[PATCH] [GSOC] remove_temporary_files(): reimplement using iterators

[PATCH] [GSOC] remove_temporary_files(): reimplement using iterators

[Robert Stanca]

Replaces recursive traversing of opendir with dir_iterator

Signed-off-by: Robert Stanca <robert.stanca7@gmail.com>
---
 builtin/repack.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/builtin/repack.c b/builtin/repack.c
index 677bc7c81..dba465814 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -7,6 +7,8 @@
 #include "strbuf.h"
 #include "string-list.h"
 #include "argv-array.h"
+#include "iterator.h"
+#include "dir-iterator.h"
 
 static int delta_base_offset = 1;
 static int pack_kept_objects = -1;
@@ -49,12 +51,7 @@ static void remove_temporary_files(void)
 {
 	struct strbuf buf = STRBUF_INIT;
 	size_t dirlen, prefixlen;
-	DIR *dir;
-	struct dirent *e;
-
-	dir = opendir(packdir);
-	if (!dir)
-		return;
+	struct dir_iterator *diter = dir_iterator_begin(packdir);
 
 	/* Point at the slash at the end of ".../objects/pack/" */
 	dirlen = strlen(packdir) + 1;
@@ -62,14 +59,13 @@ static void remove_temporary_files(void)
 	/* Hold the length of  ".tmp-%d-pack-" */
 	prefixlen = buf.len - dirlen;
 
-	while ((e = readdir(dir))) {
-		if (strncmp(e->d_name, buf.buf + dirlen, prefixlen))
+	while (dir_iterator_advance(diter) == ITER_OK) {
+		if (strncmp(diter->relative_path, buf.buf + dirlen, prefixlen))
 			continue;
 		strbuf_setlen(&buf, dirlen);
-		strbuf_addstr(&buf, e->d_name);
+		strbuf_addstr(&buf, diter->relative_path);
 		unlink(buf.buf);
 	}
-	closedir(dir);
 	strbuf_release(&buf);
 }
 
-- 
2.12.2.575.gb14f27f91.dirty

Re: [PATCH] [GSOC] remove_temporary_files(): reimplement using iterators

[Jeff King]

On Sat, Apr 01, 2017 at 03:24:58AM +0300, Robert Stanca wrote:

> @@ -49,12 +51,7 @@ static void remove_temporary_files(void)
>  {
>  	struct strbuf buf = STRBUF_INIT;
>  	size_t dirlen, prefixlen;
> -	DIR *dir;
> -	struct dirent *e;
> -
> -	dir = opendir(packdir);
> -	if (!dir)
> -		return;
> +	struct dir_iterator *diter = dir_iterator_begin(packdir);
>  
>  	/* Point at the slash at the end of ".../objects/pack/" */
>  	dirlen = strlen(packdir) + 1;
> @@ -62,14 +59,13 @@ static void remove_temporary_files(void)
>  	/* Hold the length of  ".tmp-%d-pack-" */
>  	prefixlen = buf.len - dirlen;
>  
> -	while ((e = readdir(dir))) {
> -		if (strncmp(e->d_name, buf.buf + dirlen, prefixlen))
> +	while (dir_iterator_advance(diter) == ITER_OK) {
> +		if (strncmp(diter->relative_path, buf.buf + dirlen, prefixlen))
>  			continue;
>  		strbuf_setlen(&buf, dirlen);
> -		strbuf_addstr(&buf, e->d_name);
> +		strbuf_addstr(&buf, diter->relative_path);
>  		unlink(buf.buf);
>  	}
> -	closedir(dir);

I think you could actually clean this code up more. The dir_iterator
already does this strbuf magic to hold the full path, so you should be
able to just run "unlink(iter->path.buf)", get rid of the extra strbuf
entirely.

We use that strbuf for the prefix-comparison, too, but the way it is
done is rather confusing. AFAICT, we could just be comparing against
"packtmp + strlen(packdir) + 1". Though it would be simpler still to
make "packtmp" just the basename, rather than the full path.

I do agree with the point Junio raised, though, that this loop isn't
recursive, but dir_iterator is. I think there was talk elsewhere of
giving it more options, so perhaps it could be taught a non-recursive
version. Until we have that, though, I'm not sure this is a good spot to
convert.

-Peff

Re: [PATCH] [GSOC] remove_temporary_files(): reimplement using iterators

[Jeff King]

On Sat, Apr 01, 2017 at 01:37:16AM -0400, Jeff King wrote:

> We use that strbuf for the prefix-comparison, too, but the way it is
> done is rather confusing. AFAICT, we could just be comparing against
> "packtmp + strlen(packdir) + 1". Though it would be simpler still to
> make "packtmp" just the basename, rather than the full path.

Something like the patch below, which would then free you up to replace
"buf" there with the diter->path.

diff --git a/builtin/repack.c b/builtin/repack.c
index 677bc7c81..06a14d687 100644
--- a/builtin/repack.c
+++ b/builtin/repack.c
@@ -48,7 +48,7 @@ static int repack_config(const char *var, const char *value, void *cb)
 static void remove_temporary_files(void)
 {
 	struct strbuf buf = STRBUF_INIT;
-	size_t dirlen, prefixlen;
+	size_t dirlen;
 	DIR *dir;
 	struct dirent *e;
 
@@ -56,14 +56,11 @@ static void remove_temporary_files(void)
 	if (!dir)
 		return;
 
-	/* Point at the slash at the end of ".../objects/pack/" */
-	dirlen = strlen(packdir) + 1;
-	strbuf_addstr(&buf, packtmp);
-	/* Hold the length of  ".tmp-%d-pack-" */
-	prefixlen = buf.len - dirlen;
+	strbuf_addf(&buf, "%s/", packdir);
+	dirlen = buf.len;
 
 	while ((e = readdir(dir))) {
-		if (strncmp(e->d_name, buf.buf + dirlen, prefixlen))
+		if (!starts_with(e->d_name, packtmp))
 			continue;
 		strbuf_setlen(&buf, dirlen);
 		strbuf_addstr(&buf, e->d_name);
@@ -216,7 +213,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 		die(_(incremental_bitmap_conflict_error));
 
 	packdir = mkpathdup("%s/pack", get_object_directory());
-	packtmp = mkpathdup("%s/.tmp-%d-pack", packdir, (int)getpid());
+	packtmp = mkpathdup(".tmp-%d-pack", (int)getpid());
 
 	sigchain_push_common(remove_pack_on_signal);
 
@@ -274,7 +271,7 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 	if (delta_base_offset)
 		argv_array_push(&cmd.args,  "--delta-base-offset");
 
-	argv_array_push(&cmd.args, packtmp);
+	argv_array_pushf(&cmd.args, "%s/%s", packdir, packtmp);
 
 	cmd.git_cmd = 1;
 	cmd.out = -1;
@@ -372,8 +369,8 @@ int cmd_repack(int argc, const char **argv, const char *prefix)
 			int exists = 0;
 			fname = mkpathdup("%s/pack-%s%s",
 					packdir, item->string, exts[ext].name);
-			fname_old = mkpathdup("%s-%s%s",
-					packtmp, item->string, exts[ext].name);
+			fname_old = mkpathdup("%s/%s-%s%s",
+					packdir, packtmp, item->string, exts[ext].name);
 			if (!stat(fname_old, &statbuffer)) {
 				statbuffer.st_mode &= ~(S_IWUSR | S_IWGRP | S_IWOTH);
 				chmod(fname_old, statbuffer.st_mode);