Using object_hash, you can store interesting information about
objects in a private hash map. This makes up for the lack of a
`util` member of `struct object`.
Signed-off-by: Johannes Schindelin <johannes.schindelin@xxxxxx>
---
We should have done that earlier. Now, git.git already
contains two specialised versions of an object hash map:
obj_hash and refs_hash.
obj_hash is not really a hash map, but rather a hash set,
but there is no excuse for refs_hash having its own little
private implementation nobody else can reuse.
Makefile | 2 +-
object-hash.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
object-hash.h | 19 ++++++++++++++++
3 files changed, 87 insertions(+), 1 deletions(-)
create mode 100644 object-hash.c
create mode 100644 object-hash.h
diff --git a/Makefile b/Makefile
index dfe226f..e53a5ad 100644
--- a/Makefile
+++ b/Makefile
@@ -267,7 +267,7 @@ LIB_OBJS = \
write_or_die.o trace.o list-objects.o grep.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 object-hash.o
BUILTIN_OBJS = \
builtin-add.o \
diff --git a/object-hash.c b/object-hash.c
new file mode 100644
index 0000000..2295e33
--- /dev/null
+++ b/object-hash.c
@@ -0,0 +1,67 @@
+#include "cache.h"
+#include "object.h"
+#include "object-hash.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_object_into_hash(struct object *object, void *util,
+ struct object_hash *hash)
+{
+ int j = hash_obj(object, hash->size);
+
+ while (hash->hash[j].object) {
+ j++;
+ if (j >= hash->size)
+ j = 0;
+ }
+ hash->hash[j].object = object;
+ hash->hash[j].util = util;
+}
+
+static void grow_object_hash(struct object_hash *hash)
+{
+ struct object_hash_entry *old_hash = hash->hash;
+ int new_size = (hash->size + 1000) * 3 / 2, i;
+
+ hash->hash = xcalloc(sizeof(struct object_hash_entry), new_size);
+ for (i = 0; i < hash->size; i++) {
+ struct object_hash_entry *entry = old_hash + i;
+ if (!entry->object)
+ continue;
+ insert_object_into_hash(entry->object, entry->util, hash);
+ }
+ hash->size = new_size;
+ free(old_hash);
+}
+
+void add_object_to_hash(struct object *obj, void *util,
+ struct object_hash *hash)
+{
+ if (++hash->nr > hash->size * 2 / 3)
+ grow_object_hash(hash);
+ insert_object_into_hash(obj, util, hash);
+}
+
+void *lookup_object_in_hash(struct object *obj, struct object_hash *hash)
+{
+ int j;
+
+ /* nothing to lookup */
+ if (!hash->size)
+ return NULL;
+ j = hash_obj(obj, hash->size);
+ while (hash->hash[j].object) {
+ if (hash->hash[j].object == obj)
+ return hash->hash[j].util;
+ j++;
+ if (j >= hash->size)
+ j = 0;
+ }
+ return NULL;
+}
+
+
diff --git a/object-hash.h b/object-hash.h
new file mode 100644
index 0000000..0da7824
--- /dev/null
+++ b/object-hash.h
@@ -0,0 +1,19 @@
+#ifndef OBJECT_HASH_H
+#define OBJECT_HASH_H
+
+struct object_hash_entry {
+ struct object *object;
+ void *util;
+};
+
+struct object_hash {
+ unsigned int size, nr;
+ struct object_hash_entry *hash;
+};
+
+extern void add_object_to_hash(struct object *obj, void *util,
+ struct object_hash *hash);
+extern void *lookup_object_in_hash(struct object *obj,
+ struct object_hash *hash);
+
+#endif
--
1.5.0.2139.gdafc9-dirty
-
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