threads / patch / 51945

v5commit-graph: remove a duplicate assignment

Subject: [PATCH v5] commit-graph: remove a duplicate assignment

## tl;dr

5 messages between Oct 1, 2019 and Oct 2, 2019. Diffs are folded; open one to read it.

replies: 4people: 3as markdown or json

Alex Henrie· Oct 1, 2019, 02:29 UTC · lore

Leave the variable 'g' uninitialized before it is set just before its first use in front of a loop, which is a much more appropriate place to indicate what it is used for.

Also initialize the variable 'num_commits' just before the loop instead of at the beginning of the function for the same reason.

Reviewed-by: Derrick Stolee <stolee@gmail.com>
Signed-off-by: Alex Henrie <alexhenrie24@gmail.com>
---
 commit-graph.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
Show changes to commit-graph.c +3 −2
diff --git a/commit-graph.c b/commit-graph.c
index 9b02d2c426..4028508e9c 100644
--- a/commit-graph.c
+++ b/commit-graph.c
@@ -1522,8 +1522,8 @@ static int write_commit_graph_file(struct write_commit_graph_context *ctx)
 
 static void split_graph_merge_strategy(struct write_commit_graph_context *ctx)
 {
-	struct commit_graph *g = ctx->r->objects->commit_graph;
-	uint32_t num_commits = ctx->commits.nr;
+	struct commit_graph *g;
+	uint32_t num_commits;
 	uint32_t i;
 
 	int max_commits = 0;
@@ -1535,6 +1535,7 @@ static void split_graph_merge_strategy(struct write_commit_graph_context *ctx)
 	}
 
 	g = ctx->r->objects->commit_graph;
+	num_commits = ctx->commits.nr;
 	ctx->num_commit_graphs_after = ctx->num_commit_graphs_before + 1;
 
 	while (g && (g->num_commits <= size_mult * num_commits ||

-- 
2.23.0
Alex Henrie· Oct 1, 2019, 02:29 UTC · re: Alex Henrie · lore

[PATCH v5] diffcore-break: use a goto instead of a redundant if statement

The condition "if (q->nr <= j)" checks whether the loop exited normally or via a break statement. Avoid this check by replacing the jump out of the inner loop with a jump to the end of the outer loop, which makes it obvious that diff_q is not executed when the peer survives.

Signed-off-by: Alex Henrie <alexhenrie24@gmail.com>
---
 diffcore-break.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)
Show changes to diffcore-break.c +6 −6
diff --git a/diffcore-break.c b/diffcore-break.c
index 875aefd3fe..9d20a6a6fc 100644
--- a/diffcore-break.c
+++ b/diffcore-break.c
@@ -286,17 +286,17 @@ void diffcore_merge_broken(void)
 					/* Peer survived.  Merge them */
 					merge_broken(p, pp, &outq);
 					q->queue[j] = NULL;
-					break;
+					goto next;
 				}
 			}
-			if (q->nr <= j)
-				/* The peer did not survive, so we keep
-				 * it in the output.
-				 */
-				diff_q(&outq, p);
+			/* The peer did not survive, so we keep
+			 * it in the output.
+			 */
+			diff_q(&outq, p);
 		}
 		else
 			diff_q(&outq, p);
+next:;
 	}
 	free(q->queue);
 	*q = outq;

-- 
2.23.0
Alex Henrie· Oct 1, 2019, 02:29 UTC · re: Alex Henrie · lore

[PATCH v5] wrapper: use a loop instead of repetitive statements

A check into the history of this code revealed no particular reason for the code to be written in this way. All popular compilers are capable of unrolling loops if it benefits performance, and once this code is replaced with a loop, the magic number 6 used in multiple places in this function can be replaced with a named constant.

Reviewed-by: Derrick Stolee <stolee@gmail.com>
Reviewed-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Alex Henrie <alexhenrie24@gmail.com>
---
 wrapper.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)
Show changes to wrapper.c +5 −6
diff --git a/wrapper.c b/wrapper.c
index c55d7722d7..c23ac6adcd 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -469,13 +469,12 @@ int git_mkstemps_mode(char *pattern, int suffix_len, int mode)
 	filename_template = &pattern[len - 6 - suffix_len];
 	for (count = 0; count < TMP_MAX; ++count) {
 		uint64_t v = value;
+		int i;
 		/* Fill in the random bits. */
-		filename_template[0] = letters[v % num_letters]; v /= num_letters;
-		filename_template[1] = letters[v % num_letters]; v /= num_letters;
-		filename_template[2] = letters[v % num_letters]; v /= num_letters;
-		filename_template[3] = letters[v % num_letters]; v /= num_letters;
-		filename_template[4] = letters[v % num_letters]; v /= num_letters;
-		filename_template[5] = letters[v % num_letters]; v /= num_letters;
+		for (i = 0; i < 6; i++) {
+			filename_template[i] = letters[v % num_letters];
+			v /= num_letters;
+		}
 
 		fd = open(pattern, O_CREAT | O_EXCL | O_RDWR, mode);
 		if (fd >= 0)

-- 
2.23.0
Junio C Hamano· Oct 2, 2019, 06:06 UTC · re: Alex Henrie · lore

Re: [PATCH v5] wrapper: use a loop instead of repetitive statements

All three patches looked sensible.

Even though there is no dependency or relationships among them (beyond that they got written at the same time by the same person), I'll just queue them on a single ah/cleanups topic and get them advance together, as I do not expect any one of them to be blocking the other two.

THanks.
Jeff King· Oct 2, 2019, 15:32 UTC · re: Junio C Hamano · lore

Re: [PATCH v5] wrapper: use a loop instead of repetitive statements

On Wed, Oct 02, 2019 at 03:06:10PM +0900, Junio C Hamano wrote:
Show 7 quoted lines
> All three patches looked sensible.
> 
> Even though there is no dependency or relationships among them
> (beyond that they got written at the same time by the same person),
> I'll just queue them on a single ah/cleanups topic and get them
> advance together, as I do not expect any one of them to be blocking
> the other two.

Just re-posting this follow-on from the earlier thread (it goes on top of the third one):

-- >8 --
Subject: git_mkstemps_mode(): replace magic numbers with computed value

The magic number "6" appears several times in the function, and is related to the size of the "XXXXXX" string we expect to find in the template. Let's pull that "XXXXXX" into a constant array, whose size we can get at compile time with ARRAY_SIZE().

Note that we probably can't just change this value, since callers will be feeding us a certain number of X's, but it hopefully makes the function itself easier to follow.

While we're here, let's do the same with the "letters" array (which we _could_ modify if we wanted to include more characters).

Signed-off-by: Jeff King <peff@peff.net>
---
 wrapper.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)
Show changes to wrapper.c +7 −5
diff --git a/wrapper.c b/wrapper.c
index 54541386c1..75992cff02 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -478,7 +478,9 @@ int git_mkstemps_mode(char *pattern, int suffix_len, int mode)
 		"abcdefghijklmnopqrstuvwxyz"
 		"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
 		"0123456789";
-	static const int num_letters = 62;
+	static const int num_letters = ARRAY_SIZE(letters) - 1;
+	static const char x_pattern[] = "XXXXXX";
+	static const int num_x = ARRAY_SIZE(x_pattern) - 1;
 	uint64_t value;
 	struct timeval tv;
 	char *filename_template;
@@ -487,12 +489,12 @@ int git_mkstemps_mode(char *pattern, int suffix_len, int mode)
 
 	len = strlen(pattern);
 
-	if (len < 6 + suffix_len) {
+	if (len < num_x + suffix_len) {
 		errno = EINVAL;
 		return -1;
 	}
 
-	if (strncmp(&pattern[len - 6 - suffix_len], "XXXXXX", 6)) {
+	if (strncmp(&pattern[len - num_x - suffix_len], x_pattern, num_x)) {
 		errno = EINVAL;
 		return -1;
 	}
@@ -503,12 +505,12 @@ int git_mkstemps_mode(char *pattern, int suffix_len, int mode)
 	 */
 	gettimeofday(&tv, NULL);
 	value = ((uint64_t)tv.tv_usec << 16) ^ tv.tv_sec ^ getpid();
-	filename_template = &pattern[len - 6 - suffix_len];
+	filename_template = &pattern[len - num_x - suffix_len];
 	for (count = 0; count < TMP_MAX; ++count) {
 		uint64_t v = value;
 		int i;
 		/* Fill in the random bits. */
-		for (i = 0; i < 6; i++) {
+		for (i = 0; i < num_x; i++) {
 			filename_template[i] = letters[v % num_letters];
 			v /= num_letters;
 		}

-- 
2.23.0.926.g3dc922fbbc

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