[collectd] sensors plugin: Simplify the reload machanism.

[Florian Forster]

From: Florian Forster <octo<span style="display: none;">.trailing-username</span>(a)<span style="display: none;">leading-domain.</span>huhu.verplant.org>

Instead of calling `stat' in the `read' function and then, eventually, calling
the reload stuff, just call the reload function every time and have it return
without doing anything if the config didn't change. This way the reload logic
is not in the read function.
---
 src/sensors.c |  112 ++++++++++++++++++++++----------------------------------
 1 files changed, 44 insertions(+), 68 deletions(-)

diff --git a/src/sensors.c b/src/sensors.c
index 7c05b7a..d15569c 100644
--- a/src/sensors.c
+++ b/src/sensors.c
@@ -179,17 +179,17 @@ static ignorelist_t *sensor_list;
 static int sensor_extended_naming = 0;
 
 #if SENSORS_HAVE_READ
-#ifndef SENSORS_CONF_PATH
-# define SENSORS_CONF_PATH "/etc/sensors.conf"
-#endif
+#  ifndef SENSORS_CONF_PATH
+#    define SENSORS_CONF_PATH "/etc/sensors.conf"
+#  endif
+
 static const char *conffile = SENSORS_CONF_PATH;
 /* SENSORS_CONF_PATH */
 
 /*
  * remember stat of the loaded config
  */
-static struct stat sensors_conf_stat;
-static int sensors_conf_loaded = 0;
+static time_t sensors_config_mtime = 0;
 
 typedef struct featurelist
 {
@@ -246,11 +246,10 @@ void sensors_free_features (void)
 	featurelist_t *thisft;
 	featurelist_t *nextft;
 
-	if (sensors_conf_loaded)
-	{
-		sensors_cleanup ();
-		sensors_conf_loaded = 0;
-	}
+	if (first_feature == NULL)
+		return;
+
+	sensors_cleanup ();
 
 	for (thisft = first_feature; thisft != NULL; thisft = nextft)
 	{
@@ -260,51 +259,59 @@ void sensors_free_features (void)
 	first_feature = NULL;
 }
 
-static void sensors_load_conf (int firsttime)
+static void sensors_load_conf (void)
 {
 	FILE *fh;
 	featurelist_t *last_feature = NULL;
-	featurelist_t *new_feature;
+	featurelist_t *new_feature = NULL;
 	
 	const sensors_chip_name *chip;
 	int chip_num;
 
 	const sensors_feature_data *data;
 	int data_num0, data_num1;
+
+	struct stat statbuf;
+	int status;
 	
-	sensors_free_features ();
-	new_feature = first_feature;
+	status = stat (conffile, &statbuf);
+	if (status != 0)
+	{
+		syslog (LOG_ERR, MODULE_NAME": stat(%s) failed: %s",
+				conffile, strerror (errno));
+		sensors_config_mtime = 0;
+	}
 
-#ifdef assert
-	assert (new_feature == NULL);
-	assert (last_feature == NULL);
-#endif
+	if ((sensors_config_mtime != 0)
+			&& (sensors_config_mtime == statbuf.st_mtime))
+		return;
 
-	if ((fh = fopen (conffile, "r")) == NULL)
+	if (sensors_config_mtime != 0)
 	{
-		syslog (LOG_ERR, MODULE_NAME": cannot open %s: %s. "
-				"Data will not be collected.", conffile, strerror(errno));
-		return;
+		syslog (LOG_NOTICE, MODULE_NAME": Reloading config from %s",
+				conffile);
+		sensors_free_features ();
+		sensors_config_mtime = 0;
 	}
 
-	if (sensors_init (fh))
+	fh = fopen (conffile, "r");
+	if (fh == NULL)
 	{
-		fclose (fh);
-		syslog (LOG_ERR, MODULE_NAME": Cannot initialize sensors. "
-				"Data will not be collected.");
+		syslog (LOG_ERR, MODULE_NAME": fopen(%s) failed: %s",
+				conffile, strerror(errno));
 		return;
 	}
 
-	/* remember file status to detect changes */
-	if (fstat (fileno (fh), &sensors_conf_stat) == -1)
+	status = sensors_init (fh);
+	fclose (fh);
+	if (status != 0)
 	{
-		fclose (fh);
-		syslog (LOG_ERR, MODULE_NAME": cannot fstat %s: %s "
-				"Data will not be collected.", conffile, strerror(errno));
+		syslog (LOG_ERR, MODULE_NAME": Cannot initialize sensors. "
+				"Data will not be collected.");
 		return;
 	}
 
-	fclose (fh);
+	sensors_config_mtime = statbuf.st_mtime;
 
 	chip_num = 0;
 	while ((chip = sensors_get_detected_chips (&chip_num)) != NULL)
@@ -366,26 +373,18 @@ #endif
 		} /* while sensors_get_all_features */
 	} /* while sensors_get_detected_chips */
 
-	if (!firsttime)
-		syslog (LOG_INFO, MODULE_NAME": lm_sensors' configuration reloaded.");
-
 	if (first_feature == NULL)
 	{
 		sensors_cleanup ();
-		sensors_conf_loaded = 0;
 		syslog (LOG_INFO, MODULE_NAME": lm_sensors reports no features. "
 			"Data will not be collected.");
 	}
-	else
-		sensors_conf_loaded = 1;
-}
+} /* void sensors_load_conf */
 #endif /* if SENSORS_HAVE_READ */
 
 static void collectd_sensors_init (void)
 {
-#if SENSORS_HAVE_READ
-	sensors_load_conf (1);
-#endif /* if SENSORS_HAVE_READ */
+	return;
 }
 
 static void sensors_shutdown (void)
@@ -477,31 +476,8 @@ static void sensors_read (void)
 	featurelist_t *feature;
 	double value;
 	char chip_fullprefix[BUFSIZE];
-	struct stat changedbuf;
 
-	/* check sensors.conf for changes */
-	if (sensors_conf_loaded)
-	{
-		if (stat (conffile, &changedbuf) == -1)
-		{
-			syslog (LOG_ERR, MODULE_NAME": cannot stat %s: %s",
-					conffile, strerror(errno));
-			/*
-			 * sensors.conf does not exist,
-			 * throw away previous conf
-			 */
-			sensors_load_conf (0);
-		}
-		else
-		{
-			if ((changedbuf.st_size != sensors_conf_stat.st_size) ||
-					(changedbuf.st_mtime != sensors_conf_stat.st_mtime) ||
-					(changedbuf.st_ino != sensors_conf_stat.st_ino))
-			{
-				sensors_load_conf (0);
-			}
-		}
-	}
+	sensors_load_conf ();
 
 	for (feature = first_feature; feature != NULL; feature = feature->next)
 	{
@@ -551,8 +527,8 @@ static void sensors_read (void)
 					feature->chip->prefix,
 					value, feature->type);
 		}
-	}
-}
+	} /* for feature = first_feature .. NULL */
+} /* void sensors_read */
 #else
 # define sensors_read NULL
 #endif /* SENSORS_HAVE_READ */
-- 
1.4.3.2