private JournalChannel()

in bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/JournalChannel.java [150:248]
88 lines of code
18 McCabe index (conditional complexity)

    private JournalChannel(File journalDirectory, long logId,
                           long preAllocSize, int writeBufferSize, int journalAlignSize,
                           long position, boolean fRemoveFromPageCache,
                           int formatVersionToWrite, Journal.BufferedChannelBuilder bcBuilder,
                           ServerConfiguration conf,
                           FileChannelProvider provider, Long toReplaceLogId) throws IOException {
        this.journalAlignSize = journalAlignSize;
        this.zeros = ByteBuffer.allocate(journalAlignSize);
        this.preAllocSize = preAllocSize - preAllocSize % journalAlignSize;
        this.fRemoveFromPageCache = fRemoveFromPageCache;
        this.configuration = conf;

        boolean reuseFile = false;
        File fn = new File(journalDirectory, Long.toHexString(logId) + ".txn");
        if (toReplaceLogId != null && logId != toReplaceLogId && provider.supportReuseFile()) {
            File toReplaceFile = new File(journalDirectory, Long.toHexString(toReplaceLogId) + ".txn");
            if (toReplaceFile.exists()) {
                renameJournalFile(toReplaceFile, fn);
                provider.notifyRename(toReplaceFile, fn);
                reuseFile = true;
            }
        }
        channel = provider.open(fn, configuration);

        if (formatVersionToWrite < V4) {
            throw new IOException("Invalid journal format to write : version = " + formatVersionToWrite);
        }

        LOG.info("Opening journal {}", fn);
        if (!channel.fileExists(fn)) { // create new journal file to write, write version
            if (!fn.createNewFile()) {
                LOG.error("Journal file {}, that shouldn't exist, already exists. "
                          + " is there another bookie process running?", fn);
                throw new IOException("File " + fn
                        + " suddenly appeared, is another bookie process running?");
            }
            fc = channel.getFileChannel();
            formatVersion = formatVersionToWrite;
            writeHeader(bcBuilder, writeBufferSize);
        } else if (reuseFile) { // Open an existing journal to write, it needs fileChannelProvider support reuse file.
            fc = channel.getFileChannel();
            formatVersion = formatVersionToWrite;
            writeHeader(bcBuilder, writeBufferSize);
        } else {  // open an existing file to read.
            fc = channel.getFileChannel();
            // readonly, use fileChannel directly, no need to use BufferedChannel

            ByteBuffer bb = ByteBuffer.allocate(VERSION_HEADER_SIZE);
            int c = fc.read(bb);
            bb.flip();

            if (c == VERSION_HEADER_SIZE) {
                byte[] first4 = new byte[4];
                bb.get(first4);

                if (Arrays.equals(first4, magicWord)) {
                    formatVersion = bb.getInt();
                } else {
                    // pre magic word journal, reset to 0;
                    formatVersion = V1;
                }
            } else {
                // no header, must be old version
                formatVersion = V1;
            }

            if (formatVersion < MIN_COMPAT_JOURNAL_FORMAT_VERSION
                || formatVersion > CURRENT_JOURNAL_FORMAT_VERSION) {
                String err = String.format("Invalid journal version, unable to read."
                        + " Expected between (%d) and (%d), got (%d)",
                        MIN_COMPAT_JOURNAL_FORMAT_VERSION, CURRENT_JOURNAL_FORMAT_VERSION,
                        formatVersion);
                LOG.error(err);
                throw new IOException(err);
            }

            try {
                if (position == START_OF_FILE) {
                    if (formatVersion >= V5) {
                        fc.position(HEADER_SIZE);
                    } else if (formatVersion >= V2) {
                        fc.position(VERSION_HEADER_SIZE);
                    } else {
                        fc.position(0);
                    }
                } else {
                    fc.position(position);
                }
            } catch (IOException e) {
                LOG.error("Bookie journal file can seek to position :", e);
                throw e;
            }
        }
        if (fRemoveFromPageCache) {
            this.fd = PageCacheUtil.getSysFileDescriptor(channel.getFD());
        } else {
            this.fd = -1;
        }
    }