alfred: Externalized synchronization interval

Message ID 1469738596-10972-1-git-send-email-jhaws@sdl.usu.edu
State Superseded, archived
Delegated to: Simon Wunderlich
Headers

Commit Message

Jonathan Haws July 28, 2016, 8:43 p.m. UTC
  ALFRED_INTERVAL is now externalized via the -p option (synchronization
period).  If specified as option, user supplied interval is used,
otherwise the default interval of ALFRED_INTERVAL is used.

Signed-off-by: Jonathan Haws <jhaws@sdl.usu.edu>

---
 alfred.h     |  1 +
 main.c       | 14 +++++++++++++-
 man/alfred.8 |  5 +++++
 server.c     |  4 ++--
 4 files changed, 21 insertions(+), 3 deletions(-)
  

Comments

Sven Eckelmann Aug. 6, 2016, 4:38 p.m. UTC | #1
On Donnerstag, 28. Juli 2016 14:43:16 CEST Jonathan Haws wrote:
[...]
> +			printf(" ** Setting sync interval to: %.9f seconds (%ld.%09ld)\n", sync_period, globals->sync_period.tv_sec, globals->sync_period.tv_nsec);
[...]
> -			printf("announce master ...\n");
> +			printf("[%ld.%09ld] announce master ...\n", last_check.tv_sec, last_check.tv_nsec);
[...]

Are these two things just relicts from your testing code?

Kind regards,
	Sven
  
Jonathan Haws Aug. 10, 2016, 7:59 p.m. UTC | #2
> > +			printf(" ** Setting sync interval to: %.9f seconds (%ld.%09ld)\n", sync_period, globals->sync_period.tv_sec, globals->sync_period.tv_nsec);

> [...]

> > -			printf("announce master ...\n");

> > +			printf("[%ld.%09ld] announce master ...\n", last_check.tv_sec, last_check.tv_nsec);

> [...]

> 

> Are these two things just relicts from your testing code?


Yes and no.  I left them in because I figured they were useful additions
to the main code.
  
Simon Wunderlich Aug. 12, 2016, 8:18 a.m. UTC | #3
On Thursday, July 28, 2016 2:43:16 PM CEST Jonathan Haws wrote:
> Signed-off-by: Jonathan Haws <jhaws@sdl.usu.edu>
> 
> ALFRED_INTERVAL is now externalized via the -p option (synchronization
> period).  If specified as option, user supplied interval is used,
> otherwise the default interval of ALFRED_INTERVAL is used.
[...]
> --- a/server.c
> +++ b/server.c
> @@ -372,7 +372,7 @@ int alfred_server(struct globals *globals)
> 
>  	while (1) {
>  		clock_gettime(CLOCK_MONOTONIC, &now);
> -		now.tv_sec -= ALFRED_INTERVAL;
> +		time_diff(&now, &globals->sync_period, &now);

I believe this at least deserves a comment, or must be made more clear in the 
code.
  
Simon Wunderlich Aug. 12, 2016, 8:20 a.m. UTC | #4
On Wednesday, August 10, 2016 7:59:12 PM CEST Jonathan Haws wrote:
> > > +			printf(" ** Setting sync interval to: %.9f seconds (%ld.
%09ld)\n",
> > > sync_period, globals->sync_period.tv_sec,
> > > globals->sync_period.tv_nsec);
> 
> > [...]
> > 
> > > -			printf("announce master ...\n");
> > > +			printf("[%ld.%09ld] announce master ...\n", 
last_check.tv_sec,
> > > last_check.tv_nsec);
> 
> > [...]
> > 
> > Are these two things just relicts from your testing code?
> 
> 
> Yes and no.  I left them in because I figured they were useful additions
> to the main code.

Hmm, I'm not sure if I like the format, but I guess we can keep it for now. :)

Cheers,
       Simon
  
Jonathan Haws Aug. 15, 2016, 2:59 p.m. UTC | #5
> > ALFRED_INTERVAL is now externalized via the -p option (synchronization

> > period).  If specified as option, user supplied interval is used,

> > otherwise the default interval of ALFRED_INTERVAL is used.

> [...]

> > --- a/server.c

> > +++ b/server.c

> > @@ -372,7 +372,7 @@ int alfred_server(struct globals *globals)

> > 

> >  	while (1) {

> >  		clock_gettime(CLOCK_MONOTONIC, &now);

> > -		now.tv_sec -= ALFRED_INTERVAL;

> > +		time_diff(&now, &globals->sync_period, &now);

> 

> I believe this at least deserves a comment, or must be made more clear in the 

> code.


This change simply does exactly what the previous code did - subtracts
the interval from the current time.  It utilizes the existing
time_diff() routine to account for nanoseconds.

If you need me to resubmit with that language in the commit text or in a
C comment, I can do that.

Thanks!
  
Simon Wunderlich Aug. 15, 2016, 3:09 p.m. UTC | #6
On Monday, August 15, 2016 2:59:05 PM CEST Jonathan Haws wrote:
> > > ALFRED_INTERVAL is now externalized via the -p option (synchronization
> > > period).  If specified as option, user supplied interval is used,
> > > otherwise the default interval of ALFRED_INTERVAL is used.
> > 
> > [...]
> > 
> > > --- a/server.c
> > > +++ b/server.c
> > > @@ -372,7 +372,7 @@ int alfred_server(struct globals *globals)
> > > 
> > > 
> > >  	while (1) {
> > >  	
> > >  		clock_gettime(CLOCK_MONOTONIC, &now);
> > > 
> > > -		now.tv_sec -= ALFRED_INTERVAL;
> > > +		time_diff(&now, &globals->sync_period, &now);
> > 
> > 
> > I believe this at least deserves a comment, or must be made more clear in
> > the 
 code.
> 
> 
> This change simply does exactly what the previous code did - subtracts
> the interval from the current time.  It utilizes the existing
> time_diff() routine to account for nanoseconds.
> 
> If you need me to resubmit with that language in the commit text or in a
> C comment, I can do that.
> 
> Thanks!

I was staring at your code and time_diff() which was implemented for an 
entirely different purpose, and concluded that you could be doing the right 
thing ... ;)

But yes, please re-submit with a comment explaining that, or restructure 
otherwise to make it more clear. time_diff() was written to get a difference 
of two timestamps, not to subtracts times from each other, and that confused 
me.

Thanks,
     Simon
  

Patch

diff --git a/alfred.h b/alfred.h
index a9906c8..5b7e965 100644
--- a/alfred.h
+++ b/alfred.h
@@ -131,6 +131,7 @@  struct globals {
 	uint16_t changed_data_type_count; /* maximum is 256 */
 
 	struct timespec if_check;
+	struct timespec sync_period;
 
 	struct hashtable_t *data_hash;
 	struct hashtable_t *transaction_hash;
diff --git a/main.c b/main.c
index 9cab705..3aa89fd 100644
--- a/main.c
+++ b/main.c
@@ -59,6 +59,8 @@  static void alfred_usage(void)
 	printf("  -m, --master                        start up the daemon in master mode, which\n");
 	printf("                                      accepts data from slaves and syncs it with\n");
 	printf("                                      other masters\n");
+	printf("  -p, --sync-period [period]          set synchronization period, in seconds\n");
+	printf("                                      fractional seconds are supported (i.e. 0.2 = 5 Hz)\n");
 	printf("\n");
 	printf("  -u, --unix-path [path]              path to unix socket used for client-server\n");
 	printf("                                      communication (default: \""ALFRED_SOCK_PATH_DEFAULT"\")\n");
@@ -156,6 +158,7 @@  out:
 static struct globals *alfred_init(int argc, char *argv[])
 {
 	int opt, opt_ind, i, ret;
+	double sync_period = 0.0;
 	struct globals *globals;
 	struct option long_options[] = {
 		{"set-data",		required_argument,	NULL,	's'},
@@ -170,6 +173,7 @@  static struct globals *alfred_init(int argc, char *argv[])
 		{"update-command",	required_argument,	NULL,	'c'},
 		{"version",		no_argument,		NULL,	'v'},
 		{"verbose",		no_argument,		NULL,	'd'},
+		{"sync-period",		required_argument,	NULL,	'p'},
 		{NULL,			0,			NULL,	0},
 	};
 
@@ -193,12 +197,14 @@  static struct globals *alfred_init(int argc, char *argv[])
 	globals->unix_path = ALFRED_SOCK_PATH_DEFAULT;
 	globals->verbose = 0;
 	globals->update_command = NULL;
+	globals->sync_period.tv_sec = ALFRED_INTERVAL;
+	globals->sync_period.tv_nsec = 0;
 	INIT_LIST_HEAD(&globals->changed_data_types);
 	globals->changed_data_type_count = 0;
 
 	time_random_seed();
 
-	while ((opt = getopt_long(argc, argv, "ms:r:hi:b:vV:M:I:u:dc:", long_options,
+	while ((opt = getopt_long(argc, argv, "ms:r:hi:b:vV:M:I:u:dc:p:", long_options,
 				  &opt_ind)) != -1) {
 		switch (opt) {
 		case 'r':
@@ -265,6 +271,12 @@  static struct globals *alfred_init(int argc, char *argv[])
 			printf("%s %s\n", argv[0], SOURCE_VERSION);
 			printf("A.L.F.R.E.D. - Almighty Lightweight Remote Fact Exchange Daemon\n");
 			return NULL;
+		case 'p':
+			sync_period = strtod(optarg, NULL);
+			globals->sync_period.tv_sec = (int) sync_period;
+			globals->sync_period.tv_nsec = (double)(sync_period - (int)sync_period) * 1e9;
+			printf(" ** Setting sync interval to: %.9f seconds (%ld.%09ld)\n", sync_period, globals->sync_period.tv_sec, globals->sync_period.tv_nsec);
+			break;
 		case 'h':
 		default:
 			alfred_usage();
diff --git a/man/alfred.8 b/man/alfred.8
index 49d42bc..df37040 100644
--- a/man/alfred.8
+++ b/man/alfred.8
@@ -118,6 +118,11 @@  overhead).
 \fB\-c\fP, \fB\-\-update-command\fP \fIcommand\fP
 Specify command to execute on data change. It will be called with data-type list
 as arguments.
+.TP
+\fB\-p\fP, \fB\-\-sync-period\fP \fIperiod\fP
+Specify alfred synchronization period, in seconds. If not specified, the default
+ALFRED_INTERVAL setting of 10 seconds will be used. Fractional seconds are 
+supported.
 .
 .SH EXAMPLES
 Start an alfred server listening on bridge br0 (assuming that this bridge
diff --git a/server.c b/server.c
index 47aee4f..c5df945 100644
--- a/server.c
+++ b/server.c
@@ -372,7 +372,7 @@  int alfred_server(struct globals *globals)
 
 	while (1) {
 		clock_gettime(CLOCK_MONOTONIC, &now);
-		now.tv_sec -= ALFRED_INTERVAL;
+		time_diff(&now, &globals->sync_period, &now);
 		if (!time_diff(&last_check, &now, &tv)) {
 			tv.tv_sec = 0;
 			tv.tv_nsec = 0;
@@ -409,7 +409,7 @@  int alfred_server(struct globals *globals)
 
 		if (globals->opmode == OPMODE_MASTER) {
 			/* we are a master */
-			printf("announce master ...\n");
+			printf("[%ld.%09ld] announce master ...\n", last_check.tv_sec, last_check.tv_nsec);
 			announce_master(globals);
 			sync_data(globals);
 		} else {