#include "collectd.h"
+#include "common.h"
#include "plugin.h"
#include "utils_latency.h"
-#include "common.h"
-#include <math.h>
#include <limits.h>
+#include <math.h>
#ifndef LLONG_MAX
-# define LLONG_MAX 9223372036854775807LL
+#define LLONG_MAX 9223372036854775807LL
#endif
#ifndef HISTOGRAM_DEFAULT_BIN_WIDTH
/* 1048576 = 2^20 ^= 1/1024 s */
-# define HISTOGRAM_DEFAULT_BIN_WIDTH 1048576
+#define HISTOGRAM_DEFAULT_BIN_WIDTH 1048576
#endif
-struct latency_counter_s
-{
+struct latency_counter_s {
cdtime_t start_time;
cdtime_t sum;
* When a value above this range is added, Histogram's range is increased by
* increasing the bin width (note that number of bins remains always at 1000).
* This operation of increasing bin width is little expensive as each bin need
-* to be visited to update it's count. To reduce frequent change of bin width,
+* to be visited to update its count. To reduce frequent change of bin width,
* new bin width will be the next nearest power of 2. Example: 2, 4, 8, 16, 32,
* 64, 128, 256, 512, 1024, 2048, 5086, ...
*
* So, if the required bin width is 300, then new bin width will be 512 as it is
* the next nearest power of 2.
*/
-static void change_bin_width (latency_counter_t *lc, cdtime_t latency) /* {{{ */
+static void change_bin_width(latency_counter_t *lc, cdtime_t latency) /* {{{ */
{
/* This function is called because the new value is above histogram's range.
* First find the required bin width:
* then get the next nearest power of 2
* newBinWidth = 2^(ceil(log2(requiredBinWidth)))
*/
- double required_bin_width = ((double) (latency + 1)) / ((double) HISTOGRAM_NUM_BINS);
- double required_bin_width_logbase2 = log (required_bin_width) / log (2.0);
- cdtime_t new_bin_width = (cdtime_t) (pow (2.0, ceil (required_bin_width_logbase2)) + .5);
+ double required_bin_width =
+ ((double)(latency + 1)) / ((double)HISTOGRAM_NUM_BINS);
+ double required_bin_width_logbase2 = log(required_bin_width) / log(2.0);
+ cdtime_t new_bin_width =
+ (cdtime_t)(pow(2.0, ceil(required_bin_width_logbase2)) + .5);
cdtime_t old_bin_width = lc->bin_width;
lc->bin_width = new_bin_width;
* old bin's count to new bin. */
if (lc->num > 0) // if the histogram has data then iterate else skip
{
- double width_change_ratio = ((double) old_bin_width) / ((double) new_bin_width);
-
- for (size_t i = 0; i < HISTOGRAM_NUM_BINS; i++)
- {
- size_t new_bin = (size_t) (((double) i) * width_change_ratio);
- if (i == new_bin)
- continue;
- assert (new_bin < i);
-
- lc->histogram[new_bin] += lc->histogram[i];
- lc->histogram[i] = 0;
- }
+ double width_change_ratio =
+ ((double)old_bin_width) / ((double)new_bin_width);
+
+ for (size_t i = 0; i < HISTOGRAM_NUM_BINS; i++) {
+ size_t new_bin = (size_t)(((double)i) * width_change_ratio);
+ if (i == new_bin)
+ continue;
+ assert(new_bin < i);
+
+ lc->histogram[new_bin] += lc->histogram[i];
+ lc->histogram[i] = 0;
+ }
}
DEBUG("utils_latency: change_bin_width: latency = %.3f; "
- "old_bin_width = %.3f; new_bin_width = %.3f;",
- CDTIME_T_TO_DOUBLE (latency),
- CDTIME_T_TO_DOUBLE (old_bin_width),
- CDTIME_T_TO_DOUBLE (new_bin_width));
+ "old_bin_width = %.3f; new_bin_width = %.3f;",
+ CDTIME_T_TO_DOUBLE(latency), CDTIME_T_TO_DOUBLE(old_bin_width),
+ CDTIME_T_TO_DOUBLE(new_bin_width));
} /* }}} void change_bin_width */
-latency_counter_t *latency_counter_create (void) /* {{{ */
+latency_counter_t *latency_counter_create(void) /* {{{ */
{
latency_counter_t *lc;
- lc = calloc (1, sizeof (*lc));
+ lc = calloc(1, sizeof(*lc));
if (lc == NULL)
- return (NULL);
+ return NULL;
lc->bin_width = HISTOGRAM_DEFAULT_BIN_WIDTH;
- latency_counter_reset (lc);
- return (lc);
+ latency_counter_reset(lc);
+ return lc;
} /* }}} latency_counter_t *latency_counter_create */
-void latency_counter_destroy (latency_counter_t *lc) /* {{{ */
+void latency_counter_destroy(latency_counter_t *lc) /* {{{ */
{
- sfree (lc);
+ sfree(lc);
} /* }}} void latency_counter_destroy */
-void latency_counter_add (latency_counter_t *lc, cdtime_t latency) /* {{{ */
+void latency_counter_add(latency_counter_t *lc, cdtime_t latency) /* {{{ */
{
cdtime_t bin;
- if ((lc == NULL) || (latency == 0) || (latency > ((cdtime_t) LLONG_MAX)))
+ if ((lc == NULL) || (latency == 0) || (latency > ((cdtime_t)LLONG_MAX)))
return;
lc->sum += latency;
* subtract one from the cdtime_t value so that exactly 1.0 ms get sorted
* accordingly. */
bin = (latency - 1) / lc->bin_width;
- if (bin >= HISTOGRAM_NUM_BINS)
- {
- change_bin_width (lc, latency);
- bin = (latency - 1) / lc->bin_width;
- if (bin >= HISTOGRAM_NUM_BINS)
- {
- ERROR ("utils_latency: latency_counter_add: Invalid bin: %"PRIu64, bin);
- return;
- }
+ if (bin >= HISTOGRAM_NUM_BINS) {
+ change_bin_width(lc, latency);
+ bin = (latency - 1) / lc->bin_width;
+ if (bin >= HISTOGRAM_NUM_BINS) {
+ ERROR("utils_latency: latency_counter_add: Invalid bin: %" PRIu64, bin);
+ return;
+ }
}
lc->histogram[bin]++;
} /* }}} void latency_counter_add */
-void latency_counter_reset (latency_counter_t *lc) /* {{{ */
+void latency_counter_reset(latency_counter_t *lc) /* {{{ */
{
if (lc == NULL)
return;
Value of 4 is selected to reduce frequent changes of bin width.
*/
#define REDUCE_THRESHOLD 4
- if ((lc->num > 0) && (lc->bin_width >= HISTOGRAM_DEFAULT_BIN_WIDTH * 2)
- && (max_bin < HISTOGRAM_NUM_BINS / REDUCE_THRESHOLD))
- {
+ if ((lc->num > 0) && (lc->bin_width >= HISTOGRAM_DEFAULT_BIN_WIDTH * 2) &&
+ (max_bin < HISTOGRAM_NUM_BINS / REDUCE_THRESHOLD)) {
/* new bin width will be the previous power of 2 */
bin_width = bin_width / 2;
DEBUG("utils_latency: latency_counter_reset: max_latency = %.3f; "
- "max_bin = %"PRIu64"; old_bin_width = %.3f; new_bin_width = %.3f;",
- CDTIME_T_TO_DOUBLE (lc->max),
- max_bin,
- CDTIME_T_TO_DOUBLE (lc->bin_width),
- CDTIME_T_TO_DOUBLE (bin_width));
+ "max_bin = %" PRIu64 "; old_bin_width = %.3f; new_bin_width = %.3f;",
+ CDTIME_T_TO_DOUBLE(lc->max), max_bin,
+ CDTIME_T_TO_DOUBLE(lc->bin_width), CDTIME_T_TO_DOUBLE(bin_width));
}
- memset (lc, 0, sizeof (*lc));
+ memset(lc, 0, sizeof(*lc));
/* preserve bin width */
lc->bin_width = bin_width;
- lc->start_time = cdtime ();
+ lc->start_time = cdtime();
} /* }}} void latency_counter_reset */
-cdtime_t latency_counter_get_min (latency_counter_t *lc) /* {{{ */
+cdtime_t latency_counter_get_min(latency_counter_t *lc) /* {{{ */
{
if (lc == NULL)
- return (0);
- return (lc->min);
+ return 0;
+ return lc->min;
} /* }}} cdtime_t latency_counter_get_min */
-cdtime_t latency_counter_get_max (latency_counter_t *lc) /* {{{ */
+cdtime_t latency_counter_get_max(latency_counter_t *lc) /* {{{ */
{
if (lc == NULL)
- return (0);
- return (lc->max);
+ return 0;
+ return lc->max;
} /* }}} cdtime_t latency_counter_get_max */
-cdtime_t latency_counter_get_sum (latency_counter_t *lc) /* {{{ */
+cdtime_t latency_counter_get_sum(latency_counter_t *lc) /* {{{ */
{
if (lc == NULL)
- return (0);
- return (lc->sum);
+ return 0;
+ return lc->sum;
} /* }}} cdtime_t latency_counter_get_sum */
-size_t latency_counter_get_num (latency_counter_t *lc) /* {{{ */
+size_t latency_counter_get_num(latency_counter_t *lc) /* {{{ */
{
if (lc == NULL)
- return (0);
- return (lc->num);
+ return 0;
+ return lc->num;
} /* }}} size_t latency_counter_get_num */
-cdtime_t latency_counter_get_average (latency_counter_t *lc) /* {{{ */
+cdtime_t latency_counter_get_average(latency_counter_t *lc) /* {{{ */
{
double average;
if ((lc == NULL) || (lc->num == 0))
- return (0);
+ return 0;
- average = CDTIME_T_TO_DOUBLE (lc->sum) / ((double) lc->num);
- return (DOUBLE_TO_CDTIME_T (average));
+ average = CDTIME_T_TO_DOUBLE(lc->sum) / ((double)lc->num);
+ return DOUBLE_TO_CDTIME_T(average);
} /* }}} cdtime_t latency_counter_get_average */
-cdtime_t latency_counter_get_percentile (latency_counter_t *lc, /* {{{ */
- double percent)
-{
+cdtime_t latency_counter_get_percentile(latency_counter_t *lc, /* {{{ */
+ double percent) {
double percent_upper;
double percent_lower;
double p;
size_t i;
if ((lc == NULL) || (lc->num == 0) || !((percent > 0.0) && (percent < 100.0)))
- return (0);
+ return 0;
/* Find index i so that at least "percent" events are within i+1 ms. */
percent_upper = 0.0;
percent_lower = 0.0;
sum = 0;
- for (i = 0; i < HISTOGRAM_NUM_BINS; i++)
- {
+ for (i = 0; i < HISTOGRAM_NUM_BINS; i++) {
percent_lower = percent_upper;
sum += lc->histogram[i];
if (sum == 0)
percent_upper = 0.0;
else
- percent_upper = 100.0 * ((double) sum) / ((double) lc->num);
+ percent_upper = 100.0 * ((double)sum) / ((double)lc->num);
if (percent_upper >= percent)
break;
}
if (i >= HISTOGRAM_NUM_BINS)
- return (0);
+ return 0;
- assert (percent_upper >= percent);
- assert (percent_lower < percent);
+ assert(percent_upper >= percent);
+ assert(percent_lower < percent);
if (i == 0)
- return (lc->bin_width);
+ return lc->bin_width;
- latency_lower = ((cdtime_t) i) * lc->bin_width;
+ latency_lower = ((cdtime_t)i) * lc->bin_width;
p = (percent - percent_lower) / (percent_upper - percent_lower);
- latency_interpolated = latency_lower
- + DOUBLE_TO_CDTIME_T (p * CDTIME_T_TO_DOUBLE (lc->bin_width));
+ latency_interpolated =
+ latency_lower + DOUBLE_TO_CDTIME_T(p * CDTIME_T_TO_DOUBLE(lc->bin_width));
- DEBUG ("latency_counter_get_percentile: latency_interpolated = %.3f",
- CDTIME_T_TO_DOUBLE (latency_interpolated));
- return (latency_interpolated);
+ DEBUG("latency_counter_get_percentile: latency_interpolated = %.3f",
+ CDTIME_T_TO_DOUBLE(latency_interpolated));
+ return latency_interpolated;
} /* }}} cdtime_t latency_counter_get_percentile */
-cdtime_t latency_counter_get_start_time (const latency_counter_t *lc) /* {{{ */
-{
- if (lc == NULL)
- return (0);
-
- return lc->start_time;
-} /* }}} cdtime_t latency_counter_get_start_time */
-
-
-double latency_counter_get_rate (const latency_counter_t *lc, /* {{{ */
- cdtime_t lower, cdtime_t upper, const cdtime_t now)
-{
- cdtime_t lower_bin;
- cdtime_t upper_bin;
- double sum = 0;
-
+double latency_counter_get_rate(const latency_counter_t *lc, /* {{{ */
+ cdtime_t lower, cdtime_t upper,
+ const cdtime_t now) {
if ((lc == NULL) || (lc->num == 0))
- return (0);
+ return NAN;
if (upper && (upper < lower))
- return (0);
+ return NAN;
+ if (lower == upper)
+ return 0;
/* Buckets have an exclusive lower bound and an inclusive upper bound. That
* means that the first bucket, index 0, represents (0-bin_width]. That means
- * that lower==bin_width needs to result in lower_bin=0, hence the -1. */
+ * that latency==bin_width needs to result in bin=0, that's why we need to
+ * subtract one before dividing by bin_width. */
+ cdtime_t lower_bin = 0;
if (lower)
- lower_bin = (lower - 1) / lc->bin_width;
- else
- lower_bin = 0;
+ /* lower is *exclusive* => determine bucket for lower+1 */
+ lower_bin = ((lower + 1) - 1) / lc->bin_width;
+
+ /* lower is greater than the longest latency observed => rate is zero. */
+ if (lower_bin >= HISTOGRAM_NUM_BINS)
+ return 0;
+ cdtime_t upper_bin = HISTOGRAM_NUM_BINS - 1;
if (upper)
upper_bin = (upper - 1) / lc->bin_width;
- else
- upper_bin = HISTOGRAM_NUM_BINS - 1;
-
- if (lower_bin >= HISTOGRAM_NUM_BINS)
- lower_bin = HISTOGRAM_NUM_BINS - 1;
if (upper_bin >= HISTOGRAM_NUM_BINS) {
upper_bin = HISTOGRAM_NUM_BINS - 1;
upper = 0;
}
- sum = 0;
+ double sum = 0;
for (size_t i = lower_bin; i <= upper_bin; i++)
- {
sum += lc->histogram[i];
- }
if (lower) {
/* Approximate ratio of requests in lower_bin, that fall between
* lower_bin_boundary and lower. This ratio is then subtracted from sum to
* increase accuracy. */
cdtime_t lower_bin_boundary = lower_bin * lc->bin_width;
- assert (lower > lower_bin_boundary);
- double lower_ratio = (double)(lower - lower_bin_boundary - 1) / ((double) lc->bin_width);
+ assert(lower >= lower_bin_boundary);
+ double lower_ratio =
+ (double)(lower - lower_bin_boundary) / ((double)lc->bin_width);
sum -= lower_ratio * lc->histogram[lower_bin];
}
- if (upper)
- {
+ if (upper) {
/* As above: approximate ratio of requests in upper_bin, that fall between
* upper and upper_bin_boundary. */
cdtime_t upper_bin_boundary = (upper_bin + 1) * lc->bin_width;
- assert (upper <= upper_bin_boundary);
+ assert(upper <= upper_bin_boundary);
double ratio = (double)(upper_bin_boundary - upper) / (double)lc->bin_width;
sum -= ratio * lc->histogram[upper_bin];
}
- return sum / (CDTIME_T_TO_DOUBLE (now - lc->start_time));
+ return sum / (CDTIME_T_TO_DOUBLE(now - lc->start_time));
} /* }}} double latency_counter_get_rate */
-
-/* vim: set sw=2 sts=2 et fdm=marker : */
projects / collectd.git / blobdiff