Log to file reactively in Android using RxJava and Timber

FileLoggingTree.java

/**
 * Writes logs to the file every 5 sec
 * or a maximum of 10 count is reached (which ever is first)
 */
public class FileLoggingTree extends Timber.DebugTree {

    private static final SimpleDateFormat LOG_DATE_FORMAT = new SimpleDateFormat("dd-MM-yyyy hh:mm:ss.SSS aa");
    private static final SimpleDateFormat FILE_DATE_FORMAT = new SimpleDateFormat("dd-MM-yyyy");

    private Relay<String> logBuffer = ReplayRelay.<String>create().toSerialized();

    @SuppressLint("CheckResult")
    public FileLoggingTree() {
        logBuffer.buffer(5, TimeUnit.SECONDS, 10).observeOn(Schedulers.io())
                .subscribe(this::_writeToFile);
    }

    private void _writeToFile(List<String> messages) {
        try {
            File logFile = _getFile();
            FileWriter writer = new FileWriter(logFile, true);
            for (String msg : messages) {
                try {
                    writer.append(msg);
                } catch (IOException e) {
                    Timber.e(e, "Unable to save log to file");
                }
            }
            writer.flush();
            writer.close();
        } catch (IOException e) {
            Timber.e(e, "Error writing to file, will retry");
        }
    }

    @Override
    protected void log(int priority, @Nullable String tag, @NotNull String message, @Nullable Throwable t) {
        super.log(priority, tag, message, t);
        String dateTime = LOG_DATE_FORMAT.format(new Date());
        String logType = _getLogType(priority);

        String logMessage;
        if (t == null) {
            logMessage = String.format("%s %s%s: %s\n", dateTime, logType, tag, message);
        } else {
            logMessage = String.format("%s %s%s: %s\n%s\n", dateTime, logType, tag, message, t);
        }
        logBuffer.accept(logMessage);
    }

    /**
     * Get log type string from priority.
     */
    private String _getLogType(int priority) {
        switch (priority) {
            case Log.DEBUG:
                return "D/";
            case Log.INFO:
                return "I/";
            case Log.ERROR:
                return "E/";
            default:
                return "LOG/";
        }
    }

    /**
     * Generates a file, if doesn't exist, with current date.
     */
    private File _getFile() {
        File logsDir = new File(FileUtil.baseDir(), "logs");
        if (!logsDir.exists()) {
            logsDir.mkdirs();
        }
        String filename = FILE_DATE_FORMAT.format(new Date());
        return FileUtil.getAsFile("logs", "logs_" + filename + ".log");
    }
}

The Relay must be serialized to make it thread safe