userspace/snmpd: improve counting userspace deamons in wrsBootStatusGroup

There was a problem with counting multiple instaces of a program especially for dropbear where new instance is spawned for each ssh session. It is impossible to predict number of instances at compile time or even in run time. What we know is that at least one dropbear process should be running. New method is capable of reporting when there are too many or too few processes running (exp value is positive)or reporting when too few processes are running (exp value is negative). Use full path for snmpd binary. Signed-off-by: Adam Wujek <adam.wujek@cern.ch>

userspace/snmpd: improve counting userspace deamons in wrsBootStatusGroup
There was a problem with counting multiple instaces of a program especially for dropbear where new instance is spawned for each ssh session. It is impossible to predict number of instances at compile time or even in run time. What we know is that at least one dropbear process should be running. New method is capable of reporting when there are too many or too few processes running (exp value is positive)or reporting when too few processes are running (exp value is negative). Use full path for snmpd binary. Signed-off-by: Adam Wujek <adam.wujek@cern.ch>
96974d3d · Adam Wujek · 73242ab3 · 96974d3d
Commit 96974d3d authored May 04, 2015 by Adam Wujek 💬
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Showing with 57 additions and 26 deletions

wrsBootStatusGroup.c userspace/snmpd/wrsBootStatusGroup.c +57 -26

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--- a/userspace/snmpd/wrsBootStatusGroup.c
+++ b/userspace/snmpd/wrsBootStatusGroup.c
@@ -63,19 +63,27 @@ static struct wrs_km_item kernel_modules[] = {

 /* user space deamon list item */
 struct wrs_usd_item {
-	char *key;
+	char *key;	/* process name */
+	int32_t exp;	/* expected number of processes */
+	uint32_t cnt;	/* number of processes found */
 };

 /* user space deamon list */
-static struct wrs_km_item userspace_deamons[] = {
-	[0] = {.key = "/usr/sbin/dropbear"},
-	[1] = {"/wr/bin/wrsw_hal"}, /* two wrsw_hal instances */
-	[2] = {"/wr/bin/wrsw_hal"}, /* two wrsw_hal instances */
-	[3] = {"/wr/bin/wrsw_rtud"},
-	[4] = {"/wr/bin/ppsi"},
-	[5] = {"/usr/sbin/lighttpd"},
-	[6] = {"/usr/bin/monit"},
-	[7] = {"snmpd"},
+/* - key contain process name reported by ps command
+ * - positive exp describe exact number of expected processes
+ * - negative exp describe minimum number of expected processes. Usefull for
+ *   processes that is hard to predict number of their instances. For example
+ *   new dropbear process is spawned at ssh login.
+ */
+static struct wrs_usd_item userspace_deamons[] = {
+	[0] = {.key = "/usr/sbin/dropbear", .exp = -1}, /* expect at least one
+							 * dropbear process */
+	[1] = {"/wr/bin/wrsw_hal", 2}, /* two wrsw_hal instances */
+	[2] = {"/wr/bin/wrsw_rtud", 1},
+	[3] = {"/wr/bin/ppsi", 1},
+	[4] = {"/usr/sbin/lighttpd", 1},
+	[5] = {"/usr/bin/monit", 1},
+	[6] = {"/usr/sbin/snmpd", 1},
 };

 struct wrs_bc_item {
@@ -380,21 +388,34 @@ static void get_deamons_status(void)
 	char key[41]; /* 1 for null char */
 	int ret;
 	int i;
-	int processes_found;
-	int processes_missing;
+	int processes_wrong = 0; /* number of too many or too few processes */
+
+
+	/* clear user space deamon counters */
+	for (i = 0; i < ARRAY_SIZE(userspace_deamons); i++) {
+		userspace_deamons[i].cnt = 0;
+	}

-	/* use ps command to get process list, more portable, less error prone
+	/* Use ps command to get process list, more portable, less error prone
 	 * but probably slower than manually parsing /proc/ */
 	f = popen(PROCESS_COMMAND, "r");
 	if (!f) {
 		snmp_log(LOG_ERR, "SNMP: wrsBootStatusGroup failed to execute "
 			 PROCESS_COMMAND"\n");
-		/* notify snmp about error in processes list */
-		wrsBootStatus_s.wrsBootUserspaceDaemonsMissing =
-						ARRAY_SIZE(userspace_deamons);
+		wrsBootStatus_s.wrsBootUserspaceDaemonsMissing = 0;
+		/* Notify snmp about error in processes list */
+		/* Count number of expected processes */
+		for (i = 0; i < ARRAY_SIZE(userspace_deamons); i++) {
+			/* when exp < 0 then expect at least number of
+			 * -exp processes */
+			wrsBootStatus_s.wrsBootUserspaceDaemonsMissing +=
+						abs(userspace_deamons[i].exp);
+		}
+
 		return;
 	}

+	/* count processes */
 	while (ret != EOF) {
 		/* read first word from line (process name) ignore rest of
 		 * the line */
@@ -405,22 +426,32 @@ static void get_deamons_status(void)
 		for (i = 0; i < ARRAY_SIZE(userspace_deamons); i++) {
 			if (strncmp(key, userspace_deamons[i].key, 40))
 				continue;
-			processes_found++;
+			userspace_deamons[i].cnt++;
 			break;
 		}
 	}

-	processes_missing = ARRAY_SIZE(userspace_deamons) - processes_found;
+	for (i = 0; i < ARRAY_SIZE(userspace_deamons); i++) {
+		if (userspace_deamons[i].exp < 0) {
+			/* if exp < 0 then expect at least -exp processes,
+			 * useful in situation when we cannot predict exact
+			 * number of processes.
+			 * NOTE: exp in this case is negative number */
+			/* saturate cnt */
+			if (userspace_deamons[i].cnt > (-userspace_deamons[i].exp)) {
+				userspace_deamons[i].cnt =
+						(-userspace_deamons[i].exp);
+			}
+		}
+		/* Calculate delta between expected and counted number
+		 * of processes. Neither too much or too few are ok.
+		 * NOTE: abs "exp" too */
+		processes_wrong += abs(abs(userspace_deamons[i].exp)
+				       - userspace_deamons[i].cnt);
+	}

 	/* save number of processes missing */
-	if (processes_missing < 0) {
-		/* probably something wrong with multiple process' instances */
-		wrsBootStatus_s.wrsBootUserspaceDaemonsMissing =
-						ARRAY_SIZE(userspace_deamons);
-	} else {
-		wrsBootStatus_s.wrsBootUserspaceDaemonsMissing =
-							processes_missing;
-	}
+	wrsBootStatus_s.wrsBootUserspaceDaemonsMissing = processes_wrong;

 	pclose(f);
 }