From: Junio C Hamano <gitster@pobox.com>
Date: Tue, 29 May 2012 20:09:02 +0000 (-0700)
Subject: Merge branch 'rs/refs-string-slice'
X-Git-Tag: v1.7.11-rc1~17
X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/a7060009e1272aa43c8fb941f039cff9e9a0459b?hp=-c

Merge branch 'rs/refs-string-slice'

Avoid unnecessary temporary allocations while looking for matching refs
inside refs API.

By René Scharfe (3) and Junio C Hamano (1)
* rs/refs-string-slice:
refs: do not create ref_entry when searching
refs: use strings directly in find_containing_dir()
refs: convert parameter of create_dir_entry() to length-limited string
refs: convert parameter of search_ref_dir() to length-limited string
---

a7060009e1272aa43c8fb941f039cff9e9a0459b
diff --combined refs.c
index 51c8825acf,52709ab7fc..da74a2b29a
--- a/refs.c
+++ b/refs.c
@@@ -259,13 -259,8 +259,13 @@@ static void clear_ref_dir(struct ref_di
  
  static void free_ref_entry(struct ref_entry *entry)
  {
 -	if (entry->flag & REF_DIR)
 -		clear_ref_dir(get_ref_dir(entry));
 +	if (entry->flag & REF_DIR) {
 +		/*
 +		 * Do not use get_ref_dir() here, as that might
 +		 * trigger the reading of loose refs.
 +		 */
 +		clear_ref_dir(&entry->u.subdir);
 +	}
  	free(entry);
  }
  
@@@ -278,12 -273,6 +278,12 @@@ static void add_entry_to_dir(struct ref
  {
  	ALLOC_GROW(dir->entries, dir->nr + 1, dir->alloc);
  	dir->entries[dir->nr++] = entry;
 +	/* optimize for the case that entries are added in order */
 +	if (dir->nr == 1 ||
 +	    (dir->nr == dir->sorted + 1 &&
 +	     strcmp(dir->entries[dir->nr - 2]->name,
 +		    dir->entries[dir->nr - 1]->name) < 0))
 +		dir->sorted = dir->nr;
  }
  
  /*
@@@ -305,12 -294,13 +305,13 @@@ static void clear_ref_dir(struct ref_di
   * "refs/heads/") or "" for the top-level directory.
   */
  static struct ref_entry *create_dir_entry(struct ref_cache *ref_cache,
- 					  const char *dirname, int incomplete)
+ 					  const char *dirname, size_t len,
+ 					  int incomplete)
  {
  	struct ref_entry *direntry;
- 	int len = strlen(dirname);
  	direntry = xcalloc(1, sizeof(struct ref_entry) + len + 1);
- 	memcpy(direntry->name, dirname, len + 1);
+ 	memcpy(direntry->name, dirname, len);
+ 	direntry->name[len] = '\0';
  	direntry->u.subdir.ref_cache = ref_cache;
  	direntry->flag = REF_DIR | (incomplete ? REF_INCOMPLETE : 0);
  	return direntry;
@@@ -325,28 -315,42 +326,42 @@@ static int ref_entry_cmp(const void *a
  
  static void sort_ref_dir(struct ref_dir *dir);
  
+ struct string_slice {
+ 	size_t len;
+ 	const char *str;
+ };
+ 
+ static int ref_entry_cmp_sslice(const void *key_, const void *ent_)
+ {
+ 	struct string_slice *key = (struct string_slice *)key_;
+ 	struct ref_entry *ent = *(struct ref_entry **)ent_;
+ 	int entlen = strlen(ent->name);
+ 	int cmplen = key->len < entlen ? key->len : entlen;
+ 	int cmp = memcmp(key->str, ent->name, cmplen);
+ 	if (cmp)
+ 		return cmp;
+ 	return key->len - entlen;
+ }
+ 
  /*
   * Return the entry with the given refname from the ref_dir
   * (non-recursively), sorting dir if necessary.  Return NULL if no
   * such entry is found.  dir must already be complete.
   */
- static struct ref_entry *search_ref_dir(struct ref_dir *dir, const char *refname)
+ static struct ref_entry *search_ref_dir(struct ref_dir *dir,
+ 					const char *refname, size_t len)
  {
- 	struct ref_entry *e, **r;
- 	int len;
+ 	struct ref_entry **r;
+ 	struct string_slice key;
  
  	if (refname == NULL || !dir->nr)
  		return NULL;
  
  	sort_ref_dir(dir);
- 
- 	len = strlen(refname) + 1;
- 	e = xmalloc(sizeof(struct ref_entry) + len);
- 	memcpy(e->name, refname, len);
- 
- 	r = bsearch(&e, dir->entries, dir->nr, sizeof(*dir->entries), ref_entry_cmp);
- 
- 	free(e);
+ 	key.len = len;
+ 	key.str = refname;
+ 	r = bsearch(&key, dir->entries, dir->nr, sizeof(*dir->entries),
+ 		    ref_entry_cmp_sslice);
  
  	if (r == NULL)
  		return NULL;
@@@ -362,9 -366,10 +377,10 @@@
   * directory cannot be found.  dir must already be complete.
   */
  static struct ref_dir *search_for_subdir(struct ref_dir *dir,
- 					 const char *subdirname, int mkdir)
+ 					 const char *subdirname, size_t len,
+ 					 int mkdir)
  {
- 	struct ref_entry *entry = search_ref_dir(dir, subdirname);
+ 	struct ref_entry *entry = search_ref_dir(dir, subdirname, len);
  	if (!entry) {
  		if (!mkdir)
  			return NULL;
@@@ -374,7 -379,7 +390,7 @@@
  		 * therefore, create an empty record for it but mark
  		 * the record complete.
  		 */
- 		entry = create_dir_entry(dir->ref_cache, subdirname, 0);
+ 		entry = create_dir_entry(dir->ref_cache, subdirname, len, 0);
  		add_entry_to_dir(dir, entry);
  	}
  	return get_ref_dir(entry);
@@@ -392,15 -397,11 +408,11 @@@
  static struct ref_dir *find_containing_dir(struct ref_dir *dir,
  					   const char *refname, int mkdir)
  {
- 	struct strbuf dirname;
  	const char *slash;
- 	strbuf_init(&dirname, PATH_MAX);
  	for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
+ 		size_t dirnamelen = slash - refname + 1;
  		struct ref_dir *subdir;
- 		strbuf_add(&dirname,
- 			   refname + dirname.len,
- 			   (slash + 1) - (refname + dirname.len));
- 		subdir = search_for_subdir(dir, dirname.buf, mkdir);
+ 		subdir = search_for_subdir(dir, refname, dirnamelen, mkdir);
  		if (!subdir) {
  			dir = NULL;
  			break;
@@@ -408,7 -409,6 +420,6 @@@
  		dir = subdir;
  	}
  
- 	strbuf_release(&dirname);
  	return dir;
  }
  
@@@ -423,7 -423,7 +434,7 @@@ static struct ref_entry *find_ref(struc
  	dir = find_containing_dir(dir, refname, 0);
  	if (!dir)
  		return NULL;
- 	entry = search_ref_dir(dir, refname);
+ 	entry = search_ref_dir(dir, refname, strlen(refname));
  	return (entry && !(entry->flag & REF_DIR)) ? entry : NULL;
  }
  
@@@ -833,7 -833,7 +844,7 @@@ static struct ref_dir *get_packed_refs(
  		const char *packed_refs_file;
  		FILE *f;
  
- 		refs->packed = create_dir_entry(refs, "", 0);
+ 		refs->packed = create_dir_entry(refs, "", 0, 0);
  		if (*refs->name)
  			packed_refs_file = git_path_submodule(refs->name, "packed-refs");
  		else
@@@ -898,7 -898,8 +909,8 @@@ static void read_loose_refs(const char 
  		} else if (S_ISDIR(st.st_mode)) {
  			strbuf_addch(&refname, '/');
  			add_entry_to_dir(dir,
- 					 create_dir_entry(refs, refname.buf, 1));
+ 					 create_dir_entry(refs, refname.buf,
+ 							  refname.len, 1));
  		} else {
  			if (*refs->name) {
  				hashclr(sha1);
@@@ -928,12 -929,12 +940,12 @@@ static struct ref_dir *get_loose_refs(s
  		 * are about to read the only subdirectory that can
  		 * hold references:
  		 */
- 		refs->loose = create_dir_entry(refs, "", 0);
+ 		refs->loose = create_dir_entry(refs, "", 0, 0);
  		/*
  		 * Create an incomplete entry for "refs/":
  		 */
  		add_entry_to_dir(get_ref_dir(refs->loose),
- 				 create_dir_entry(refs, "refs/", 1));
+ 				 create_dir_entry(refs, "refs/", 5, 1));
  	}
  	return get_ref_dir(refs->loose);
  }