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packed-backend: new module for handling packed references

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Now that the interface between `files_ref_store` and
`packed_ref_store` is relatively narrow, move the latter into a new
module, "refs/packed-backend.h" and "refs/packed-backend.c". It still
doesn't quite implement the `ref_store` interface, but it will soon.

This commit moves code around and adjusts its visibility, but doesn't
change anything.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Michael Haggerty 2017-06-23 09:01:37 +02:00 committed by Junio C Hamano
parent d13fa1a9ba
commit 67be7c5a59
6 changed files with 685 additions and 639 deletions
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1
Makefile
View File

@ -817,6 +817,7 @@ LIB_OBJS += reflog-walk.o
LIB_OBJS += refs.o
LIB_OBJS += refs/files-backend.o
LIB_OBJS += refs/iterator.o
LIB_OBJS += refs/packed-backend.o
LIB_OBJS += refs/ref-cache.o
LIB_OBJS += ref-filter.o
LIB_OBJS += remote.o

18
refs.c
View File

@ -173,6 +173,24 @@ int refname_is_safe(const char *refname)
return 1;
}
/*
* Return true if refname, which has the specified oid and flags, can
* be resolved to an object in the database. If the referred-to object
* does not exist, emit a warning and return false.
*/
int ref_resolves_to_object(const char *refname,
const struct object_id *oid,
unsigned int flags)
{
if (flags & REF_ISBROKEN)
return 0;
if (!has_sha1_file(oid->hash)) {
error("%s does not point to a valid object!", refname);
return 0;
}
return 1;
}
char *refs_resolve_refdup(struct ref_store *refs,
const char *refname, int resolve_flags,
unsigned char *sha1, int *flags)

640
refs/files-backend.c
View File

@ -2,6 +2,7 @@
#include "../refs.h"
#include "refs-internal.h"
#include "ref-cache.h"
#include "packed-backend.h"
#include "../iterator.h"
#include "../dir-iterator.h"
#include "../lockfile.h"
@ -14,85 +15,6 @@ struct ref_lock {
struct object_id old_oid;
};
/*
* Return true if refname, which has the specified oid and flags, can
* be resolved to an object in the database. If the referred-to object
* does not exist, emit a warning and return false.
*/
static int ref_resolves_to_object(const char *refname,
const struct object_id *oid,
unsigned int flags)
{
if (flags & REF_ISBROKEN)
return 0;
if (!has_sha1_file(oid->hash)) {
error("%s does not point to a valid object!", refname);
return 0;
}
return 1;
}
struct packed_ref_cache {
struct ref_cache *cache;
/*
* Count of references to the data structure in this instance,
* including the pointer from files_ref_store::packed if any.
* The data will not be freed as long as the reference count
* is nonzero.
*/
unsigned int referrers;
/* The metadata from when this packed-refs cache was read */
struct stat_validity validity;
};
/*
* A container for `packed-refs`-related data. It is not (yet) a
* `ref_store`.
*/
struct packed_ref_store {
unsigned int store_flags;
/* The path of the "packed-refs" file: */
char *path;
/*
* A cache of the values read from the `packed-refs` file, if
* it might still be current; otherwise, NULL.
*/
struct packed_ref_cache *cache;
/*
* Lock used for the "packed-refs" file. Note that this (and
* thus the enclosing `packed_ref_store`) must not be freed.
*/
struct lock_file lock;
};
static struct packed_ref_store *packed_ref_store_create(
const char *path, unsigned int store_flags)
{
struct packed_ref_store *refs = xcalloc(1, sizeof(*refs));
refs->store_flags = store_flags;
refs->path = xstrdup(path);
return refs;
}
/*
* Die if refs is not the main ref store. caller is used in any
* necessary error messages.
*/
static void packed_assert_main_repository(struct packed_ref_store *refs,
const char *caller)
{
if (refs->store_flags & REF_STORE_MAIN)
return;
die("BUG: operation %s only allowed for main ref store", caller);
}
/*
* Future: need to be in "struct repository"
* when doing a full libification.
@ -109,42 +31,6 @@ struct files_ref_store {
struct packed_ref_store *packed_ref_store;
};
/*
* Increment the reference count of *packed_refs.
*/
static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
{
packed_refs->referrers++;
}
/*
* Decrease the reference count of *packed_refs. If it goes to zero,
* free *packed_refs and return true; otherwise return false.
*/
static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
{
if (!--packed_refs->referrers) {
free_ref_cache(packed_refs->cache);
stat_validity_clear(&packed_refs->validity);
free(packed_refs);
return 1;
} else {
return 0;
}
}
static void clear_packed_ref_cache(struct packed_ref_store *refs)
{
if (refs->cache) {
struct packed_ref_cache *cache = refs->cache;
if (is_lock_file_locked(&refs->lock))
die("BUG: packed-ref cache cleared while locked");
refs->cache = NULL;
release_packed_ref_cache(cache);
}
}
static void clear_loose_ref_cache(struct files_ref_store *refs)
{
if (refs->loose) {
@ -215,151 +101,6 @@ static struct files_ref_store *files_downcast(struct ref_store *ref_store,
return refs;
}
/* The length of a peeled reference line in packed-refs, including EOL: */
#define PEELED_LINE_LENGTH 42
/*
* The packed-refs header line that we write out. Perhaps other
* traits will be added later. The trailing space is required.
*/
static const char PACKED_REFS_HEADER[] =
"# pack-refs with: peeled fully-peeled \n";
/*
* Parse one line from a packed-refs file. Write the SHA1 to sha1.
* Return a pointer to the refname within the line (null-terminated),
* or NULL if there was a problem.
*/
static const char *parse_ref_line(struct strbuf *line, struct object_id *oid)
{
const char *ref;
if (parse_oid_hex(line->buf, oid, &ref) < 0)
return NULL;
if (!isspace(*ref++))
return NULL;
if (isspace(*ref))
return NULL;
if (line->buf[line->len - 1] != '\n')
return NULL;
line->buf[--line->len] = 0;
return ref;
}
/*
* Read from `packed_refs_file` into a newly-allocated
* `packed_ref_cache` and return it. The return value will already
* have its reference count incremented.
*
* A comment line of the form "# pack-refs with: " may contain zero or
* more traits. We interpret the traits as follows:
*
* No traits:
*
* Probably no references are peeled. But if the file contains a
* peeled value for a reference, we will use it.
*
* peeled:
*
* References under "refs/tags/", if they *can* be peeled, *are*
* peeled in this file. References outside of "refs/tags/" are
* probably not peeled even if they could have been, but if we find
* a peeled value for such a reference we will use it.
*
* fully-peeled:
*
* All references in the file that can be peeled are peeled.
* Inversely (and this is more important), any references in the
* file for which no peeled value is recorded is not peelable. This
* trait should typically be written alongside "peeled" for
* compatibility with older clients, but we do not require it
* (i.e., "peeled" is a no-op if "fully-peeled" is set).
*/
static struct packed_ref_cache *read_packed_refs(const char *packed_refs_file)
{
FILE *f;
struct packed_ref_cache *packed_refs = xcalloc(1, sizeof(*packed_refs));
struct ref_entry *last = NULL;
struct strbuf line = STRBUF_INIT;
enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
struct ref_dir *dir;
acquire_packed_ref_cache(packed_refs);
packed_refs->cache = create_ref_cache(NULL, NULL);
packed_refs->cache->root->flag &= ~REF_INCOMPLETE;
f = fopen(packed_refs_file, "r");
if (!f) {
if (errno == ENOENT) {
/*
* This is OK; it just means that no
* "packed-refs" file has been written yet,
* which is equivalent to it being empty.
*/
return packed_refs;
} else {
die_errno("couldn't read %s", packed_refs_file);
}
}
stat_validity_update(&packed_refs->validity, fileno(f));
dir = get_ref_dir(packed_refs->cache->root);
while (strbuf_getwholeline(&line, f, '\n') != EOF) {
struct object_id oid;
const char *refname;
const char *traits;
if (skip_prefix(line.buf, "# pack-refs with:", &traits)) {
if (strstr(traits, " fully-peeled "))
peeled = PEELED_FULLY;
else if (strstr(traits, " peeled "))
peeled = PEELED_TAGS;
/* perhaps other traits later as well */
continue;
}
refname = parse_ref_line(&line, &oid);
if (refname) {
int flag = REF_ISPACKED;
if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
if (!refname_is_safe(refname))
die("packed refname is dangerous: %s", refname);
oidclr(&oid);
flag |= REF_BAD_NAME | REF_ISBROKEN;
}
last = create_ref_entry(refname, &oid, flag);
if (peeled == PEELED_FULLY ||
(peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
last->flag |= REF_KNOWS_PEELED;
add_ref_entry(dir, last);
continue;
}
if (last &&
line.buf[0] == '^' &&
line.len == PEELED_LINE_LENGTH &&
line.buf[PEELED_LINE_LENGTH - 1] == '\n' &&
!get_oid_hex(line.buf + 1, &oid)) {
oidcpy(&last->u.value.peeled, &oid);
/*
* Regardless of what the file header said,
* we definitely know the value of *this*
* reference:
*/
last->flag |= REF_KNOWS_PEELED;
}
}
fclose(f);
strbuf_release(&line);
return packed_refs;
}
static void files_reflog_path(struct files_ref_store *refs,
struct strbuf *sb,
const char *refname)
@ -405,77 +146,6 @@ static void files_ref_path(struct files_ref_store *refs,
}
}
/*
* Check that the packed refs cache (if any) still reflects the
* contents of the file. If not, clear the cache.
*/
static void validate_packed_ref_cache(struct packed_ref_store *refs)
{
if (refs->cache &&
!stat_validity_check(&refs->cache->validity, refs->path))
clear_packed_ref_cache(refs);
}
/*
* Get the packed_ref_cache for the specified packed_ref_store,
* creating and populating it if it hasn't been read before or if the
* file has been changed (according to its `validity` field) since it
* was last read. On the other hand, if we hold the lock, then assume
* that the file hasn't been changed out from under us, so skip the
* extra `stat()` call in `stat_validity_check()`.
*/
static struct packed_ref_cache *get_packed_ref_cache(struct packed_ref_store *refs)
{
if (!is_lock_file_locked(&refs->lock))
validate_packed_ref_cache(refs);
if (!refs->cache)
refs->cache = read_packed_refs(refs->path);
return refs->cache;
}
static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
{
return get_ref_dir(packed_ref_cache->cache->root);
}
static struct ref_dir *get_packed_refs(struct packed_ref_store *refs)
{
return get_packed_ref_dir(get_packed_ref_cache(refs));
}
/*
* Add or overwrite a reference in the in-memory packed reference
* cache. This may only be called while the packed-refs file is locked
* (see lock_packed_refs()). To actually write the packed-refs file,
* call commit_packed_refs().
*/
static void add_packed_ref(struct packed_ref_store *refs,
const char *refname, const struct object_id *oid)
{
struct ref_dir *packed_refs;
struct ref_entry *packed_entry;
if (!is_lock_file_locked(&refs->lock))
die("BUG: packed refs not locked");
if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
die("Reference has invalid format: '%s'", refname);
packed_refs = get_packed_refs(refs);
packed_entry = find_ref_entry(packed_refs, refname);
if (packed_entry) {
/* Overwrite the existing entry: */
oidcpy(&packed_entry->u.value.oid, oid);
packed_entry->flag = REF_ISPACKED;
oidclr(&packed_entry->u.value.peeled);
} else {
packed_entry = create_ref_entry(refname, oid, REF_ISPACKED);
add_ref_entry(packed_refs, packed_entry);
}
}
/*
* Read the loose references from the namespace dirname into dir
* (without recursing). dirname must end with '/'. dir must be the
@ -598,35 +268,6 @@ static struct ref_cache *get_loose_ref_cache(struct files_ref_store *refs)
return refs->loose;
}
/*
* Return the ref_entry for the given refname from the packed
* references. If it does not exist, return NULL.
*/
static struct ref_entry *get_packed_ref(struct packed_ref_store *refs,
const char *refname)
{
return find_ref_entry(get_packed_refs(refs), refname);
}
static int packed_read_raw_ref(struct packed_ref_store *refs,
const char *refname, unsigned char *sha1,
struct strbuf *referent, unsigned int *type)
{
struct ref_entry *entry;
*type = 0;
entry = get_packed_ref(refs, refname);
if (!entry) {
errno = ENOENT;
return -1;
}
hashcpy(sha1, entry->u.value.oid.hash);
*type = REF_ISPACKED;
return 0;
}
static int files_read_raw_ref(struct ref_store *ref_store,
const char *refname, unsigned char *sha1,
struct strbuf *referent, unsigned int *type)
@ -1011,18 +652,6 @@ out:
return ret;
}
static int packed_peel_ref(struct packed_ref_store *refs,
const char *refname, unsigned char *sha1)
{
struct ref_entry *r = get_packed_ref(refs, refname);
if (!r || peel_entry(r, 0))
return -1;
hashcpy(sha1, r->u.value.peeled.hash);
return 0;
}
static int files_peel_ref(struct ref_store *ref_store,
const char *refname, unsigned char *sha1)
{
@ -1060,99 +689,6 @@ static int files_peel_ref(struct ref_store *ref_store,
return peel_object(base, sha1);
}
struct packed_ref_iterator {
struct ref_iterator base;
struct packed_ref_cache *cache;
struct ref_iterator *iter0;
unsigned int flags;
};
static int packed_ref_iterator_advance(struct ref_iterator *ref_iterator)
{
struct packed_ref_iterator *iter =
(struct packed_ref_iterator *)ref_iterator;
int ok;
while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) {
if (iter->flags & DO_FOR_EACH_PER_WORKTREE_ONLY &&
ref_type(iter->iter0->refname) != REF_TYPE_PER_WORKTREE)
continue;
if (!(iter->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
!ref_resolves_to_object(iter->iter0->refname,
iter->iter0->oid,
iter->iter0->flags))
continue;
iter->base.refname = iter->iter0->refname;
iter->base.oid = iter->iter0->oid;
iter->base.flags = iter->iter0->flags;
return ITER_OK;
}
iter->iter0 = NULL;
if (ref_iterator_abort(ref_iterator) != ITER_DONE)
ok = ITER_ERROR;
return ok;
}
static int packed_ref_iterator_peel(struct ref_iterator *ref_iterator,
struct object_id *peeled)
{
struct packed_ref_iterator *iter =
(struct packed_ref_iterator *)ref_iterator;
return ref_iterator_peel(iter->iter0, peeled);
}
static int packed_ref_iterator_abort(struct ref_iterator *ref_iterator)
{
struct packed_ref_iterator *iter =
(struct packed_ref_iterator *)ref_iterator;
int ok = ITER_DONE;
if (iter->iter0)
ok = ref_iterator_abort(iter->iter0);
release_packed_ref_cache(iter->cache);
base_ref_iterator_free(ref_iterator);
return ok;
}
static struct ref_iterator_vtable packed_ref_iterator_vtable = {
packed_ref_iterator_advance,
packed_ref_iterator_peel,
packed_ref_iterator_abort
};
static struct ref_iterator *packed_ref_iterator_begin(
struct packed_ref_store *refs,
const char *prefix, unsigned int flags)
{
struct packed_ref_iterator *iter;
struct ref_iterator *ref_iterator;
iter = xcalloc(1, sizeof(*iter));
ref_iterator = &iter->base;
base_ref_iterator_init(ref_iterator, &packed_ref_iterator_vtable);
/*
* Note that get_packed_ref_cache() internally checks whether
* the packed-ref cache is up to date with what is on disk,
* and re-reads it if not.
*/
iter->cache = get_packed_ref_cache(refs);
acquire_packed_ref_cache(iter->cache);
iter->iter0 = cache_ref_iterator_begin(iter->cache->cache, prefix, 0);
iter->flags = flags;
return ref_iterator;
}
struct files_ref_iterator {
struct ref_iterator base;
@ -1434,124 +970,6 @@ static struct ref_lock *lock_ref_sha1_basic(struct files_ref_store *refs,
return lock;
}
/*
* Write an entry to the packed-refs file for the specified refname.
* If peeled is non-NULL, write it as the entry's peeled value.
*/
static void write_packed_entry(FILE *fh, const char *refname,
const unsigned char *sha1,
const unsigned char *peeled)
{
fprintf_or_die(fh, "%s %s\n", sha1_to_hex(sha1), refname);
if (peeled)
fprintf_or_die(fh, "^%s\n", sha1_to_hex(peeled));
}
/*
* Lock the packed-refs file for writing. Flags is passed to
* hold_lock_file_for_update(). Return 0 on success. On errors, set
* errno appropriately and return a nonzero value.
*/
static int lock_packed_refs(struct packed_ref_store *refs, int flags)
{
static int timeout_configured = 0;
static int timeout_value = 1000;
struct packed_ref_cache *packed_ref_cache;
packed_assert_main_repository(refs, "lock_packed_refs");
if (!timeout_configured) {
git_config_get_int("core.packedrefstimeout", &timeout_value);
timeout_configured = 1;
}
if (hold_lock_file_for_update_timeout(
&refs->lock,
refs->path,
flags, timeout_value) < 0)
return -1;
/*
* Now that we hold the `packed-refs` lock, make sure that our
* cache matches the current version of the file. Normally
* `get_packed_ref_cache()` does that for us, but that
* function assumes that when the file is locked, any existing
* cache is still valid. We've just locked the file, but it
* might have changed the moment *before* we locked it.
*/
validate_packed_ref_cache(refs);
packed_ref_cache = get_packed_ref_cache(refs);
/* Increment the reference count to prevent it from being freed: */
acquire_packed_ref_cache(packed_ref_cache);
return 0;
}
/*
* Write the current version of the packed refs cache from memory to
* disk. The packed-refs file must already be locked for writing (see
* lock_packed_refs()). Return zero on success. On errors, set errno
* and return a nonzero value
*/
static int commit_packed_refs(struct packed_ref_store *refs)
{
struct packed_ref_cache *packed_ref_cache =
get_packed_ref_cache(refs);
int ok, error = 0;
int save_errno = 0;
FILE *out;
struct ref_iterator *iter;
packed_assert_main_repository(refs, "commit_packed_refs");
if (!is_lock_file_locked(&refs->lock))
die("BUG: packed-refs not locked");
out = fdopen_lock_file(&refs->lock, "w");
if (!out)
die_errno("unable to fdopen packed-refs descriptor");
fprintf_or_die(out, "%s", PACKED_REFS_HEADER);
iter = cache_ref_iterator_begin(packed_ref_cache->cache, NULL, 0);
while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
struct object_id peeled;
int peel_error = ref_iterator_peel(iter, &peeled);
write_packed_entry(out, iter->refname, iter->oid->hash,
peel_error ? NULL : peeled.hash);
}
if (ok != ITER_DONE)
die("error while iterating over references");
if (commit_lock_file(&refs->lock)) {
save_errno = errno;
error = -1;
}
release_packed_ref_cache(packed_ref_cache);
errno = save_errno;
return error;
}
/*
* Rollback the lockfile for the packed-refs file, and discard the
* in-memory packed reference cache. (The packed-refs file will be
* read anew if it is needed again after this function is called.)
*/
static void rollback_packed_refs(struct packed_ref_store *refs)
{
struct packed_ref_cache *packed_ref_cache = get_packed_ref_cache(refs);
packed_assert_main_repository(refs, "rollback_packed_refs");
if (!is_lock_file_locked(&refs->lock))
die("BUG: packed-refs not locked");
rollback_lock_file(&refs->lock);
release_packed_ref_cache(packed_ref_cache);
clear_packed_ref_cache(refs);
}
struct ref_to_prune {
struct ref_to_prune *next;
unsigned char sha1[20];
@ -1717,62 +1135,6 @@ static int files_pack_refs(struct ref_store *ref_store, unsigned int flags)
return 0;
}
/*
* Rewrite the packed-refs file, omitting any refs listed in
* 'refnames'. On error, leave packed-refs unchanged, write an error
* message to 'err', and return a nonzero value.
*
* The refs in 'refnames' needn't be sorted. `err` must not be NULL.
*/
static int repack_without_refs(struct packed_ref_store *refs,
struct string_list *refnames, struct strbuf *err)
{
struct ref_dir *packed;
struct string_list_item *refname;
int ret, needs_repacking = 0, removed = 0;
packed_assert_main_repository(refs, "repack_without_refs");
assert(err);
/* Look for a packed ref */
for_each_string_list_item(refname, refnames) {
if (get_packed_ref(refs, refname->string)) {
needs_repacking = 1;
break;
}
}
/* Avoid locking if we have nothing to do */
if (!needs_repacking)
return 0; /* no refname exists in packed refs */
if (lock_packed_refs(refs, 0)) {
unable_to_lock_message(refs->path, errno, err);
return -1;
}
packed = get_packed_refs(refs);
/* Remove refnames from the cache */
for_each_string_list_item(refname, refnames)
if (remove_entry_from_dir(packed, refname->string) != -1)
removed = 1;
if (!removed) {
/*
* All packed entries disappeared while we were
* acquiring the lock.
*/
rollback_packed_refs(refs);
return 0;
}
/* Write what remains */
ret = commit_packed_refs(refs);
if (ret)
strbuf_addf(err, "unable to overwrite old ref-pack file: %s",
strerror(errno));
return ret;
}
static int files_delete_refs(struct ref_store *ref_store, const char *msg,
struct string_list *refnames, unsigned int flags)
{

623
refs/packed-backend.c Normal file
View File

@ -0,0 +1,623 @@
#include "../cache.h"
#include "../refs.h"
#include "refs-internal.h"
#include "ref-cache.h"
#include "packed-backend.h"
#include "../iterator.h"
#include "../lockfile.h"
struct packed_ref_cache {
struct ref_cache *cache;
/*
* Count of references to the data structure in this instance,
* including the pointer from files_ref_store::packed if any.
* The data will not be freed as long as the reference count
* is nonzero.
*/
unsigned int referrers;
/* The metadata from when this packed-refs cache was read */
struct stat_validity validity;
};
/*
* Increment the reference count of *packed_refs.
*/
static void acquire_packed_ref_cache(struct packed_ref_cache *packed_refs)
{
packed_refs->referrers++;
}
/*
* Decrease the reference count of *packed_refs. If it goes to zero,
* free *packed_refs and return true; otherwise return false.
*/
static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
{
if (!--packed_refs->referrers) {
free_ref_cache(packed_refs->cache);
stat_validity_clear(&packed_refs->validity);
free(packed_refs);
return 1;
} else {
return 0;
}
}
/*
* A container for `packed-refs`-related data. It is not (yet) a
* `ref_store`.
*/
struct packed_ref_store {
unsigned int store_flags;
/* The path of the "packed-refs" file: */
char *path;
/*
* A cache of the values read from the `packed-refs` file, if
* it might still be current; otherwise, NULL.
*/
struct packed_ref_cache *cache;
/*
* Lock used for the "packed-refs" file. Note that this (and
* thus the enclosing `packed_ref_store`) must not be freed.
*/
struct lock_file lock;
};
struct packed_ref_store *packed_ref_store_create(
const char *path, unsigned int store_flags)
{
struct packed_ref_store *refs = xcalloc(1, sizeof(*refs));
refs->store_flags = store_flags;
refs->path = xstrdup(path);
return refs;
}
/*
* Die if refs is not the main ref store. caller is used in any
* necessary error messages.
*/
static void packed_assert_main_repository(struct packed_ref_store *refs,
const char *caller)
{
if (refs->store_flags & REF_STORE_MAIN)
return;
die("BUG: operation %s only allowed for main ref store", caller);
}
static void clear_packed_ref_cache(struct packed_ref_store *refs)
{
if (refs->cache) {
struct packed_ref_cache *cache = refs->cache;
if (is_lock_file_locked(&refs->lock))
die("BUG: packed-ref cache cleared while locked");
refs->cache = NULL;
release_packed_ref_cache(cache);
}
}
/* The length of a peeled reference line in packed-refs, including EOL: */
#define PEELED_LINE_LENGTH 42
/*
* Parse one line from a packed-refs file. Write the SHA1 to sha1.
* Return a pointer to the refname within the line (null-terminated),
* or NULL if there was a problem.
*/
static const char *parse_ref_line(struct strbuf *line, struct object_id *oid)
{
const char *ref;
if (parse_oid_hex(line->buf, oid, &ref) < 0)
return NULL;
if (!isspace(*ref++))
return NULL;
if (isspace(*ref))
return NULL;
if (line->buf[line->len - 1] != '\n')
return NULL;
line->buf[--line->len] = 0;
return ref;
}
/*
* Read from `packed_refs_file` into a newly-allocated
* `packed_ref_cache` and return it. The return value will already
* have its reference count incremented.
*
* A comment line of the form "# pack-refs with: " may contain zero or
* more traits. We interpret the traits as follows:
*
* No traits:
*
* Probably no references are peeled. But if the file contains a
* peeled value for a reference, we will use it.
*
* peeled:
*
* References under "refs/tags/", if they *can* be peeled, *are*
* peeled in this file. References outside of "refs/tags/" are
* probably not peeled even if they could have been, but if we find
* a peeled value for such a reference we will use it.
*
* fully-peeled:
*
* All references in the file that can be peeled are peeled.
* Inversely (and this is more important), any references in the
* file for which no peeled value is recorded is not peelable. This
* trait should typically be written alongside "peeled" for
* compatibility with older clients, but we do not require it
* (i.e., "peeled" is a no-op if "fully-peeled" is set).
*/
static struct packed_ref_cache *read_packed_refs(const char *packed_refs_file)
{
FILE *f;
struct packed_ref_cache *packed_refs = xcalloc(1, sizeof(*packed_refs));
struct ref_entry *last = NULL;
struct strbuf line = STRBUF_INIT;
enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
struct ref_dir *dir;
acquire_packed_ref_cache(packed_refs);
packed_refs->cache = create_ref_cache(NULL, NULL);
packed_refs->cache->root->flag &= ~REF_INCOMPLETE;
f = fopen(packed_refs_file, "r");
if (!f) {
if (errno == ENOENT) {
/*
* This is OK; it just means that no
* "packed-refs" file has been written yet,
* which is equivalent to it being empty.
*/
return packed_refs;
} else {
die_errno("couldn't read %s", packed_refs_file);
}
}
stat_validity_update(&packed_refs->validity, fileno(f));
dir = get_ref_dir(packed_refs->cache->root);
while (strbuf_getwholeline(&line, f, '\n') != EOF) {
struct object_id oid;
const char *refname;
const char *traits;
if (skip_prefix(line.buf, "# pack-refs with:", &traits)) {
if (strstr(traits, " fully-peeled "))
peeled = PEELED_FULLY;
else if (strstr(traits, " peeled "))
peeled = PEELED_TAGS;
/* perhaps other traits later as well */
continue;
}
refname = parse_ref_line(&line, &oid);
if (refname) {
int flag = REF_ISPACKED;
if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
if (!refname_is_safe(refname))
die("packed refname is dangerous: %s", refname);
oidclr(&oid);
flag |= REF_BAD_NAME | REF_ISBROKEN;
}
last = create_ref_entry(refname, &oid, flag);
if (peeled == PEELED_FULLY ||
(peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
last->flag |= REF_KNOWS_PEELED;
add_ref_entry(dir, last);
continue;
}
if (last &&
line.buf[0] == '^' &&
line.len == PEELED_LINE_LENGTH &&
line.buf[PEELED_LINE_LENGTH - 1] == '\n' &&
!get_oid_hex(line.buf + 1, &oid)) {
oidcpy(&last->u.value.peeled, &oid);
/*
* Regardless of what the file header said,
* we definitely know the value of *this*
* reference:
*/
last->flag |= REF_KNOWS_PEELED;
}
}
fclose(f);
strbuf_release(&line);
return packed_refs;
}
/*
* Check that the packed refs cache (if any) still reflects the
* contents of the file. If not, clear the cache.
*/
static void validate_packed_ref_cache(struct packed_ref_store *refs)
{
if (refs->cache &&
!stat_validity_check(&refs->cache->validity, refs->path))
clear_packed_ref_cache(refs);
}
/*
* Get the packed_ref_cache for the specified packed_ref_store,
* creating and populating it if it hasn't been read before or if the
* file has been changed (according to its `validity` field) since it
* was last read. On the other hand, if we hold the lock, then assume
* that the file hasn't been changed out from under us, so skip the
* extra `stat()` call in `stat_validity_check()`.
*/
static struct packed_ref_cache *get_packed_ref_cache(struct packed_ref_store *refs)
{
if (!is_lock_file_locked(&refs->lock))
validate_packed_ref_cache(refs);
if (!refs->cache)
refs->cache = read_packed_refs(refs->path);
return refs->cache;
}
static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
{
return get_ref_dir(packed_ref_cache->cache->root);
}
static struct ref_dir *get_packed_refs(struct packed_ref_store *refs)
{
return get_packed_ref_dir(get_packed_ref_cache(refs));
}
/*
* Add or overwrite a reference in the in-memory packed reference
* cache. This may only be called while the packed-refs file is locked
* (see lock_packed_refs()). To actually write the packed-refs file,
* call commit_packed_refs().
*/
void add_packed_ref(struct packed_ref_store *refs,
const char *refname, const struct object_id *oid)
{
struct ref_dir *packed_refs;
struct ref_entry *packed_entry;
if (!is_lock_file_locked(&refs->lock))
die("BUG: packed refs not locked");
if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
die("Reference has invalid format: '%s'", refname);
packed_refs = get_packed_refs(refs);
packed_entry = find_ref_entry(packed_refs, refname);
if (packed_entry) {
/* Overwrite the existing entry: */
oidcpy(&packed_entry->u.value.oid, oid);
packed_entry->flag = REF_ISPACKED;
oidclr(&packed_entry->u.value.peeled);
} else {
packed_entry = create_ref_entry(refname, oid, REF_ISPACKED);
add_ref_entry(packed_refs, packed_entry);
}
}
/*
* Return the ref_entry for the given refname from the packed
* references. If it does not exist, return NULL.
*/
static struct ref_entry *get_packed_ref(struct packed_ref_store *refs,
const char *refname)
{
return find_ref_entry(get_packed_refs(refs), refname);
}
int packed_read_raw_ref(struct packed_ref_store *refs,
const char *refname, unsigned char *sha1,
struct strbuf *referent, unsigned int *type)
{
struct ref_entry *entry;
*type = 0;
entry = get_packed_ref(refs, refname);
if (!entry) {
errno = ENOENT;
return -1;
}
hashcpy(sha1, entry->u.value.oid.hash);
*type = REF_ISPACKED;
return 0;
}
int packed_peel_ref(struct packed_ref_store *refs,
const char *refname, unsigned char *sha1)
{
struct ref_entry *r = get_packed_ref(refs, refname);
if (!r || peel_entry(r, 0))
return -1;
hashcpy(sha1, r->u.value.peeled.hash);
return 0;
}
struct packed_ref_iterator {
struct ref_iterator base;
struct packed_ref_cache *cache;
struct ref_iterator *iter0;
unsigned int flags;
};
static int packed_ref_iterator_advance(struct ref_iterator *ref_iterator)
{
struct packed_ref_iterator *iter =
(struct packed_ref_iterator *)ref_iterator;
int ok;
while ((ok = ref_iterator_advance(iter->iter0)) == ITER_OK) {
if (iter->flags & DO_FOR_EACH_PER_WORKTREE_ONLY &&
ref_type(iter->iter0->refname) != REF_TYPE_PER_WORKTREE)
continue;
if (!(iter->flags & DO_FOR_EACH_INCLUDE_BROKEN) &&
!ref_resolves_to_object(iter->iter0->refname,
iter->iter0->oid,
iter->iter0->flags))
continue;
iter->base.refname = iter->iter0->refname;
iter->base.oid = iter->iter0->oid;
iter->base.flags = iter->iter0->flags;
return ITER_OK;
}
iter->iter0 = NULL;
if (ref_iterator_abort(ref_iterator) != ITER_DONE)
ok = ITER_ERROR;
return ok;
}
static int packed_ref_iterator_peel(struct ref_iterator *ref_iterator,
struct object_id *peeled)
{
struct packed_ref_iterator *iter =
(struct packed_ref_iterator *)ref_iterator;
return ref_iterator_peel(iter->iter0, peeled);
}
static int packed_ref_iterator_abort(struct ref_iterator *ref_iterator)
{
struct packed_ref_iterator *iter =
(struct packed_ref_iterator *)ref_iterator;
int ok = ITER_DONE;
if (iter->iter0)
ok = ref_iterator_abort(iter->iter0);
release_packed_ref_cache(iter->cache);
base_ref_iterator_free(ref_iterator);
return ok;
}
static struct ref_iterator_vtable packed_ref_iterator_vtable = {
packed_ref_iterator_advance,
packed_ref_iterator_peel,
packed_ref_iterator_abort
};
struct ref_iterator *packed_ref_iterator_begin(
struct packed_ref_store *refs,
const char *prefix, unsigned int flags)
{
struct packed_ref_iterator *iter;
struct ref_iterator *ref_iterator;
iter = xcalloc(1, sizeof(*iter));
ref_iterator = &iter->base;
base_ref_iterator_init(ref_iterator, &packed_ref_iterator_vtable);
/*
* Note that get_packed_ref_cache() internally checks whether
* the packed-ref cache is up to date with what is on disk,
* and re-reads it if not.
*/
iter->cache = get_packed_ref_cache(refs);
acquire_packed_ref_cache(iter->cache);
iter->iter0 = cache_ref_iterator_begin(iter->cache->cache, prefix, 0);
iter->flags = flags;
return ref_iterator;
}
/*
* Write an entry to the packed-refs file for the specified refname.
* If peeled is non-NULL, write it as the entry's peeled value.
*/
static void write_packed_entry(FILE *fh, const char *refname,
const unsigned char *sha1,
const unsigned char *peeled)
{
fprintf_or_die(fh, "%s %s\n", sha1_to_hex(sha1), refname);
if (peeled)
fprintf_or_die(fh, "^%s\n", sha1_to_hex(peeled));
}
int lock_packed_refs(struct packed_ref_store *refs, int flags)
{
static int timeout_configured = 0;
static int timeout_value = 1000;
struct packed_ref_cache *packed_ref_cache;
packed_assert_main_repository(refs, "lock_packed_refs");
if (!timeout_configured) {
git_config_get_int("core.packedrefstimeout", &timeout_value);
timeout_configured = 1;
}
if (hold_lock_file_for_update_timeout(
&refs->lock,
refs->path,
flags, timeout_value) < 0)
return -1;
/*
* Now that we hold the `packed-refs` lock, make sure that our
* cache matches the current version of the file. Normally
* `get_packed_ref_cache()` does that for us, but that
* function assumes that when the file is locked, any existing
* cache is still valid. We've just locked the file, but it
* might have changed the moment *before* we locked it.
*/
validate_packed_ref_cache(refs);
packed_ref_cache = get_packed_ref_cache(refs);
/* Increment the reference count to prevent it from being freed: */
acquire_packed_ref_cache(packed_ref_cache);
return 0;
}
/*
* The packed-refs header line that we write out. Perhaps other
* traits will be added later. The trailing space is required.
*/
static const char PACKED_REFS_HEADER[] =
"# pack-refs with: peeled fully-peeled \n";
/*
* Write the current version of the packed refs cache from memory to
* disk. The packed-refs file must already be locked for writing (see
* lock_packed_refs()). Return zero on success. On errors, set errno
* and return a nonzero value.
*/
int commit_packed_refs(struct packed_ref_store *refs)
{
struct packed_ref_cache *packed_ref_cache =
get_packed_ref_cache(refs);
int ok, error = 0;
int save_errno = 0;
FILE *out;
struct ref_iterator *iter;
packed_assert_main_repository(refs, "commit_packed_refs");
if (!is_lock_file_locked(&refs->lock))
die("BUG: packed-refs not locked");
out = fdopen_lock_file(&refs->lock, "w");
if (!out)
die_errno("unable to fdopen packed-refs descriptor");
fprintf_or_die(out, "%s", PACKED_REFS_HEADER);
iter = cache_ref_iterator_begin(packed_ref_cache->cache, NULL, 0);
while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
struct object_id peeled;
int peel_error = ref_iterator_peel(iter, &peeled);
write_packed_entry(out, iter->refname, iter->oid->hash,
peel_error ? NULL : peeled.hash);
}
if (ok != ITER_DONE)
die("error while iterating over references");
if (commit_lock_file(&refs->lock)) {
save_errno = errno;
error = -1;
}
release_packed_ref_cache(packed_ref_cache);
errno = save_errno;
return error;
}
/*
* Rollback the lockfile for the packed-refs file, and discard the
* in-memory packed reference cache. (The packed-refs file will be
* read anew if it is needed again after this function is called.)
*/
static void rollback_packed_refs(struct packed_ref_store *refs)
{
struct packed_ref_cache *packed_ref_cache = get_packed_ref_cache(refs);
packed_assert_main_repository(refs, "rollback_packed_refs");
if (!is_lock_file_locked(&refs->lock))
die("BUG: packed-refs not locked");
rollback_lock_file(&refs->lock);
release_packed_ref_cache(packed_ref_cache);
clear_packed_ref_cache(refs);
}
/*
* Rewrite the packed-refs file, omitting any refs listed in
* 'refnames'. On error, leave packed-refs unchanged, write an error
* message to 'err', and return a nonzero value.
*
* The refs in 'refnames' needn't be sorted. `err` must not be NULL.
*/
int repack_without_refs(struct packed_ref_store *refs,
struct string_list *refnames, struct strbuf *err)
{
struct ref_dir *packed;
struct string_list_item *refname;
int ret, needs_repacking = 0, removed = 0;
packed_assert_main_repository(refs, "repack_without_refs");
assert(err);
/* Look for a packed ref */
for_each_string_list_item(refname, refnames) {
if (get_packed_ref(refs, refname->string)) {
needs_repacking = 1;
break;
}
}
/* Avoid locking if we have nothing to do */
if (!needs_repacking)
return 0; /* no refname exists in packed refs */
if (lock_packed_refs(refs, 0)) {
unable_to_lock_message(refs->path, errno, err);
return -1;
}
packed = get_packed_refs(refs);
/* Remove refnames from the cache */
for_each_string_list_item(refname, refnames)
if (remove_entry_from_dir(packed, refname->string) != -1)
removed = 1;
if (!removed) {
/*
* All packed entries disappeared while we were
* acquiring the lock.
*/
rollback_packed_refs(refs);
return 0;
}
/* Write what remains */
ret = commit_packed_refs(refs);
if (ret)
strbuf_addf(err, "unable to overwrite old ref-pack file: %s",
strerror(errno));
return ret;
}

33
refs/packed-backend.h Normal file
View File

@ -0,0 +1,33 @@
#ifndef REFS_PACKED_BACKEND_H
#define REFS_PACKED_BACKEND_H
struct packed_ref_store *packed_ref_store_create(
const char *path, unsigned int store_flags);
int packed_read_raw_ref(struct packed_ref_store *refs,
const char *refname, unsigned char *sha1,
struct strbuf *referent, unsigned int *type);
int packed_peel_ref(struct packed_ref_store *refs,
const char *refname, unsigned char *sha1);
struct ref_iterator *packed_ref_iterator_begin(
struct packed_ref_store *refs,
const char *prefix, unsigned int flags);
/*
* Lock the packed-refs file for writing. Flags is passed to
* hold_lock_file_for_update(). Return 0 on success. On errors, set
* errno appropriately and return a nonzero value.
*/
int lock_packed_refs(struct packed_ref_store *refs, int flags);
void add_packed_ref(struct packed_ref_store *refs,
const char *refname, const struct object_id *oid);
int commit_packed_refs(struct packed_ref_store *refs);
int repack_without_refs(struct packed_ref_store *refs,
struct string_list *refnames, struct strbuf *err);
#endif /* REFS_PACKED_BACKEND_H */

9
refs/refs-internal.h
View File

@ -77,6 +77,15 @@
*/
int refname_is_safe(const char *refname);
/*
* Helper function: return true if refname, which has the specified
* oid and flags, can be resolved to an object in the database. If the
* referred-to object does not exist, emit a warning and return false.
*/
int ref_resolves_to_object(const char *refname,
const struct object_id *oid,
unsigned int flags);
enum peel_status {
/* object was peeled successfully: */
PEEL_PEELED = 0,