perf: Optimize call to get backend server port.

When building the "Videos" dialog, the calls to gCoreContext->GetBackendServerPort consume 3% of the total time to build the window. Given that this value will probably never change once it is set, cache the result to save time.
MythTV · Sep 11, 2021 · 2f8749b · 2f8749b
1 parent d1656f3
commit 2f8749b
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Showing 5 changed files with 26 additions and 3 deletions.
diff --git a/mythtv/libs/libmythbase/mythcorecontext.cpp b/mythtv/libs/libmythbase/mythcorecontext.cpp
@@ -1090,12 +1090,24 @@ int MythCoreContext::GetBackendServerPort(void)
     return GetBackendServerPort(d->m_localHostname);
 }
 
+QHash<QString,int> MythCoreContext::s_serverPortCache;
+
+void MythCoreContext::ClearBackendServerPortCache()
+{
+    s_serverPortCache.clear();
+}
+
 /**
  * Returns the backend "hosts"'s control port
  */
 int MythCoreContext::GetBackendServerPort(const QString &host)
 {
-    return GetNumSettingOnHost("BackendServerPort", host, 6543);
+    int port = s_serverPortCache.value(host, -1);
+    if (port != -1)
+        return port;
+    port = GetNumSettingOnHost("BackendServerPort", host, 6543);
+    s_serverPortCache[host] = port;
+    return port;
 }
 
 /**

diff --git a/mythtv/libs/libmythbase/mythcorecontext.h b/mythtv/libs/libmythbase/mythcorecontext.h
@@ -202,8 +202,10 @@ class MBASE_PUBLIC MythCoreContext : public QObject, public MythObservable, publ
     int GetMasterServerStatusPort(void);
     int GetBackendServerPort(void);
     int GetBackendServerPort(const QString &host);
+    static void ClearBackendServerPortCache();
     int GetBackendStatusPort(void);
     int GetBackendStatusPort(const QString &host);
+    static QHash<QString,int> s_serverPortCache;
 
     bool GetScopeForAddress(QHostAddress &addr) const;
     void SetScopeForAddress(const QHostAddress &addr);

diff --git a/mythtv/programs/mythfrontend/videodlg.cpp b/mythtv/programs/mythfrontend/videodlg.cpp
@@ -864,6 +864,7 @@ VideoDialog::VideoDialog(MythScreenStack *lparent, const QString& lname,
                             ParentalLevel::plLowest)));
 
     StorageGroup::ClearGroupToUseCache();
+    MythCoreContext::ClearBackendServerPortCache();
 }
 
 VideoDialog::~VideoDialog()

diff --git a/mythtv/programs/mythtv-setup/backendsettings.cpp b/mythtv/programs/mythtv-setup/backendsettings.cpp
@@ -144,14 +144,20 @@ class IpAddressSettings : public HostCheckBoxSetting
 };
 
 
+void BackendSettings::LocalServerPortChanged ()
+{
+    MythCoreContext::ClearBackendServerPortCache();
+}
 
-static HostTextEditSetting *LocalServerPort()
+HostTextEditSetting *BackendSettings::LocalServerPort() const
 {
     auto *gc = new HostTextEditSetting("BackendServerPort");
     gc->setLabel(QObject::tr("Port"));
     gc->setValue("6543");
     gc->setHelpText(QObject::tr("Unless you've got good reason, don't "
                     "change this."));
+    connect(gc,   &StandardSetting::ChangeSaved,
+            this, &BackendSettings::LocalServerPortChanged);
     return gc;
 };
 

diff --git a/mythtv/programs/mythtv-setup/backendsettings.h b/mythtv/programs/mythtv-setup/backendsettings.h
@@ -14,6 +14,8 @@ class BackendSettings : public GroupSetting
     ~BackendSettings() override;
 
   private:
+    HostTextEditSetting *LocalServerPort(void) const;
+
     TransMythUICheckBoxSetting *m_isMasterBackend   {nullptr};
     HostTextEditSetting        *m_localServerPort   {nullptr};
     HostComboBoxSetting        *m_backendServerAddr {nullptr};
@@ -29,7 +31,7 @@ class BackendSettings : public GroupSetting
   private slots:
     void masterBackendChanged(void);
     void listenChanged(void);
+    static void LocalServerPortChanged(void);
 };
 
 #endif
-