Bug 1064304 - Part 3: Persist group collapsed/expanded state in SharedPreferences. r=rnewman

mobile/android/base/home/RemoteTabsExpandableListFragment.java

@@ -8,6 +8,7 @@ package org.mozilla.gecko.home;
 import java.util.EnumSet;
 import java.util.List;
 
+import org.mozilla.gecko.GeckoSharedPrefs;
 import org.mozilla.gecko.R;
 import org.mozilla.gecko.RemoteTabsExpandableListAdapter;
 import org.mozilla.gecko.TabsAccessor;
@@ -52,6 +53,10 @@ public class RemoteTabsExpandableListFragment extends HomeFragment {
 
     private static final String[] STAGES_TO_SYNC_ON_REFRESH = new String[] { "clients", "tabs" };
 
+    // Maintain group collapsed and hidden state.
+    // Only accessed from the UI thread.
+    private static RemoteTabsExpandableListState sState;
+
     // Adapter for the list of remote tabs.
     private RemoteTabsExpandableListAdapter mAdapter;
 
@@ -117,9 +122,15 @@ public class RemoteTabsExpandableListFragment extends HomeFragment {
         mList.setOnGroupClickListener(new OnGroupClickListener() {
             @Override
             public boolean onGroupClick(ExpandableListView parent, View v, int groupPosition, long id) {
-                // Since we don't indicate the expansion state yet, don't allow
+                final ExpandableListAdapter adapter = parent.getExpandableListAdapter();
-                // collapsing groups at all.
+                final RemoteClient client = (RemoteClient) adapter.getGroup(groupPosition);
-                return true;
+                if (client != null) {
+                    // After we process this click, the group's expanded state will have flipped.
+                    sState.setClientCollapsed(client.guid, mList.isGroupExpanded(groupPosition));
+                }
+
+                // We want the system to handle the click, expanding or collapsing as necessary.
+                return false;
             }
         });
 
@@ -165,6 +176,15 @@ public class RemoteTabsExpandableListFragment extends HomeFragment {
     public void onActivityCreated(Bundle savedInstanceState) {
         super.onActivityCreated(savedInstanceState);
 
+        // This races when multiple Fragments are created. That's okay: one
+        // will win, and thereafter, all will be okay. If we create and then
+        // drop an instance the shared SharedPreferences backing all the
+        // instances will maintain the state for us. Since everything happens on
+        // the UI thread, this doesn't even need to be volatile.
+        if (sState == null) {
+            sState = new RemoteTabsExpandableListState(GeckoSharedPrefs.forProfile(getActivity()));
+        }
+
         // Intialize adapter
         mAdapter = new RemoteTabsExpandableListAdapter(R.layout.home_remote_tabs_group, R.layout.home_remote_tabs_child, null);
         mList.setAdapter(mAdapter);
@@ -176,8 +196,15 @@ public class RemoteTabsExpandableListFragment extends HomeFragment {
 
     private void updateUiFromClients(List<RemoteClient> clients) {
         if (clients != null && !clients.isEmpty()) {
-            for (int i = 0; i < mList.getExpandableListAdapter().getGroupCount(); i++) {
+            // No sense crashing if we've made an error.
-                mList.expandGroup(i);
+            int groupCount = Math.min(mList.getExpandableListAdapter().getGroupCount(), clients.size());
+            for (int i = 0; i < groupCount; i++) {
+                final RemoteClient client = clients.get(i);
+                if (sState.isClientCollapsed(client.guid)) {
+                    mList.collapseGroup(i);
+                } else {
+                    mList.expandGroup(i);
+                }
             }
             return;
         }

mobile/android/base/home/RemoteTabsExpandableListState.java

@@ -0,0 +1,139 @@
+/* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.gecko.home;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import org.mozilla.gecko.util.PrefUtils;
+
+import android.content.SharedPreferences;
+import android.content.SharedPreferences.Editor;
+
+/**
+ * Encapsulate visual state maintained by the Remote Tabs home panel.
+ * <p>
+ * This state should persist across database updates by Sync and the like. This
+ * state could be stored in a separate "clients_metadata" table and served by
+ * the Tabs provider, but that is heavy-weight for what we want to achieve. Such
+ * a scheme would require either an expensive table join, or a tricky
+ * co-ordination between multiple cursors. In contrast, this is easy and cheap
+ * enough to do on the main thread.
+ * <p>
+ * This state is "per SharedPreferences" object. In practice, there should exist
+ * one state object per Gecko Profile; since we can't change profiles without
+ * killing our process, this can be a static singleton.
+ */
+public class RemoteTabsExpandableListState {
+    private static final String PREF_COLLAPSED_CLIENT_GUIDS = "remote_tabs_collapsed_client_guids";
+    private static final String PREF_HIDDEN_CLIENT_GUIDS = "remote_tabs_hidden_client_guids";
+
+    protected final SharedPreferences sharedPrefs;
+
+    // Synchronized by the state instance. The default is to expand a clients
+    // tabs, so "not present" means "expanded".
+    // Only accessed from the UI thread.
+    protected final Set<String> collapsedClients;
+
+    // Synchronized by the state instance. The default is to show a client, so
+    // "not present" means "shown".
+    // Only accessed from the UI thread.
+    protected final Set<String> hiddenClients;
+
+    public RemoteTabsExpandableListState(SharedPreferences sharedPrefs) {
+        if (null == sharedPrefs) {
+            throw new IllegalArgumentException("sharedPrefs must not be null");
+        }
+        this.sharedPrefs = sharedPrefs;
+
+        this.collapsedClients = getStringSet(PREF_COLLAPSED_CLIENT_GUIDS);
+        this.hiddenClients = getStringSet(PREF_HIDDEN_CLIENT_GUIDS);
+    }
+
+    /**
+     * Extract a string set from shared preferences.
+     * <p>
+     * Nota bene: it is not OK to modify the set returned by {@link SharedPreferences#getStringSet(String, Set)}.
+     *
+     * @param pref to read from.
+     * @returns string set; never null.
+     */
+    protected Set<String> getStringSet(String pref) {
+        final Set<String> loaded = PrefUtils.getStringSet(sharedPrefs, pref, null);
+        if (loaded != null) {
+            return new HashSet<String>(loaded);
+        } else {
+            return new HashSet<String>();
+        }
+    }
+
+    /**
+     * Update client membership in a set.
+     *
+     * @param pref
+     *            to write updated set to.
+     * @param clients
+     *            set to update membership in.
+     * @param clientGuid
+     *            to update membership of.
+     * @param isMember
+     *            whether the client is a member of the set.
+     * @return true if the set of clients was modified.
+     */
+    protected boolean updateClientMembership(String pref, Set<String> clients, String clientGuid, boolean isMember) {
+        final boolean modified;
+        if (isMember) {
+            modified = clients.add(clientGuid);
+        } else {
+            modified = clients.remove(clientGuid);
+        }
+
+        if (modified) {
+            // This starts an asynchronous write. We don't care if we drop the
+            // write, and we don't really care if we race between writes, since
+            // we will return results from our in-memory cache.
+            final Editor editor = sharedPrefs.edit();
+            PrefUtils.putStringSet(editor, pref, clients);
+            editor.apply();
+        }
+
+        return modified;
+    }
+
+    /**
+     * Mark a client as collapsed.
+     *
+     * @param clientGuid
+     *            to update.
+     * @param collapsed
+     *            whether the client is collapsed.
+     * @return true if the set of collapsed clients was modified.
+     */
+    protected synchronized boolean setClientCollapsed(String clientGuid, boolean collapsed) {
+        return updateClientMembership(PREF_COLLAPSED_CLIENT_GUIDS, collapsedClients, clientGuid, collapsed);
+    }
+
+    public synchronized boolean isClientCollapsed(String clientGuid) {
+        return collapsedClients.contains(clientGuid);
+    }
+
+    /**
+     * Mark a client as hidden.
+     *
+     * @param clientGuid
+     *            to update.
+     * @param hidden
+     *            whether the client is hidden.
+     * @return true if the set of hidden clients was modified.
+     */
+    protected synchronized boolean setClientHidden(String clientGuid, boolean hidden) {
+        return updateClientMembership(PREF_HIDDEN_CLIENT_GUIDS, hiddenClients, clientGuid, hidden);
+    }
+
+    public synchronized boolean isClientHidden(String clientGuid) {
+        return hiddenClients.contains(clientGuid);
+    }
+}

mobile/android/base/moz.build

@@ -294,6 +294,7 @@ gbjar.sources += [
     'home/ReadingListRow.java',
     'home/RecentTabsPanel.java',
     'home/RemoteTabsExpandableListFragment.java',
+    'home/RemoteTabsExpandableListState.java',
     'home/RemoteTabsPanel.java',
     'home/RemoteTabsStaticFragment.java',
     'home/SearchEngine.java',