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/* Copyright (c) 2020-2021, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* @file prometheus.c
* @brief Metrics format driver for Prometheus data model.
**/
#define METRICS_STORE_ENTRY_PRIVATE
#include "orconfig.h"
#include "lib/container/smartlist.h"
#include "lib/log/util_bug.h"
#include "lib/malloc/malloc.h"
#include "lib/string/printf.h"
#include "lib/metrics/prometheus.h"
#include <string.h>
/** Return a static buffer containing all the labels properly formatted
* for the output as a string.
*
* Subsequent calls to this invalidates the previous result. */
static const char *
format_labels(smartlist_t *labels)
{
static char buf[1024];
char *line = NULL;
if (smartlist_len(labels) == 0) {
buf[0] = '\0';
goto end;
}
line = smartlist_join_strings(labels, ",", 0, NULL);
tor_snprintf(buf, sizeof(buf), "%s", line);
end:
tor_free(line);
return buf;
}
/** Write the string representation of the histogram entry to the specified
* buffer.
*
* Note: entry **must** be a histogram.
*/
static void
format_histogram(const metrics_store_entry_t *entry, buf_t *data)
{
tor_assert(entry->type == METRICS_TYPE_HISTOGRAM);
const char *labels = format_labels(entry->labels);
for (size_t i = 0; i < entry->u.histogram.bucket_count; ++i) {
metrics_histogram_bucket_t hb = entry->u.histogram.buckets[i];
if (strlen(labels) > 0) {
buf_add_printf(data, "%s_bucket{%s,le=\"%.2f\"} %" PRIi64 "\n",
entry->name, labels, (double)hb.bucket, hb.value);
} else {
buf_add_printf(data, "%s_bucket{le=\"%.2f\"} %" PRIi64 "\n",
entry->name, (double)hb.bucket, hb.value);
}
}
if (strlen(labels) > 0) {
buf_add_printf(data, "%s_bucket{%s,le=\"+Inf\"} %" PRIi64 "\n",
entry->name, labels,
metrics_store_hist_entry_get_count(entry));
buf_add_printf(data, "%s_sum{%s} %" PRIi64 "\n", entry->name, labels,
metrics_store_hist_entry_get_sum(entry));
buf_add_printf(data, "%s_count{%s} %" PRIi64 "\n", entry->name, labels,
metrics_store_hist_entry_get_count(entry));
} else {
buf_add_printf(data, "%s_bucket{le=\"+Inf\"} %" PRIi64 "\n", entry->name,
metrics_store_hist_entry_get_count(entry));
buf_add_printf(data, "%s_sum %" PRIi64 "\n", entry->name,
metrics_store_hist_entry_get_sum(entry));
buf_add_printf(data, "%s_count %" PRIi64 "\n", entry->name,
metrics_store_hist_entry_get_count(entry));
}
}
/** Format the given entry in to the buffer data. */
void
prometheus_format_store_entry(const metrics_store_entry_t *entry, buf_t *data,
bool no_comment)
{
tor_assert(entry);
tor_assert(data);
if (!no_comment) {
buf_add_printf(data, "# HELP %s %s\n", entry->name, entry->help);
buf_add_printf(data, "# TYPE %s %s\n", entry->name,
metrics_type_to_str(entry->type));
}
switch (entry->type) {
case METRICS_TYPE_COUNTER: FALLTHROUGH;
case METRICS_TYPE_GAUGE:
{
const char *labels = format_labels(entry->labels);
if (strlen(labels) > 0) {
buf_add_printf(data, "%s{%s} %" PRIi64 "\n", entry->name,
labels,
metrics_store_entry_get_value(entry));
} else {
buf_add_printf(data, "%s %" PRIi64 "\n", entry->name,
metrics_store_entry_get_value(entry));
}
break;
}
case METRICS_TYPE_HISTOGRAM:
format_histogram(entry, data);
break;
default:
tor_assert_unreached();
}
}
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