1 files changed, 55 insertions, 0 deletions
diff --git a/src/feature/relay/relay_metrics.h b/src/feature/relay/relay_metrics.h
new file mode 100644
index 0000000000..00dfeaa624
--- /dev/null
+++ b/src/feature/relay/relay_metrics.h
@@ -0,0 +1,55 @@
+/* Copyright (c) 2021, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * @file relay_metrics.h
+ * @brief Header for feature/relay/relay_metrics.c
+ **/
+
+#ifndef TOR_FEATURE_RELAY_RELAY_METRICS_H
+#define TOR_FEATURE_RELAY_RELAY_METRICS_H
+
+#include "lib/container/smartlist.h"
+#include "lib/metrics/metrics_common.h"
+
+/** Metrics key for each reported metrics. This key is also used as an index in
+ * the base_metrics array. */
+typedef enum {
+  /** Number of OOM invocation. */
+  RELAY_METRICS_NUM_OOM_BYTES  = 0,
+  /** Number of onionskines handled. */
+  RELAY_METRICS_NUM_ONIONSKINS = 1,
+  /** Number of sockets. */
+  RELAY_METRICS_NUM_SOCKETS    = 2,
+  /** Number of global connection rate limit. */
+  RELAY_METRICS_NUM_GLOBAL_RW_LIMIT = 3,
+  /** Number of DNS queries. */
+  RELAY_METRICS_NUM_DNS        = 4,
+  /** Number of DNS query errors. */
+  RELAY_METRICS_NUM_DNS_ERRORS = 5,
+  /** Number of TCP exhaustion reached. */
+  RELAY_METRICS_NUM_TCP_EXHAUSTION = 6,
+} relay_metrics_key_t;
+
+/** The metadata of a relay metric. */
+typedef struct relay_metrics_entry_t {
+  /* Metric key used as a static array index. */
+  relay_metrics_key_t key;
+  /* Metric type. */
+  metrics_type_t type;
+  /* Metrics output name. */
+  const char *name;
+  /* Metrics output help comment. */
+  const char *help;
+  /* Update value function. */
+  void (*fill_fn)(void);
+} relay_metrics_entry_t;
+
+/* Init. */
+void relay_metrics_init(void);
+void relay_metrics_free(void);
+
+/* Accessors. */
+const smartlist_t *relay_metrics_get_stores(void);
+
+#endif /* !defined(TOR_FEATURE_RELAY_RELAY_METRICS_H) */