Ask LocalStorage database to free as much memory as possible on memor…

…y pressure

https://bugs.webkit.org/show_bug.cgi?id=225109

Reviewed by Geoffrey Garen.

Source/WebCore:

Add releaseMemory() function to SQLiteDatabase that calls sqlite3_db_release_memory()
to free as much memory as possible.

* platform/sql/SQLiteDatabase.cpp:
(WebCore::SQLiteDatabase::releaseMemory):
* platform/sql/SQLiteDatabase.h:

Source/WebKit:

Ask LocalStorage database to free as much memory as possible on memory pressure.
Some of the strings in the database can be large and we don't want SQLite to be
holding on to those for performance reason when we are under memory pressure.

This seems to be a ~1.75% improvement on PLUM/nytimes-home and a ~1% improvement
on PLUM/wikipedia, sadly not enough to show an impact on the overal PLUM score.

* NetworkProcess/NetworkProcess.cpp:
(WebKit::NetworkProcess::lowMemoryHandler):
* NetworkProcess/NetworkProcess.h:
* NetworkProcess/WebStorage/LocalStorageDatabase.cpp:
(WebKit::LocalStorageDatabase::handleLowMemoryWarning):
* NetworkProcess/WebStorage/LocalStorageDatabase.h:
* NetworkProcess/WebStorage/StorageArea.cpp:
(WebKit::StorageArea::handleLowMemoryWarning):
* NetworkProcess/WebStorage/StorageArea.h:
* NetworkProcess/WebStorage/StorageManagerSet.cpp:
(WebKit::StorageManagerSet::handleLowMemoryWarning):
* NetworkProcess/WebStorage/StorageManagerSet.h:


Canonical link: https://commits.webkit.org/237075@main
git-svn-id: https://svn.webkit.org/repository/webkit/trunk@276648 268f45cc-cd09-0410-ab3c-d52691b4dbfc

Source/WebCore/ChangeLog

@@ -1,3 +1,17 @@
+2021-04-27  Chris Dumez  <cdumez@apple.com>
+
+        Ask LocalStorage database to free as much memory as possible on memory pressure
+        https://bugs.webkit.org/show_bug.cgi?id=225109
+
+        Reviewed by Geoffrey Garen.
+
+        Add releaseMemory() function to SQLiteDatabase that calls sqlite3_db_release_memory()
+        to free as much memory as possible.
+
+        * platform/sql/SQLiteDatabase.cpp:
+        (WebCore::SQLiteDatabase::releaseMemory):
+        * platform/sql/SQLiteDatabase.h:
+
 2021-04-27  Brent Fulgham  <bfulgham@apple.com>
 
         [iOS] [GPU] The UI process should issue the mach sandbox extension to 'com.apple.AGXCompilerService' 

Source/WebCore/platform/sql/SQLiteDatabase.cpp

@@ -635,4 +635,12 @@ void SQLiteDatabase::removeCollationFunction(const String& collationName)
     sqlite3_create_collation_v2(m_db, collationName.utf8().data(), SQLITE_UTF8, nullptr, nullptr, nullptr);
 }
 
+void SQLiteDatabase::releaseMemory()
+{
+    if (!m_db)
+        return;
+
+    sqlite3_db_release_memory(m_db);
+}
+
 } // namespace WebCore

Source/WebCore/platform/sql/SQLiteDatabase.h

@@ -146,6 +146,8 @@ class SQLiteDatabase {
 
     WEBCORE_EXPORT static void setIsDatabaseOpeningForbidden(bool);
 
+    WEBCORE_EXPORT void releaseMemory();
+
 private:
     static int authorizerFunction(void*, int, const char*, const char*, const char*, const char*);
 

Source/WebKit/ChangeLog

@@ -1,3 +1,30 @@
+2021-04-27  Chris Dumez  <cdumez@apple.com>
+
+        Ask LocalStorage database to free as much memory as possible on memory pressure
+        https://bugs.webkit.org/show_bug.cgi?id=225109
+
+        Reviewed by Geoffrey Garen.
+
+        Ask LocalStorage database to free as much memory as possible on memory pressure.
+        Some of the strings in the database can be large and we don't want SQLite to be
+        holding on to those for performance reason when we are under memory pressure.
+
+        This seems to be a ~1.75% improvement on PLUM/nytimes-home and a ~1% improvement
+        on PLUM/wikipedia, sadly not enough to show an impact on the overal PLUM score.
+
+        * NetworkProcess/NetworkProcess.cpp:
+        (WebKit::NetworkProcess::lowMemoryHandler):
+        * NetworkProcess/NetworkProcess.h:
+        * NetworkProcess/WebStorage/LocalStorageDatabase.cpp:
+        (WebKit::LocalStorageDatabase::handleLowMemoryWarning):
+        * NetworkProcess/WebStorage/LocalStorageDatabase.h:
+        * NetworkProcess/WebStorage/StorageArea.cpp:
+        (WebKit::StorageArea::handleLowMemoryWarning):
+        * NetworkProcess/WebStorage/StorageArea.h:
+        * NetworkProcess/WebStorage/StorageManagerSet.cpp:
+        (WebKit::StorageManagerSet::handleLowMemoryWarning):
+        * NetworkProcess/WebStorage/StorageManagerSet.h:
+
 2021-04-27  Don Olmstead  <don.olmstead@sony.com>
 
         [CMake] Don't use FORWARDING_HEADERS_DIR for GTK WebKit headers

Source/WebKit/NetworkProcess/NetworkProcess.cpp

@@ -309,6 +309,8 @@ void NetworkProcess::lowMemoryHandler(Critical critical)
         networkSession.clearPrefetchCache();
     });
 
+    m_storageManagerSet->handleLowMemoryWarning();
+
 #if ENABLE(SERVICE_WORKER)
     for (auto& swServer : m_swServers.values())
         swServer->handleLowMemoryWarning();

Source/WebKit/NetworkProcess/NetworkProcess.h

@@ -549,7 +549,7 @@ class NetworkProcess : public AuxiliaryProcess, private DownloadManager::Client,
     HashMap<PAL::SessionID, std::unique_ptr<NetworkSession>> m_networkSessions;
     HashMap<PAL::SessionID, std::unique_ptr<WebCore::NetworkStorageSession>> m_networkStorageSessions;
 
-    RefPtr<StorageManagerSet> m_storageManagerSet;
+    Ref<StorageManagerSet> m_storageManagerSet;
 
 #if PLATFORM(COCOA)
     void platformInitializeNetworkProcessCocoa(const NetworkProcessCreationParameters&);

Source/WebKit/NetworkProcess/WebStorage/LocalStorageDatabase.cpp

@@ -362,4 +362,10 @@ bool LocalStorageDatabase::databaseIsEmpty()
     return !query.getColumnInt(0);
 }
 
+void LocalStorageDatabase::handleLowMemoryWarning()
+{
+    if (m_database.isOpen())
+        m_database.releaseMemory();
+}
+
 } // namespace WebKit

Source/WebKit/NetworkProcess/WebStorage/LocalStorageDatabase.h

@@ -59,6 +59,8 @@ class LocalStorageDatabase : public RefCounted<LocalStorageDatabase> {
     // Will block until all pending changes have been written to disk.
     void close();
 
+    void handleLowMemoryWarning();
+
 private:
     LocalStorageDatabase(Ref<WorkQueue>&&, Ref<LocalStorageDatabaseTracker>&&, const WebCore::SecurityOriginData&);
 

Source/WebKit/NetworkProcess/WebStorage/StorageArea.cpp

@@ -227,4 +227,10 @@ void StorageArea::close()
     m_localStorageDatabase->close();
 }
 
+void StorageArea::handleLowMemoryWarning()
+{
+    if (m_localStorageDatabase)
+        m_localStorageDatabase->handleLowMemoryWarning();
+}
+
 } // namespace WebKit

Source/WebKit/NetworkProcess/WebStorage/StorageArea.h

@@ -73,6 +73,8 @@ class StorageArea : public CanMakeWeakPtr<StorageArea> {
     void syncToDatabase();
     void close();
 
+    void handleLowMemoryWarning();
+
 private:
     void dispatchEvents(IPC::Connection::UniqueID sourceConnection, StorageAreaImplIdentifier, const String& key, const String& oldValue, const String& newValue, const String& urlString) const;
 

Source/WebKit/NetworkProcess/WebStorage/StorageManagerSet.cpp

@@ -129,6 +129,15 @@ void StorageManagerSet::removeConnection(IPC::Connection& connection)
     });
 }
 
+void StorageManagerSet::handleLowMemoryWarning()
+{
+    ASSERT(RunLoop::isMain());
+    m_queue->dispatch([this, protectedThis = makeRef(*this)] {
+        for (auto& storageArea : m_storageAreas.values())
+            storageArea->handleLowMemoryWarning();
+    });
+}
+
 void StorageManagerSet::waitUntilTasksFinished()
 {
     ASSERT(RunLoop::isMain());

Source/WebKit/NetworkProcess/WebStorage/StorageManagerSet.h

@@ -57,6 +57,7 @@ class StorageManagerSet : public IPC::Connection::WorkQueueMessageReceiver {
     void addConnection(IPC::Connection&);
     void removeConnection(IPC::Connection&);
 
+    void handleLowMemoryWarning();
     void waitUntilTasksFinished();
     void waitUntilSyncingLocalStorageFinished();
     void suspend(CompletionHandler<void()>&&);