packed_ref_store: move `packed_refs_path` here
[gitweb.git] / refs / files-backend.c
index 8d0ce739a602b69df5ea2bc77ecd6b8c9a6ec4e3..c4b8e2f63b862990e57bc9e78a904d7937fb2a6d 100644 (file)
@@ -47,6 +47,33 @@ struct packed_ref_cache {
        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;
+};
+
+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;
+}
+
 /*
  * Future: need to be in "struct repository"
  * when doing a full libification.
@@ -57,16 +84,16 @@ struct files_ref_store {
 
        char *gitdir;
        char *gitcommondir;
-       char *packed_refs_path;
 
        struct ref_cache *loose;
-       struct packed_ref_cache *packed;
 
        /*
         * Lock used for the "packed-refs" file. Note that this (and
         * thus the enclosing `files_ref_store`) must not be freed.
         */
        struct lock_file packed_refs_lock;
+
+       struct packed_ref_store *packed_ref_store;
 };
 
 /*
@@ -95,12 +122,12 @@ static int release_packed_ref_cache(struct packed_ref_cache *packed_refs)
 
 static void clear_packed_ref_cache(struct files_ref_store *refs)
 {
-       if (refs->packed) {
-               struct packed_ref_cache *packed_refs = refs->packed;
+       if (refs->packed_ref_store->cache) {
+               struct packed_ref_cache *packed_refs = refs->packed_ref_store->cache;
 
                if (is_lock_file_locked(&refs->packed_refs_lock))
                        die("BUG: packed-ref cache cleared while locked");
-               refs->packed = NULL;
+               refs->packed_ref_store->cache = NULL;
                release_packed_ref_cache(packed_refs);
        }
 }
@@ -131,7 +158,8 @@ static struct ref_store *files_ref_store_create(const char *gitdir,
        get_common_dir_noenv(&sb, gitdir);
        refs->gitcommondir = strbuf_detach(&sb, NULL);
        strbuf_addf(&sb, "%s/packed-refs", refs->gitcommondir);
-       refs->packed_refs_path = strbuf_detach(&sb, NULL);
+       refs->packed_ref_store = packed_ref_store_create(sb.buf, flags);
+       strbuf_release(&sb);
 
        return ref_store;
 }
@@ -209,7 +237,9 @@ static const char *parse_ref_line(struct strbuf *line, struct object_id *oid)
 }
 
 /*
- * Read f, which is a packed-refs file, into dir.
+ * 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:
@@ -235,12 +265,36 @@ static const char *parse_ref_line(struct strbuf *line, struct object_id *oid)
  *      compatibility with older clients, but we do not require it
  *      (i.e., "peeled" is a no-op if "fully-peeled" is set).
  */
-static void read_packed_refs(FILE *f, struct ref_dir *dir)
+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;
@@ -265,7 +319,7 @@ static void read_packed_refs(FILE *f, struct ref_dir *dir)
                                oidclr(&oid);
                                flag |= REF_BAD_NAME | REF_ISBROKEN;
                        }
-                       last = create_ref_entry(refname, &oid, flag, 0);
+                       last = create_ref_entry(refname, &oid, flag);
                        if (peeled == PEELED_FULLY ||
                            (peeled == PEELED_TAGS && starts_with(refname, "refs/tags/")))
                                last->flag |= REF_KNOWS_PEELED;
@@ -287,12 +341,10 @@ static void read_packed_refs(FILE *f, struct ref_dir *dir)
                }
        }
 
+       fclose(f);
        strbuf_release(&line);
-}
 
-static const char *files_packed_refs_path(struct files_ref_store *refs)
-{
-       return refs->packed_refs_path;
+       return packed_refs;
 }
 
 static void files_reflog_path(struct files_ref_store *refs,
@@ -340,33 +392,37 @@ 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 files_ref_store *refs)
+{
+       if (refs->packed_ref_store->cache &&
+           !stat_validity_check(&refs->packed_ref_store->cache->validity,
+                                refs->packed_ref_store->path))
+               clear_packed_ref_cache(refs);
+}
+
 /*
  * Get the packed_ref_cache for the specified files_ref_store,
- * creating it if necessary.
+ * 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 files_ref_store *refs)
 {
-       const char *packed_refs_file = files_packed_refs_path(refs);
+       const char *packed_refs_file = refs->packed_ref_store->path;
 
-       if (refs->packed &&
-           !stat_validity_check(&refs->packed->validity, packed_refs_file))
-               clear_packed_ref_cache(refs);
+       if (!is_lock_file_locked(&refs->packed_refs_lock))
+               validate_packed_ref_cache(refs);
 
-       if (!refs->packed) {
-               FILE *f;
-
-               refs->packed = xcalloc(1, sizeof(*refs->packed));
-               acquire_packed_ref_cache(refs->packed);
-               refs->packed->cache = create_ref_cache(&refs->base, NULL);
-               refs->packed->cache->root->flag &= ~REF_INCOMPLETE;
-               f = fopen(packed_refs_file, "r");
-               if (f) {
-                       stat_validity_update(&refs->packed->validity, fileno(f));
-                       read_packed_refs(f, get_ref_dir(refs->packed->cache->root));
-                       fclose(f);
-               }
-       }
-       return refs->packed;
+       if (!refs->packed_ref_store->cache)
+               refs->packed_ref_store->cache = read_packed_refs(packed_refs_file);
+
+       return refs->packed_ref_store->cache;
 }
 
 static struct ref_dir *get_packed_ref_dir(struct packed_ref_cache *packed_ref_cache)
@@ -380,20 +436,34 @@ static struct ref_dir *get_packed_refs(struct files_ref_store *refs)
 }
 
 /*
- * Add a reference to 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().
+ * 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 files_ref_store *refs,
                           const char *refname, const struct object_id *oid)
 {
-       struct packed_ref_cache *packed_ref_cache = get_packed_ref_cache(refs);
+       struct ref_dir *packed_refs;
+       struct ref_entry *packed_entry;
 
        if (!is_lock_file_locked(&refs->packed_refs_lock))
                die("BUG: packed refs not locked");
-       add_ref_entry(get_packed_ref_dir(packed_ref_cache),
-                     create_ref_entry(refname, oid, REF_ISPACKED, 1));
+
+       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);
+       }
 }
 
 /*
@@ -470,7 +540,7 @@ static void loose_fill_ref_dir(struct ref_store *ref_store,
                                flag |= REF_BAD_NAME | REF_ISBROKEN;
                        }
                        add_entry_to_dir(dir,
-                                        create_ref_entry(refname.buf, &oid, flag, 0));
+                                        create_ref_entry(refname.buf, &oid, flag));
                }
                strbuf_setlen(&refname, dirnamelen);
                strbuf_setlen(&path, path_baselen);
@@ -1051,15 +1121,12 @@ static struct ref_iterator *files_ref_iterator_begin(
        struct ref_iterator *loose_iter, *packed_iter;
        struct files_ref_iterator *iter;
        struct ref_iterator *ref_iterator;
+       unsigned int required_flags = REF_STORE_READ;
 
-       if (ref_paranoia < 0)
-               ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 0);
-       if (ref_paranoia)
-               flags |= DO_FOR_EACH_INCLUDE_BROKEN;
+       if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN))
+               required_flags |= REF_STORE_ODB;
 
-       refs = files_downcast(ref_store,
-                             REF_STORE_READ | (ref_paranoia ? 0 : REF_STORE_ODB),
-                             "ref_iterator_begin");
+       refs = files_downcast(ref_store, required_flags, "ref_iterator_begin");
 
        iter = xcalloc(1, sizeof(*iter));
        ref_iterator = &iter->base;
@@ -1284,15 +1351,20 @@ static int lock_packed_refs(struct files_ref_store *refs, int flags)
        }
 
        if (hold_lock_file_for_update_timeout(
-                           &refs->packed_refs_lock, files_packed_refs_path(refs),
+                           &refs->packed_refs_lock, refs->packed_ref_store->path,
                            flags, timeout_value) < 0)
                return -1;
+
        /*
-        * Get the current packed-refs while holding the lock.  If the
-        * packed-refs file has been modified since we last read it,
-        * this will automatically invalidate the cache and re-read
-        * the packed-refs file.
+        * 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);
@@ -1455,18 +1527,42 @@ static void prune_refs(struct files_ref_store *refs, struct ref_to_prune *r)
        }
 }
 
+/*
+ * Return true if the specified reference should be packed.
+ */
+static int should_pack_ref(const char *refname,
+                          const struct object_id *oid, unsigned int ref_flags,
+                          unsigned int pack_flags)
+{
+       /* Do not pack per-worktree refs: */
+       if (ref_type(refname) != REF_TYPE_NORMAL)
+               return 0;
+
+       /* Do not pack non-tags unless PACK_REFS_ALL is set: */
+       if (!(pack_flags & PACK_REFS_ALL) && !starts_with(refname, "refs/tags/"))
+               return 0;
+
+       /* Do not pack symbolic refs: */
+       if (ref_flags & REF_ISSYMREF)
+               return 0;
+
+       /* Do not pack broken refs: */
+       if (!ref_resolves_to_object(refname, oid, ref_flags))
+               return 0;
+
+       return 1;
+}
+
 static int files_pack_refs(struct ref_store *ref_store, unsigned int flags)
 {
        struct files_ref_store *refs =
                files_downcast(ref_store, REF_STORE_WRITE | REF_STORE_ODB,
                               "pack_refs");
        struct ref_iterator *iter;
-       struct ref_dir *packed_refs;
        int ok;
        struct ref_to_prune *refs_to_prune = NULL;
 
        lock_packed_refs(refs, LOCK_DIE_ON_ERROR);
-       packed_refs = get_packed_refs(refs);
 
        iter = cache_ref_iterator_begin(get_loose_ref_cache(refs), NULL, 0);
        while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
@@ -1475,22 +1571,8 @@ static int files_pack_refs(struct ref_store *ref_store, unsigned int flags)
                 * in the packed ref cache. If the reference should be
                 * pruned, also add it to refs_to_prune.
                 */
-               struct ref_entry *packed_entry;
-               int is_tag_ref = starts_with(iter->refname, "refs/tags/");
-
-               /* Do not pack per-worktree refs: */
-               if (ref_type(iter->refname) != REF_TYPE_NORMAL)
-                       continue;
-
-               /* ALWAYS pack tags */
-               if (!(flags & PACK_REFS_ALL) && !is_tag_ref)
-                       continue;
-
-               /* Do not pack symbolic or broken refs: */
-               if (iter->flags & REF_ISSYMREF)
-                       continue;
-
-               if (!ref_resolves_to_object(iter->refname, iter->oid, iter->flags))
+               if (!should_pack_ref(iter->refname, iter->oid, iter->flags,
+                                    flags))
                        continue;
 
                /*
@@ -1499,17 +1581,7 @@ static int files_pack_refs(struct ref_store *ref_store, unsigned int flags)
                 * we don't copy the peeled status, because we want it
                 * to be re-peeled.
                 */
-               packed_entry = find_ref_entry(packed_refs, iter->refname);
-               if (packed_entry) {
-                       /* Overwrite existing packed entry with info from loose entry */
-                       packed_entry->flag = REF_ISPACKED;
-                       oidcpy(&packed_entry->u.value.oid, iter->oid);
-               } else {
-                       packed_entry = create_ref_entry(iter->refname, iter->oid,
-                                                       REF_ISPACKED, 0);
-                       add_ref_entry(packed_refs, packed_entry);
-               }
-               oidclr(&packed_entry->u.value.peeled);
+               add_packed_ref(refs, iter->refname, iter->oid);
 
                /* Schedule the loose reference for pruning if requested. */
                if ((flags & PACK_REFS_PRUNE)) {
@@ -1560,7 +1632,7 @@ static int repack_without_refs(struct files_ref_store *refs,
                return 0; /* no refname exists in packed refs */
 
        if (lock_packed_refs(refs, 0)) {
-               unable_to_lock_message(files_packed_refs_path(refs), errno, err);
+               unable_to_lock_message(refs->packed_ref_store->path, errno, err);
                return -1;
        }
        packed = get_packed_refs(refs);