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 /* 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.background.healthreport;

 import java.io.File;

 import java.util.Collection;

 import java.util.HashMap;

 import java.util.concurrent.ConcurrentHashMap;

 import java.util.concurrent.Executor;

 import java.util.concurrent.Executors;

 import org.json.JSONObject;

 import org.mozilla.gecko.background.common.DateUtils;

 import org.mozilla.gecko.background.common.log.Logger;

 import org.mozilla.gecko.background.healthreport.HealthReportStorage.MeasurementFields.FieldSpec;

 import android.content.ContentValues;

 import android.content.Context;

 import android.content.ContextWrapper;

 import android.database.Cursor;

 import android.database.SQLException;

 import android.database.sqlite.SQLiteConstraintException;

 import android.database.sqlite.SQLiteDatabase;

 import android.database.sqlite.SQLiteOpenHelper;

 import android.os.Build;

 import android.util.SparseArray;

 /**

  * <code>HealthReportDatabaseStorage</code> provides an interface on top of

  * SQLite storage for Health Report data. It exposes methods for management of

  * environments, measurements, fields, and values, and a cursor-based API for

  * querying.

  *

  * Health Report data is structured as follows.

  *

  * Records are primarily broken down by date, at day granularity. Each day's data

  * is then split according to environment. An environment is a collection of

  * constant attributes, such as version and processor; if one of these attributes

  * changes, a new environment becomes active.

  *

  * Environments are identified by a stable hash of their attributes.

  *

  * The database includes a persistent numeric identifier for each environment. Create

  * or fetch this identifier via:

  *

  * <pre>

  *  final Environment environment = storage.getEnvironment();

  *  // Init the environment now.

  *  String envHash = environment.getHash();

  *  int env = environment.register();

  * </pre>

  *

  * You can safely cache this environment identifier for the life of the database.

  *

  * Orthogonal to environments are measurements. Each measurement is a named and

  * versioned scope for a collection of fields. It is assumed that if a measurement

  * with the given name and version is known to the database, then all of its fields

  * are also known; if you change the collection of fields in the measurement, the

  * measurement's version must be incremented, too.

  *

  * As with environments, measurements have an internal numeric identifier.

  *

  * Calling code should initialize its measurements as follows:

  *

  * <pre>

  *   public static class FooFieldsV1 implements MeasurementFields {

  *     {@literal @}Override

  *     public Iterable<String> getFields() {

  *       ArrayList<String> fields = new ArrayList<String>();

  *       fields.add("bar");

  *       fields.add("baz");

  *       return fields;

  *     }

  *   }

  *

  *   storage.beginInitialization();

  *

  *   try {

  *     storage.ensureMeasurementInitialized("org.mozilla.fooProvider.fooMeasurement",

  *                                          1, new FooFieldsV1());

  *     storage.finishInitialization();

  *   } catch (Exception e) {

  *     storage.abortInitialization();

  *   }

  * </pre>

  *

  * Measurements have fields. Fields can conceptually be divided into "daily last"

  * (we only care about the last value), "daily counter" (increments per day),

  * "daily discrete" (multiple records per day). Simply call the correct method for each.

  *

  * To do so you need a field ID, to avoid constant costly string lookups. You can get

  * this value from storage:

  *

  * <pre>

  *   Field field = storage.getField("org.mozilla.fooProvider.fooMeasurement", 1, "bar");

  *   int fieldID = field.getID();

  * </pre>

  *

  * This lookup is cached, and so is relatively inexpensive.

  *

  * You can then do something like the following:

  *

  * <pre>

  *   storage.recordDailyLast(storage.getDay(), env, fieldID, "last value");

  * </pre>

  *

  * or equivalently for numeric values, discrete or counters, etc.

  *

  * To retrieve values, use {@link #getRawEventsSince(long)}.

  *

  * For safety, perform operations on the storage executor thread:

  *

  * <pre>

  *   storage.enqueueOperation(runnable);

  * </pre>

  */

 public class HealthReportDatabaseStorage implements HealthReportStorage {

   private static final String WHERE_DATE_AND_ENV_AND_FIELD = "date = ? AND env = ? AND field = ?";

   public static final String[] COLUMNS_HASH = new String[] {"hash"};

   public static final String[] COLUMNS_DATE_ENV_FIELD_VALUE = new String[] {"date", "env", "field", "value"};

   public static final String[] COLUMNS_DATE_ENVSTR_M_MV_F_VALUE = new String[] {

     "date", "environment", "measurement_name", "measurement_version",

     "field_name", "field_flags", "value"

   };

   private static final String[] COLUMNS_ENVIRONMENT_DETAILS = new String[] {

       "id", "version", "hash",

       "profileCreation", "cpuCount", "memoryMB",

       "isBlocklistEnabled", "isTelemetryEnabled", "extensionCount",

       "pluginCount", "themeCount",

       "architecture", "sysName", "sysVersion", "vendor", "appName", "appID",

       "appVersion", "appBuildID", "platformVersion", "platformBuildID", "os",

       "xpcomabi", "updateChannel",

       "distribution", "osLocale", "appLocale", "acceptLangSet",

       // Joined to the add-ons table.

       "addonsBody"

   };

   public static final String[] COLUMNS_MEASUREMENT_DETAILS = new String[] {"id", "name", "version"};

   public static final String[] COLUMNS_MEASUREMENT_AND_FIELD_DETAILS =

       new String[] {"measurement_name", "measurement_id", "measurement_version",

                     "field_name", "field_id", "field_flags"};

   private static final String[] COLUMNS_VALUE = new String[] {"value"};

   private static final String[] COLUMNS_ID = new String[] {"id"};

   private static final String EVENTS_TEXTUAL = "events_textual";

   private static final String EVENTS_INTEGER = "events_integer";

   protected static final String DB_NAME = "health.db";

   private static final String LOG_TAG = "HealthReportStorage";

   private final Executor executor = Executors.newSingleThreadExecutor();

   @Override

   public void enqueueOperation(Runnable runnable) {

     executor.execute(runnable);

   }

   public HealthReportDatabaseStorage(final Context context,

                                      final File profileDirectory) {

     this.helper = new HealthReportSQLiteOpenHelper(context, profileDirectory,

                                                    DB_NAME);

     executor.execute(new Runnable() {

       @Override

       public void run() {

         Logger.setThreadLogTag(HealthReportConstants.GLOBAL_LOG_TAG);

         Logger.debug(LOG_TAG, "Creating HealthReportDatabaseStorage.");

       }

     });

   }

   @Override

   public void close() {

     this.helper.close();

     this.fields.clear();

     this.envs.clear();

     this.measurementVersions.clear();

   }

   protected final HealthReportSQLiteOpenHelper helper;

   public static class HealthReportSQLiteOpenHelper extends SQLiteOpenHelper {

     public static final int CURRENT_VERSION = 6;

     public static final String LOG_TAG = "HealthReportSQL";

     /**

      * A little helper to avoid SQLiteOpenHelper misbehaving on Android 2.1.

      * Partly cribbed from

      * <http://stackoverflow.com/questions/5332328/sqliteopenhelper-problem-with-fully-qualified-db-path-name>.

      */

     public static class AbsolutePathContext extends ContextWrapper {

       private final File parent;

       public AbsolutePathContext(Context base, File parent) {

         super(base);

         this.parent = parent;

       }

       @Override

       public File getDatabasePath(String name) {

         return new File(getAbsolutePath(parent, name));

       }

       // Won't be called after API v11, but we can't override the version that

       // *is* called and still support v8.

       // Instead we check the version code in the HealthReportSQLiteOpenHelper

       // constructor, and only use this workaround if we need to.

       @Override

       public SQLiteDatabase openOrCreateDatabase(String name,

                                                  int mode,

                                                  SQLiteDatabase.CursorFactory factory) {

         final File path = getDatabasePath(name);

         Logger.pii(LOG_TAG, "Opening database through absolute path " + path.getAbsolutePath());

         return SQLiteDatabase.openOrCreateDatabase(path, null);

       }

     }

     public static String getAbsolutePath(File parent, String name) {

       return parent.getAbsolutePath() + File.separator + name;

     }

     public static boolean CAN_USE_ABSOLUTE_DB_PATH = (Build.VERSION.SDK_INT >= Build.VERSION_CODES.FROYO);

     public HealthReportSQLiteOpenHelper(Context context, File profileDirectory, String name) {

       this(context, profileDirectory, name, CURRENT_VERSION);

     }

     // For testing DBs of different versions.

     public HealthReportSQLiteOpenHelper(Context context, File profileDirectory, String name, int version) {

       super(

           (CAN_USE_ABSOLUTE_DB_PATH ? context : new AbsolutePathContext(context, profileDirectory)),

           (CAN_USE_ABSOLUTE_DB_PATH ? getAbsolutePath(profileDirectory, name) : name),

           null,

           version);

       if (CAN_USE_ABSOLUTE_DB_PATH) {

         Logger.pii(LOG_TAG, "Opening: " + getAbsolutePath(profileDirectory, name));

       }

     }

     @Override

     public void onCreate(SQLiteDatabase db) {

       db.execSQL("CREATE TABLE addons (id INTEGER PRIMARY KEY AUTOINCREMENT, " +

                  "                     body TEXT, " +

                  "                     UNIQUE (body) " +

                  ")");

       // N.B., hash collisions can occur across versions. In that case, the system

       // is likely to persist the original environment version.

       db.execSQL("CREATE TABLE environments (id INTEGER PRIMARY KEY AUTOINCREMENT, " +

                  "                           version INTEGER, " +

                  "                           hash TEXT, " +

                  "                           profileCreation INTEGER, " +

                  "                           cpuCount        INTEGER, " +

                  "                           memoryMB        INTEGER, " +

                  "                           isBlocklistEnabled INTEGER, " +

                  "                           isTelemetryEnabled INTEGER, " +

                  "                           extensionCount     INTEGER, " +

                  "                           pluginCount        INTEGER, " +

                  "                           themeCount         INTEGER, " +

                  "                           architecture    TEXT, " +

                  "                           sysName         TEXT, " +

                  "                           sysVersion      TEXT, " +

                  "                           vendor          TEXT, " +

                  "                           appName         TEXT, " +

                  "                           appID           TEXT, " +

                  "                           appVersion      TEXT, " +

                  "                           appBuildID      TEXT, " +

                  "                           platformVersion TEXT, " +

                  "                           platformBuildID TEXT, " +

                  "                           os              TEXT, " +

                  "                           xpcomabi        TEXT, " +

                  "                           updateChannel   TEXT, " +

                  "                           distribution    TEXT, " +

                  "                           osLocale        TEXT, " +

                  "                           appLocale       TEXT, " +

                  "                           acceptLangSet   INTEGER, " +

                  "                           addonsID        INTEGER, " +

                  "                           FOREIGN KEY (addonsID) REFERENCES addons(id) ON DELETE RESTRICT, " +

                  "                           UNIQUE (hash) " +

                  ")");

       db.execSQL("CREATE TABLE measurements (id INTEGER PRIMARY KEY AUTOINCREMENT, " +

                  "                           name TEXT, " +

                  "                           version INTEGER, " +

                  "                           UNIQUE (name, version) " +

                  ")");

       db.execSQL("CREATE TABLE fields (id INTEGER PRIMARY KEY AUTOINCREMENT, " +

                  "                     measurement INTEGER, " +

                  "                     name TEXT, " +

                  "                     flags INTEGER, " +

                  "                     FOREIGN KEY (measurement) REFERENCES measurements(id) ON DELETE CASCADE, " +

                  "                     UNIQUE (measurement, name)" +

                  ")");

       db.execSQL("CREATE TABLE " + EVENTS_INTEGER + "(" +

                  "                 date  INTEGER, " +

                  "                 env   INTEGER, " +

                  "                 field INTEGER, " +

                  "                 value INTEGER, " +

                  "                 FOREIGN KEY (field) REFERENCES fields(id) ON DELETE CASCADE, " +

                  "                 FOREIGN KEY (env) REFERENCES environments(id) ON DELETE CASCADE" +

                  ")");

       db.execSQL("CREATE TABLE " + EVENTS_TEXTUAL + "(" +

                  "                 date  INTEGER, " +

                  "                 env   INTEGER, " +

                  "                 field INTEGER, " +

                  "                 value TEXT, " +

                  "                 FOREIGN KEY (field) REFERENCES fields(id) ON DELETE CASCADE, " +

                  "                 FOREIGN KEY (env) REFERENCES environments(id) ON DELETE CASCADE" +

                  ")");

       db.execSQL("CREATE INDEX idx_events_integer_date_env_field ON events_integer (date, env, field)");

       db.execSQL("CREATE INDEX idx_events_textual_date_env_field ON events_textual (date, env, field)");

       db.execSQL("CREATE VIEW events AS " +

                  "SELECT date, env, field, value FROM " + EVENTS_INTEGER + " " +

                  "UNION ALL " +

                  "SELECT date, env, field, value FROM " + EVENTS_TEXTUAL);

       db.execSQL("CREATE VIEW named_events AS " +

                  "SELECT date, " +

                  "       environments.hash AS environment, " +

                  "       measurements.name AS measurement_name, " +

                  "       measurements.version AS measurement_version, " +

                  "       fields.name AS field_name, " +

                  "       fields.flags AS field_flags, " +

                  "       value FROM " +

                  "events JOIN environments ON events.env = environments.id " +

                  "       JOIN fields ON events.field = fields.id " +

                  "       JOIN measurements ON fields.measurement = measurements.id");

       db.execSQL("CREATE VIEW named_fields AS " +

                  "SELECT measurements.name AS measurement_name, " +

                  "       measurements.id AS measurement_id, " +

                  "       measurements.version AS measurement_version, " +

                  "       fields.name AS field_name, " +

                  "       fields.id AS field_id, " +

                  "       fields.flags AS field_flags " +

                  "FROM fields JOIN measurements ON fields.measurement = measurements.id");

       db.execSQL("CREATE VIEW current_measurements AS " +

                  "SELECT name, MAX(version) AS version FROM measurements GROUP BY name");

       createAddonsEnvironmentsView(db);

     }

     @Override

     public void onOpen(SQLiteDatabase db) {

       if (!db.isReadOnly()) {

         db.execSQL("PRAGMA foreign_keys=ON;");

       }

     }

     private void createAddonsEnvironmentsView(SQLiteDatabase db) {

       db.execSQL("CREATE VIEW environments_with_addons AS " +

           "SELECT e.id AS id, " +

           "       e.version AS version, " +

           "       e.hash AS hash, " +

           "       e.profileCreation AS profileCreation, " +

           "       e.cpuCount AS cpuCount, " +

           "       e.memoryMB AS memoryMB, " +

           "       e.isBlocklistEnabled AS isBlocklistEnabled, " +

           "       e.isTelemetryEnabled AS isTelemetryEnabled, " +

           "       e.extensionCount AS extensionCount, " +

           "       e.pluginCount AS pluginCount, " +

           "       e.themeCount AS themeCount, " +

           "       e.architecture AS architecture, " +

           "       e.sysName AS sysName, " +

           "       e.sysVersion AS sysVersion, " +

           "       e.vendor AS vendor, " +

           "       e.appName AS appName, " +

           "       e.appID AS appID, " +

           "       e.appVersion AS appVersion, " +

           "       e.appBuildID AS appBuildID, " +

           "       e.platformVersion AS platformVersion, " +

           "       e.platformBuildID AS platformBuildID, " +

           "       e.os AS os, " +

           "       e.xpcomabi AS xpcomabi, " +

           "       e.updateChannel AS updateChannel, " +

           "       e.distribution AS distribution, " +

           "       e.osLocale AS osLocale, " +

           "       e.appLocale AS appLocale, " +

           "       e.acceptLangSet AS acceptLangSet, " +

           "       addons.body AS addonsBody " +

           "FROM environments AS e, addons " +

           "WHERE e.addonsID = addons.id");

     }

     private void upgradeDatabaseFrom2To3(SQLiteDatabase db) {

       db.execSQL("CREATE TABLE addons (id INTEGER PRIMARY KEY AUTOINCREMENT, " +

                  "                     body TEXT, " +

                  "                     UNIQUE (body) " +

                  ")");

       db.execSQL("ALTER TABLE environments ADD COLUMN addonsID INTEGER REFERENCES addons(id) ON DELETE RESTRICT");

       createAddonsEnvironmentsView(db);

     }

     private void upgradeDatabaseFrom3To4(SQLiteDatabase db) {

       // Update search measurements to use a different type.

       db.execSQL("UPDATE OR IGNORE fields SET flags = " + Field.TYPE_COUNTED_STRING_DISCRETE +

                  " WHERE measurement IN (SELECT id FROM measurements WHERE name = 'org.mozilla.searches.counts')");

     }

     private void upgradeDatabaseFrom4to5(SQLiteDatabase db) {

       // Delete NULL in addons.body, which appeared as a result of Bug 886156. Note that the

       // foreign key constraint, "ON DELETE RESTRICT", may be violated, but since onOpen() is

       // called after this method, foreign keys are not yet enabled and constraints can be broken.

       db.delete("addons", "body IS NULL", null);

       // Purge any data inconsistent with foreign key references (which may have appeared before

       // foreign keys were enabled in Bug 900289).

       db.delete("fields", "measurement NOT IN (SELECT id FROM measurements)", null);

       db.delete("environments", "addonsID NOT IN (SELECT id from addons)", null);

       db.delete(EVENTS_INTEGER, "env NOT IN (SELECT id FROM environments)", null);

       db.delete(EVENTS_TEXTUAL, "env NOT IN (SELECT id FROM environments)", null);

       db.delete(EVENTS_INTEGER, "field NOT IN (SELECT id FROM fields)", null);

       db.delete(EVENTS_TEXTUAL, "field NOT IN (SELECT id FROM fields)", null);

     }

     private void upgradeDatabaseFrom5to6(SQLiteDatabase db) {

       db.execSQL("DROP VIEW environments_with_addons");

       // Add version to environment (default to 1).

       db.execSQL("ALTER TABLE environments ADD COLUMN version INTEGER DEFAULT 1");

       // Add fields to environment (default to empty string).

       db.execSQL("ALTER TABLE environments ADD COLUMN distribution TEXT DEFAULT ''");

       db.execSQL("ALTER TABLE environments ADD COLUMN osLocale TEXT DEFAULT ''");

       db.execSQL("ALTER TABLE environments ADD COLUMN appLocale TEXT DEFAULT ''");

       db.execSQL("ALTER TABLE environments ADD COLUMN acceptLangSet INTEGER DEFAULT 0");

       // Recreate view.

       createAddonsEnvironmentsView(db);

     }

     @Override

     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

       if (oldVersion >= newVersion) {

         return;

       }

       Logger.info(LOG_TAG, "onUpgrade: from " + oldVersion + " to " + newVersion + ".");

       try {

         switch (oldVersion) {

         case 2:

           upgradeDatabaseFrom2To3(db);

         case 3:

           upgradeDatabaseFrom3To4(db);

         case 4:

           upgradeDatabaseFrom4to5(db);

         case 5:

           upgradeDatabaseFrom5to6(db);

         }

       } catch (Exception e) {

         Logger.error(LOG_TAG, "Failure in onUpgrade.", e);

         throw new RuntimeException(e);

       }

    }

     public void deleteEverything() {

       final SQLiteDatabase db = this.getWritableDatabase();

       Logger.info(LOG_TAG, "Deleting everything.");

       db.beginTransaction();

       try {

         // Cascade will clear the rest.

         db.delete("measurements", null, null);

         db.delete("environments", null, null);

         db.delete("addons", null, null);

         db.setTransactionSuccessful();

         Logger.info(LOG_TAG, "Deletion successful.");

       } finally {

         db.endTransaction();

       }

     }

   }

   public class DatabaseField extends Field {

     public DatabaseField(String mName, int mVersion, String fieldName) {

       this(mName, mVersion, fieldName, UNKNOWN_TYPE_OR_FIELD_ID, UNKNOWN_TYPE_OR_FIELD_ID);

     }

     public DatabaseField(String mName, int mVersion, String fieldName, int flags) {

       this(mName, mVersion, fieldName, UNKNOWN_TYPE_OR_FIELD_ID, flags);

     }

     public DatabaseField(String mName, int mVersion, String fieldName, int fieldID, int flags) {

       super(mName, mVersion, fieldName, flags);

       this.fieldID = fieldID;

     }

     private void loadFlags() {

       if (this.flags == UNKNOWN_TYPE_OR_FIELD_ID) {

         if (this.fieldID == UNKNOWN_TYPE_OR_FIELD_ID) {

           this.getID();

         }

         this.flags = integerQuery("fields", "flags", "id = ?", new String[] { Integer.toString(this.fieldID, 10) }, -1);

       }

     }

     @Override

     public synchronized boolean isIntegerField() {

       loadFlags();

       return super.isIntegerField();

     }

     @Override

     public synchronized boolean isStringField() {

       loadFlags();

       return super.isStringField();

     }

     @Override

     public synchronized boolean isDiscreteField() {

       loadFlags();

       return super.isDiscreteField();

     }

     @Override

     public synchronized int getID() throws IllegalStateException {

       if (this.fieldID == UNKNOWN_TYPE_OR_FIELD_ID) {

         this.fieldID = integerQuery("named_fields", "field_id",

                                     "measurement_name = ? AND measurement_version = ? AND field_name = ?",

                                     new String[] {measurementName, measurementVersion, fieldName},

                                     UNKNOWN_TYPE_OR_FIELD_ID);

         if (this.fieldID == UNKNOWN_TYPE_OR_FIELD_ID) {

           throw new IllegalStateException("No field with name " + fieldName +

                                           " (" + measurementName + ", " + measurementVersion + ")");

         }

       }

       return this.fieldID;

     }

   }

   // `envs` and `fields` look similar, but they are touched differently and

   // store differently stable kinds of data, hence type difference.

   // Note that we don't pre-populate the environment cache. We'll typically only

   // handle one per session.

   //

   // protected for testing purposes only.

   protected final ConcurrentHashMap<String, Integer> envs = new ConcurrentHashMap<String, Integer>();

   /**

    * An {@link Environment} that knows how to persist to and from our database.

    */

   public static class DatabaseEnvironment extends Environment {

     protected final HealthReportDatabaseStorage storage;

     @Override

     public int register() {

       final String h = getHash();

       if (storage.envs.containsKey(h)) {

         this.id = storage.envs.get(h);

         return this.id;

       }

       // Otherwise, add data and hash to the DB.

       ContentValues v = new ContentValues();

       v.put("version", version);

       v.put("hash", h);

       v.put("profileCreation", profileCreation);

       v.put("cpuCount", cpuCount);

       v.put("memoryMB", memoryMB);

       v.put("isBlocklistEnabled", isBlocklistEnabled);

       v.put("isTelemetryEnabled", isTelemetryEnabled);

       v.put("extensionCount", extensionCount);

       v.put("pluginCount", pluginCount);

       v.put("themeCount", themeCount);

       v.put("architecture", architecture);

       v.put("sysName", sysName);

       v.put("sysVersion", sysVersion);

       v.put("vendor", vendor);

       v.put("appName", appName);

       v.put("appID", appID);

       v.put("appVersion", appVersion);

       v.put("appBuildID", appBuildID);

       v.put("platformVersion", platformVersion);

       v.put("platformBuildID", platformBuildID);

       v.put("os", os);

       v.put("xpcomabi", xpcomabi);

       v.put("updateChannel", updateChannel);

       v.put("distribution", distribution);

       v.put("osLocale", osLocale);

       v.put("appLocale", appLocale);

       v.put("acceptLangSet", acceptLangSet);

       final SQLiteDatabase db = storage.helper.getWritableDatabase();

       // If we're not already, we want all of our inserts to be in a transaction.

       boolean newTransaction = !db.inTransaction();

       // Insert, with a little error handling to populate the cache in case of

       // omission and consequent collision.

       //

       // We would like to hang a trigger off a view here, and just use that for

       // inserts. But triggers don't seem to correctly update the last inserted

       // ID, so Android's insertOrThrow method returns -1.

       //

       // Instead, we go without the trigger, simply running the inserts ourselves.

       //

       // insertWithOnConflict doesn't work as documented: <http://stackoverflow.com/questions/11328877/android-sqllite-on-conflict-ignore-is-ignored-in-ics/11424150>.

       // So we do this the hard way.

       // We presume that almost every get will hit the cache (except for the first, obviously), so we

       // bias here towards inserts for the environments.

       // For add-ons we assume that different environments will share add-ons, so we query first.

       final String addonsJSON = getNormalizedAddonsJSON();

       if (newTransaction) {

         db.beginTransaction();

       }

       try {

         int addonsID = ensureAddons(db, addonsJSON);

         v.put("addonsID", addonsID);

         try {

           int inserted = (int) db.insertOrThrow("environments", null, v);

           Logger.debug(LOG_TAG, "Inserted ID: " + inserted + " for hash " + h);

           if (inserted == -1) {

             throw new SQLException("Insert returned -1!");

           }

           this.id = inserted;

           storage.envs.put(h, this.id);

           if (newTransaction) {

             db.setTransactionSuccessful();

           }

           return inserted;

         } catch (SQLException e) {

           // The inserter should take care of updating `envs`. But if it

           // doesn't...

           Cursor c = db.query("environments", COLUMNS_ID, "hash = ?",

                               new String[] { h }, null, null, null);

           try {

             if (!c.moveToFirst()) {

               throw e;

             }

             this.id = (int) c.getLong(0);

             Logger.debug(LOG_TAG, "Found " + this.id + " for hash " + h);

             storage.envs.put(h, this.id);

             if (newTransaction) {

               db.setTransactionSuccessful();

             }

             return this.id;

           } finally {

             c.close();

           }

         }

       } finally {

         if (newTransaction) {

           db.endTransaction();

         }

       }

     }

     protected static int ensureAddons(SQLiteDatabase db, String json) {

       Cursor c = db.query("addons", COLUMNS_ID, "body = ?",

                           new String[] { (json == null) ? "null" : json }, null, null, null);

       try {

         if (c.moveToFirst()) {

           return c.getInt(0);

         }

         ContentValues values = new ContentValues();

         values.put("body", json);

         return (int) db.insert("addons", null, values);

       } finally {

         c.close();

       }

     }

     public void init(ContentValues v) {

       version         = v.containsKey("version") ? v.getAsInteger("version") : Environment.CURRENT_VERSION;

       profileCreation = v.getAsInteger("profileCreation");

       cpuCount        = v.getAsInteger("cpuCount");

       memoryMB        = v.getAsInteger("memoryMB");

       isBlocklistEnabled = v.getAsInteger("isBlocklistEnabled");

       isTelemetryEnabled = v.getAsInteger("isTelemetryEnabled");

       extensionCount     = v.getAsInteger("extensionCount");

       pluginCount        = v.getAsInteger("pluginCount");

       themeCount         = v.getAsInteger("themeCount");

       architecture    = v.getAsString("architecture");

       sysName         = v.getAsString("sysName");

       sysVersion      = v.getAsString("sysVersion");

       vendor          = v.getAsString("vendor");

       appName         = v.getAsString("appName");

       appID           = v.getAsString("appID");

       appVersion      = v.getAsString("appVersion");

       appBuildID      = v.getAsString("appBuildID");

       platformVersion = v.getAsString("platformVersion");

       platformBuildID = v.getAsString("platformBuildID");

       os              = v.getAsString("os");

       xpcomabi        = v.getAsString("xpcomabi");

       updateChannel   = v.getAsString("updateChannel");

       distribution    = v.getAsString("distribution");

       osLocale        = v.getAsString("osLocale");

       appLocale       = v.getAsString("appLocale");

       acceptLangSet   = v.getAsInteger("acceptLangSet");

       try {

         setJSONForAddons(v.getAsString("addonsBody"));

       } catch (Exception e) {

         // Nothing we can do.

       }

       this.hash = null;

       this.id = -1;

     }

     /**

      * Fill ourselves with data from the DB, then advance the cursor.

      *

      * @param cursor a {@link Cursor} pointing at a record to load.

      * @return true if the cursor was successfully advanced.

      */

     public boolean init(Cursor cursor) {

       int i = 0;

       this.id         = cursor.getInt(i++);

       this.version    = cursor.getInt(i++);

       this.hash       = cursor.getString(i++);

       profileCreation = cursor.getInt(i++);

       cpuCount        = cursor.getInt(i++);

       memoryMB        = cursor.getInt(i++);

       isBlocklistEnabled = cursor.getInt(i++);

       isTelemetryEnabled = cursor.getInt(i++);

       extensionCount     = cursor.getInt(i++);

       pluginCount        = cursor.getInt(i++);

       themeCount         = cursor.getInt(i++);

       architecture    = cursor.getString(i++);

       sysName         = cursor.getString(i++);

       sysVersion      = cursor.getString(i++);

       vendor          = cursor.getString(i++);

       appName         = cursor.getString(i++);

       appID           = cursor.getString(i++);

       appVersion      = cursor.getString(i++);

       appBuildID      = cursor.getString(i++);

       platformVersion = cursor.getString(i++);

       platformBuildID = cursor.getString(i++);

       os              = cursor.getString(i++);

       xpcomabi        = cursor.getString(i++);

       updateChannel   = cursor.getString(i++);

       distribution    = cursor.getString(i++);

       osLocale        = cursor.getString(i++);

       appLocale       = cursor.getString(i++);

       acceptLangSet   = cursor.getInt(i++);

       try {

         setJSONForAddons(cursor.getBlob(i++));

       } catch (Exception e) {

         // Nothing we can do.

       }

       return cursor.moveToNext();

     }

     public DatabaseEnvironment(HealthReportDatabaseStorage storage, Class<? extends EnvironmentAppender> appender) {

       super(appender);

       this.storage = storage;

     }

     public DatabaseEnvironment(HealthReportDatabaseStorage storage) {

       this.storage = storage;

     }

   }

   /**

    * Factory method. Returns a new {@link Environment} that callers can

    * populate and then register.

    */

   @Override

   public DatabaseEnvironment getEnvironment() {

     return new DatabaseEnvironment(this);

   }

   @Override

   public SparseArray<Environment> getEnvironmentRecordsByID() {

     final SQLiteDatabase db = this.helper.getReadableDatabase();

     Cursor c = db.query("environments_with_addons", COLUMNS_ENVIRONMENT_DETAILS, null, null, null, null, null);

     try {

       SparseArray<Environment> results = new SparseArray<Environment>();

       if (!c.moveToFirst()) {

         return results;

       }

       DatabaseEnvironment e = getEnvironment();

       while (e.init(c)) {

         results.put(e.id, e);

         e = getEnvironment();

       }

       results.put(e.id, e);

       return results;

     } finally {

       c.close();

     }

   }

   /**

    * Reverse lookup for an env. Only really used for tests: document generation

    * fetches all environments at once, and insertion only uses the integer key

    * that's returned during insertion.

    *

    * @param id

    *          the identifier for the environment.

    * @return a cursor over its details.

    */

   @Override

   public Cursor getEnvironmentRecordForID(int id) {

     final SQLiteDatabase db = this.helper.getReadableDatabase();

     return db.query("environments_with_addons", COLUMNS_ENVIRONMENT_DETAILS, "id = " + id, null, null, null, null);

   }

   @Override

   public SparseArray<String> getEnvironmentHashesByID() {

     final SQLiteDatabase db = this.helper.getReadableDatabase();

     Cursor c = db.query("environments", new String[] {"id", "hash"}, null, null, null, null, null);

     try {

       SparseArray<String> results = new SparseArray<String>();

       if (!c.moveToFirst()) {

         return results;

       }

       while (!c.isAfterLast()) {

         results.put(c.getInt(0), c.getString(1));

         c.moveToNext();

       }

       return results;

     } finally {

       c.close();

     }

   }

   /**

    * Cache the lookup from measurement and field specifier to field instance.

    * This allows us to memoize the field ID lookup, too.

    */

   private HashMap<String, Field> fields = new HashMap<String, Field>();

   private boolean fieldsCacheUpdated = false;

   private void invalidateFieldsCache() {

     synchronized (this.fields) {

       fieldsCacheUpdated = false;

     }

   }

   private String getFieldKey(String mName, int mVersion, String fieldName) {

     return mVersion + "." + mName + "/" + fieldName;

   }

   @Override

   public Field getField(String mName, int mVersion, String fieldName) {

     final String key = getFieldKey(mName, mVersion, fieldName);

     synchronized (fields) {

       if (fields.containsKey(key)) {

         return fields.get(key);

       }

       Field f = new DatabaseField(mName, mVersion, fieldName);

       fields.put(key, f);

       return f;

     }

   }

   private void populateFieldCache() {

     synchronized (fields) {

       if (fieldsCacheUpdated) {

         return;

       }

       fields.clear();

       Cursor c = getFieldVersions();

       try {

         if (!c.moveToFirst()) {

           return;

         }

         do {

           // We don't use the measurement ID here, so column 1 is unused.

           final String mName = c.getString(0);

           final int mVersion = c.getInt(2);

           final String fieldName = c.getString(3);

           final int fieldID = c.getInt(4);

           final int flags = c.getInt(5);

           final String key = getFieldKey(mName, mVersion, fieldName);

           Field f = new DatabaseField(mName, mVersion, fieldName, fieldID, flags);

           fields.put(key, f);

         } while (c.moveToNext());

         fieldsCacheUpdated = true;

       } finally {

         c.close();

       }

     }

   }

   /**

    * Return mappings from field ID to Field instance. Do so by looking in the DB.

    */

   @Override

   public SparseArray<Field> getFieldsByID() {

     final SparseArray<Field> out = new SparseArray<Field>();

     synchronized (fields) {

       populateFieldCache();

       Collection<Field> values = fields.values();

       for (Field field : values) {

         // Cache is up-to-date at this point, so we don't need to hit the DB.

         out.put(field.getID(), field);

       }

     }

     return out;

   }

   private final HashMap<String, Integer> measurementVersions = new HashMap<String, Integer>();

   private void populateMeasurementVersionsCache(SQLiteDatabase db) {

     HashMap<String, Integer> results = getIntegers(db, "current_measurements", "name", "version");

     if (results == null) {

       measurementVersions.clear();

       return;

     }

     synchronized (measurementVersions) {

       measurementVersions.clear();

       measurementVersions.putAll(results);

     }

   }

   /**

    * Return the version of the measurement for which the DB is currently configured, or

    * 0 if unknown.

    * @param measurement String measurement identifier.

    * @return Current version.

    */

   private int getMeasurementVersion(String measurement) {

     synchronized (measurementVersions) {

       if (measurementVersions.containsKey(measurement)) {

         return measurementVersions.get(measurement);

       }

       // This should never be necessary, unless the measurement does not exist.

       int value = integerQuery("measurements", "version", "name = ?", new String[] {measurement}, 0);

       measurementVersions.put(measurement, value);

       return value;

     }

   }

   /**

    * Inform the storage layer that fields for the given measurement have been updated

    * to this version.

    *

    * This should be one of the final calls in a configuration transaction.

    * Always call this inside a transaction.

    */

   private void notifyMeasurementVersionUpdated(String measurement, int version) {

     Logger.info(LOG_TAG, "Measurement " + measurement + " now at " + version);

     final SQLiteDatabase db = this.helper.getWritableDatabase();

     final ContentValues values = new ContentValues();

     values.put("name", measurement);

     values.put("version", version);

     synchronized (measurementVersions) {

       measurementVersions.put(measurement, version);

     }

     db.insertWithOnConflict("measurements", null, values, SQLiteDatabase.CONFLICT_IGNORE);

   }

   /**

    * Call in a transaction.

    * This method could race with other accesses, but (a) it's within a transaction,

    * (b) configuration should be single-threaded, (c) we initialize the cache up-front.

    */

   @Override

   public void ensureMeasurementInitialized(String measurement, int version, MeasurementFields fields) {

     final int currentVersion = getMeasurementVersion(measurement);

     Logger.info(LOG_TAG, "Initializing measurement " + measurement + " to " +

                          version + " (current " + currentVersion + ")");

     if (currentVersion == version) {

       Logger.info(LOG_TAG, "Measurement " + measurement + " already at v" + version);

       return;

     }

     final SQLiteDatabase db = this.helper.getWritableDatabase();

     if (!db.inTransaction()) {

       Logger.warn(LOG_TAG, "ensureMeasurementInitialized should be called within a transaction.");

     }

     final ContentValues mv = new ContentValues();

     mv.put("name", measurement);

     mv.put("version", version);

     final int measurementID = (int) db.insert("measurements", null, mv);

     final ContentValues v = new ContentValues();

     v.put("measurement", measurementID);

     for (FieldSpec field : fields.getFields()) {

       v.put("name", field.name);

       v.put("flags", field.type);

       Logger.debug(LOG_TAG, "M: " + measurementID + " F: " + field.name + " (" + field.type + ")");

       db.insert("fields", null, v);

     }

     notifyMeasurementVersionUpdated(measurement, version);

     // Let's be easy for now.

     invalidateFieldsCache();

   }

   /**

    * Return a cursor over the measurements and fields in the DB.

    * Columns are {@link HealthReportDatabaseStorage#COLUMNS_MEASUREMENT_AND_FIELD_DETAILS}.

    */

   @Override

   public Cursor getFieldVersions() {

     final SQLiteDatabase db = this.helper.getReadableDatabase();

     return db.query("named_fields", COLUMNS_MEASUREMENT_AND_FIELD_DETAILS,

                     null, null, null, null, "measurement_name, measurement_version, field_name");

   }

   @Override

   public Cursor getFieldVersions(String measurement, int measurementVersion) {

     final SQLiteDatabase db = this.helper.getReadableDatabase();

     return db.query("named_fields", COLUMNS_MEASUREMENT_AND_FIELD_DETAILS,

                     "measurement_name = ? AND measurement_version = ?",

                     new String[] {measurement, Integer.toString(measurementVersion)},

                     null, null, "field_name");

   }

   @Override

   public Cursor getMeasurementVersions() {

     final SQLiteDatabase db = this.helper.getReadableDatabase();

     return db.query("measurements", COLUMNS_MEASUREMENT_DETAILS,

                     null, null, null, null, "name, version");

   }

   /**

    * A thin wrapper around the database transactional semantics. Clients can

    * use this to more efficiently ensure that measurements are initialized.

    *

    * Note that caches are also initialized here.

    */

   public void beginInitialization() {

     SQLiteDatabase db = this.helper.getWritableDatabase();

     db.beginTransaction();

     populateMeasurementVersionsCache(db);

   }

   public void finishInitialization() {

     SQLiteDatabase db = this.helper.getWritableDatabase();

     db.setTransactionSuccessful();

     db.endTransaction();

   }

   public void abortInitialization() {

     this.helper.getWritableDatabase().endTransaction();

   }

   protected int getIntFromQuery(final String sql, final String[] selectionArgs) {

     final SQLiteDatabase db = this.helper.getReadableDatabase();

     final Cursor c = db.rawQuery(sql, selectionArgs);

     try {

       if (!c.moveToFirst()) {

         throw new IllegalStateException("Cursor is empty.");

       }

       return c.getInt(0);

     } finally {

       c.close();

     }

   }

   @Override

   public int getDay(long time) {

     return DateUtils.getDay(time);

   }

   @Override

   public int getDay() {

     return this.getDay(System.currentTimeMillis());

   }

   private void recordDailyLast(int env, int day, int field, Object value, String table) {

     if (env == -1) {

       Logger.warn(LOG_TAG, "Refusing to record with environment = -1.");

       return;

     }

     final SQLiteDatabase db = this.helper.getWritableDatabase();

     final String envString = Integer.toString(env);

     final String fieldIDString = Integer.toString(field, 10);

     final String dayString = Integer.toString(day, 10);

     // Java, your capacity for abstraction leaves me wanting.

     final ContentValues v = new ContentValues();

     putValue(v, value);

     // If we used a separate table, such that we could have a

     // UNIQUE(env, field, day) constraint for daily-last values, then we could

     // use INSERT OR REPLACE.

     final int updated = db.update(table, v, WHERE_DATE_AND_ENV_AND_FIELD,

                                   new String[] {dayString, envString, fieldIDString});

     if (0 == updated) {

       v.put("env", env);

       v.put("field", field);

       v.put("date", day);

       try {

         db.insertOrThrow(table, null, v);

       } catch (SQLiteConstraintException e) {

         throw new IllegalStateException("Event did not reference existing an environment or field.", e);

       }

     }

   }

   @Override

   public void recordDailyLast(int env, int day, int field, JSONObject value) {

     this.recordDailyLast(env, day, field, value == null ? "null" : value.toString(), EVENTS_TEXTUAL);

   }

   @Override

   public void recordDailyLast(int env, int day, int field, String value) {

     this.recordDailyLast(env, day, field, value, EVENTS_TEXTUAL);

   }

   @Override

   public void recordDailyLast(int env, int day, int field, int value) {

     this.recordDailyLast(env, day, field, Integer.valueOf(value), EVENTS_INTEGER);

   }

   private void recordDailyDiscrete(int env, int day, int field, Object value, String table) {

     if (env == -1) {

       Logger.warn(LOG_TAG, "Refusing to record with environment = -1.");

       return;

     }

     final ContentValues v = new ContentValues();

     v.put("env", env);

     v.put("field", field);

     v.put("date", day);

     final SQLiteDatabase db = this.helper.getWritableDatabase();

     putValue(v, value);

     // Using SQLiteDatabase.insertOrThrow throws SQLiteConstraintException we cannot catch for

     // unknown reasons (bug 961526 comment 13). We believe these are thrown because we attempt to

     // record events using environment IDs removed from the database by the prune service. We

     // invalidate the currentEnvironment ID after pruning, preventing further propagation,

     // however, any event recording waiting for the prune service to complete on the background

     // thread may carry an invalid ID: we expect an insertion failure and drop these events here.

     final long res = db.insert(table, null, v);

     if (res == -1) {

       Logger.error(LOG_TAG, "Unable to record daily discrete event. Ignoring.");

     }

   }

   @Override

   public void recordDailyDiscrete(int env, int day, int field, JSONObject value) {

     this.recordDailyDiscrete(env, day, field, value == null ? "null" : value.toString(), EVENTS_TEXTUAL);

   }

   @Override

   public void recordDailyDiscrete(int env, int day, int field, String value) {

     this.recordDailyDiscrete(env, day, field, value, EVENTS_TEXTUAL);

   }

   @Override

   public void recordDailyDiscrete(int env, int day, int field, int value) {

     this.recordDailyDiscrete(env, day, field, value, EVENTS_INTEGER);

   }

   /**

    * Increment the specified field value by the specified amount. Counts start

    * at zero.

    *

    * Note that this method can misbehave or throw if not executed within a

    * transaction, because correct behavior involves querying then

    * insert-or-update, and a race condition can otherwise occur.

    *

    * @param env the environment ID

    * @param day the current day, in days since epoch

    * @param field the field ID

    * @param by how much to increment the counter.

    */

   @Override

   public void incrementDailyCount(int env, int day, int field, int by) {

     if (env == -1) {

       Logger.warn(LOG_TAG, "Refusing to record with environment = -1.");

       return;

     }

     final SQLiteDatabase db = this.helper.getWritableDatabase();

     final String envString = Integer.toString(env);

     final String fieldIDString = Integer.toString(field, 10);

     final String dayString = Integer.toString(day, 10);

     // Can't run a complex UPDATE and get the number of changed rows, so we'll

     // do this the hard way.

     // This relies on being called within a transaction.

     final String[] args = new String[] {dayString, envString, fieldIDString};

     final Cursor c = db.query(EVENTS_INTEGER,

                               COLUMNS_VALUE,

                               WHERE_DATE_AND_ENV_AND_FIELD,

                               args, null, null, null, "1");

     boolean present = false;

     try {

       present = c.moveToFirst();

     } finally {

       c.close();

     }

     if (present) {

       // It's an int, so safe to concatenate. Avoids us having to mess with args.

       db.execSQL("UPDATE " + EVENTS_INTEGER + " SET value = value + " + by + " WHERE " +

                  WHERE_DATE_AND_ENV_AND_FIELD,

                  args);

     } else {

       final ContentValues v = new ContentValues();

       v.put("env", env);

       v.put("value", by);

       v.put("field", field);

       v.put("date", day);

       try {

         db.insertOrThrow(EVENTS_INTEGER, null, v);

       } catch (SQLiteConstraintException e) {

         throw new IllegalStateException("Event did not reference existing an environment or field.", e);

       }

     }

   }

   @Override

   public void incrementDailyCount(int env, int day, int field) {

     this.incrementDailyCount(env, day, field, 1);

   }

   /**

    * Are there events recorded on or after <code>time</code>?

    *

    * @param time milliseconds since epoch. Will be converted by {@link #getDay(long)}.

    * @return true if such events exist, false otherwise.

    */

   @Override

   public boolean hasEventSince(long time) {

     final int start = this.getDay(time);

     final SQLiteDatabase db = this.helper.getReadableDatabase();

     final String dayString = Integer.toString(start, 10);

     Cursor cur = db.query("events", COLUMNS_DATE_ENV_FIELD_VALUE,

         "date >= ?", new String[] {dayString}, null, null, null, "1");

     if (cur == null) {

       // Something is horribly wrong; let the caller who actually reads the

       // events deal with it.

       return true;

     }

     try {

       return cur.getCount() > 0;

     } finally {

       cur.close();

     }

   }

   /**

    * Returns a cursor over field events in the database. The results will be

    * strictly ordered first by date, then by environment, and finally by field.

    *

    * Each row includes columns in {@link #COLUMNS_DATE_ENV_FIELD_VALUE}:

    * "date", "env", "field", "value".

    *

    * @param time milliseconds since epoch. Will be converted by {@link #getDay(long)}.

    * @return a cursor. The caller is responsible for closing this.

    */

   @Override

   public Cursor getRawEventsSince(long time) {

     final int start = this.getDay(time);

     final SQLiteDatabase db = this.helper.getReadableDatabase();

     final String dayString = Integer.toString(start, 10);

     return db.query("events", COLUMNS_DATE_ENV_FIELD_VALUE,

                     "date >= ?", new String[] {dayString}, null, null, "date, env, field");

   }

   /**

    * Returns a cursor over field events in the database. The results will be

    * strictly ordered first by date, then by environment, and finally by field.

    *

    * Each row includes columns in {@link #COLUMNS_DATE_ENVSTR_M_MV_F_VALUE}:

    * "date", "environment" (as a String), "measurement_name", "measurement_version",

    * "field_name", "field_flags", "value".

    *

    * @param time milliseconds since epoch. Will be converted by {@link #getDay(long)}.

    * @return a cursor. The caller is responsible for closing this.

    */

   @Override

   public Cursor getEventsSince(long time) {

     final int start = this.getDay(time);

     final SQLiteDatabase db = this.helper.getReadableDatabase();

     final String dayString = Integer.toString(start, 10);

     return db.query("named_events", COLUMNS_DATE_ENVSTR_M_MV_F_VALUE,

                     "date >= ?", new String[] {dayString}, null, null,

                     "date, environment, measurement_name, measurement_version, field_name");

   }

   public int getEventCount() {

     return getRowCount("events");

   }

   public int getEnvironmentCount() {

     return getRowCount("environments");

   }

   private int getRowCount(String table) {

     // table should be parameterized, but SQL throws a compilation error if the table in unknown

     // in advance.

     return getIntFromQuery("SELECT COUNT(*) from " + table, null);

   }

   /**

    * Deletes all environments, addons, and events from the database before the given time. If this

    * data does not have recorded dates but are no longer referenced by other fields, they are also

    * removed (with exception to the current environment).

    *

    * @param time milliseconds since epoch. Will be converted by {@link #getDay(long)}.

    * @param curEnv The ID of the current environment.

    * @return The number of environments and addon entries deleted.

    */

   public int deleteDataBefore(final long time, final int curEnv) {

     final SQLiteDatabase db = this.helper.getWritableDatabase();

     db.beginTransaction();

     int numRowsDeleted = 0;

     try {

       numRowsDeleted += deleteEnvAndEventsBefore(db, time, curEnv);

       numRowsDeleted += deleteOrphanedAddons(db);

       db.setTransactionSuccessful();

     } finally {

       db.endTransaction();

     }

     return numRowsDeleted;

   }

   /**

    * Deletes environments and their referring events recorded before the given time. Environments

    * referenced by no events are deleted, except for the current environment.

    *

    * @param time milliseconds since epoch. Will be converted by {@link #getDay(long)}.

    * @param curEnv The ID of the current environment.

    * @return The number of environments (not events) deleted.

    */

   protected int deleteEnvAndEventsBefore(final long time, final int curEnv) {

     final SQLiteDatabase db = this.helper.getWritableDatabase();

     return deleteEnvAndEventsBefore(db, time, curEnv);

   }

   // Called internally only to ensure the same db instance is used.

   protected int deleteEnvAndEventsBefore(final SQLiteDatabase db, final long time, final int curEnv) {

     // Delete environments only referenced by events occuring before the given time. Cascade

     // delete these events.

     String whereClause =

         "(SELECT COUNT(*) FROM events WHERE date >= ? " +

         "    AND events.env = environments.id) = 0 " +

         "AND id IN (SELECT DISTINCT env FROM events WHERE date < ?)";

     final int day = this.getDay(time);

     final String dayString = Integer.toString(day, 10);

     String[] whereArgs = new String[] {dayString, dayString};

     int numEnvDeleted = 0;

     db.beginTransaction();

     try {

       numEnvDeleted += db.delete("environments", whereClause, whereArgs);

       numEnvDeleted += deleteOrphanedEnv(db, curEnv);

       // We can't get the number of events deleted through cascading deletions so we do not record

       // the number of events deleted here.

       deleteEventsBefore(db, dayString);

       db.setTransactionSuccessful();

     } finally {

       db.endTransaction();

     }

     return numEnvDeleted;

   }

   /**

    * Deletes environments not referenced by any events except for the given current environment.

    */

   protected int deleteOrphanedEnv(final int curEnv) {

     final SQLiteDatabase db = this.helper.getWritableDatabase();

     return deleteOrphanedEnv(db, curEnv);

   }

   // Called internally only to ensure the same db instance is used.

   @SuppressWarnings("static-method")

   protected int deleteOrphanedEnv(final SQLiteDatabase db, final int curEnv) {

     final String whereClause =

         "id != ? AND " +

         "id NOT IN (SELECT env FROM events)";

     final String[] whereArgs = new String[] {Integer.toString(curEnv)};

     return db.delete("environments", whereClause, whereArgs);

   }

   protected int deleteEventsBefore(final String dayString) {

     final SQLiteDatabase db = this.helper.getWritableDatabase();

     return deleteEventsBefore(db, dayString);

   }

   // Called internally only to ensure the same db instance is used.

   @SuppressWarnings("static-method")

   protected int deleteEventsBefore(final SQLiteDatabase db, final String dayString) {

     final String whereClause = "date < ?";

     final String[] whereArgs = new String[] {dayString};

     int numEventsDeleted = 0;

     db.beginTransaction();

     try {

       numEventsDeleted += db.delete("events_integer", whereClause, whereArgs);

       numEventsDeleted += db.delete("events_textual", whereClause, whereArgs);

       db.setTransactionSuccessful();

     } finally {

       db.endTransaction();

     }

     return numEventsDeleted;

   }

   /**

    * Deletes addons not referenced by any environments.

    */

   protected int deleteOrphanedAddons() {

     final SQLiteDatabase db = this.helper.getWritableDatabase();

     return deleteOrphanedAddons(db);

   }

   // Called internally only to ensure the same db instance is used.

   @SuppressWarnings("static-method")

   protected int deleteOrphanedAddons(final SQLiteDatabase db) {

     final String whereClause = "id NOT IN (SELECT addonsID FROM environments)";

     return db.delete("addons", whereClause, null);

   }

   /**

    * Retrieve a mapping from a table. Keys should be unique; only one key-value

    * pair will be returned for each key.

    */

   private static HashMap<String, Integer> getIntegers(SQLiteDatabase db, String table, String columnA, String columnB) {

     Cursor c = db.query(table, new String[] {columnA, columnB}, null, null, null, null, null);

     try {

       if (!c.moveToFirst()) {

         return null;

       }

       HashMap<String, Integer> results = new HashMap<String, Integer>();

       while (!c.isAfterLast()) {

         results.put(c.getString(0), c.getInt(1));

         c.moveToNext();

       }

       return results;

     } finally {

       c.close();

     }

   }

   /**

    * Retrieve a single value from a mapping table.

    */

   private int integerQuery(String table, String column, String where, String[] args, int defaultValue) {

     final SQLiteDatabase db = this.helper.getReadableDatabase();

     Cursor c = db.query(table, new String[] {column}, where, args, null, null, column + " DESC", "1");

     try {

       if (!c.moveToFirst()) {

         return defaultValue;

       }

       return c.getInt(0);

     } finally {

       c.close();

     }

   }

   /**

    * Helper to allow us to avoid excessive code duplication.

    *

    * @param v

    *          the destination <code>ContentValues</code>.

    * @param value

    *          either a <code>String</code> or an <code>Integer</code>. No type

    *          checking is performed.

    */

   private static final void putValue(final ContentValues v, Object value) {

     if (value instanceof String) {

       v.put("value", (String) value);

     } else {

       v.put("value", (Integer) value);

     }

   }

   @Override

   public void deleteEverything() {

     this.helper.deleteEverything();

   }

   @Override

   public void deleteEnvironments() {

     final SQLiteDatabase db = this.helper.getWritableDatabase();

     db.beginTransaction();

     try {

       // Cascade will clear the rest.

       db.delete("environments", null, null);

       db.setTransactionSuccessful();

     } finally {

       db.endTransaction();

     }

   }

   @Override

   public void deleteMeasurements() {

     final SQLiteDatabase db = this.helper.getWritableDatabase();

     db.beginTransaction();

     try {

       // Cascade will clear the rest.

       db.delete("measurements", null, null);

       // Clear measurements and fields cache, because some of their IDs are now invalid.

       invalidateFieldsCache(); // Let it repopulate on its own.

       populateMeasurementVersionsCache(db); // Performed at Storage init so repopulate now.

       db.setTransactionSuccessful();

     } finally {

       db.endTransaction();

     }

   }

   /**

    * Prunes the given number of least-recently used environments. Note that orphaned environments

    * are not removed and the environment cache is cleared.

    */

   public void pruneEnvironments(final int numToPrune) {

     final SQLiteDatabase db = this.helper.getWritableDatabase();

     db.beginTransaction();

     try {

       db.delete("environments",

           "id in (SELECT env " +

           "       FROM events " +

           "       GROUP BY env " +

           "       ORDER BY MAX(date), env " +

           "       LIMIT " + numToPrune + ")",

           null);

       db.setTransactionSuccessful();

       // Clear environment cache, because some of their IDs are now invalid.

       this.envs.clear();

     } finally {

       db.endTransaction();

     }

   }

   /**

    * Prunes up to a maximum of the given number of the oldest events. While it is more correct to

    * prune the exact given amount, there is no unique identifier among events so we cannot be so

    * precise. Instead, we prune on date, deleting all events up to the day before our count of

    * events reaches the given maximum. Note that this technicality means this method cannot be

    * used to delete all events.

    */

   public void pruneEvents(final int maxNumToPrune) {

     final SQLiteDatabase db = this.helper.getWritableDatabase();

     final Cursor c = db.rawQuery(

         "SELECT MAX(date) " +

         "FROM (SELECT date " +

         "      FROM events " +

         "      ORDER BY date " +

         "      LIMIT " + maxNumToPrune + ")",

         null);

     long pruneDate = -1;

     try {

       if (!c.moveToFirst()) {

         Logger.debug(LOG_TAG, "No max date found in events: table is likely empty. Not pruning " +

             "events.");

         return;

       }

       pruneDate = c.getLong(0);

     } finally {

       c.close();

     }

     final String selection = "date < " + pruneDate;

     db.beginTransaction();

     try {

       db.delete(EVENTS_INTEGER, selection, null);

       db.delete(EVENTS_TEXTUAL, selection, null);

       db.setTransactionSuccessful();

     } finally {

       db.endTransaction();

     }

   }

   public void vacuum() {

     final SQLiteDatabase db = this.helper.getWritableDatabase();

     db.execSQL("vacuum");

   }

   /**

    * Disables auto_vacuuming. Changes may only take effect after a "vacuum" command.

    */

   public void disableAutoVacuuming() {

     final SQLiteDatabase db = this.helper.getWritableDatabase();

     db.execSQL("PRAGMA auto_vacuum=0");

   }

 }