Merge "Prune files from /data/anr/ by number as well as age."

     * since it's the system_server that creates trace files for most ANRs.

     */

    private static void maybePruneOldTraces(File tracesDir) {

        final long now = System.currentTimeMillis();

        final File[] traceFiles = tracesDir.listFiles();

        final File[] files = tracesDir.listFiles();

        if (files == null) return;

        if (traceFiles != null) {

            for (File file : traceFiles) {

                if ((now - file.lastModified()) > DAY_IN_MILLIS)  {

                    if (!file.delete()) {

                        Slog.w(TAG, "Unable to prune stale trace file: " + file);

                    }

        final int max = SystemProperties.getInt("tombstoned.max_anr_count", 64);

        final long now = System.currentTimeMillis();

        Arrays.sort(files, Comparator.comparingLong(File::lastModified).reversed());

        for (int i = 0; i < files.length; ++i) {

            if (i > max || (now - files[i].lastModified()) > DAY_IN_MILLIS) {

                if (!files[i].delete()) {

                    Slog.w(TAG, "Unable to prune stale trace file: " + files[i]);

                }

            }

        }