From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: [PATCH] process_{tree,blob}: Remove useless xstrdup calls Date: Fri, 10 Apr 2009 17:27:58 -0700 (PDT) Message-ID: References: <20090408112854.GA8624@atjola.homenet> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Nicolas Pitre , Jakub Narebski , Sverre Rabbelier , david@lang.hm, Junio C Hamano , Nicolas Sebrecht , "Robin H. Johnson" , Git Mailing List To: =?ISO-8859-15?Q?Bj=F6rn_Steinbrink?= X-From: git-owner@vger.kernel.org Sat Apr 11 02:35:39 2009 Return-path: Envelope-to: gcvg-git-2@gmane.org Received: from vger.kernel.org ([209.132.176.167]) by lo.gmane.org with esmtp (Exim 4.50) id 1LsRC5-000450-TQ for gcvg-git-2@gmane.org; Sat, 11 Apr 2009 02:35:38 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752705AbZDKAdx (ORCPT ); Fri, 10 Apr 2009 20:33:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753118AbZDKAdw (ORCPT ); Fri, 10 Apr 2009 20:33:52 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:54590 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752478AbZDKAdv (ORCPT ); Fri, 10 Apr 2009 20:33:51 -0400 Received: from imap1.linux-foundation.org (imap1.linux-foundation.org [140.211.169.55]) by smtp1.linux-foundation.org (8.14.2/8.13.5/Debian-3ubuntu1.1) with ESMTP id n3B0Rx1T008915 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Fri, 10 Apr 2009 17:28:30 -0700 Received: from localhost (localhost [127.0.0.1]) by imap1.linux-foundation.org (8.13.5.20060308/8.13.5/Debian-3ubuntu1.1) with ESMTP id n3B0RwRv009345; Fri, 10 Apr 2009 17:27:58 -0700 X-X-Sender: torvalds@localhost.localdomain In-Reply-To: User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) X-Spam-Status: No, hits=-5.445 required=5 tests=AWL,BAYES_00,OSDL_HEADER_SUBJECT_BRACKETED,PATCH_SUBJECT_OSDL X-Spam-Checker-Version: SpamAssassin 3.2.4-osdl_revision__1.47__ X-MIMEDefang-Filter: lf$Revision: 1.188 $ X-Scanned-By: MIMEDefang 2.63 on 140.211.169.13 Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: On Fri, 10 Apr 2009, Linus Torvalds wrote: > > There's another easy 5% or so for the built-in object walker: once we've > created the hash from the name, the name isn't interesting any more, and > so something trivial like this can help a bit. Hmm. Here's a less trivial thing, and slightly more dubious one. I was looking at that "struct object_array objects", and wondering why we do that. I have honestly totally forgotten. Why not just call the "show()" function as we encounter the objects? Rather than add the objects to the object_array, and then at the very end going through the array and doing a 'show' on all, just do things more incrementally. Now, there are possible downsides to this: - the "buffer using object_array" _can_ in theory result in at least better I-cache usage (two tight loops rather than one more spread out one). I don't think this is a real issue, but in theory.. - this _does_ change the order of the objects printed. Instead of doing a "process_tree(revs, commit->tree, &objects, NULL, "");" in the loop over the commits (which puts all the root trees _first_ in the object list, this patch just adds them to the list of pending objects, and then we'll traverse them in that order (and thus show each root tree object together with the objects we discover under it) I _think_ the new ordering actually makes more sense, but the object ordering is actually a subtle thing when it comes to packing efficiency, so any change in order is going to have implications for packing. Good or bad, I dunno. - There may be some reason why we did it that odd way with the object array, that I have simply forgotten. Anyway, this includes the "free(name)" in builtin-pack-objects.c: show_object() logic, and now that we don't buffer up the objects before showing them that may actually result in lower memory usage during that whole traverse_commit_list() phase. This is seriously not very deeply tested. It makes sense to me, it seems to pass all the tests, it looks ok, but... Does anybody remember why we did that "object_array" thing? It used to be an "object_list" a long long time ago, but got changed into the array due to better memory usage patterns (those linked lists of obejcts are horrible from a memory allocation standpoint). But I wonder why we didn't do this back then. Maybe there's a reason for it. Or maybe there _used_ to be a reason, and no longer is. Linus --- builtin-pack-objects.c | 14 ++++++++++---- builtin-rev-list.c | 20 ++++++++++---------- list-objects.c | 35 ++++++++++++++++++----------------- list-objects.h | 2 +- revision.c | 2 +- revision.h | 2 ++ upload-pack.c | 12 ++++++------ 7 files changed, 48 insertions(+), 39 deletions(-) diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c index 9fc3b35..e028a02 100644 --- a/builtin-pack-objects.c +++ b/builtin-pack-objects.c @@ -1907,11 +1907,17 @@ static void show_commit(struct commit *commit) commit->object.flags |= OBJECT_ADDED; } -static void show_object(struct object_array_entry *p) +static void show_object(struct object *obj, const char *name) { - add_preferred_base_object(p->name); - add_object_entry(p->item->sha1, p->item->type, p->name, 0); - p->item->flags |= OBJECT_ADDED; + add_preferred_base_object(name); + add_object_entry(obj->sha1, obj->type, name, 0); + obj->flags |= OBJECT_ADDED; + + /* + * We will have generated the hash from the name, + * but not saved a pointer to it - we can free it + */ + free(name); } static void show_edge(struct commit *commit) diff --git a/builtin-rev-list.c b/builtin-rev-list.c index 40d5fcb..0815cf3 100644 --- a/builtin-rev-list.c +++ b/builtin-rev-list.c @@ -168,27 +168,27 @@ static void finish_commit(struct commit *commit) commit->buffer = NULL; } -static void finish_object(struct object_array_entry *p) +static void finish_object(struct object *obj, const char *name) { - if (p->item->type == OBJ_BLOB && !has_sha1_file(p->item->sha1)) - die("missing blob object '%s'", sha1_to_hex(p->item->sha1)); + if (obj->type == OBJ_BLOB && !has_sha1_file(obj->sha1)) + die("missing blob object '%s'", sha1_to_hex(obj->sha1)); } -static void show_object(struct object_array_entry *p) +static void show_object(struct object *obj, const char *name) { /* An object with name "foo\n0000000..." can be used to * confuse downstream "git pack-objects" very badly. */ - const char *ep = strchr(p->name, '\n'); + const char *ep = strchr(name, '\n'); - finish_object(p); + finish_object(obj, name); if (ep) { - printf("%s %.*s\n", sha1_to_hex(p->item->sha1), - (int) (ep - p->name), - p->name); + printf("%s %.*s\n", sha1_to_hex(obj->sha1), + (int) (ep - name), + name); } else - printf("%s %s\n", sha1_to_hex(p->item->sha1), p->name); + printf("%s %s\n", sha1_to_hex(obj->sha1), name); } static void show_edge(struct commit *commit) diff --git a/list-objects.c b/list-objects.c index dd243c7..5a4af62 100644 --- a/list-objects.c +++ b/list-objects.c @@ -10,7 +10,7 @@ static void process_blob(struct rev_info *revs, struct blob *blob, - struct object_array *p, + show_object_fn show, struct name_path *path, const char *name) { @@ -23,7 +23,7 @@ static void process_blob(struct rev_info *revs, if (obj->flags & (UNINTERESTING | SEEN)) return; obj->flags |= SEEN; - add_object(obj, p, path, name); + show(obj, path_name(path, name)); } /* @@ -50,7 +50,7 @@ static void process_blob(struct rev_info *revs, */ static void process_gitlink(struct rev_info *revs, const unsigned char *sha1, - struct object_array *p, + show_object_fn show, struct name_path *path, const char *name) { @@ -59,7 +59,7 @@ static void process_gitlink(struct rev_info *revs, static void process_tree(struct rev_info *revs, struct tree *tree, - struct object_array *p, + show_object_fn show, struct name_path *path, const char *name) { @@ -77,7 +77,7 @@ static void process_tree(struct rev_info *revs, if (parse_tree(tree) < 0) die("bad tree object %s", sha1_to_hex(obj->sha1)); obj->flags |= SEEN; - add_object(obj, p, path, name); + show(obj, path_name(path, name)); me.up = path; me.elem = name; me.elem_len = strlen(name); @@ -88,14 +88,14 @@ static void process_tree(struct rev_info *revs, if (S_ISDIR(entry.mode)) process_tree(revs, lookup_tree(entry.sha1), - p, &me, entry.path); + show, &me, entry.path); else if (S_ISGITLINK(entry.mode)) process_gitlink(revs, entry.sha1, - p, &me, entry.path); + show, &me, entry.path); else process_blob(revs, lookup_blob(entry.sha1), - p, &me, entry.path); + show, &me, entry.path); } free(tree->buffer); tree->buffer = NULL; @@ -134,16 +134,20 @@ void mark_edges_uninteresting(struct commit_list *list, } } +static void add_pending_tree(struct rev_info *revs, struct tree *tree) +{ + add_pending_object(revs, &tree->object, ""); +} + void traverse_commit_list(struct rev_info *revs, void (*show_commit)(struct commit *), - void (*show_object)(struct object_array_entry *)) + void (*show_object)(struct object *, const char *)) { int i; struct commit *commit; - struct object_array objects = { 0, 0, NULL }; while ((commit = get_revision(revs)) != NULL) { - process_tree(revs, commit->tree, &objects, NULL, ""); + add_pending_tree(revs, commit->tree); show_commit(commit); } for (i = 0; i < revs->pending.nr; i++) { @@ -154,25 +158,22 @@ void traverse_commit_list(struct rev_info *revs, continue; if (obj->type == OBJ_TAG) { obj->flags |= SEEN; - add_object_array(obj, name, &objects); + show_object(obj, name); continue; } if (obj->type == OBJ_TREE) { - process_tree(revs, (struct tree *)obj, &objects, + process_tree(revs, (struct tree *)obj, show_object, NULL, name); continue; } if (obj->type == OBJ_BLOB) { - process_blob(revs, (struct blob *)obj, &objects, + process_blob(revs, (struct blob *)obj, show_object, NULL, name); continue; } die("unknown pending object %s (%s)", sha1_to_hex(obj->sha1), name); } - for (i = 0; i < objects.nr; i++) - show_object(&objects.objects[i]); - free(objects.objects); if (revs->pending.nr) { free(revs->pending.objects); revs->pending.nr = 0; diff --git a/list-objects.h b/list-objects.h index 0f41391..13b0dd9 100644 --- a/list-objects.h +++ b/list-objects.h @@ -2,7 +2,7 @@ #define LIST_OBJECTS_H typedef void (*show_commit_fn)(struct commit *); -typedef void (*show_object_fn)(struct object_array_entry *); +typedef void (*show_object_fn)(struct object *, const char *); typedef void (*show_edge_fn)(struct commit *); void traverse_commit_list(struct rev_info *revs, show_commit_fn, show_object_fn); diff --git a/revision.c b/revision.c index b6215cc..44a9ce2 100644 --- a/revision.c +++ b/revision.c @@ -15,7 +15,7 @@ volatile show_early_output_fn_t show_early_output; -static char *path_name(struct name_path *path, const char *name) +char *path_name(struct name_path *path, const char *name) { struct name_path *p; char *n, *m; diff --git a/revision.h b/revision.h index 5adfc91..c89e8ff 100644 --- a/revision.h +++ b/revision.h @@ -146,6 +146,8 @@ struct name_path { const char *elem; }; +char *path_name(struct name_path *path, const char *name); + extern void add_object(struct object *obj, struct object_array *p, struct name_path *path, diff --git a/upload-pack.c b/upload-pack.c index a49d872..5524ac4 100644 --- a/upload-pack.c +++ b/upload-pack.c @@ -78,20 +78,20 @@ static void show_commit(struct commit *commit) commit->buffer = NULL; } -static void show_object(struct object_array_entry *p) +static void show_object(struct object *obj, const char *name) { /* An object with name "foo\n0000000..." can be used to * confuse downstream git-pack-objects very badly. */ - const char *ep = strchr(p->name, '\n'); + const char *ep = strchr(name, '\n'); if (ep) { - fprintf(pack_pipe, "%s %.*s\n", sha1_to_hex(p->item->sha1), - (int) (ep - p->name), - p->name); + fprintf(pack_pipe, "%s %.*s\n", sha1_to_hex(obj->sha1), + (int) (ep - name), + name); } else fprintf(pack_pipe, "%s %s\n", - sha1_to_hex(p->item->sha1), p->name); + sha1_to_hex(obj->sha1), name); } static void show_edge(struct commit *commit)