From 4ab1b0b43681323e5d0e6b0572781ff70ab74a15 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Sat, 13 Jun 2020 13:47:01 +0200
Subject: [PATCH] LibIPC: Only start responsiveness timer after sending client
 a message

Instead of always running the responsiveness timer for IPC clients,
we now only start it after sending a message. This avoids waking up
otherwise idle clients to do ping/pong busywork.
---
 Libraries/LibIPC/ClientConnection.h        | 9 +++++++--
 Services/WindowServer/ClientConnection.cpp | 5 +++++
 Services/WindowServer/ClientConnection.h   | 1 +
 3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/Libraries/LibIPC/ClientConnection.h b/Libraries/LibIPC/ClientConnection.h
index 429958e6440..516fb7c0e0b 100644
--- a/Libraries/LibIPC/ClientConnection.h
+++ b/Libraries/LibIPC/ClientConnection.h
@@ -101,6 +101,7 @@ public:
     }
 
     virtual void may_have_become_unresponsive() {}
+    virtual void did_become_responsive() {}
 
     void post_message(const Message& message)
     {
@@ -130,6 +131,8 @@ public:
         }
 
         ASSERT(static_cast<size_t>(nwritten) == buffer.size());
+
+        m_responsiveness_timer->start();
     }
 
     void drain_messages_from_client()
@@ -156,8 +159,10 @@ public:
             bytes.append(buffer, nread);
         }
 
-        if (!bytes.is_empty())
-            m_responsiveness_timer->restart();
+        if (!bytes.is_empty()) {
+            m_responsiveness_timer->stop();
+            did_become_responsive();
+        }
 
         size_t decoded_bytes = 0;
         for (size_t index = 0; index < bytes.size(); index += decoded_bytes) {
diff --git a/Services/WindowServer/ClientConnection.cpp b/Services/WindowServer/ClientConnection.cpp
index dff7ae8d51b..56353cda365 100644
--- a/Services/WindowServer/ClientConnection.cpp
+++ b/Services/WindowServer/ClientConnection.cpp
@@ -844,4 +844,9 @@ void ClientConnection::may_have_become_unresponsive()
     });
 }
 
+void ClientConnection::did_become_responsive()
+{
+    set_unresponsive(false);
+}
+
 }
diff --git a/Services/WindowServer/ClientConnection.h b/Services/WindowServer/ClientConnection.h
index b662d31110c..ea4d822d55e 100644
--- a/Services/WindowServer/ClientConnection.h
+++ b/Services/WindowServer/ClientConnection.h
@@ -89,6 +89,7 @@ private:
     // ^ClientConnection
     virtual void die() override;
     virtual void may_have_become_unresponsive() override;
+    virtual void did_become_responsive() override;
 
     void set_unresponsive(bool);
     void destroy_window(Window&, Vector<i32>& destroyed_window_ids);