(map, &iter);
while ((e = hashmap_iter_next(&iter)))
free(e);
}
free(map->table);
memset(map, 0, sizeof(*map));
}
void *hashmap_get(const struct hashmap *map, const void *key, const void *keydata)
{
return *find_entry_ptr(map, key, keydata);
}
void *hashmap_get_next(const struct hashmap *map, const void *entry)
{
struct hashmap_entry *e = ((struct hashmap_entry *) entry)->next;
for (; e; e = e->next)
if (entry_equals(map, entry, e, NULL))
return e;
return NULL;
}
void hashmap_add(struct hashmap *map, void *entry)
{
unsigned int b = bucket(map, entry);
/* add entry */
((struct hashmap_entry *) entry)->next = map->table[b];
map->table[b] = entry;
/* fix size and rehash if appropriate */
if (map->do_count_items) {
map->private_size++;
if (map->private_size > map->grow_at)
rehash(map, map->tablesize << HASHMAP_RESIZE_BITS);
}
}
void *hashmap_remove(struct hashmap *map, const void *key, const void *keydata)
{
struct hashmap_entry *old;
struct hashmap_entry **e = find_entry_ptr(map, key, keydata);
if (!*e)
return NULL;
/* remove existing entry */
old = *e;
*e = old->next;
old->next = NULL;
/* fix size and rehash if appropriate */
if (map->do_count_items) {
map->private_size--;
if (map->private_size < map->shrink_at)
rehash(map, map->tablesize >> HASHMAP_RESIZE_BITS);
}
return old;
}
void *hashmap_put(struct hashmap *map, void *entry)
{
struct hashmap_entry *old = hashmap_remove(map, entry, NULL);
hashmap_add(map, entry);
return old;
}
void hashmap_iter_init(struct hashmap *map, struct hashmap_iter *iter)
{
iter->map = map;
iter->tablepos = 0;
iter->next = NULL;
}
void *hashmap_iter_next(struct hashmap_iter *iter)
{
struct hashmap_entry *current = iter->next;
for (;;) {
if (current) {
iter->next = current->next;
return current;
}
if (iter->tablepos >= iter->map->tablesize)
return NULL;
current = iter->map->table[iter->tablepos++];
}
}
struct pool_entry {
struct hashmap_entry ent;
size_t len;
unsigned char data[FLEX_ARRAY];
};
static int pool_entry_cmp(const void *unused_cmp_data,
const struct pool_entry *e1,
const struct pool_entry *e2,
const unsigned char *keydata)
{
return e1->data != keydata &&
(e1->len != e2->len || memcmp(e1->data, keydata, e1->len));
}
const void *memintern(const void *data, size_t len)
{
static struct hashmap map;
struct pool_entry key, *e;
/* initialize string pool hashmap */
if (!map.tablesize)
hashmap_init(&map, (hashmap_cmp_fn) pool_entry_cmp, NULL, 0);
/* lookup interned string in pool */
hashmap_entry_init(&key, memhash(data, len));
key.len = len;
e = hashmap_get(&map, &key, data);
if (!e) {
/* not found: create it */
FLEX_ALLOC_MEM(e, data, data, len);
hashmap_entry_init(e, key.ent.hash);
e->len = len;
hashmap_add(&map, e);
}
return e->data;
}
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