Implement UserHistoryDictionary for each user account.

UserHistoryDictionary currently uses locale to determine the
UserHistoryDictionary on the filesystem. With this change we
use the account name as well. Thus each UserHistoryDictionary
would following the following spec:

UserHistoryDictionary.<locale>.<account>.dict.
In case no account is selected, we default to the existing
spec:
UserHistoryDictionary.<locale>.dict

Example
UserHistoryDictionary.en_US.testaccount@example.com.dict

Bug: 18104749
Change-Id: Iab031e166b55cf2ded68275a7e9be22475737b37

2 files changed, 74 insertions, 11 deletions

diff --git a/java/src/com/android/inputmethod/latin/personalization/PersonalizationHelper.java b/java/src/com/android/inputmethod/latin/personalization/PersonalizationHelper.java
index ac2fc07c2..8c5eb0aa7 100644
--- a/java/src/com/android/inputmethod/latin/personalization/PersonalizationHelper.java
+++ b/java/src/com/android/inputmethod/latin/personalization/PersonalizationHelper.java
@@ -28,32 +28,45 @@ import java.util.Locale;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.TimeUnit;
 
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
+/**
+ * Helps handle and manage personalized dictionaries such as {@link UserHistoryDictionary} and
+ * {@link PersonalizationDictionary}.
+ */
 public class PersonalizationHelper {
     private static final String TAG = PersonalizationHelper.class.getSimpleName();
     private static final boolean DEBUG = false;
+
     private static final ConcurrentHashMap<String, SoftReference<UserHistoryDictionary>>
             sLangUserHistoryDictCache = new ConcurrentHashMap<>();
     private static final ConcurrentHashMap<String, SoftReference<PersonalizationDictionary>>
             sLangPersonalizationDictCache = new ConcurrentHashMap<>();
 
+    @Nonnull
     public static UserHistoryDictionary getUserHistoryDictionary(
-            final Context context, final Locale locale) {
-        final String localeStr = locale.toString();
+            final Context context, final Locale locale, @Nullable final String accountName) {
+        String lookupStr = locale.toString();
+        if (accountName != null) {
+            lookupStr += "." + accountName;
+        }
         synchronized (sLangUserHistoryDictCache) {
-            if (sLangUserHistoryDictCache.containsKey(localeStr)) {
+            if (sLangUserHistoryDictCache.containsKey(lookupStr)) {
                 final SoftReference<UserHistoryDictionary> ref =
-                        sLangUserHistoryDictCache.get(localeStr);
+                        sLangUserHistoryDictCache.get(lookupStr);
                 final UserHistoryDictionary dict = ref == null ? null : ref.get();
                 if (dict != null) {
                     if (DEBUG) {
-                        Log.w(TAG, "Use cached UserHistoryDictionary for " + locale);
+                        Log.d(TAG, "Use cached UserHistoryDictionary for " + locale +
+                                " & account" + accountName);
                     }
                     dict.reloadDictionaryIfRequired();
                     return dict;
                 }
             }
             final UserHistoryDictionary dict = new UserHistoryDictionary(context, locale);
-            sLangUserHistoryDictCache.put(localeStr, new SoftReference<>(dict));
+            sLangUserHistoryDictCache.put(lookupStr, new SoftReference<>(dict));
             return dict;
         }
     }
diff --git a/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionary.java b/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionary.java
index 58782c646..946835cbc 100644
--- a/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionary.java
+++ b/java/src/com/android/inputmethod/latin/personalization/UserHistoryDictionary.java
@@ -17,30 +17,73 @@
 package com.android.inputmethod.latin.personalization;
 
 import android.content.Context;
+import android.content.SharedPreferences;
+import android.preference.PreferenceManager;
 
 import com.android.inputmethod.annotations.ExternallyReferenced;
+import com.android.inputmethod.annotations.UsedForTesting;
 import com.android.inputmethod.latin.Dictionary;
 import com.android.inputmethod.latin.ExpandableBinaryDictionary;
 import com.android.inputmethod.latin.NgramContext;
 import com.android.inputmethod.latin.common.Constants;
+import com.android.inputmethod.latin.define.ProductionFlags;
+import com.android.inputmethod.latin.settings.LocalSettingsConstants;
 import com.android.inputmethod.latin.utils.DistracterFilter;
 
 import java.io.File;
 import java.util.Locale;
 
 import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
 
 /**
  * Locally gathers stats about the words user types and various other signals like auto-correction
  * cancellation or manual picks. This allows the keyboard to adapt to the typist over time.
  */
 public class UserHistoryDictionary extends DecayingExpandableBinaryDictionaryBase {
-    /* package */ static final String NAME = UserHistoryDictionary.class.getSimpleName();
+    static final String NAME = UserHistoryDictionary.class.getSimpleName();
 
     // TODO: Make this constructor private
-    /* package */ UserHistoryDictionary(final Context context, final Locale locale) {
-        super(context, getDictName(NAME, locale, null /* dictFile */), locale,
-                Dictionary.TYPE_USER_HISTORY, null /* dictFile */);
+    UserHistoryDictionary(final Context context, final Locale locale) {
+        super(context,
+                getUserHistoryDictName(
+                        NAME,
+                        locale,
+                        null /* dictFile */,
+                        context),
+                locale,
+                Dictionary.TYPE_USER_HISTORY,
+                null /* dictFile */);
+    }
+
+    /**
+     * @returns the name of the {@link UserHistoryDictionary}.
+     */
+    @UsedForTesting
+    static String getUserHistoryDictName(final String name, final Locale locale,
+            @Nullable final File dictFile, final Context context) {
+        if (!ProductionFlags.ENABLE_PER_ACCOUNT_USER_HISTORY_DICTIONARY) {
+            return getDictName(name, locale, dictFile);
+        }
+        return getUserHistoryDictNamePerAccount(name, locale, dictFile, context);
+    }
+
+    /**
+     * Uses the currently signed in account to determine the dictionary name.
+     */
+    private static String getUserHistoryDictNamePerAccount(final String name, final Locale locale,
+            @Nullable final File dictFile, final Context context) {
+        if (dictFile != null) {
+            return dictFile.getName();
+        }
+        final SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
+        final String account = prefs.getString(LocalSettingsConstants.PREF_ACCOUNT_NAME,
+                null /* default */);
+        String dictName = name + "." + locale.toString();
+        if (account != null) {
+            dictName += "." + account;
+        }
+        return dictName;
     }
 
     // Note: This method is called by {@link DictionaryFacilitator} using Java reflection.
@@ -48,7 +91,14 @@ public class UserHistoryDictionary extends DecayingExpandableBinaryDictionaryBas
     @ExternallyReferenced
     public static UserHistoryDictionary getDictionary(final Context context, final Locale locale,
             final File dictFile, final String dictNamePrefix) {
-        return PersonalizationHelper.getUserHistoryDictionary(context, locale);
+        final String account;
+        if (ProductionFlags.ENABLE_PER_ACCOUNT_USER_HISTORY_DICTIONARY) {
+            account = PreferenceManager.getDefaultSharedPreferences(context)
+                    .getString(LocalSettingsConstants.PREF_ACCOUNT_NAME, null /* default */);
+        } else {
+            account = null;
+        }
+        return PersonalizationHelper.getUserHistoryDictionary(context, locale, account);
     }
 
     /**