threads / patch / 45107

patch, 2 partsls-files: pass prefix length explicitly to prune_cache()

Subject: [PATCH 1/2] ls-files: pass prefix length explicitly to prune_cache()

## tl;dr

3 messages between Feb 10, 2017 and Feb 10, 2017. Diffs are folded; open one to read it.

replies: 2people: 2as markdown or json

René Scharfe· Feb 10, 2017, 19:42 UTC · lore

The function prune_cache() relies on the fact that it is only called on max_prefix and sneakily uses the matching global variable max_prefix_len directly. Tighten its interface by passing both the string and its length as parameters. While at it move the NULL check into the function to collect all cache-pruning related logic in one place.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
---
Not urgent, of course.

 builtin/ls-files.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

Show changes to builtin/ls-files.c +7 −5

diff --git a/builtin/ls-files.c b/builtin/ls-files.c
index 1592290815..18105ec7ea 100644
--- a/builtin/ls-files.c
+++ b/builtin/ls-files.c
@@ -369,11 +369,14 @@ static void show_files(struct dir_struct *dir)
 /*
  * Prune the index to only contain stuff starting with "prefix"
  */
-static void prune_cache(const char *prefix)
+static void prune_cache(const char *prefix, size_t prefixlen)
 {
-	int pos = cache_name_pos(prefix, max_prefix_len);
+	int pos;
 	unsigned int first, last;
 
+	if (!prefix)
+		return;
+	pos = cache_name_pos(prefix, prefixlen);
 	if (pos < 0)
 		pos = -pos-1;
 	memmove(active_cache, active_cache + pos,
@@ -384,7 +387,7 @@ static void prune_cache(const char *prefix)
 	while (last > first) {
 		int next = (last + first) >> 1;
 		const struct cache_entry *ce = active_cache[next];
-		if (!strncmp(ce->name, prefix, max_prefix_len)) {
+		if (!strncmp(ce->name, prefix, prefixlen)) {
 			first = next+1;
 			continue;
 		}
@@ -641,8 +644,7 @@ int cmd_ls_files(int argc, const char **argv, const char *cmd_prefix)
 	      show_killed || show_modified || show_resolve_undo))
 		show_cached = 1;
 
-	if (max_prefix)
-		prune_cache(max_prefix);
+	prune_cache(max_prefix, max_prefix_len);
 	if (with_tree) {
 		/*
 		 * Basic sanity check; show-stages and show-unmerged

-- 
2.11.1

René Scharfe· Feb 10, 2017, 20:03 UTC · re: René Scharfe · lore

[PATCH 2/2] ls-files: move only kept cache entries in prune_cache()

prune_cache() first identifies those entries at the start of the sorted array that can be discarded. Then it moves the rest of the entries up. Last it identifies the unwanted trailing entries among the moved ones and cuts them off.

Change the order: Identify both start *and* end of the range to keep first and then move only those entries to the top. The resulting code is slightly shorter and a bit more efficient.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
---
The performance impact is probably only measurable with a *really* big
index.

 builtin/ls-files.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

Show changes to builtin/ls-files.c +4 −5

diff --git a/builtin/ls-files.c b/builtin/ls-files.c
index 18105ec7ea..1c0f057d02 100644
--- a/builtin/ls-files.c
+++ b/builtin/ls-files.c
@@ -379,10 +379,7 @@ static void prune_cache(const char *prefix, size_t prefixlen)
 	pos = cache_name_pos(prefix, prefixlen);
 	if (pos < 0)
 		pos = -pos-1;
-	memmove(active_cache, active_cache + pos,
-		(active_nr - pos) * sizeof(struct cache_entry *));
-	active_nr -= pos;
-	first = 0;
+	first = pos;
 	last = active_nr;
 	while (last > first) {
 		int next = (last + first) >> 1;
@@ -393,7 +390,9 @@ static void prune_cache(const char *prefix, size_t prefixlen)
 		}
 		last = next;
 	}
-	active_nr = last;
+	memmove(active_cache, active_cache + pos,
+		(last - pos) * sizeof(struct cache_entry *));
+	active_nr = last - pos;
 }
 
 /*

-- 
2.11.1

Brandon Williams· Feb 10, 2017, 22:51 UTC · re: René Scharfe · lore

Re: [PATCH 2/2] ls-files: move only kept cache entries in prune_cache()

On 02/10, René Scharfe wrote:

Show 13 quoted lines

> prune_cache() first identifies those entries at the start of the sorted
> array that can be discarded.  Then it moves the rest of the entries up.
> Last it identifies the unwanted trailing entries among the moved ones
> and cuts them off.
> 
> Change the order: Identify both start *and* end of the range to keep
> first and then move only those entries to the top.  The resulting code
> is slightly shorter and a bit more efficient.
> 
> Signed-off-by: Rene Scharfe <l.s.r@web.de>
> ---
> The performance impact is probably only measurable with a *really* big
> index.

Well there's been a lot of talk recently about *really* big indexes, so I'm sure someone out there will be happy :)

Show 34 quoted lines

> 
>  builtin/ls-files.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/builtin/ls-files.c b/builtin/ls-files.c
> index 18105ec7ea..1c0f057d02 100644
> --- a/builtin/ls-files.c
> +++ b/builtin/ls-files.c
> @@ -379,10 +379,7 @@ static void prune_cache(const char *prefix, size_t prefixlen)
>  	pos = cache_name_pos(prefix, prefixlen);
>  	if (pos < 0)
>  		pos = -pos-1;
> -	memmove(active_cache, active_cache + pos,
> -		(active_nr - pos) * sizeof(struct cache_entry *));
> -	active_nr -= pos;
> -	first = 0;
> +	first = pos;
>  	last = active_nr;
>  	while (last > first) {
>  		int next = (last + first) >> 1;
> @@ -393,7 +390,9 @@ static void prune_cache(const char *prefix, size_t prefixlen)
>  		}
>  		last = next;
>  	}
> -	active_nr = last;
> +	memmove(active_cache, active_cache + pos,
> +		(last - pos) * sizeof(struct cache_entry *));
> +	active_nr = last - pos;
>  }
>  
>  /*
> -- 
> 2.11.1
>

Both these patches look good to me.

-- 
Brandon Williams