Show changes to 6 files +686 −639
Makefile, refs.c, refs/files-backend.c, refs/packed-backend.c, refs/packed-backend.h, refs/refs-internal.h
diff --git a/Makefile b/Makefile
index 33b888730f..478a8eac5d 100644
--- a/Makefile
+++ b/Makefile
@@ -821,6 +821,7 @@ 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
diff --git a/refs.c b/refs.c
index 32177969f0..5880c12372 100644
--- a/refs.c
+++ b/refs.c
@@ -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)
diff --git a/refs/files-backend.c b/refs/files-backend.c
index ac4764f6f7..83ea773728 100644
--- a/refs/files-backend.c
+++ b/refs/files-backend.c
@@ -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 @@ static int lock_raw_ref(struct files_ref_store *refs,
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;
@@ -1422,124 +958,6 @@ 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];
@@ -1705,62 +1123,6 @@ 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)
{
diff --git a/refs/packed-backend.c b/refs/packed-backend.c
new file mode 100644
index 0000000000..6fa988c953
--- /dev/null
+++ b/refs/packed-backend.c
@@ -0,0 +1,624 @@
+#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;
+}
+
diff --git a/refs/packed-backend.h b/refs/packed-backend.h
new file mode 100644
index 0000000000..22e8817ac4
--- /dev/null
+++ b/refs/packed-backend.h
@@ -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 */
diff --git a/refs/refs-internal.h b/refs/refs-internal.h
index 192f9f85c9..6f8f9f5619 100644
--- a/refs/refs-internal.h
+++ b/refs/refs-internal.h
@@ -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,
Michael Haggerty
