Document the media scanner's flow through native and java code, since

import java.util.Iterator;

import java.util.Iterator;

/**

/**

 * Internal service that no-one should use directly.

 * Internal service helper that no-one should use directly.

 * 

 * The way the scan currently works is:

 * - The Java MediaScannerService creates a MediaScanner (this class), and calls

 *   MediaScanner.scanDirectories on it.

 * - scanDirectories() calls the native processDirectory() for each of the specified directories.

 * - the processDirectory() JNI method wraps the provided mediascanner client in a native

 *   'MyMediaScannerClient' class, then calls processDirectory() on the native MediaScanner

 *   object (which got created when the Java MediaScanner was created).

 * - native MediaScanner.processDirectory() (currently part of opencore) calls

 *   doProcessDirectory(), which recurses over the folder, and calls

 *   native MyMediaScannerClient.scanFile() for every file whose extension matches.

 * - native MyMediaScannerClient.scanFile() calls back on Java MediaScannerClient.scanFile,

 *   which calls doScanFile, which after some setup calls back down to native code, calling

 *   MediaScanner.processFile().

 * - MediaScanner.processFile() calls one of several methods, depending on the type of the

 *   file: parseMP3, parseMP4, parseMidi, parseOgg or parseWMA.

 * - each of these methods gets metadata key/value pairs from the file, and repeatedly

 *   calls native MyMediaScannerClient.handleStringTag, which calls back up to its Java

 *   counterparts in this file.

 * - Java handleStringTag() gathers the key/value pairs that it's interested in.

 * - once processFile returns and we're back in Java code in doScanFile(), it calls

 *   Java MyMediaScannerClient.endFile(), which takes all the data that's been

 *   gathered and inserts an entry in to the database.

 *

 * In summary:

 * Java MediaScannerService calls

 * Java MediaScanner scanDirectories, which calls

 * Java MediaScanner processDirectory (native method), which calls

 * native MediaScanner processDirectory, which calls

 * native MyMediaScannerClient scanFile, which calls

 * Java MyMediaScannerClient scanFile, which calls

 * Java MediaScannerClient doScanFile, which calls

 * Java MediaScanner processFile (native method), which calls

 * native MediaScanner processFile, which calls

 * native parseMP3, parseMP4, parseMidi, parseOgg or parseWMA, which calls

 * native MyMediaScanner handleStringTag, which calls

 * Java MyMediaScanner handleStringTag.

 * Once MediaScanner processFile returns, an entry is inserted in to the database.

 *

 *

 * {@hide}

 * {@hide}

 */

 */