New file, that collects some statistical information about the

operation of the server.

src/server/stats.c

+/*
+ * Copyright (C) 2003  Lysator Academic Computer Association.
+ *
+ * This file is part of the LysKOM server.
+ * 
+ * LysKOM is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by 
+ * the Free Software Foundation; either version 1, or (at your option) 
+ * any later version.
+ * 
+ * LysKOM is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with LysKOM; see the file COPYING.  If not, write to
+ * Lysator, c/o ISY, Linkoping University, S-581 83 Linkoping, SWEDEN,
+ * or the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, 
+ * MA 02139, USA.
+ *
+ * Please mail bug reports to bug-lyskom@lysator.liu.se. 
+ */
+/*
+ * stats.c -- Handle statistical information, such as load averages.
+ */
+
+
+#ifdef HAVE_CONFIG_H
+#  include <config.h>
+#endif
+
+#include <assert.h>
+#include "timewrap.h"
+#include <string.h>
+#include <stdio.h>
+
+#include "stats.h"
+#include "log.h"
+#include "lyskomd.h"
+
+#define FACT_00 (1)		/*  1 second */
+#define FACT_0 (15)		/* 15 seconds */
+#define FACT_1 ( 4 * FACT_0)	/*  1 minute */
+#define FACT_2 ( 5 * FACT_1)	/*  5 minutes */
+#define FACT_3 ( 3 * FACT_2)	/* 15 minutes */
+#define N_FACTS 5
+#define HISTORY_LENGTH (FACT_3)
+
+/* Define this to debug the average counting code.  This will slow
+   down the code a lot, so it is not recommended for production use.  */
+#undef DEBUG_STATS
+
+struct avg_status {
+    struct timeval when;
+    long value;
+    float acc;
+    float avg_history[HISTORY_LENGTH];
+    double avenrun[N_FACTS];
+    long updates[N_FACTS];
+};
+
+static struct avg_status status[NUM_STAT];
+static struct avg_status copy[NUM_STAT];
+
+static const int factors[] = {
+    FACT_00,
+    FACT_0,
+    FACT_1,
+    FACT_2,
+    FACT_3,
+};
+
+
+static int
+ind(unsigned long sec,
+    unsigned int offset)
+{
+    int ret = (sec + offset) % HISTORY_LENGTH;
+    assert(ret >= 0);
+    assert(ret < HISTORY_LENGTH);
+    return ret;
+}
+
+    
+#ifdef DEBUG_STATS
+static void
+dump_stats(struct avg_status *s)
+{
+    int st;
+    int i;
+
+    fprintf(stderr, "START DUMP\n");
+    for (st = 0; st < NUM_STAT; st++)
+    {
+	fprintf(stderr, "stats for type %d: when=%ld:%ld value=%ld acc=%f\n",
+		st, (long)s[st].when.tv_sec, (long)s[st].when.tv_usec,
+		s[st].value, s[st].acc);
+	fprintf(stderr, "  indices:");
+	fprintf(stderr, " ():0:%d", ind(s[st].when.tv_sec, 0));
+	for (i = 0; i < N_FACTS; i++)
+	    fprintf(stderr, " %d:%d:%d", i, factors[i], ind(s[st].when.tv_sec,
+							    -factors[i]));
+	fprintf(stderr, "\n  avenrun:");
+	for (i = 0; i < N_FACTS; i++)
+	    fprintf(stderr, " %f", s[st].avenrun[i]);
+	fprintf(stderr, "\n  updates:");
+	for (i = 0; i < N_FACTS; i++)
+	    fprintf(stderr, " %ld", s[st].updates[i]);
+	fprintf(stderr, "\n  history:");
+	for (i = 0; i < HISTORY_LENGTH; i++)
+	    fprintf(stderr, " %f", s[st].avg_history[i]);
+	fprintf(stderr, "\n");
+    }
+}
+#endif
+
+void
+init_stats(void)
+{
+    int t;
+    int i;
+    struct timeval now;
+
+    assert(sizeof(factors)/sizeof(factors[0]) == N_FACTS);
+    assert(factors[N_FACTS-1] == HISTORY_LENGTH);
+
+    gettimeofday(&now, NULL);
+
+    for (t = 0; t < NUM_STAT; t++)
+    {
+	status[t].when = now;
+	status[t].value = 0;
+	status[t].acc = 0.0;
+	for (i = 0; i < HISTORY_LENGTH; i++)
+	    status[t].avg_history[i] = 0.0;
+	for (i = 0; i < N_FACTS; i++)
+	{
+	    status[t].avenrun[i] = 0.0;
+	    status[t].updates[i] = 0;
+	}
+    }
+}
+
+
+static void
+update_history(struct avg_status *s,
+	       time_t end,
+	       float value)
+{
+    int i;
+
+    for (; s->when.tv_sec < end; s->when.tv_sec++)
+    {
+	for (i = 0; i < N_FACTS; i++)
+	    s->avenrun[i] += (value - s->avg_history[ind(s->when.tv_sec,
+							 -factors[i])])
+		/ (double)factors[i];
+	s->avg_history[ind(s->when.tv_sec, 0)] = value;
+    }
+
+}
+
+	       
+void
+update_stat(enum stat_type st,
+	    long delta)
+{
+    struct timeval now;
+    long time_delta;
+    int i;
+    struct avg_status *s = &status[st];
+
+    assert(st < STAT_FIRST_EVENT || delta >= 0);
+
+    memcpy(copy, status, sizeof(status));
+
+    gettimeofday(&now, NULL);
+
+    if (now.tv_sec == s->when.tv_sec)
+    {
+	if (st < STAT_FIRST_EVENT)
+	{
+	    time_delta = now.tv_usec - s->when.tv_usec;
+	    if (time_delta != 0)
+		s->acc += (float)s->value / time_delta;
+	    s->when.tv_usec = now.tv_usec;
+	}
+    }
+    else if (now.tv_sec - s->when.tv_sec <= HISTORY_LENGTH)
+    {
+	if (st < STAT_FIRST_EVENT)
+	{
+	    time_delta = 1000000 - s->when.tv_usec;
+	    if (time_delta != 0)
+		s->acc += (float)s->value / time_delta;
+	}
+	else
+	    s->acc = s->value;
+
+	update_history(s, s->when.tv_sec+1, s->acc);
+	if (st >= STAT_FIRST_EVENT)
+	{
+	    s->acc = 0;
+	    s->value = 0;
+	}
+	update_history(s, now.tv_sec, s->value);
+	assert(s->when.tv_sec == now.tv_sec);
+	if (st < STAT_FIRST_EVENT)
+	{
+	    if (now.tv_usec == 0)
+		s->acc = 0;
+	    else
+		s->acc = (float)s->value / now.tv_usec;
+	    s->when.tv_usec = now.tv_usec;
+	}
+    }
+    else
+    {
+	if (st >= STAT_FIRST_EVENT)
+	{
+	    s->acc = 0;
+	    s->value = 0;
+	}
+	for (i = 0; i < N_FACTS; i++)
+	    s->avenrun[i] = s->value;
+	for (i = 0; i < HISTORY_LENGTH; i++)
+	    s->avg_history[i] = s->value;
+	if (st < STAT_FIRST_EVENT)
+	{
+	    if (now.tv_usec == 0)
+		s->acc = 0;
+	    else
+		s->acc = (float)s->value / now.tv_usec;
+	}
+	s->when = now;
+    }
+
+    s->value += delta;
+    for (i = 0; i < N_FACTS; i++)
+	s->updates[i]++;
+    if (s->value < 0)
+    {
+	kom_log("update_stat(%d, %ld): current value became negative: %ld\n",
+		st, delta, s->value);
+	s->value = 0;
+    }
+#ifdef DEBUG_STATS
+    if (check_stat("update_stats") > 0)
+    {
+	kom_log("This was caused by an update of delta=%ld for type %d\n",
+		delta, st);
+	kom_log("Dump of before:\n");
+	dump_stats(copy);
+	kom_log("Dump of after:\n");
+	dump_stats(status);
+    }
+#endif
+}
+
+extern int
+check_stat(const char *when)
+{
+    struct avg_status *s;
+    double acc;
+    double err;
+    float val;
+    int st;
+    int f;
+    int i;
+    int changes = 0;
+
+    for (st = 0; st < NUM_STAT; st++)
+    {
+	s = &status[st];
+	for (f = 0; f < N_FACTS; f++)
+	{
+	    acc = 0;
+	    for (i = 0; i < factors[f]; i++)
+	    {
+		val = s->avg_history[ind(s->when.tv_sec, -i-1)];
+		assert(val >= 0);
+		acc += val;
+	    }
+	    acc /= factors[f];
+	    err = acc - s->avenrun[f];
+	    if (err < 0)
+		err = -err;
+	    if ((acc < 1e-6 && err > 1e-5)
+		|| (acc >= 1e-6 && err / acc > 0.01))
+	    {
+		kom_log("Accumulated rounding errors fixed (%s) after"
+			" %ld updates (type=%d, f=%d, factor=%d): %f => %f\n",
+			when,
+			s->updates[f], st, f, factors[f], s->avenrun[f], acc);
+		s->avenrun[f] = acc;
+		s->updates[f] = 0;
+		changes++;
+	    }
+	}
+    }
+    return changes;
+}

src/server/stats.h

+/*
+ * Copyright (C) 2003  Lysator Academic Computer Association.
+ *
+ * This file is part of the LysKOM server.
+ * 
+ * LysKOM is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by 
+ * the Free Software Foundation; either version 1, or (at your option) 
+ * any later version.
+ * 
+ * LysKOM is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with LysKOM; see the file COPYING.  If not, write to
+ * Lysator, c/o ISY, Linkoping University, S-581 83 Linkoping, SWEDEN,
+ * or the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, 
+ * MA 02139, USA.
+ *
+ * Please mail bug reports to bug-lyskom@lysator.liu.se. 
+ */
+
+/*
+ * stats.h -- Handle statistical information, such as load averages.
+ */
+
+enum stat_type {
+    /* Average values. */
+    STAT_RUN_QUEUE,
+#if 0
+    STAT_DNS_QUEUE,
+    STAT_IDENT_QUEUE,
+#endif
+
+    /* Events. */
+    STAT_FIRST_EVENT,
+    STAT_PROCESSED_CALLS = STAT_FIRST_EVENT,
+    STAT_RUN_QUEUE_ENTER,
+    STAT_RUN_QUEUE_LEAVE,
+
+    NUM_STAT
+};
+
+extern void init_stats(void);
+extern void update_stat(enum stat_type st, long delta);
+extern int check_stat(const char *when);