From c2075586084ece032e47adba2aacbc507adc2b26 Mon Sep 17 00:00:00 2001
From: Jesper Jensen <jesper@jnsn.dev>
Date: Sun, 4 May 2025 22:21:05 +0200
Subject: Expose the hash table size as a metric

---
 src/metrics.c | 10 ++++++++++
 src/metrics.h |  1 +
 src/peers.c   |  1 +
 3 files changed, 12 insertions(+)

diff --git a/src/metrics.c b/src/metrics.c
index eb50f09..c1113a7 100644
--- a/src/metrics.c
+++ b/src/metrics.c
@@ -10,6 +10,7 @@ prom_counter_t *meta = NULL;
 prom_counter_t *peers = NULL;
 prom_gauge_t *current_hashes = NULL;
 prom_counter_t *hashes = NULL;
+prom_gauge_t *hashes_size = NULL;
 prom_counter_t *hash_expired = NULL;
 prom_gauge_t *hash_next_expire = NULL;
 prom_counter_t *queries = NULL;
@@ -132,6 +133,15 @@ void metric_init() {
 		)
 	);
 
+	hashes_size = prom_collector_registry_must_register_metric(
+		prom_gauge_new(
+			"dht_hashes_size",
+			"InfoHash table capacity",
+			0,
+			NULL
+		)
+	);
+
 	hash_expired = prom_collector_registry_must_register_metric(
 		prom_counter_new(
 			"dht_hashes_expired_total",
diff --git a/src/metrics.h b/src/metrics.h
index 309177c..befd3aa 100644
--- a/src/metrics.h
+++ b/src/metrics.h
@@ -12,6 +12,7 @@ extern prom_counter_t *meta;
 extern prom_counter_t *peers;
 extern prom_gauge_t *current_hashes;
 extern prom_counter_t *hashes;
+extern prom_gauge_t *hashes_size;
 extern prom_counter_t *hash_expired;
 extern prom_gauge_t *hash_next_expire;
 extern prom_counter_t *queries;
diff --git a/src/peers.c b/src/peers.c
index 9aff14b..239326a 100644
--- a/src/peers.c
+++ b/src/peers.c
@@ -202,5 +202,6 @@ void peer_update_metrics() {
 	prom_gauge_set(hash_next_expire, next_expire, NULL);
 	assert(computed_load == peer_table_load);
 
+	prom_gauge_set(hashes_size, peer_table_size, NULL);
 	prom_gauge_set(current_hashes, (double)peer_table_load, NULL);
 }
-- 
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