Jettison on top level navigation

Author: pgorszkowski-igalia

Source/WebCore/loader/FrameLoader.cpp

@@ -84,6 +84,7 @@
 #include "IgnoreOpensDuringUnloadCountIncrementer.h"
 #include "InspectorController.h"
 #include "InspectorInstrumentation.h"
+#include "LegacySchemeRegistry.h"
 #include "LinkLoader.h"
 #include "LoaderStrategy.h"
 #include "LocalDOMWindow.h"
@@ -2237,7 +2238,8 @@ void FrameLoader::commitProvisionalLoad()
         // We are doing this here because we know for sure that a new page is about to be loaded.
         BackForwardCache::singleton().addIfCacheable(*frame->history().protectedCurrentItem(), frame->protectedPage().get());
 
-        WebCore::jettisonExpensiveObjectsOnTopLevelNavigation();
+        if (pdl && LegacySchemeRegistry::shouldLoadURLSchemeAsEmptyDocument(pdl->request().url().protocol().toStringWithoutCopying()))
+            WebCore::jettisonExpensiveObjectsOnTopLevelNavigation();
     }
 
     if (m_loadType != FrameLoadType::Replace)

Source/WebCore/page/MemoryRelease.cpp

@@ -262,7 +262,24 @@ void logMemoryStatistics(LogMemoryStatisticsReason reason)
 void platformReleaseMemory(Critical) { }
 #endif
 void platformReleaseGraphicsMemory(Critical) { }
-void jettisonExpensiveObjectsOnTopLevelNavigation() { }
+void jettisonExpensiveObjectsOnTopLevelNavigation()
+{
+    // based on code from cocoa/MemoryReleaseCocoa.mm
+    // Protect against doing excessive jettisoning during repeated navigations.
+    const auto minimumTimeSinceNavigation = std::chrono::seconds(2);
+
+    const auto now = std::chrono::steady_clock::now();
+    static auto timeOfLastNavigation = now;
+    const bool shouldJettison = (timeOfLastNavigation == now) || (std::chrono::duration_cast<std::chrono::seconds>(now - timeOfLastNavigation) >= minimumTimeSinceNavigation);
+    timeOfLastNavigation = now;
+
+    if (!shouldJettison)
+        return;
+
+    RunLoop::main().dispatch([]{
+        releaseMemory(Critical::Yes, Synchronous::Yes);
+    });
+}
 void registerMemoryReleaseNotifyCallbacks() { }
 #endif