git/list[1] front-page[2] threads[3] people[4] search[5] about
 

[PATCH 9/9] Use timer_settime for new platforms

From
Jonas 'Sortie' Termansen <sortie@maxsi.org>
Date
Aug 28, 2014, 01:04 UTC
Message-ID
<1409187862-21257-10-git-send-email-sortie@maxsi.org>
In-Reply-To
<1409187862-21257-1-git-send-email-sortie@maxsi.org>

setitimer() is an obsolescent XSI interface and may be removed in a future standard. Applications should use the core POSIX timer_settime() instead.

This patch cleans up the progress reporting and changes it to try using timer_settime, or if that fails, setitimer. If either function is not provided by the system, then git-compat-util.h provides replacements that always fail with ENOSYS.

It's important that code doesn't simply check if timer_settime is available as it can give false positives. Some systems like contemporary OpenBSD provides the function, but it unconditionally fails with ENOSYS at runtime.

This approach allows the code using timer_settime() and setitimer() to be simple and readable. My first attempt used #ifdef around each use of timer_settime(), this quickly turned a into unmaintainable maze of preprocessor conditionals.

Signed-off-by: Jonas 'Sortie' Termansen <sortie@maxsi.org>
---
 builtin/log.c | 47 ++++++++++++++++++++++++++++++++++++++++-------
 progress.c    | 34 +++++++++++++++++++++++++++-------
 2 files changed, 67 insertions(+), 14 deletions(-)
diff --git a/builtin/log.c b/builtin/log.c
index 4389722..54c85a6 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -229,7 +229,8 @@ static void show_early_header(struct rev_info *rev, const char *stage, int nr)
 	printf(_("Final output: %d %s\n"), nr, stage);
 }
 
-static struct itimerval early_output_timer;
+static int is_using_timer_settime;
+static timer_t early_output_timer;
 
 static void log_show_early(struct rev_info *revs, struct commit_list *list)
 {
@@ -271,9 +272,21 @@ static void log_show_early(struct rev_info *revs, struct commit_list *list)
 	 * trigger every second even if we're blocked on a
 	 * reader!
 	 */
-	early_output_timer.it_value.tv_sec = 0;
-	early_output_timer.it_value.tv_usec = 500000;
-	setitimer(ITIMER_REAL, &early_output_timer, NULL);
+	if (is_using_timer_settime) {
+		struct itimerspec value;
+		value.it_value.tv_sec = 0;
+		value.it_value.tv_nsec = 500000L * 1000L;
+		value.it_interval.tv_sec = 0;
+		value.it_interval.tv_nsec = 0;
+		timer_settime(early_output_timer, 0, &value, NULL);
+	} else {
+		struct itimerval value;
+		value.it_value.tv_sec = 0;
+		value.it_value.tv_usec = 500000;
+		value.it_interval.tv_sec = 0;
+		value.it_interval.tv_usec = 0;
+		setitimer(ITIMER_REAL, &value, NULL);
+	}
 }
 
 static void early_output(int signal)
@@ -284,6 +297,7 @@ static void early_output(int signal)
 static void setup_early_output(struct rev_info *rev)
 {
 	struct sigaction sa;
+	struct sigevent sev;
 
 	/*
 	 * Set up the signal handler, minimally intrusively:
@@ -305,14 +319,33 @@ static void setup_early_output(struct rev_info *rev)
 	 *
 	 * This is a one-time-only trigger.
 	 */
-	early_output_timer.it_value.tv_sec = 0;
-	early_output_timer.it_value.tv_usec = 100000;
-	setitimer(ITIMER_REAL, &early_output_timer, NULL);
+	memset(&sev, 0, sizeof(sev));
+	sev.sigev_notify = SIGEV_SIGNAL;
+	sev.sigev_signo = SIGALRM;
+	if (!timer_create(CLOCK_MONOTONIC, &sev, &early_output_timer)) {
+		struct itimerspec value;
+		value.it_value.tv_sec = 0;
+		value.it_value.tv_nsec = 100000L * 1000L;
+		value.it_interval.tv_sec = 0;
+		value.it_interval.tv_nsec = 0;
+		timer_settime(early_output_timer, 0, &value, NULL);
+		is_using_timer_settime = 1;
+	} else {
+		struct itimerval value;
+		value.it_value.tv_sec = 0;
+		value.it_value.tv_usec = 100000;
+		value.it_interval.tv_sec = 0;
+		value.it_interval.tv_usec = 0;
+		setitimer(ITIMER_REAL, &value, NULL);
+		is_using_timer_settime = 0;
+	}
 }
 
 static void finish_early_output(struct rev_info *rev)
 {
 	int n = estimate_commit_count(rev, rev->commits);
+	if (is_using_timer_settime)
+		timer_delete(early_output_timer);
 	signal(SIGALRM, SIG_IGN);
 	show_early_header(rev, "done", n);
 }
diff --git a/progress.c b/progress.c
index 412e6b1..b396ee1 100644
--- a/progress.c
+++ b/progress.c
@@ -38,6 +38,8 @@ struct progress {
 	struct throughput *throughput;
 };
 
+static int is_using_timer_settime;
+static timer_t progress_timer;
 static volatile sig_atomic_t progress_update;
 
 static void progress_interval(int signum)
@@ -48,7 +50,7 @@ static void progress_interval(int signum)
 static void set_progress_signal(void)
 {
 	struct sigaction sa;
-	struct itimerval v;
+	struct sigevent sev;
 
 	progress_update = 0;
 
@@ -58,16 +60,34 @@ static void set_progress_signal(void)
 	sa.sa_flags = SA_RESTART;
 	sigaction(SIGALRM, &sa, NULL);
 
-	v.it_interval.tv_sec = 1;
-	v.it_interval.tv_usec = 0;
-	v.it_value = v.it_interval;
-	setitimer(ITIMER_REAL, &v, NULL);
+	memset(&sev, 0, sizeof(sev));
+	sev.sigev_notify = SIGEV_SIGNAL;
+	sev.sigev_signo = SIGALRM;
+	if (!timer_create(CLOCK_MONOTONIC, &sev, &progress_timer)) {
+		struct itimerspec value;
+		value.it_interval.tv_sec = 1;
+		value.it_interval.tv_nsec = 0;
+		value.it_value = value.it_interval;
+		timer_settime(progress_timer, 0, &value, NULL);
+		is_using_timer_settime = 1;
+	} else {
+		struct itimerval value;
+		value.it_interval.tv_sec = 1;
+		value.it_interval.tv_usec = 0;
+		value.it_value = value.it_interval;
+		setitimer(ITIMER_REAL, &value, NULL);
+		is_using_timer_settime = 0;
+	}
 }
 
 static void clear_progress_signal(void)
 {
-	struct itimerval v = {{0,},};
-	setitimer(ITIMER_REAL, &v, NULL);
+	if (is_using_timer_settime) {
+		timer_delete(progress_timer);
+	} else {
+		struct itimerval v = {{0,},};
+		setitimer(ITIMER_REAL, &v, NULL);
+	}
 	signal(SIGALRM, SIG_IGN);
 	progress_update = 0;
 }

-- 
2.1.0
Previous: Jonas 'Sortie' TermansenNext: Junio C Hamano
Message 14 of 16 in “Use timer_settime for new platforms”
  1. 0/9 Use timer_settime for new platformsJonas 'Sortie' Termansen, Aug 28, 2014
  2. 1/9 git-compat-util.h: Add missing semicolon after struct itimervalJonas 'Sortie' Termansen, Aug 28, 2014
  3. 2/9 autoconf: Check for timer_tJonas 'Sortie' Termansen, Aug 28, 2014
  4. Jonas 'Sortie' TermansenAug 28, 2014
  5. 3/9 autoconf: Check for struct timespecJonas 'Sortie' Termansen, Aug 28, 2014
  6. 4/9 autoconf: Check for struct sigeventJonas 'Sortie' Termansen, Aug 28, 2014
  7. 5/9 autoconf: Check for struct itimervalJonas 'Sortie' Termansen, Aug 28, 2014
  8. Junio C HamanoAug 28, 2014
  9. 6/9 autoconf: Check for struct itimerspecJonas 'Sortie' Termansen, Aug 28, 2014
  10. 7/9 autoconf: Check for setitimerJonas 'Sortie' Termansen, Aug 28, 2014
  11. 8/9 autoconf: Check for timer_settimeJonas 'Sortie' Termansen, Aug 28, 2014
  12. Keller, Jacob EAug 29, 2014
  13. Jonas 'Sortie' TermansenAug 29, 2014
  14. 9/9 Use timer_settime for new platformsJonas 'Sortie' Termansen, Aug 28, 2014
  15. Junio C HamanoAug 28, 2014
  16. Keller, Jacob EAug 29, 2014

Read the whole thread, see it on lore, or plain text.

$ cat FOOTERMessages come from the public archive at lore.kernel.org/git, fetched every hour. The front page is chosen and written each morning by an AI editor and can be wrong; the threads themselves are the record. About and API. For agents: an MCP server at https://gitlist.dev/mcp, and any thread, story or person page as Markdown by adding .md to its URL (or sending Accept: text/markdown). Details in /llms.txt.