No ability to detect dump processing failure

[brett-matson]

Hi there,

I'm still pretty new to Java, but from what I can tell, there doesn't appear to be any way for a calling program to detect a failure (e.g. IOException caused by file not found) in DumpProcessingController.processDump(). There's no method return value and the exceptions are caught and logged in the Wikidata-Toolkit (see code below). As far as I can tell, the only way an external program could detect an error would be to try to parse the Wikidata log file.

/**
	 * Processes the contents of the given dump file. All registered processor
	 * objects will be notified of all data. Note that JSON dumps do not
	 * contains any revision information, so that registered
	 * {@link MwRevisionProcessor} objects will not be notified in this case.
	 * Dumps of type {@link DumpContentType#SITES} cannot be processed with this
	 * method; use {@link #getSitesInformation()} to process these dumps.
	 *
	 * @param dumpFile
	 *            the dump to process
	 */
	public void processDump(MwDumpFile dumpFile) {
		if (dumpFile == null) {
			return;
		}

		MwDumpFileProcessor dumpFileProcessor;
		switch (dumpFile.getDumpContentType()) {
		case CURRENT:
		case DAILY:
		case FULL:
			dumpFileProcessor = getRevisionDumpFileProcessor();
			break;
		case JSON:
			dumpFileProcessor = getJsonDumpFileProcessor();
			break;
		case SITES:
		default:
			logger.error("Dumps of type " + dumpFile.getDumpContentType()
					+ " cannot be processed as entity-document dumps.");
			return;
		}

		processDumpFile(dumpFile, dumpFileProcessor);
	}

/**
	 * Processes one dump file with the given dump file processor, handling
	 * exceptions appropriately.
	 *
	 * @param dumpFile
	 *            the dump file to process
	 * @param dumpFileProcessor
	 *            the dump file processor to use
	 */
	void processDumpFile(MwDumpFile dumpFile,
			MwDumpFileProcessor dumpFileProcessor) {
		try (InputStream inputStream = dumpFile.getDumpFileStream()) {
			dumpFileProcessor.processDumpFileContents(inputStream, dumpFile);
		} catch (FileAlreadyExistsException e) {
			logger.error("Dump file "
					+ dumpFile.toString()
					+ " could not be processed since file "
					+ e.getFile()
					+ " already exists. Try deleting the file or dumpfile directory to attempt a new download.");
		} catch (IOException e) {
			logger.error("Dump file " + dumpFile.toString()
					+ " could not be processed: " + e.toString());
		}
	}