vmstat_aix4.c

snmp的源代码,已经在我的ubuntu下编译通过

 * ARGSUSED0 
 */
static void
update_stats(unsigned int registrationNumber, void *clientarg)
{
	/*
	 * The time between the samples we compare 
	 */
	unsigned long long time_diff;

	/*
	 * Easier to use these than the snapshots, short hand pointers 
	 */
	struct cpu_stat_snapshot *css_old, *css_new;

	/*
	 * The usual stuff to count on, err, by 
	 */
	int			 i;

	/*
	 * The sum of the CPU ticks that have passed on the different CPU states, so we can calculate 
	 * the percentages of each state 
	 */
	unsigned long long cpu_sum = 0;

	DEBUGMSGTL(("ucd-snmp/vmstat_aix4.c:update_stats",
				"updating stats\n"));

	/*
	 * Take the current snapshot 
	 */
	if (take_snapshot(&snapshot[0]) == -1) {
		snmp_log(LOG_WARNING,
				 "vmstat_aix4 (update_stats): Something went wrong with take_snapshot.\n");
		return;
	}

	/*
	 * Do we have some data we can use ?  An issue right after the start of the agent 
	 */
	if (number_of_snapshots > 0) {
		/*
		 * Huh, the number of CPUs changed during run time.  That is indeed s.th. worth noting, we 
		 * output a humorous (more or less) syslog message and need to retake the snapshots 
		 */
		if (snapshot[0].css_cpus != snapshot[1].css_cpus) {
			if (snapshot[0].css_cpus > snapshot[1].css_cpus) {
				snmp_log(LOG_NOTICE,
						 "vmstat_aix4 (update_stats): Cool ! Number of CPUs increased, must be hot-pluggable.\n");
			} else {
				snmp_log(LOG_NOTICE,
						 "vmstat_aix4 (update_stats): Lost at least one CPU, RIP.\n");
			}
			/*
			 * Make all snapshots but the current one invalid 
			 */
			number_of_snapshots = 1;
			/*
			 * Move the current one in the "first" [1] slot 
			 */
			memmove(&snapshot[1], &snapshot[0], sizeof snapshot[0]);
			/*
			 * Erase the current one 
			 */
			memset(&snapshot[0], 0, sizeof snapshot[0]);
			/*
			 * Try to get a new snapshot in five seconds so we can return s.th. useful 
			 */
			if (snmp_alarm_register(5, NULL, update_stats, NULL) == 0) {
				snmp_log(LOG_WARNING,
						 "vmstat_aix4 (update_stats): snmp_alarm_register failed.\n");
			}
			return;
		}

		/*
		 * Short hand pointers 
		 */
		css_new = &snapshot[0];
		css_old = &snapshot[number_of_snapshots];

		/*
		 * How much time has passed between the snapshots we get the values from ? 
		 */
		time_diff =
			(snapshot[0].css_time -
			 snapshot[number_of_snapshots].css_time) / 1000;

		DEBUGMSGTL(("ucd-snmp/vmstat_aix4.c:update_stats",
					"time_diff: %lld\n", time_diff));

		/*
		 * swapin and swapout are in pages, MIB wants kB/s,so we just need to get kB and seconds 
		 * For the others we need to get value per second 
		 * getpagesize() returns pagesize in bytes 
		 */
		/*
		 * LINTED cast needed, really 
		 */
		swapin =
			(uint_t) ((css_new->css_swapin - css_old->css_swapin) *
					  getpagesize() / 1024 / time_diff);
		/*
		 * LINTED cast needed, really 
		 */
		swapout =
			(uint_t) ((css_new->css_swapout - css_old->css_swapout) *
					  getpagesize() / 1024 / time_diff);
		/*
		 * LINTED cast needed, really 
		 */
		blocks_read =
			(uint_t) ((css_new->css_blocks_read - css_old->css_blocks_read) /
					  time_diff);
		/*
		 * LINTED cast needed, really 
		 */
		blocks_write =
			(uint_t) ((css_new->css_blocks_write - css_old->css_blocks_write) /
					  time_diff);
		/*
		 * LINTED cast needed, really 
		 */
		interrupts =
			(uint_t) ((css_new->css_interrupts - css_old->css_interrupts) /
					  time_diff);
		/*
		 * LINTED cast needed, really 
		 */
		context_sw =
			(uint_t) ((css_new->css_context_sw - css_old->css_context_sw) /
					  time_diff);

		/*
		 * Loop thru all the CPU_STATES and get the differences 
		 */
		for (i = 0; i < CPU_STATES; i++) {
			cpu_sum += (css_new->css_cpu[i] - css_old->css_cpu[i]);
		}

		/*
		 * Now calculate the absolute percentage values 
		 * Looks somewhat complicated sometimes but tries to get around using floats to increase speed 
		 */
		for (i = 0; i < CPU_STATES; i++) {
			/*
			 * Since we don't return fractions we use + 0.5 to get between 99 and 101 percent adding the values 
			 * together, otherwise we would get less than 100 most of the time 
			 */
			/*
			 * LINTED has to be 'long' 
			 */
			cpu_perc[i] =
				(long) (((css_new->css_cpu[i] - css_old->css_cpu[i]) * 100 +
						 (cpu_sum / 2)) / cpu_sum);
		}
		/* "system" is "kernel", we have to add "wait" to get the correct value */
		cpu_perc[CPU_SYSTEM] += cpu_perc[CPU_WAIT];
	}

	/*
	 * Make the current one the first one and move the whole thing one place down 
	 */
	memmove(&snapshot[1], &snapshot[0],
			(size_t) (((char *) &snapshot[POLL_VALUES]) -
					  ((char *) &snapshot[0])));

	/*
	 * Erase the current one 
	 */
	memset(&snapshot[0], 0, sizeof snapshot[0]);

	/*
	 * Only important on start up, we keep track of how many snapshots we have taken so far 
	 */
	if (number_of_snapshots < POLL_VALUES) {
		number_of_snapshots++;
	}
}							   /* update_stats ends here */

/*
 * *var_extensible_vmstat starts here 
 * The guts of the module, this routine gets called to service a request 
 */
unsigned char *
var_extensible_vmstat(struct variable *vp,
					  oid * name,
					  size_t * length,
					  int exact,
					  size_t * var_len, WriteMethod ** write_method)
{
	/*
	 * Needed for returning the values 
	 */
	static long	 long_ret;
	static char	 errmsg[300];

	/*
	 * set to 0 as default 
	 */
	long_ret = 0;

	/*
	 * generic check whether the options passed make sense and whether the 
	 */
	/*
	 * right variable is requested 
	 */
	if (header_generic(vp, name, length, exact, var_len, write_method) !=
		MATCH_SUCCEEDED) {
		return (NULL);
	}

	/*
	 * The function that actually returns s.th. 
	 */
	switch (vp->magic) {
	case MIBINDEX:
		long_ret = 1;
		return ((u_char *) (&long_ret));
	case ERRORNAME:			/* dummy name */
		sprintf(errmsg, "systemStats");
		*var_len = strlen(errmsg);
		return ((u_char *) (errmsg));
	case SWAPIN:
		return ((u_char *) (&swapin));
	case SWAPOUT:
		return ((u_char *) (&swapout));
	case IOSENT:
		return ((u_char *) (&blocks_write));
	case IORECEIVE:
		return ((u_char *) (&blocks_read));
	case SYSINTERRUPTS:
		return ((u_char *) (&interrupts));
	case SYSCONTEXT:
		return ((u_char *) (&context_sw));
	case CPUUSER:
		return ((u_char *) (&cpu_perc[CPU_USER]));
	case CPUSYSTEM:
		return ((u_char *) (&cpu_perc[CPU_SYSTEM]));
	case CPUIDLE:
		return ((u_char *) (&cpu_perc[CPU_IDLE]));
	case CPURAWUSER:
		take_snapshot(&raw_values);
		/*
		 * LINTED has to be 'long' 
		 */
		long_ret =
			(long) (raw_values.css_cpu[CPU_USER] / raw_values.css_cpus);
		return ((u_char *) (&long_ret));
		/*
		 * We are missing CPURAWNICE, AIX does not account for this in the kernel so this OID can not 
		 * be returned.  Also, these values will roll over sooner or later and then return inaccurate data 
		 * but the MIB wants Integer32 so we cannot put a counter here 
		 * (Has been changed to Counter32 in the latest MIB version!) 
		 */
	case CPURAWSYSTEM:
		take_snapshot(&raw_values);
		/*
		 * LINTED has to be 'long' 
		 */
		long_ret =
			(long) ((raw_values.css_cpu[CPU_SYSTEM] +
					 raw_values.css_cpu[CPU_WAIT]) / raw_values.css_cpus);
		return ((u_char *) (&long_ret));
	case CPURAWIDLE:
		take_snapshot(&raw_values);
		/*
		 * LINTED has to be 'long' 
		 */
		long_ret =
			(long) (raw_values.css_cpu[CPU_IDLE] / raw_values.css_cpus);
		return ((u_char *) (&long_ret));
	case CPURAWWAIT:
		take_snapshot(&raw_values);
		/*
		 * LINTED has to be 'long' 
		 */
		long_ret =
			(long) (raw_values.css_cpu[CPU_WAIT] / raw_values.css_cpus);
		return ((u_char *) (&long_ret));
	case CPURAWKERNEL:
		take_snapshot(&raw_values);
		/*
		 * LINTED has to be 'long' 
		 */
		long_ret =
			(long) (raw_values.css_cpu[CPU_SYSTEM] / raw_values.css_cpus);
		return ((u_char *) (&long_ret));
	case IORAWSENT:
		long_ret = (long) (raw_values.css_blocks_write);
		return ((u_char *) (&long_ret));
	case IORAWRECEIVE:
		long_ret = (long) (raw_values.css_blocks_read);
		return ((u_char *) (&long_ret));
	case SYSRAWINTERRUPTS:
		long_ret = (long) (raw_values.css_interrupts);
		return ((u_char *) (&long_ret));
	case SYSRAWCONTEXT:
		long_ret = (long) (raw_values.css_context_sw);
		return ((u_char *) (&long_ret));

		/*
		 * reserved for future use 
		 */
		/*
		 * case ERRORFLAG:
		 * return((u_char *) (&long_ret));
		 * case ERRORMSG:
		 * return((u_char *) (&long_ret));
		 */
	default:
		snmp_log(LOG_ERR,
				 "vmstat_aix4: Error in request, no match found.\n");
	}
	return (NULL);
}							   /* *var_extensible_vmstat ends here */

/*
 * Functions end here 
 */

/*
 * Program ends here 
 */