1 files changed, 237 insertions, 0 deletions
diff --git a/name-hash.c b/name-hash.c
new file mode 100644
index 0000000000..702cd0518f
--- /dev/null
+++ b/name-hash.c
@@ -0,0 +1,237 @@
+/*
+ * name-hash.c
+ *
+ * Hashing names in the index state
+ *
+ * Copyright (C) 2008 Linus Torvalds
+ */
+#define NO_THE_INDEX_COMPATIBILITY_MACROS
+#include "cache.h"
+
+struct dir_entry {
+	struct hashmap_entry ent;
+	struct dir_entry *parent;
+	struct cache_entry *ce;
+	int nr;
+	unsigned int namelen;
+};
+
+static int dir_entry_cmp(const struct dir_entry *e1,
+		const struct dir_entry *e2, const char *name)
+{
+	return e1->namelen != e2->namelen || strncasecmp(e1->ce->name,
+			name ? name : e2->ce->name, e1->namelen);
+}
+
+static struct dir_entry *find_dir_entry(struct index_state *istate,
+		const char *name, unsigned int namelen)
+{
+	struct dir_entry key;
+	hashmap_entry_init(&key, memihash(name, namelen));
+	key.namelen = namelen;
+	return hashmap_get(&istate->dir_hash, &key, name);
+}
+
+static struct dir_entry *hash_dir_entry(struct index_state *istate,
+		struct cache_entry *ce, int namelen)
+{
+	/*
+	 * Throw each directory component in the hash for quick lookup
+	 * during a git status. Directory components are stored without their
+	 * closing slash.  Despite submodules being a directory, they never
+	 * reach this point, because they are stored
+	 * in index_state.name_hash (as ordinary cache_entries).
+	 *
+	 * Note that the cache_entry stored with the dir_entry merely
+	 * supplies the name of the directory (up to dir_entry.namelen). We
+	 * track the number of 'active' files in a directory in dir_entry.nr,
+	 * so we can tell if the directory is still relevant, e.g. for git
+	 * status. However, if cache_entries are removed, we cannot pinpoint
+	 * an exact cache_entry that's still active. It is very possible that
+	 * multiple dir_entries point to the same cache_entry.
+	 */
+	struct dir_entry *dir;
+
+	/* get length of parent directory */
+	while (namelen > 0 && !is_dir_sep(ce->name[namelen - 1]))
+		namelen--;
+	if (namelen <= 0)
+		return NULL;
+	namelen--;
+
+	/* lookup existing entry for that directory */
+	dir = find_dir_entry(istate, ce->name, namelen);
+	if (!dir) {
+		/* not found, create it and add to hash table */
+		dir = xcalloc(1, sizeof(struct dir_entry));
+		hashmap_entry_init(dir, memihash(ce->name, namelen));
+		dir->namelen = namelen;
+		dir->ce = ce;
+		hashmap_add(&istate->dir_hash, dir);
+
+		/* recursively add missing parent directories */
+		dir->parent = hash_dir_entry(istate, ce, namelen);
+	}
+	return dir;
+}
+
+static void add_dir_entry(struct index_state *istate, struct cache_entry *ce)
+{
+	/* Add reference to the directory entry (and parents if 0). */
+	struct dir_entry *dir = hash_dir_entry(istate, ce, ce_namelen(ce));
+	while (dir && !(dir->nr++))
+		dir = dir->parent;
+}
+
+static void remove_dir_entry(struct index_state *istate, struct cache_entry *ce)
+{
+	/*
+	 * Release reference to the directory entry. If 0, remove and continue
+	 * with parent directory.
+	 */
+	struct dir_entry *dir = hash_dir_entry(istate, ce, ce_namelen(ce));
+	while (dir && !(--dir->nr)) {
+		struct dir_entry *parent = dir->parent;
+		hashmap_remove(&istate->dir_hash, dir, NULL);
+		free(dir);
+		dir = parent;
+	}
+}
+
+static void hash_index_entry(struct index_state *istate, struct cache_entry *ce)
+{
+	if (ce->ce_flags & CE_HASHED)
+		return;
+	ce->ce_flags |= CE_HASHED;
+	hashmap_entry_init(ce, memihash(ce->name, ce_namelen(ce)));
+	hashmap_add(&istate->name_hash, ce);
+
+	if (ignore_case)
+		add_dir_entry(istate, ce);
+}
+
+static int cache_entry_cmp(const struct cache_entry *ce1,
+		const struct cache_entry *ce2, const void *remove)
+{
+	/*
+	 * For remove_name_hash, find the exact entry (pointer equality); for
+	 * index_file_exists, find all entries with matching hash code and
+	 * decide whether the entry matches in same_name.
+	 */
+	return remove ? !(ce1 == ce2) : 0;
+}
+
+static void lazy_init_name_hash(struct index_state *istate)
+{
+	int nr;
+
+	if (istate->name_hash_initialized)
+		return;
+	hashmap_init(&istate->name_hash, (hashmap_cmp_fn) cache_entry_cmp,
+			istate->cache_nr);
+	hashmap_init(&istate->dir_hash, (hashmap_cmp_fn) dir_entry_cmp, 0);
+	for (nr = 0; nr < istate->cache_nr; nr++)
+		hash_index_entry(istate, istate->cache[nr]);
+	istate->name_hash_initialized = 1;
+}
+
+void add_name_hash(struct index_state *istate, struct cache_entry *ce)
+{
+	if (istate->name_hash_initialized)
+		hash_index_entry(istate, ce);
+}
+
+void remove_name_hash(struct index_state *istate, struct cache_entry *ce)
+{
+	if (!istate->name_hash_initialized || !(ce->ce_flags & CE_HASHED))
+		return;
+	ce->ce_flags &= ~CE_HASHED;
+	hashmap_remove(&istate->name_hash, ce, ce);
+
+	if (ignore_case)
+		remove_dir_entry(istate, ce);
+}
+
+static int slow_same_name(const char *name1, int len1, const char *name2, int len2)
+{
+	if (len1 != len2)
+		return 0;
+
+	while (len1) {
+		unsigned char c1 = *name1++;
+		unsigned char c2 = *name2++;
+		len1--;
+		if (c1 != c2) {
+			c1 = toupper(c1);
+			c2 = toupper(c2);
+			if (c1 != c2)
+				return 0;
+		}
+	}
+	return 1;
+}
+
+static int same_name(const struct cache_entry *ce, const char *name, int namelen, int icase)
+{
+	int len = ce_namelen(ce);
+
+	/*
+	 * Always do exact compare, even if we want a case-ignoring comparison;
+	 * we do the quick exact one first, because it will be the common case.
+	 */
+	if (len == namelen && !memcmp(name, ce->name, len))
+		return 1;
+
+	if (!icase)
+		return 0;
+
+	return slow_same_name(name, namelen, ce->name, len);
+}
+
+struct cache_entry *index_dir_exists(struct index_state *istate, const char *name, int namelen)
+{
+	struct cache_entry *ce;
+	struct dir_entry *dir;
+
+	lazy_init_name_hash(istate);
+	dir = find_dir_entry(istate, name, namelen);
+	if (dir && dir->nr)
+		return dir->ce;
+
+	/*
+	 * It might be a submodule. Unlike plain directories, which are stored
+	 * in the dir-hash, submodules are stored in the name-hash, so check
+	 * there, as well.
+	 */
+	ce = index_file_exists(istate, name, namelen, 1);
+	if (ce && S_ISGITLINK(ce->ce_mode))
+		return ce;
+
+	return NULL;
+}
+
+struct cache_entry *index_file_exists(struct index_state *istate, const char *name, int namelen, int icase)
+{
+	struct cache_entry *ce;
+
+	lazy_init_name_hash(istate);
+
+	ce = hashmap_get_from_hash(&istate->name_hash,
+				   memihash(name, namelen), NULL);
+	while (ce) {
+		if (same_name(ce, name, namelen, icase))
+			return ce;
+		ce = hashmap_get_next(&istate->name_hash, ce);
+	}
+	return NULL;
+}
+
+void free_name_hash(struct index_state *istate)
+{
+	if (!istate->name_hash_initialized)
+		return;
+	istate->name_hash_initialized = 0;
+
+	hashmap_free(&istate->name_hash, 0);
+	hashmap_free(&istate->dir_hash, 1);
+}