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git/refs/ref-cache.c

504 lines
13 KiB

#include "../cache.h"
#include "../refs.h"
#include "refs-internal.h"
#include "ref-cache.h"
#include "../iterator.h"
void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry)
{
ALLOC_GROW(dir->entries, dir->nr + 1, dir->alloc);
dir->entries[dir->nr++] = entry;
/* optimize for the case that entries are added in order */
if (dir->nr == 1 ||
(dir->nr == dir->sorted + 1 &&
strcmp(dir->entries[dir->nr - 2]->name,
dir->entries[dir->nr - 1]->name) < 0))
dir->sorted = dir->nr;
}
struct ref_dir *get_ref_dir(struct ref_entry *entry)
{
struct ref_dir *dir;
assert(entry->flag & REF_DIR);
dir = &entry->u.subdir;
if (entry->flag & REF_INCOMPLETE) {
if (!dir->cache->fill_ref_dir)
BUG("incomplete ref_store without fill_ref_dir function");
dir->cache->fill_ref_dir(dir->cache->ref_store, dir, entry->name);
entry->flag &= ~REF_INCOMPLETE;
}
return dir;
}
struct ref_entry *create_ref_entry(const char *refname,
const struct object_id *oid, int flag)
{
struct ref_entry *ref;
FLEX_ALLOC_STR(ref, name, refname);
oidcpy(&ref->u.value.oid, oid);
ref->flag = flag;
return ref;
}
struct ref_cache *create_ref_cache(struct ref_store *refs,
fill_ref_dir_fn *fill_ref_dir)
{
struct ref_cache *ret = xcalloc(1, sizeof(*ret));
ret->ref_store = refs;
ret->fill_ref_dir = fill_ref_dir;
ret->root = create_dir_entry(ret, "", 0);
return ret;
}
static void clear_ref_dir(struct ref_dir *dir);
static void free_ref_entry(struct ref_entry *entry)
{
if (entry->flag & REF_DIR) {
/*
* Do not use get_ref_dir() here, as that might
* trigger the reading of loose refs.
*/
clear_ref_dir(&entry->u.subdir);
}
free(entry);
}
void free_ref_cache(struct ref_cache *cache)
{
free_ref_entry(cache->root);
free(cache);
}
/*
* Clear and free all entries in dir, recursively.
*/
static void clear_ref_dir(struct ref_dir *dir)
{
int i;
for (i = 0; i < dir->nr; i++)
free_ref_entry(dir->entries[i]);
FREE_AND_NULL(dir->entries);
dir->sorted = dir->nr = dir->alloc = 0;
}
struct ref_entry *create_dir_entry(struct ref_cache *cache,
const char *dirname, size_t len)
{
struct ref_entry *direntry;
FLEX_ALLOC_MEM(direntry, name, dirname, len);
direntry->u.subdir.cache = cache;
direntry->flag = REF_DIR | REF_INCOMPLETE;
return direntry;
}
static int ref_entry_cmp(const void *a, const void *b)
{
struct ref_entry *one = *(struct ref_entry **)a;
struct ref_entry *two = *(struct ref_entry **)b;
return strcmp(one->name, two->name);
}
static void sort_ref_dir(struct ref_dir *dir);
struct string_slice {
size_t len;
const char *str;
};
static int ref_entry_cmp_sslice(const void *key_, const void *ent_)
{
const struct string_slice *key = key_;
const struct ref_entry *ent = *(const struct ref_entry * const *)ent_;
int cmp = strncmp(key->str, ent->name, key->len);
if (cmp)
return cmp;
return '\0' - (unsigned char)ent->name[key->len];
}
int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len)
{
struct ref_entry **r;
struct string_slice key;
if (refname == NULL || !dir->nr)
return -1;
sort_ref_dir(dir);
key.len = len;
key.str = refname;
r = bsearch(&key, dir->entries, dir->nr, sizeof(*dir->entries),
ref_entry_cmp_sslice);
if (r == NULL)
return -1;
return r - dir->entries;
}
/*
* Search for a directory entry directly within dir (without
* recursing). Sort dir if necessary. subdirname must be a directory
* name (i.e., end in '/'). Returns NULL if the desired
* directory cannot be found. dir must already be complete.
*/
static struct ref_dir *search_for_subdir(struct ref_dir *dir,
const char *subdirname, size_t len)
{
int entry_index = search_ref_dir(dir, subdirname, len);
struct ref_entry *entry;
if (entry_index == -1)
return NULL;
entry = dir->entries[entry_index];
return get_ref_dir(entry);
}
/*
* If refname is a reference name, find the ref_dir within the dir
* tree that should hold refname. If refname is a directory name
* (i.e., it ends in '/'), then return that ref_dir itself. dir must
* represent the top-level directory and must already be complete.
* Sort ref_dirs and recurse into subdirectories as necessary. Will
* return NULL if the desired directory cannot be found.
*/
static struct ref_dir *find_containing_dir(struct ref_dir *dir,
const char *refname)
{
const char *slash;
for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
size_t dirnamelen = slash - refname + 1;
struct ref_dir *subdir;
subdir = search_for_subdir(dir, refname, dirnamelen);
if (!subdir) {
dir = NULL;
break;
}
dir = subdir;
}
return dir;
}
struct ref_entry *find_ref_entry(struct ref_dir *dir, const char *refname)
{
int entry_index;
struct ref_entry *entry;
dir = find_containing_dir(dir, refname);
if (!dir)
return NULL;
entry_index = search_ref_dir(dir, refname, strlen(refname));
if (entry_index == -1)
return NULL;
entry = dir->entries[entry_index];
return (entry->flag & REF_DIR) ? NULL : entry;
}
/*
* Emit a warning and return true iff ref1 and ref2 have the same name
* and the same oid. Die if they have the same name but different
* oids.
*/
static int is_dup_ref(const struct ref_entry *ref1, const struct ref_entry *ref2)
{
if (strcmp(ref1->name, ref2->name))
return 0;
/* Duplicate name; make sure that they don't conflict: */
if ((ref1->flag & REF_DIR) || (ref2->flag & REF_DIR))
/* This is impossible by construction */
die("Reference directory conflict: %s", ref1->name);
if (!oideq(&ref1->u.value.oid, &ref2->u.value.oid))
die("Duplicated ref, and SHA1s don't match: %s", ref1->name);
warning("Duplicated ref: %s", ref1->name);
return 1;
}
/*
* Sort the entries in dir non-recursively (if they are not already
* sorted) and remove any duplicate entries.
*/
static void sort_ref_dir(struct ref_dir *dir)
{
int i, j;
struct ref_entry *last = NULL;
/*
* This check also prevents passing a zero-length array to qsort(),
* which is a problem on some platforms.
*/
if (dir->sorted == dir->nr)
return;
QSORT(dir->entries, dir->nr, ref_entry_cmp);
/* Remove any duplicates: */
for (i = 0, j = 0; j < dir->nr; j++) {
struct ref_entry *entry = dir->entries[j];
if (last && is_dup_ref(last, entry))
free_ref_entry(entry);
else
last = dir->entries[i++] = entry;
}
dir->sorted = dir->nr = i;
}
enum prefix_state {
/* All refs within the directory would match prefix: */
PREFIX_CONTAINS_DIR,
/* Some, but not all, refs within the directory might match prefix: */
PREFIX_WITHIN_DIR,
/* No refs within the directory could possibly match prefix: */
PREFIX_EXCLUDES_DIR
};
/*
* Return a `prefix_state` constant describing the relationship
* between the directory with the specified `dirname` and `prefix`.
*/
static enum prefix_state overlaps_prefix(const char *dirname,
const char *prefix)
{
while (*prefix && *dirname == *prefix) {
dirname++;
prefix++;
}
if (!*prefix)
return PREFIX_CONTAINS_DIR;
else if (!*dirname)
return PREFIX_WITHIN_DIR;
else
return PREFIX_EXCLUDES_DIR;
}
/*
* Load all of the refs from `dir` (recursively) that could possibly
* contain references matching `prefix` into our in-memory cache. If
* `prefix` is NULL, prime unconditionally.
*/
static void prime_ref_dir(struct ref_dir *dir, const char *prefix)
{
/*
* The hard work of loading loose refs is done by get_ref_dir(), so we
* just need to recurse through all of the sub-directories. We do not
* even need to care about sorting, as traversal order does not matter
* to us.
*/
int i;
for (i = 0; i < dir->nr; i++) {
struct ref_entry *entry = dir->entries[i];
if (!(entry->flag & REF_DIR)) {
/* Not a directory; no need to recurse. */
} else if (!prefix) {
/* Recurse in any case: */
prime_ref_dir(get_ref_dir(entry), NULL);
} else {
switch (overlaps_prefix(entry->name, prefix)) {
case PREFIX_CONTAINS_DIR:
/*
* Recurse, and from here down we
* don't have to check the prefix
* anymore:
*/
prime_ref_dir(get_ref_dir(entry), NULL);
break;
case PREFIX_WITHIN_DIR:
prime_ref_dir(get_ref_dir(entry), prefix);
break;
case PREFIX_EXCLUDES_DIR:
/* No need to prime this directory. */
break;
}
}
}
}
/*
* A level in the reference hierarchy that is currently being iterated
* through.
*/
struct cache_ref_iterator_level {
/*
* The ref_dir being iterated over at this level. The ref_dir
* is sorted before being stored here.
*/
struct ref_dir *dir;
enum prefix_state prefix_state;
/*
* The index of the current entry within dir (which might
* itself be a directory). If index == -1, then the iteration
* hasn't yet begun. If index == dir->nr, then the iteration
* through this level is over.
*/
int index;
};
/*
* Represent an iteration through a ref_dir in the memory cache. The
* iteration recurses through subdirectories.
*/
struct cache_ref_iterator {
struct ref_iterator base;
/*
* The number of levels currently on the stack. This is always
* at least 1, because when it becomes zero the iteration is
* ended and this struct is freed.
*/
size_t levels_nr;
/* The number of levels that have been allocated on the stack */
size_t levels_alloc;
/*
* Only include references with this prefix in the iteration.
* The prefix is matched textually, without regard for path
* component boundaries.
*/
const char *prefix;
/*
* A stack of levels. levels[0] is the uppermost level that is
* being iterated over in this iteration. (This is not
* necessary the top level in the references hierarchy. If we
* are iterating through a subtree, then levels[0] will hold
* the ref_dir for that subtree, and subsequent levels will go
* on from there.)
*/
struct cache_ref_iterator_level *levels;
struct repository *repo;
};
static int cache_ref_iterator_advance(struct ref_iterator *ref_iterator)
{
struct cache_ref_iterator *iter =
(struct cache_ref_iterator *)ref_iterator;
while (1) {
struct cache_ref_iterator_level *level =
&iter->levels[iter->levels_nr - 1];
struct ref_dir *dir = level->dir;
struct ref_entry *entry;
enum prefix_state entry_prefix_state;
if (level->index == -1)
sort_ref_dir(dir);
if (++level->index == level->dir->nr) {
/* This level is exhausted; pop up a level */
if (--iter->levels_nr == 0)
return ref_iterator_abort(ref_iterator);
continue;
}
entry = dir->entries[level->index];
if (level->prefix_state == PREFIX_WITHIN_DIR) {
entry_prefix_state = overlaps_prefix(entry->name, iter->prefix);
if (entry_prefix_state == PREFIX_EXCLUDES_DIR)
continue;
} else {
entry_prefix_state = level->prefix_state;
}
if (entry->flag & REF_DIR) {
/* push down a level */
ALLOC_GROW(iter->levels, iter->levels_nr + 1,
iter->levels_alloc);
level = &iter->levels[iter->levels_nr++];
level->dir = get_ref_dir(entry);
level->prefix_state = entry_prefix_state;
level->index = -1;
} else {
iter->base.refname = entry->name;
iter->base.oid = &entry->u.value.oid;
iter->base.flags = entry->flag;
return ITER_OK;
}
}
}
static int cache_ref_iterator_peel(struct ref_iterator *ref_iterator,
struct object_id *peeled)
{
struct cache_ref_iterator *iter =
(struct cache_ref_iterator *)ref_iterator;
if (iter->repo != the_repository)
BUG("peeling for non-the_repository is not supported");
return peel_object(ref_iterator->oid, peeled) ? -1 : 0;
}
static int cache_ref_iterator_abort(struct ref_iterator *ref_iterator)
{
struct cache_ref_iterator *iter =
(struct cache_ref_iterator *)ref_iterator;
free((char *)iter->prefix);
free(iter->levels);
base_ref_iterator_free(ref_iterator);
return ITER_DONE;
}
static struct ref_iterator_vtable cache_ref_iterator_vtable = {
.advance = cache_ref_iterator_advance,
.peel = cache_ref_iterator_peel,
.abort = cache_ref_iterator_abort
};
struct ref_iterator *cache_ref_iterator_begin(struct ref_cache *cache,
const char *prefix,
struct repository *repo,
int prime_dir)
{
struct ref_dir *dir;
struct cache_ref_iterator *iter;
struct ref_iterator *ref_iterator;
struct cache_ref_iterator_level *level;
dir = get_ref_dir(cache->root);
if (prefix && *prefix)
dir = find_containing_dir(dir, prefix);
if (!dir)
/* There's nothing to iterate over. */
return empty_ref_iterator_begin();
if (prime_dir)
prime_ref_dir(dir, prefix);
CALLOC_ARRAY(iter, 1);
ref_iterator = &iter->base;
base_ref_iterator_init(ref_iterator, &cache_ref_iterator_vtable, 1);
ALLOC_GROW(iter->levels, 10, iter->levels_alloc);
iter->levels_nr = 1;
level = &iter->levels[0];
level->index = -1;
level->dir = dir;
if (prefix && *prefix) {
iter->prefix = xstrdup(prefix);
level->prefix_state = PREFIX_WITHIN_DIR;
} else {
level->prefix_state = PREFIX_CONTAINS_DIR;
}
iter->repo = repo;
return ref_iterator;
}