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Diffstat (limited to 'odb.h')
| -rw-r--r-- | odb.h | 355 |
1 files changed, 355 insertions, 0 deletions
@@ -0,0 +1,355 @@ +#ifndef ODB_H +#define ODB_H + +#include "hashmap.h" +#include "object.h" +#include "list.h" +#include "oidset.h" +#include "oidmap.h" +#include "thread-utils.h" + +struct oidmap; +struct oidtree; +struct strbuf; +struct repository; + +/* + * The source is the part of the object database that stores the actual + * objects. It thus encapsulates the logic to read and write the specific + * on-disk format. An object database can have multiple sources: + * + * - The primary source, which is typically located in "$GIT_DIR/objects". + * This is where new objects are usually written to. + * + * - Alternate sources, which are configured via "objects/info/alternates" or + * via the GIT_ALTERNATE_OBJECT_DIRECTORIES environment variable. These + * alternate sources are only used to read objects. + */ +struct odb_source { + struct odb_source *next; + + /* + * Used to store the results of readdir(3) calls when we are OK + * sacrificing accuracy due to races for speed. That includes + * object existence with OBJECT_INFO_QUICK, as well as + * our search for unique abbreviated hashes. Don't use it for tasks + * requiring greater accuracy! + * + * Be sure to call odb_load_loose_cache() before using. + */ + uint32_t loose_objects_subdir_seen[8]; /* 256 bits */ + struct oidtree *loose_objects_cache; + + /* Map between object IDs for loose objects. */ + struct loose_object_map *loose_map; + + /* + * This is a temporary object store created by the tmp_objdir + * facility. Disable ref updates since the objects in the store + * might be discarded on rollback. + */ + int disable_ref_updates; + + /* + * This object store is ephemeral, so there is no need to fsync. + */ + int will_destroy; + + /* + * Path to the source. If this is a relative path, it is relative to + * the current working directory. + */ + char *path; +}; + +void prepare_alt_odb(struct repository *r); +int has_alt_odb(struct repository *r); +char *compute_alternate_path(const char *path, struct strbuf *err); +struct odb_source *find_odb(struct repository *r, const char *obj_dir); +typedef int alt_odb_fn(struct odb_source *, void *); +int foreach_alt_odb(alt_odb_fn, void*); +typedef void alternate_ref_fn(const struct object_id *oid, void *); +void for_each_alternate_ref(alternate_ref_fn, void *); + +/* + * Add the directory to the on-disk alternates file; the new entry will also + * take effect in the current process. + */ +void add_to_alternates_file(const char *dir); + +/* + * Add the directory to the in-memory list of alternates (along with any + * recursive alternates it points to), but do not modify the on-disk alternates + * file. + */ +void add_to_alternates_memory(const char *dir); + +/* + * Replace the current writable object directory with the specified temporary + * object directory; returns the former primary object directory. + */ +struct odb_source *set_temporary_primary_odb(const char *dir, int will_destroy); + +/* + * Restore a previous ODB replaced by set_temporary_main_odb. + */ +void restore_primary_odb(struct odb_source *restore_alternate, const char *old_path); + +struct packed_git; +struct multi_pack_index; +struct cached_object_entry; + +/* + * The object database encapsulates access to objects in a repository. It + * manages one or more sources that store the actual objects which are + * configured via alternates. + */ +struct object_database { + /* + * Set of all object directories; the main directory is first (and + * cannot be NULL after initialization). Subsequent directories are + * alternates. + */ + struct odb_source *sources; + struct odb_source **sources_tail; + struct kh_odb_path_map *source_by_path; + + int loaded_alternates; + + /* + * A list of alternate object directories loaded from the environment; + * this should not generally need to be accessed directly, but will + * populate the "sources" list when prepare_alt_odb() is run. + */ + char *alternate_db; + + /* + * Objects that should be substituted by other objects + * (see git-replace(1)). + */ + struct oidmap replace_map; + unsigned replace_map_initialized : 1; + pthread_mutex_t replace_mutex; /* protect object replace functions */ + + struct commit_graph *commit_graph; + unsigned commit_graph_attempted : 1; /* if loading has been attempted */ + + /* + * private data + * + * should only be accessed directly by packfile.c and midx.c + */ + struct multi_pack_index *multi_pack_index; + + /* + * private data + * + * should only be accessed directly by packfile.c + */ + + struct packed_git *packed_git; + /* A most-recently-used ordered version of the packed_git list. */ + struct list_head packed_git_mru; + + struct { + struct packed_git **packs; + unsigned flags; + } kept_pack_cache; + + /* + * This is meant to hold a *small* number of objects that you would + * want repo_read_object_file() to be able to return, but yet you do not want + * to write them into the object store (e.g. a browse-only + * application). + */ + struct cached_object_entry *cached_objects; + size_t cached_object_nr, cached_object_alloc; + + /* + * A map of packfiles to packed_git structs for tracking which + * packs have been loaded already. + */ + struct hashmap pack_map; + + /* + * A fast, rough count of the number of objects in the repository. + * These two fields are not meant for direct access. Use + * repo_approximate_object_count() instead. + */ + unsigned long approximate_object_count; + unsigned approximate_object_count_valid : 1; + + /* + * Whether packed_git has already been populated with this repository's + * packs. + */ + unsigned packed_git_initialized : 1; +}; + +struct object_database *odb_new(void); +void odb_clear(struct object_database *o); + +/* + * Create a temporary file rooted in the object database directory, or + * die on failure. The filename is taken from "pattern", which should have the + * usual "XXXXXX" trailer, and the resulting filename is written into the + * "template" buffer. Returns the open descriptor. + */ +int odb_mkstemp(struct strbuf *temp_filename, const char *pattern); + +void *repo_read_object_file(struct repository *r, + const struct object_id *oid, + enum object_type *type, + unsigned long *size); + +/* Read and unpack an object file into memory, write memory to an object file */ +int oid_object_info(struct repository *r, const struct object_id *, unsigned long *); + +/* + * Add an object file to the in-memory object store, without writing it + * to disk. + * + * Callers are responsible for calling write_object_file to record the + * object in persistent storage before writing any other new objects + * that reference it. + */ +int pretend_object_file(struct repository *repo, + void *buf, unsigned long len, enum object_type type, + struct object_id *oid); + +struct object_info { + /* Request */ + enum object_type *typep; + unsigned long *sizep; + off_t *disk_sizep; + struct object_id *delta_base_oid; + void **contentp; + + /* Response */ + enum { + OI_CACHED, + OI_LOOSE, + OI_PACKED, + OI_DBCACHED + } whence; + union { + /* + * struct { + * ... Nothing to expose in this case + * } cached; + * struct { + * ... Nothing to expose in this case + * } loose; + */ + struct { + struct packed_git *pack; + off_t offset; + unsigned int is_delta; + } packed; + } u; +}; + +/* + * Initializer for a "struct object_info" that wants no items. You may + * also memset() the memory to all-zeroes. + */ +#define OBJECT_INFO_INIT { 0 } + +/* Invoke lookup_replace_object() on the given hash */ +#define OBJECT_INFO_LOOKUP_REPLACE 1 +/* Do not retry packed storage after checking packed and loose storage */ +#define OBJECT_INFO_QUICK 8 +/* + * Do not attempt to fetch the object if missing (even if fetch_is_missing is + * nonzero). + */ +#define OBJECT_INFO_SKIP_FETCH_OBJECT 16 +/* + * This is meant for bulk prefetching of missing blobs in a partial + * clone. Implies OBJECT_INFO_SKIP_FETCH_OBJECT and OBJECT_INFO_QUICK + */ +#define OBJECT_INFO_FOR_PREFETCH (OBJECT_INFO_SKIP_FETCH_OBJECT | OBJECT_INFO_QUICK) + +/* Die if object corruption (not just an object being missing) was detected. */ +#define OBJECT_INFO_DIE_IF_CORRUPT 32 + +int oid_object_info_extended(struct repository *r, + const struct object_id *, + struct object_info *, unsigned flags); + +enum { + /* Retry packed storage after checking packed and loose storage */ + HAS_OBJECT_RECHECK_PACKED = (1 << 0), + /* Allow fetching the object in case the repository has a promisor remote. */ + HAS_OBJECT_FETCH_PROMISOR = (1 << 1), +}; + +/* + * Returns 1 if the object exists. This function will not lazily fetch objects + * in a partial clone by default. + */ +int has_object(struct repository *r, const struct object_id *oid, + unsigned flags); + +void assert_oid_type(const struct object_id *oid, enum object_type expect); + +/* + * Enabling the object read lock allows multiple threads to safely call the + * following functions in parallel: repo_read_object_file(), + * read_object_with_reference(), oid_object_info() and oid_object_info_extended(). + * + * obj_read_lock() and obj_read_unlock() may also be used to protect other + * section which cannot execute in parallel with object reading. Since the used + * lock is a recursive mutex, these sections can even contain calls to object + * reading functions. However, beware that in these cases zlib inflation won't + * be performed in parallel, losing performance. + * + * TODO: oid_object_info_extended()'s call stack has a recursive behavior. If + * any of its callees end up calling it, this recursive call won't benefit from + * parallel inflation. + */ +void enable_obj_read_lock(void); +void disable_obj_read_lock(void); + +extern int obj_read_use_lock; +extern pthread_mutex_t obj_read_mutex; + +static inline void obj_read_lock(void) +{ + if(obj_read_use_lock) + pthread_mutex_lock(&obj_read_mutex); +} + +static inline void obj_read_unlock(void) +{ + if(obj_read_use_lock) + pthread_mutex_unlock(&obj_read_mutex); +} +/* Flags for for_each_*_object(). */ +enum for_each_object_flags { + /* Iterate only over local objects, not alternates. */ + FOR_EACH_OBJECT_LOCAL_ONLY = (1<<0), + + /* Only iterate over packs obtained from the promisor remote. */ + FOR_EACH_OBJECT_PROMISOR_ONLY = (1<<1), + + /* + * Visit objects within a pack in packfile order rather than .idx order + */ + FOR_EACH_OBJECT_PACK_ORDER = (1<<2), + + /* Only iterate over packs that are not marked as kept in-core. */ + FOR_EACH_OBJECT_SKIP_IN_CORE_KEPT_PACKS = (1<<3), + + /* Only iterate over packs that do not have .keep files. */ + FOR_EACH_OBJECT_SKIP_ON_DISK_KEPT_PACKS = (1<<4), +}; + + +void *read_object_with_reference(struct repository *r, + const struct object_id *oid, + enum object_type required_type, + unsigned long *size, + struct object_id *oid_ret); + +#endif /* ODB_H */ |