From 4e9d240585ad5e19f1e145e8334b36b32dbd7620 Mon Sep 17 00:00:00 2001
From: arvidn <arvid@libtorrent.org>
Date: Sat, 2 Nov 2024 12:08:10 +0100
Subject: [PATCH] measure disk cache size in performance counters

---
 include/libtorrent/performance_counters.hpp | 1 +
 src/pread_disk_io.cpp                       | 1 +
 src/session_stats.cpp                       | 1 +
 tools/parse_session_stats.py                | 4 ++++
 4 files changed, 7 insertions(+)

diff --git a/include/libtorrent/performance_counters.hpp b/include/libtorrent/performance_counters.hpp
index e7f63ae2929..44ca6042443 100644
--- a/include/libtorrent/performance_counters.hpp
+++ b/include/libtorrent/performance_counters.hpp
@@ -378,6 +378,7 @@ namespace libtorrent {
 			request_latency,
 
 			disk_blocks_in_use,
+			disk_cache_pieces,
 			queued_disk_jobs,
 			num_running_disk_jobs,
 			num_read_jobs,
diff --git a/src/pread_disk_io.cpp b/src/pread_disk_io.cpp
index 449646c7aee..da7cb49f1ae 100644
--- a/src/pread_disk_io.cpp
+++ b/src/pread_disk_io.cpp
@@ -1145,6 +1145,7 @@ void pread_disk_io::update_stats_counters(counters& c) const
 
 	// gauges
 	c.set_value(counters::disk_blocks_in_use, m_buffer_pool.in_use());
+	c.set_value(counters::disk_cache_pieces, m_cache.size());
 }
 
 status_t pread_disk_io::do_job(aux::job::file_priority& a, aux::pread_disk_job* j)
diff --git a/src/session_stats.cpp b/src/session_stats.cpp
index 49f0d1f91f0..b2e75da6148 100644
--- a/src/session_stats.cpp
+++ b/src/session_stats.cpp
@@ -306,6 +306,7 @@ namespace {
 		METRIC(disk, request_latency)
 
 		METRIC(disk, disk_blocks_in_use)
+		METRIC(disk, disk_cache_pieces)
 
 		// ``queued_disk_jobs`` is the number of disk jobs currently queued,
 		// waiting to be executed by a disk thread.
diff --git a/tools/parse_session_stats.py b/tools/parse_session_stats.py
index bf27d4133c3..368388dde05 100755
--- a/tools/parse_session_stats.py
+++ b/tools/parse_session_stats.py
@@ -623,6 +623,10 @@ def gen_html(reports, generations):
     ('queued_trackers', 'number of queued tracker announces', '', '', [ \
         'tracker.num_queued_tracker_announces' \
     ]),
+    ('disk_cache', 'disk cache size', '', '', [ \
+        'disk.disk_cache_pieces', \
+        'disk.disk_blocks_in_use', \
+    ]),
 
     # ('picker_full_partials_distribution', 'full pieces', '', '', ['num full partial pieces'],
     #  {'type': histogram, 'binwidth': 5, 'numbins': 120}),