From 3692955f9f5c15af6449c06137f58e84231d801f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Matou=C5=A1=20Dzivjak?= <matousdzivjak@gmail.com>
Date: Mon, 16 Dec 2024 10:34:34 +0100
Subject: [PATCH] Fix client diagnostics (#377)

Bevy diagnostics (measurements) should only record the change in
the value since lass time the measurements were collected.
_Not_ the life-time total.
---
 CHANGELOG.md              |  4 ++++
 src/client.rs             |  2 +-
 src/client/diagnostics.rs | 24 ++++++++++++++++++------
 3 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 31019760..6d4a8c18 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- Report bevy diagnostics correctly as a delta since last measurement collection.
+
 ## [0.29.0] - 2024-12-02
 
 ### Added
diff --git a/src/client.rs b/src/client.rs
index 6fa3fadd..7ba3e882 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -801,7 +801,7 @@ pub(super) struct BufferedMutate {
 ///
 /// See also [`ClientDiagnosticsPlugin`](diagnostics::ClientDiagnosticsPlugin)
 /// for automatic integration with Bevy diagnostics.
-#[derive(Default, Resource, Debug)]
+#[derive(Clone, Copy, Default, Resource, Debug)]
 pub struct ClientReplicationStats {
     /// Incremented per entity that changes.
     pub entities_changed: usize,
diff --git a/src/client/diagnostics.rs b/src/client/diagnostics.rs
index b35902ba..73df8e7b 100644
--- a/src/client/diagnostics.rs
+++ b/src/client/diagnostics.rs
@@ -107,6 +107,7 @@ impl ClientDiagnosticsPlugin {
     fn add_measurements(
         mut diagnostics: Diagnostics,
         stats: Res<ClientReplicationStats>,
+        mut last_stats: Local<ClientReplicationStats>,
         client: Res<RepliconClient>,
     ) {
         diagnostics.add_measurement(&Self::RTT, || client.rtt());
@@ -114,13 +115,24 @@ impl ClientDiagnosticsPlugin {
         diagnostics.add_measurement(&Self::SENT_BPS, || client.sent_bps());
         diagnostics.add_measurement(&Self::RECEIVED_BPS, || client.received_bps());
 
-        diagnostics.add_measurement(&Self::ENTITIES_CHANGED, || stats.entities_changed as f64);
+        diagnostics.add_measurement(&Self::ENTITIES_CHANGED, || {
+            (stats.entities_changed - last_stats.entities_changed) as f64
+        });
         diagnostics.add_measurement(&Self::COMPONENTS_CHANGED, || {
-            stats.components_changed as f64
+            (stats.components_changed - last_stats.components_changed) as f64
+        });
+        diagnostics.add_measurement(&Self::MAPPINGS, || {
+            (stats.mappings - last_stats.mappings) as f64
+        });
+        diagnostics.add_measurement(&Self::DESPAWNS, || {
+            (stats.despawns - last_stats.despawns) as f64
+        });
+        diagnostics.add_measurement(&Self::REPLICATION_MESSAGES, || {
+            (stats.messages - last_stats.messages) as f64
+        });
+        diagnostics.add_measurement(&Self::REPLICATION_BYTES, || {
+            (stats.bytes - last_stats.bytes) as f64
         });
-        diagnostics.add_measurement(&Self::MAPPINGS, || stats.mappings as f64);
-        diagnostics.add_measurement(&Self::DESPAWNS, || stats.despawns as f64);
-        diagnostics.add_measurement(&Self::REPLICATION_MESSAGES, || stats.messages as f64);
-        diagnostics.add_measurement(&Self::REPLICATION_BYTES, || stats.bytes as f64);
+        *last_stats = *stats;
     }
 }