Limit total number of GeckoSessions created to prevent OOM

app/src/common/shared/org/mozilla/vrbrowser/browser/engine/Session.java

@@ -99,6 +99,7 @@ protected Session(Context aContext, GeckoRuntime aRuntime,
         mRuntime = aRuntime;
         initialize();
         mState = createSession(aSettings, aOpenMode);
+        mState.setActive(true);
     }
 
     protected Session(Context aContext, GeckoRuntime aRuntime, @NonNull SessionState aRestoreState) {
@@ -325,7 +326,7 @@ private void cleanSessionListeners(GeckoSession aSession) {
     }
 
     public void suspend() {
-        if (mState.mIsActive) {
+        if (mState.isActive()) {
             Log.e(LOGTAG, "Active Sessions can not be suspended");
             return;
         }
@@ -345,29 +346,34 @@ private void restore() {
                     .build();
         }
 
-        String restoreUri = mState.mUri;
-
         mState.mSession = createGeckoSession(settings);
         if (!mState.mSession.isOpen()) {
             mState.mSession.open(mRuntime);
         }
 
+        // data:text URLs can not be restored.
+        if (mState.mSessionState != null && ((mState.mUri == null) || mState.mUri.startsWith("data:text"))) {
+            mState.mSessionState = null;
+            mState.mUri = null;
+        }
+
         if (mState.mSessionState != null) {
             mState.mSession.restoreState(mState.mSessionState);
         }
 
-        if ((mState.mSessionState == null) && (restoreUri != null)) {
-            mState.mSession.loadUri(restoreUri);
+        if ((mState.mSessionState == null) && (mState.mUri != null)) {
+            mState.mSession.loadUri(mState.mUri);
         } else if (mState.mSettings.isPrivateBrowsingEnabled() && mState.mUri == null) {
             loadPrivateBrowsingPage();
-        } else if(mState.mSessionState == null || mState.mUri.equals(mContext.getResources().getString(R.string.about_blank)) ||
+        } else if(mState.mSessionState == null || ((mState.mUri == null) || mState.mUri.equals(mContext.getResources().getString(R.string.about_blank))) ||
                 (mState.mSessionState != null && mState.mSessionState.size() == 0)) {
             loadHomePage();
         } else if (mState.mUri != null && mState.mUri.contains(".youtube.com")) {
             mState.mSession.loadUri(mState.mUri, GeckoSession.LOAD_FLAGS_REPLACE_HISTORY);
         }
 
         dumpAllState();
+        mState.setActive(true);
     }
 
 
@@ -410,6 +416,7 @@ private void recreateSession() {
         SessionState previous = mState;
 
         mState = createSession(previous.mSettings, SESSION_OPEN);
+        mState.setActive(true);
         if (previous.mSessionState != null) {
             mState.mSession.restoreState(previous.mSessionState);
         }
@@ -435,7 +442,7 @@ private void closeSession(@NonNull SessionState aState) {
             aState.mDisplay = null;
         }
         aState.mSession.close();
-        aState.mIsActive = false;
+        aState.setActive(false);
     }
 
     public void captureBitmap() {
@@ -596,18 +603,19 @@ public void goForward() {
 
     public void setActive(boolean aActive) {
         // Flush the events queued while the session was inactive
-        if (mState.mSession != null && !mState.mIsActive && aActive) {
+        if (mState.mSession != null && !mState.isActive() && aActive) {
             flushQueuedEvents();
         }
 
         if (mState.mSession != null) {
             mState.mSession.setActive(aActive);
-        } else {
+            mState.setActive(aActive);
+        } else if (aActive) {
             restore();
+        } else {
+            Log.e(LOGTAG, "ERROR: Setting null GeckoView to inactive!");
         }
 
-        mState.mIsActive = aActive;
-
         for (SessionChangeListener listener: mSessionChangeListeners) {
             listener.onActiveStateChange(this, aActive);
         }
@@ -661,6 +669,7 @@ public void toggleServo() {
 
         mState = createSession(settings, SESSION_OPEN);
         closeSession(previous);
+        mState.setActive(true);
         loadUri(uri);
     }
 
@@ -705,7 +714,7 @@ public int getUaMode() {
     }
 
     public boolean isActive() {
-        return mState.mIsActive;
+        return mState.isActive();
     }
 
     private static final String M_PREFIX = "m.";

app/src/common/shared/org/mozilla/vrbrowser/browser/engine/SessionState.java

@@ -1,12 +1,7 @@
 package org.mozilla.vrbrowser.browser.engine;
 
-import android.graphics.Bitmap;
-
-import androidx.annotation.Nullable;
-
 import com.google.gson.Gson;
 import com.google.gson.JsonParser;
-import com.google.gson.JsonSyntaxException;
 import com.google.gson.TypeAdapter;
 import com.google.gson.TypeAdapterFactory;
 import com.google.gson.annotations.JsonAdapter;
@@ -25,7 +20,7 @@
 
 @JsonAdapter(SessionState.SessionStateAdapterFactory.class)
 public class SessionState {
-    public transient boolean mIsActive;
+    private transient boolean mIsActive;
     public boolean mCanGoBack;
     public boolean mCanGoForward;
     public boolean mIsLoading;
@@ -64,6 +59,18 @@ public GeckoSession.SessionState read(JsonReader in) {
         }
     }
 
+    boolean isActive() {
+        return mIsActive;
+    }
+
+    void setActive(boolean active) {
+        if (active == mIsActive) {
+            return;
+        }
+        mIsActive = active;
+        SessionStore.get().sessionActiveStateChanged();
+    }
+
     public class SessionStateAdapterFactory implements TypeAdapterFactory {
         public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) {
             final TypeAdapter<T> delegate = gson.getDelegateAdapter(this, type);

app/src/common/shared/org/mozilla/vrbrowser/browser/engine/SessionStore.java

@@ -1,12 +1,15 @@
 package org.mozilla.vrbrowser.browser.engine;
 
+import android.app.Activity;
 import android.content.Context;
 import android.content.res.Configuration;
 import android.os.Bundle;
+import android.util.Log;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
+import org.mozilla.gecko.util.ThreadUtils;
 import org.mozilla.geckoview.ContentBlocking;
 import org.mozilla.geckoview.GeckoRuntime;
 import org.mozilla.geckoview.GeckoRuntimeSettings;
@@ -20,11 +23,15 @@
 import org.mozilla.vrbrowser.browser.Services;
 import org.mozilla.vrbrowser.browser.SettingsStore;
 import org.mozilla.vrbrowser.crashreporting.CrashReporterService;
+import org.mozilla.vrbrowser.utils.SystemUtils;
 
+import java.security.KeyStore;
 import java.util.ArrayList;
 import java.util.List;
 
 public class SessionStore implements GeckoSession.PermissionDelegate {
+    private static final String LOGTAG = SystemUtils.createLogtag(SessionStore.class);
+    private static final int MAX_GECKO_SESSIONS = 5;
 
     private static final String[] WEB_EXTENSIONS = new String[] {
             "webcompat_vimeo",
@@ -48,6 +55,7 @@ public static SessionStore get() {
     private BookmarksStore mBookmarksStore;
     private HistoryStore mHistoryStore;
     private Services mServices;
+    private boolean mSuspendPending;
 
     private SessionStore() {
         mSessions = new ArrayList<>();
@@ -113,6 +121,7 @@ private Session addSession(@NonNull Session aSession) {
         aSession.setPermissionDelegate(this);
         aSession.addNavigationListener(mServices);
         mSessions.add(aSession);
+        sessionActiveStateChanged();
         return aSession;
     }
 
@@ -173,9 +182,46 @@ public void suspendAllInactiveSessions() {
     }
 
     public void setActiveSession(Session aSession) {
+        if (aSession != null) {
+            aSession.setActive(true);
+        }
         mActiveSession = aSession;
     }
 
+
+    private void limitInactiveSessions() {
+        Log.d(LOGTAG, "Limiting Inactive Sessions");
+        suspendAllInactiveSessions();
+        mSuspendPending = false;
+    }
+
+    void sessionActiveStateChanged() {
+        if (mSuspendPending) {
+            return;
+        }
+        int count = 0;
+        int activeCount = 0;
+        int inactiveCount = 0;
+        int suspendedCount = 0;
+        for(Session session: mSessions) {
+            if (session.getGeckoSession() != null) {
+                count++;
+                if (session.isActive()) {
+                    activeCount++;
+                } else {
+                    inactiveCount++;
+                }
+            } else {
+                suspendedCount++;
+            }
+        }
+        if (count > MAX_GECKO_SESSIONS) {
+            Log.d(LOGTAG, "Too many GeckoSessions. Active: " + activeCount + " Inactive: " + inactiveCount + " Suspended: " + suspendedCount);
+            mSuspendPending = true;
+            ThreadUtils.postToUiThread(this::limitInactiveSessions);
+        }
+    }
+
     public Session getActiveSession() {
         return mActiveSession;
     }

app/src/common/shared/org/mozilla/vrbrowser/ui/widgets/WindowWidget.java

@@ -991,6 +991,7 @@ public boolean isLayer() {
         return mSurface != null && mTexture == null;
     }
 
+
     @Override
     public void setVisible(boolean aVisible) {
         if (mWidgetPlacement.visible == aVisible) {

app/src/common/shared/org/mozilla/vrbrowser/ui/widgets/Windows.java

@@ -667,6 +667,9 @@ private void removeWindow(@NonNull WindowWidget aWindow) {
     }
 
     private void setWindowVisible(@NonNull WindowWidget aWindow, boolean aVisible) {
+        if (aVisible && (aWindow.getSession() != null) && (aWindow.getSession().getGeckoSession() == null)) {
+            setFirstPaint(aWindow, aWindow.getSession());
+        }
         aWindow.setVisible(aVisible);
         aWindow.getTopBar().setVisible(aVisible);
         aWindow.getTitleBar().setVisible(aVisible);