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git/refs/ref-cache.h

220 lines
7.8 KiB

#ifndef REFS_REF_CACHE_H
#define REFS_REF_CACHE_H
#include "cache.h"
struct ref_dir;
struct ref_store;
/*
* If this ref_cache is filled lazily, this function is used to load
* information into the specified ref_dir (shallow or deep, at the
* option of the ref_store). dirname includes a trailing slash.
*/
typedef void fill_ref_dir_fn(struct ref_store *ref_store,
struct ref_dir *dir, const char *dirname);
struct ref_cache {
struct ref_entry *root;
/* A pointer to the ref_store whose cache this is: */
struct ref_store *ref_store;
/*
* Function used (if necessary) to lazily-fill cache. May be
* NULL.
*/
fill_ref_dir_fn *fill_ref_dir;
};
/*
* Information used (along with the information in ref_entry) to
* describe a single cached reference. This data structure only
* occurs embedded in a union in struct ref_entry, and only when
* (ref_entry->flag & REF_DIR) is zero.
*/
struct ref_value {
/*
* The name of the object to which this reference resolves
* (which may be a tag object). If REF_ISBROKEN, this is
* null. If REF_ISSYMREF, then this is the name of the object
* referred to by the last reference in the symlink chain.
*/
struct object_id oid;
};
/*
* Information used (along with the information in ref_entry) to
* describe a level in the hierarchy of references. This data
* structure only occurs embedded in a union in struct ref_entry, and
* only when (ref_entry.flag & REF_DIR) is set. In that case,
* (ref_entry.flag & REF_INCOMPLETE) determines whether the references
* in the directory have already been read:
*
* (ref_entry.flag & REF_INCOMPLETE) unset -- a directory of loose
* or packed references, already read.
*
* (ref_entry.flag & REF_INCOMPLETE) set -- a directory of loose
* references that hasn't been read yet (nor has any of its
* subdirectories).
*
* Entries within a directory are stored within a growable array of
* pointers to ref_entries (entries, nr, alloc). Entries 0 <= i <
* sorted are sorted by their component name in strcmp() order and the
* remaining entries are unsorted.
*
* Loose references are read lazily, one directory at a time. When a
* directory of loose references is read, then all of the references
* in that directory are stored, and REF_INCOMPLETE stubs are created
* for any subdirectories, but the subdirectories themselves are not
* read. The reading is triggered by get_ref_dir().
*/
struct ref_dir {
int nr, alloc;
/*
* Entries with index 0 <= i < sorted are sorted by name. New
* entries are appended to the list unsorted, and are sorted
* only when required; thus we avoid the need to sort the list
* after the addition of every reference.
*/
int sorted;
/* The ref_cache containing this entry: */
struct ref_cache *cache;
struct ref_entry **entries;
};
/*
* Bit values for ref_entry::flag. REF_ISSYMREF=0x01,
* REF_ISPACKED=0x02, REF_ISBROKEN=0x04 and REF_BAD_NAME=0x08 are
* public values; see refs.h.
*/
/* ref_entry represents a directory of references */
#define REF_DIR 0x10
/*
* Entry has not yet been read from disk (used only for REF_DIR
* entries representing loose references)
*/
#define REF_INCOMPLETE 0x20
/*
* A ref_entry represents either a reference or a "subdirectory" of
* references.
*
* Each directory in the reference namespace is represented by a
* ref_entry with (flags & REF_DIR) set and containing a subdir member
* that holds the entries in that directory that have been read so
* far. If (flags & REF_INCOMPLETE) is set, then the directory and
* its subdirectories haven't been read yet. REF_INCOMPLETE is only
* used for loose reference directories.
*
* References are represented by a ref_entry with (flags & REF_DIR)
* unset and a value member that describes the reference's value. The
* flag member is at the ref_entry level, but it is also needed to
* interpret the contents of the value field (in other words, a
* ref_value object is not very much use without the enclosing
* ref_entry).
*
* Reference names cannot end with slash and directories' names are
* always stored with a trailing slash (except for the top-level
* directory, which is always denoted by ""). This has two nice
* consequences: (1) when the entries in each subdir are sorted
* lexicographically by name (as they usually are), the references in
* a whole tree can be generated in lexicographic order by traversing
* the tree in left-to-right, depth-first order; (2) the names of
* references and subdirectories cannot conflict, and therefore the
* presence of an empty subdirectory does not block the creation of a
* similarly-named reference. (The fact that reference names with the
* same leading components can conflict *with each other* is a
* separate issue that is regulated by refs_verify_refname_available().)
*
* Please note that the name field contains the fully-qualified
* reference (or subdirectory) name. Space could be saved by only
* storing the relative names. But that would require the full names
* to be generated on the fly when iterating in do_for_each_ref(), and
* would break callback functions, who have always been able to assume
* that the name strings that they are passed will not be freed during
* the iteration.
*/
struct ref_entry {
unsigned char flag; /* ISSYMREF? ISPACKED? */
union {
struct ref_value value; /* if not (flags&REF_DIR) */
struct ref_dir subdir; /* if (flags&REF_DIR) */
} u;
/*
* The full name of the reference (e.g., "refs/heads/master")
* or the full name of the directory with a trailing slash
* (e.g., "refs/heads/"):
*/
char name[FLEX_ARRAY];
};
/*
* Return the index of the entry with the given refname from the
* ref_dir (non-recursively), sorting dir if necessary. Return -1 if
* no such entry is found. dir must already be complete.
*/
int search_ref_dir(struct ref_dir *dir, const char *refname, size_t len);
struct ref_dir *get_ref_dir(struct ref_entry *entry);
/*
* Create a struct ref_entry object for the specified dirname.
* dirname is the name of the directory with a trailing slash (e.g.,
* "refs/heads/") or "" for the top-level directory.
*/
struct ref_entry *create_dir_entry(struct ref_cache *cache,
const char *dirname, size_t len);
struct ref_entry *create_ref_entry(const char *refname,
const struct object_id *oid, int flag);
/*
* Return a pointer to a new `ref_cache`. Its top-level starts out
* marked incomplete. If `fill_ref_dir` is non-NULL, it is the
* function called to fill in incomplete directories in the
* `ref_cache` when they are accessed. If it is NULL, then the whole
* `ref_cache` must be filled (including clearing its directories'
* `REF_INCOMPLETE` bits) before it is used, and `refs` can be NULL,
* too.
*/
struct ref_cache *create_ref_cache(struct ref_store *refs,
fill_ref_dir_fn *fill_ref_dir);
/*
* Free the `ref_cache` and all of its associated data.
*/
void free_ref_cache(struct ref_cache *cache);
/*
* Add a ref_entry to the end of dir (unsorted). Entry is always
* stored directly in dir; no recursion into subdirectories is
* done.
*/
void add_entry_to_dir(struct ref_dir *dir, struct ref_entry *entry);
/*
* Find the value entry with the given name in dir, sorting ref_dirs
* and recursing into subdirectories as necessary. If the name is not
* found or it corresponds to a directory entry, return NULL.
*/
struct ref_entry *find_ref_entry(struct ref_dir *dir, const char *refname);
/*
* Start iterating over references in `cache`. If `prefix` is
* specified, only include references whose names start with that
* prefix. If `prime_dir` is true, then fill any incomplete
* directories before beginning the iteration. The output is ordered
* by refname.
*/
struct ref_iterator *cache_ref_iterator_begin(struct ref_cache *cache,
const char *prefix,
struct repository *repo,
int prime_dir);
#endif /* REFS_REF_CACHE_H */