[network] Implement a smart cache size

src/app/options/qgsoptions.cpp

@@ -486,10 +486,10 @@ QgsOptions::QgsOptions( QWidget *parent, Qt::WindowFlags fl, const QList<QgsOpti
   mCacheDirectory->setPlaceholderText( QStandardPaths::writableLocation( QStandardPaths::CacheLocation ) );
   mCacheSize->setMinimum( 0 );
   mCacheSize->setMaximum( std::numeric_limits<int>::max() );
-  mCacheSize->setSingleStep( 1024 );
-  qint64 cacheSize = mSettings->value( QStringLiteral( "cache/size" ), 256 * 1024 * 1024 ).toLongLong();
-  mCacheSize->setValue( static_cast<int>( cacheSize / 1024 ) );
-  mCacheSize->setClearValue( 50 * 1024 );
+  mCacheSize->setSingleStep( 50 );
+  qint64 cacheSize = mSettings->value( QStringLiteral( "cache/size2" ), 0 ).toLongLong();
+  mCacheSize->setValue( static_cast<int>( cacheSize / 1024 / 1024 ) );
+  mCacheSize->setClearValue( 0 );
   connect( mBrowseCacheDirectory, &QAbstractButton::clicked, this, &QgsOptions::browseCacheDirectory );
   connect( mClearCache, &QAbstractButton::clicked, this, &QgsOptions::clearCache );
 
@@ -1583,7 +1583,7 @@ void QgsOptions::saveOptions()
   else
     mSettings->remove( QStringLiteral( "cache/directory" ) );
 
-  mSettings->setValue( QStringLiteral( "cache/size" ), QVariant::fromValue( mCacheSize->value() * 1024LL ) );
+  mSettings->setValue( QStringLiteral( "cache/size2" ), QVariant::fromValue( mCacheSize->value() * 1024LL * 1024LL ) );
 
   //url with no proxy at all
   QStringList noProxyUrls;

src/core/network/qgsnetworkaccessmanager.cpp

@@ -752,8 +752,13 @@ void QgsNetworkAccessManager::setupDefaultProxyAndCache( Qt::ConnectionType conn
   QString cacheDirectory = settings.value( QStringLiteral( "cache/directory" ) ).toString();
   if ( cacheDirectory.isEmpty() )
     cacheDirectory = QStandardPaths::writableLocation( QStandardPaths::CacheLocation );
-  const qint64 cacheSize = settings.value( QStringLiteral( "cache/size" ), 256 * 1024 * 1024 ).toLongLong();
   newcache->setCacheDirectory( cacheDirectory );
+  qint64 cacheSize = settings.value( QStringLiteral( "cache/size2" ), 0 ).toLongLong();
+  if ( cacheSize == 0 )
+  {
+    // Calculatre maximum cache size based on available free space
+    cacheSize = QgsNetworkDiskCache::smartCacheSize( cacheDirectory );
+  }
   newcache->setMaximumCacheSize( cacheSize );
   QgsDebugMsgLevel( QStringLiteral( "cacheDirectory: %1" ).arg( newcache->cacheDirectory() ), 4 );
   QgsDebugMsgLevel( QStringLiteral( "maximumCacheSize: %1" ).arg( newcache->maximumCacheSize() ), 4 );

src/core/network/qgsnetworkdiskcache.cpp

@@ -18,6 +18,9 @@
 
 #include "qgsnetworkdiskcache.h"
 
+#include <QStorageInfo>
+#include <mutex>
+
 ///@cond PRIVATE
 ExpirableNetworkDiskCache QgsNetworkDiskCache::sDiskCache;
 ///@endcond
@@ -111,3 +114,73 @@ void QgsNetworkDiskCache::clear()
   const QMutexLocker lock( &sDiskCacheMutex );
   return sDiskCache.clear();
 }
+
+qint64 QgsNetworkDiskCache::smartCacheSize( const QString &cacheDir )
+{
+  static qint64 cacheSize = 0;
+  static std::once_flag initialized;
+  std::call_once( initialized, [ = ]
+  {
+    std::function<qint64( const QString & )> dirSize;
+    dirSize = [&dirSize]( const QString & dirPath ) -> qint64
+    {
+      qint64 size = 0;
+      QDir dir( dirPath );
+
+      const QStringList filePaths = dir.entryList( QDir::Files | QDir::System | QDir::Hidden );
+      for ( const QString &filePath : filePaths )
+      {
+        QFileInfo fi( dir, filePath );
+        size += fi.size();
+      }
+
+      const QStringList childDirPaths = dir.entryList( QDir::Dirs | QDir::NoDotAndDotDot | QDir::System | QDir::Hidden );
+      for ( const QString &childDirPath : childDirPaths )
+      {
+        size += dirSize( dirPath + QDir::separator() + childDirPath );
+      }
+
+      return size;
+    };
+
+    qint64 bytesFree;
+    QStorageInfo storageInfo( cacheDir );
+    bytesFree = storageInfo.bytesFree() + dirSize( cacheDir );
+
+    // Logic taken from Firefox's smart cache size handling
+    int available10MB = bytesFree / 1024 / ( 1024 * 10 );
+    if ( available10MB > 2500 )
+    {
+      // Cap the cache size to 1GB
+      cacheSize = 100;
+    }
+    else
+    {
+      if ( available10MB > 700 )
+      {
+        // Add 2.5% of the free space above 7GB
+        cacheSize += static_cast<qint64>( ( available10MB - 700 ) * 0.025 );
+        available10MB = 700;
+      }
+      if ( available10MB > 50 )
+      {
+        // Add 7.5% of free sapce between 500MB to 7GB
+        cacheSize += static_cast<qint64>( ( available10MB - 50 ) * 0.075 );
+        available10MB = 50;
+      }
+
+#if defined( Q_OS_ANDROID )
+      // On Android, smaller/older devices may have very little storage
+
+      // Add 16% of free space up to 500 MB
+      cacheSize += std::max( 2, static_cast<int>( available10MB * 0.16 ) );
+#else
+      // Add 30% of free space up to 500 MB
+      cacheSize += std::max( 5, static_cast<int>( available10MB * 0.30 ) );
+#endif
+    }
+    cacheSize = cacheSize * 10 * 1024 * 1024;
+  } );
+
+  return cacheSize;
+}

src/core/network/qgsnetworkdiskcache.h

@@ -20,6 +20,8 @@
 
 #define SIP_NO_FILE
 
+#include "qgis_core.h"
+
 #include <QNetworkDiskCache>
 #include <QMutex>
 
@@ -45,7 +47,7 @@ class ExpirableNetworkDiskCache : public QNetworkDiskCache
  *
  * \note not available in Python bindings
  */
-class QgsNetworkDiskCache : public QNetworkDiskCache
+class CORE_EXPORT QgsNetworkDiskCache : public QNetworkDiskCache
 {
     Q_OBJECT
 
@@ -87,6 +89,12 @@ class QgsNetworkDiskCache : public QNetworkDiskCache
     //! \see QNetworkDiskCache::fileMetaData()
     QNetworkCacheMetaData fileMetaData( const QString &fileName ) const;
 
+    /**
+     * Returns a smart cache size based on available megabytes.
+     * \since QGIS 3.40
+     */
+    static qint64 smartCacheSize( const QString &path );
+
   public slots:
     //! \see QNetworkDiskCache::clear()
     void clear() override;

src/core/qgstiledownloadmanager.cpp

@@ -19,6 +19,7 @@
 
 #include "qgslogger.h"
 #include "qgsnetworkaccessmanager.h"
+#include "qgsnetworkdiskcache.h"
 #include "qgsrangerequestcache.h"
 #include "qgssettings.h"
 
@@ -198,9 +199,13 @@ QgsTileDownloadManager::QgsTileDownloadManager()
     cacheDirectory.push_back( QDir::separator() );
   }
   cacheDirectory += QLatin1String( "http-ranges" );
-  const qint64 cacheSize = settings.value( QStringLiteral( "cache/size" ), 256 * 1024 * 1024 ).toLongLong();
-
   mRangesCache->setCacheDirectory( cacheDirectory );
+  qint64 cacheSize = settings.value( QStringLiteral( "cache/size2" ), 0 ).toLongLong();
+  if ( cacheSize == 0 )
+  {
+    // Calculatre maximum cache size based on available free space
+    cacheSize = QgsNetworkDiskCache::smartCacheSize( cacheDirectory );
+  }
   mRangesCache->setCacheSize( cacheSize );
 }
 

src/server/qgsserver.cpp

@@ -31,6 +31,7 @@
 #include "qgslogger.h"
 #include "qgsmapserviceexception.h"
 #include "qgsnetworkaccessmanager.h"
+#include "qgsnetworkdiskcache.h"
 #include "qgsserverlogger.h"
 #include "qgsserverrequest.h"
 #include "qgsfilterresponsedecorator.h"
@@ -88,9 +89,14 @@ void QgsServer::setupNetworkAccessManager()
   const QSettings settings;
   QgsNetworkAccessManager *nam = QgsNetworkAccessManager::instance();
   QNetworkDiskCache *cache = new QNetworkDiskCache( nullptr );
-  const qint64 cacheSize = sSettings()->cacheSize();
   const QString cacheDirectory = sSettings()->cacheDirectory();
   cache->setCacheDirectory( cacheDirectory );
+  qint64 cacheSize = sSettings()->cacheSize();
+  if ( cacheSize == 0 )
+  {
+    // Calculatre maximum cache size based on available free space
+    cacheSize = QgsNetworkDiskCache::smartCacheSize( cacheDirectory );
+  }
   cache->setMaximumCacheSize( cacheSize );
   QgsMessageLog::logMessage( QStringLiteral( "cacheDirectory: %1" ).arg( cache->cacheDirectory() ), QStringLiteral( "Server" ), Qgis::MessageLevel::Info );
   QgsMessageLog::logMessage( QStringLiteral( "maximumCacheSize: %1" ).arg( cache->maximumCacheSize() ), QStringLiteral( "Server" ), Qgis::MessageLevel::Info );

src/server/qgsserversettings.cpp

@@ -124,9 +124,9 @@ void QgsServerSettings::initSettings()
   const Setting sCacheSize = { QgsServerSettingsEnv::QGIS_SERVER_CACHE_SIZE,
                                QgsServerSettingsEnv::DEFAULT_VALUE,
                                QStringLiteral( "Specify the cache size" ),
-                               QStringLiteral( "/cache/size" ),
+                               QStringLiteral( "/cache/size2" ),
                                QMetaType::Type::LongLong,
-                               QVariant( 256 * 1024 * 1024 ),
+                               0,
                                QVariant()
                              };
   mSettings[ sCacheSize.envVar ] = sCacheSize;

src/ui/qgsoptionsbase.ui

@@ -4862,7 +4862,7 @@ The bigger the number, the faster zooming with the mouse wheel will be.</string>
                       <item row="4" column="0">
                        <widget class="QLabel" name="label_11">
                         <property name="text">
-                         <string>Size [KiB]</string>
+                         <string>Size</string>
                         </property>
                        </widget>
                       </item>
@@ -4877,7 +4877,29 @@ The bigger the number, the faster zooming with the mouse wheel will be.</string>
                        <widget class="QLineEdit" name="mCacheDirectory"/>
                       </item>
                       <item row="4" column="1">
-                       <widget class="QgsSpinBox" name="mCacheSize"/>
+                       <widget class="QgsSpinBox" name="mCacheSize">
+                        <property name="suffix">
+                         <string> MB</string>
+                        </property>
+                        <property name="minimum">
+                         <number>0</number>
+                        </property>
+                        <property name="maximum">
+                         <number>10000</number>
+                        </property>
+                        <property name="singleStep">
+                         <number>100</number>
+                        </property>
+                        <property name="clearValue">
+                         <number>0</number>
+                        </property>
+                        <property name="showClearButton" stdset="0">
+                         <bool>true</bool>
+                        </property>
+                        <property name="specialValueText">
+                         <string>Smart cache size</string>
+                        </property>
+                       </widget>
                       </item>
                       <item row="0" column="2">
                        <widget class="QToolButton" name="mBrowseCacheDirectory">