From: Linus Torvalds Date: Mon, 16 Apr 2007 23:03:15 +0000 (-0700) Subject: Add a generic "object decorator" interface, and make object refs use it X-Git-Tag: v1.5.2-rc0~46 X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=a59b276e18f3d4a548caf549e05188cb1bd3a709;p=git.git Add a generic "object decorator" interface, and make object refs use it This allows you to add an arbitrary "decoration" of your choice to any object. It's a space- and time-efficient way to add information to arbitrary objects, especially if most objects probably do not have the decoration. Signed-off-by: Linus Torvalds Signed-off-by: Junio C Hamano --- diff --git a/Makefile b/Makefile index b8e603094..251fc31fc 100644 --- a/Makefile +++ b/Makefile @@ -283,7 +283,7 @@ LIB_H = \ diff.h object.h pack.h pkt-line.h quote.h refs.h list-objects.h sideband.h \ run-command.h strbuf.h tag.h tree.h git-compat-util.h revision.h \ tree-walk.h log-tree.h dir.h path-list.h unpack-trees.h builtin.h \ - utf8.h reflog-walk.h patch-ids.h + utf8.h reflog-walk.h patch-ids.h decorate.h DIFF_OBJS = \ diff.o diff-lib.o diffcore-break.o diffcore-order.o \ @@ -305,7 +305,7 @@ LIB_OBJS = \ write_or_die.o trace.o list-objects.o grep.o match-trees.o \ alloc.o merge-file.o path-list.o help.o unpack-trees.o $(DIFF_OBJS) \ color.o wt-status.o archive-zip.o archive-tar.o shallow.o utf8.o \ - convert.o + convert.o decorate.o BUILTIN_OBJS = \ builtin-add.o \ diff --git a/decorate.c b/decorate.c new file mode 100644 index 000000000..396b41311 --- /dev/null +++ b/decorate.c @@ -0,0 +1,89 @@ +/* + * decorate.c - decorate a git object with some arbitrary + * data. + */ +#include "cache.h" +#include "object.h" +#include "decorate.h" + +static unsigned int hash_obj(struct object *obj, unsigned int n) +{ + unsigned int hash = *(unsigned int *)obj->sha1; + return hash % n; +} + +static void *insert_decoration(struct decoration *n, struct object *base, void *decoration) +{ + int size = n->size; + struct object_decoration *hash = n->hash; + int j = hash_obj(base, size); + + while (hash[j].base) { + if (hash[j].base == base) { + void *old = hash[j].decoration; + hash[j].decoration = decoration; + return old; + } + j++; + if (++j >= size) + j = 0; + } + hash[j].base = base; + hash[j].decoration = decoration; + n->nr++; + return NULL; +} + +static void grow_decoration(struct decoration *n) +{ + int i; + int old_size = n->size; + struct object_decoration *old_hash; + + old_size = n->size; + old_hash = n->hash; + + n->size = (old_size + 1000) * 3 / 2; + n->hash = xcalloc(n->size, sizeof(struct object_decoration)); + n->nr = 0; + + for (i = 0; i < old_size; i++) { + struct object *base = old_hash[i].base; + void *decoration = old_hash[i].decoration; + + if (!base) + continue; + insert_decoration(n, base, decoration); + } + free(old_hash); +} + +/* Add a decoration pointer, return any old one */ +void *add_decoration(struct decoration *n, struct object *obj, void *decoration) +{ + int nr = n->nr + 1; + + if (nr > n->size * 2 / 3) + grow_decoration(n); + return insert_decoration(n, obj, decoration); +} + +/* Lookup a decoration pointer */ +void *lookup_decoration(struct decoration *n, struct object *obj) +{ + int j; + + /* nothing to lookup */ + if (!n->size) + return NULL; + j = hash_obj(obj, n->size); + for (;;) { + struct object_decoration *ref = n->hash + j; + if (ref->base == obj) + return ref->decoration; + if (!ref->base) + return NULL; + if (++j == n->size) + j = 0; + } +} diff --git a/decorate.h b/decorate.h new file mode 100644 index 000000000..1fa4ad9be --- /dev/null +++ b/decorate.h @@ -0,0 +1,18 @@ +#ifndef DECORATE_H +#define DECORATE_H + +struct object_decoration { + struct object *base; + void *decoration; +}; + +struct decoration { + const char *name; + unsigned int size, nr; + struct object_decoration *hash; +}; + +extern void *add_decoration(struct decoration *n, struct object *obj, void *decoration); +extern void *lookup_decoration(struct decoration *n, struct object *obj); + +#endif diff --git a/object-refs.c b/object-refs.c index 98ea10005..022e8d841 100644 --- a/object-refs.c +++ b/object-refs.c @@ -1,75 +1,20 @@ #include "cache.h" #include "object.h" +#include "decorate.h" int track_object_refs = 0; -static unsigned int refs_hash_size, nr_object_refs; -static struct object_refs **refs_hash; +static struct decoration ref_decorate; -static unsigned int hash_obj(struct object *obj, unsigned int n) +struct object_refs *lookup_object_refs(struct object *base) { - unsigned int hash = *(unsigned int *)obj->sha1; - return hash % n; + return lookup_decoration(&ref_decorate, base); } -static void insert_ref_hash(struct object_refs *ref, struct object_refs **hash, unsigned int size) +static void add_object_refs(struct object *obj, struct object_refs *refs) { - int j = hash_obj(ref->base, size); - - while (hash[j]) { - j++; - if (j >= size) - j = 0; - } - hash[j] = ref; -} - -static void grow_refs_hash(void) -{ - int i; - int new_hash_size = (refs_hash_size + 1000) * 3 / 2; - struct object_refs **new_hash; - - new_hash = xcalloc(new_hash_size, sizeof(struct object_refs *)); - for (i = 0; i < refs_hash_size; i++) { - struct object_refs *ref = refs_hash[i]; - if (!ref) - continue; - insert_ref_hash(ref, new_hash, new_hash_size); - } - free(refs_hash); - refs_hash = new_hash; - refs_hash_size = new_hash_size; -} - -static void add_object_refs(struct object *obj, struct object_refs *ref) -{ - int nr = nr_object_refs + 1; - - if (nr > refs_hash_size * 2 / 3) - grow_refs_hash(); - ref->base = obj; - insert_ref_hash(ref, refs_hash, refs_hash_size); - nr_object_refs = nr; -} - -struct object_refs *lookup_object_refs(struct object *obj) -{ - struct object_refs *ref; - int j; - - /* nothing to lookup */ - if (!refs_hash_size) - return NULL; - j = hash_obj(obj, refs_hash_size); - while ((ref = refs_hash[j]) != NULL) { - if (ref->base == obj) - break; - j++; - if (j >= refs_hash_size) - j = 0; - } - return ref; + if (add_decoration(&ref_decorate, obj, refs)) + die("object %s tried to add refs twice!", sha1_to_hex(obj->sha1)); } struct object_refs *alloc_object_refs(unsigned count) diff --git a/object.h b/object.h index bdbf0facd..bdbbc1889 100644 --- a/object.h +++ b/object.h @@ -8,7 +8,6 @@ struct object_list { struct object_refs { unsigned count; - struct object *base; struct object *ref[FLEX_ARRAY]; /* more */ };