src/lib/metrics/metrics_store.c

   1 /* Copyright (c) 2020-2021, The Tor Project, Inc. */
   2 /* See LICENSE for licensing information */
   3
   4 /**
   5  * @file metrics_store.c
   6  * @brief Metrics interface to store them based on specific store type and get
   7  *        their MetricsPort output.
   8  **/
   9
  10 #define METRICS_STORE_ENTRY_PRIVATE
  11
  12 #include "orconfig.h"
  13
  14 #include "lib/container/map.h"
  15 #include "lib/log/util_bug.h"
  16 #include "lib/malloc/malloc.h"
  17
  18 #include "lib/metrics/metrics_store.h"
  19 #include "lib/metrics/metrics_store_entry.h"
  20
  21 /* Format Drivers. */
  22 #include "lib/metrics/prometheus.h"
  23
  24 /** A metric store which contains a map of entries. */
  25 struct metrics_store_t {
  26   /** Indexed by metrics entry name. An entry is a smartlist_t of one or more
  27    * metrics_store_entry_t allowing for multiple metrics of the same name.
  28    *
  29    * The reason we allow multiple entries is because there are cases where one
  30    * metrics can be used twice by the same entity but with different labels.
  31    * One example is an onion service with multiple ports, the port specific
  32    * metrics will have a port value as a label. */
  33   strmap_t *entries;
  34 };
  35
  36 /** Function pointer to the format function of a specific driver. */
  37 typedef void (fmt_driver_fn_t)(const metrics_store_entry_t *, buf_t *);
  38
  39 /** Helper: Free a single entry in a metrics_store_t taking a void pointer
  40  * parameter. */
  41 static void
  42 metrics_store_free_void(void *p)
  43 {
  44   smartlist_t *list = p;
  45   SMARTLIST_FOREACH(list, metrics_store_entry_t *, entry,
  46                     metrics_store_entry_free(entry));
  47   smartlist_free(list);
  48 }
  49
  50 /** Put the given store output in the buffer data and use the format function
  51  * given in fmt to get it for each entry. */
  52 static void
  53 get_output(const metrics_store_t *store, buf_t *data, fmt_driver_fn_t fmt)
  54 {
  55   tor_assert(store);
  56   tor_assert(data);
  57   tor_assert(fmt);
  58
  59   STRMAP_FOREACH(store->entries, key, const smartlist_t *, entries) {
  60     SMARTLIST_FOREACH_BEGIN(entries, const metrics_store_entry_t *, entry) {
  61       fmt(entry, data);
  62     } SMARTLIST_FOREACH_END(entry);
  63   } STRMAP_FOREACH_END;
  64 }
  65
  66 /** Return a newly allocated and initialized store of the given type. */
  67 metrics_store_t *
  68 metrics_store_new(void)
  69 {
  70   metrics_store_t *store = tor_malloc_zero(sizeof(*store));
  71
  72   store->entries = strmap_new();
  73
  74   return store;
  75 }
  76
  77 /** Free the given store including all its entries. */
  78 void
  79 metrics_store_free_(metrics_store_t *store)
  80 {
  81   if (store == NULL) {
  82     return;
  83   }
  84
  85   strmap_free(store->entries, metrics_store_free_void);
  86   tor_free(store);
  87 }
  88
  89 /** Find all metrics entry in the given store identified by name. If not found,
  90  * NULL is returned. */
  91 smartlist_t *
  92 metrics_store_get_all(const metrics_store_t *store, const char *name)
  93 {
  94   tor_assert(store);
  95   tor_assert(name);
  96
  97   return strmap_get(store->entries, name);
  98 }
  99
 100 /** Add a new metrics entry to the given store and type. The name MUST be the
 101  * unique identifier. The help string can be omitted. */
 102 metrics_store_entry_t *
 103 metrics_store_add(metrics_store_t *store, metrics_type_t type,
 104                   const char *name, const char *help)
 105 {
 106   smartlist_t *entries;
 107   metrics_store_entry_t *entry;
 108
 109   tor_assert(store);
 110   tor_assert(name);
 111
 112   entries = metrics_store_get_all(store, name);
 113   if (!entries) {
 114     entries = smartlist_new();
 115     strmap_set(store->entries, name, entries);
 116   }
 117   entry = metrics_store_entry_new(type, name, help);
 118   smartlist_add(entries, entry);
 119
 120   return entry;
 121 }
 122
 123 /** Set the output of the given store of the format fmt into the given buffer
 124  * data. */
 125 void
 126 metrics_store_get_output(const metrics_format_t fmt,
 127                          const metrics_store_t *store, buf_t *data)
 128 {
 129   tor_assert(store);
 130
 131   switch (fmt) {
 132   case METRICS_FORMAT_PROMETHEUS:
 133     get_output(store, data, prometheus_format_store_entry);
 134     break;
 135   default:
 136     // LCOV_EXCL_START
 137     tor_assert_unreached();
 138     // LCOV_EXCL_STOP
 139   }
 140 }