Example usage for java.nio.channels FileChannel lock

List of usage examples for java.nio.channels FileChannel lock

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Introduction

In this page you can find the example usage for java.nio.channels FileChannel lock.

Prototype

public final FileLock lock() throws IOException

Source Link

Document

Acquires an exclusive lock on this channel's file.

Usage

From source file:org.geoserver.rest.util.IOUtils.java

/**
 * Optimize version of copy method for file channels.
 * //from   ww w  .  j a v  a2 s  . c om
 * @param bufferSize size of the temp buffer to use for this copy.
 * @param source the source {@link ReadableByteChannel}.
 * @param destination the destination {@link WritableByteChannel};.
 * @throws IOException in case something bad happens.
 */
public static void copyFileChannel(int bufferSize, FileChannel source, FileChannel destination)
        throws IOException {

    inputNotNull(source, destination);
    if (!source.isOpen() || !destination.isOpen())
        throw new IllegalStateException("Source and destination channels must be open.");
    FileLock lock = null;
    try {

        lock = destination.lock();
        final long sourceSize = source.size();
        long pos = 0;
        while (pos < sourceSize) {
            // read and flip
            final long remaining = (sourceSize - pos);
            final int mappedZoneSize = remaining >= bufferSize ? bufferSize : (int) remaining;
            destination.transferFrom(source, pos, mappedZoneSize);
            // update zone
            pos += mappedZoneSize;

        }
    } finally {
        if (lock != null) {
            try {
                lock.release();
            } catch (Throwable t) {
                if (LOGGER.isLoggable(Level.INFO))
                    LOGGER.log(Level.INFO, t.getLocalizedMessage(), t);
            }
        }

    }
}

From source file:com.sqlite.multiread.java

public void run() {
    newSqLiteAdapter.openToRead();// www.  ja  va2  s .com
    long seconds1 = 0;
    long seconds2 = 0;
    Cursor cur = null;
    Transactions transactions = new Transactions();
    ArrayList<Long> array = new ArrayList<Long>();
    for (int i = 0; i < 10; i++) {
        seconds1 = System.currentTimeMillis();
        //cur = newSqLiteAdapter.queueAll("dammyTable", false, false, false,
        //         false, false, false, true, threadNum);
        seconds2 = System.currentTimeMillis();
        array.add(seconds2 - seconds1);
    }
    //   newSqLiteAdapter.close();
    FileOutputStream fos = null;
    try {
        byte[] data = new String("\nTotal time: " + transactions.average_time(array) / 8 + "ms  Thread Id: "
                + currentThread().getId() + " I Have read " + cur.getCount()).getBytes();

        File file = new File(Environment.getExternalStorageDirectory() + "/Aaa/", "threadsResults.txt");

        FileChannel channel = new RandomAccessFile(file, "rw").getChannel();

        FileLock lock = channel.lock();

        try {
            lock = channel.tryLock();
        } catch (OverlappingFileLockException e) {

        }

        fos = new FileOutputStream(file, true);
        fos.write(data);

        fos.flush();

        lock.release();
        channel.close();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

}

From source file:org.forgerock.openidm.script.javascript.JavaScriptFactory.java

private Script initializeScript(String name, String source, boolean sharedScope) throws ScriptException {
    initDebugListener();/*from w ww . j a va 2  s  . com*/
    if (debugInitialised) {
        try {
            FileChannel outChannel = new FileOutputStream(getTargetFile(name)).getChannel();
            FileLock outLock = outChannel.lock();
            ByteBuffer buf = ByteBuffer.allocate(source.length());
            buf.put(source.getBytes("UTF-8"));
            buf.flip();
            outChannel.write(buf);
            outLock.release();
            outChannel.close();
        } catch (IOException e) {
            logger.warn("JavaScript source was not updated for {}", name, e);
        }
    }
    return new JavaScript(name, source, sharedScope);
}

From source file:org.forgerock.openidm.script.javascript.JavaScriptFactory.java

private Script initializeScript(String name, File source, boolean sharedScope) throws ScriptException {
    initDebugListener();/*ww w.  j ava2 s.  c  om*/
    if (debugInitialised) {
        try {
            FileChannel inChannel = new FileInputStream(source).getChannel();
            FileChannel outChannel = new FileOutputStream(getTargetFile(name)).getChannel();
            FileLock outLock = outChannel.lock();
            FileLock inLock = inChannel.lock(0, inChannel.size(), true);
            inChannel.transferTo(0, inChannel.size(), outChannel);

            outLock.release();
            inLock.release();

            inChannel.close();
            outChannel.close();
        } catch (IOException e) {
            logger.warn("JavaScript source was not updated for {}", name, e);
        }
    }
    return new JavaScript(name, source, sharedScope);
}

From source file:com.ephesoft.dcma.util.FileUtils.java

/**
 * API to take read write lock on the folder represented by the given folder path.
 * /*from w w  w  . ja va 2  s .com*/
 * @param folderPath {@link String}
 * @return true if lock is successfully acquired, else false
 */
public static boolean lockFolder(String folderPath) {
    String lockFileName = folderPath + File.separator + "_lock";
    boolean isLockAcquired = true;
    try {
        File lockFile = new File(lockFileName);
        FileChannel fileChannel = new RandomAccessFile(lockFile, "rw").getChannel();

        FileLock lock = fileChannel.lock();

        try {
            if (lock == null) {
                lock = fileChannel.tryLock();
            }
        } catch (OverlappingFileLockException e) {
            LOGGER.trace("File is already locked in this thread or virtual machine");
        }
        if (lock == null) {
            LOGGER.trace("File is already locked in this thread or virtual machine");
        }

    } catch (Exception e) {
        LOGGER.error("Unable to aquire lock on file : " + lockFileName, e);
        isLockAcquired = false;
    }
    return isLockAcquired;
}

From source file:com.thoughtworks.go.config.GoConfigFileWriter.java

public synchronized void writeToConfigXmlFile(String content) {
    FileChannel channel = null;
    FileOutputStream outputStream = null;
    FileLock lock = null;//from w  ww  . j a va 2s.com

    try {
        RandomAccessFile randomAccessFile = new RandomAccessFile(fileLocation(), "rw");
        channel = randomAccessFile.getChannel();
        lock = channel.lock();
        randomAccessFile.seek(0);
        randomAccessFile.setLength(0);
        outputStream = new FileOutputStream(randomAccessFile.getFD());

        IOUtils.write(content, outputStream, UTF_8);
    } catch (Exception e) {
        throw new RuntimeException(e);
    } finally {
        if (channel != null && lock != null) {
            try {
                lock.release();
                channel.close();
                IOUtils.closeQuietly(outputStream);
            } catch (IOException e) {
                LOGGER.error("Error occured when releasing file lock and closing file.", e);
            }
        }
    }
}

From source file:com.emc.vipr.sync.source.FilesystemSource.java

protected void delete(File file) {
    // Try to lock the file first.  If this fails, the file is
    // probably open for write somewhere.
    // Note that on a mac, you can apparently delete files that
    // someone else has open for writing, and can lock files
    // too./*from w  w w  .j  a  va  2  s .co m*/
    // Must make sure to throw exceptions when necessary to flag actual failures as opposed to skipped files.
    if (file.isDirectory()) {
        File metaDir = getMetaFile(file).getParentFile();
        if (metaDir.exists())
            metaDir.delete();
        // Just try and delete dir
        if (!file.delete()) {
            LogMF.warn(l4j, "Failed to delete directory {0}", file);
        }
    } else {
        boolean tryDelete = true;
        if (deleteOlderThan > 0) {
            if (System.currentTimeMillis() - file.lastModified() < deleteOlderThan) {
                LogMF.info(l4j, "not deleting {0}; it is not at least {1} ms old", file, deleteOlderThan);
                tryDelete = false;
            }
        }
        if (deleteCheckScript != null) {
            String[] args = new String[] { deleteCheckScript.getAbsolutePath(), file.getAbsolutePath() };
            try {
                l4j.debug("delete check: " + Arrays.asList(args));
                Process p = Runtime.getRuntime().exec(args);
                while (true) {
                    try {
                        int exitCode = p.exitValue();

                        if (exitCode == 0) {
                            LogMF.debug(l4j, "delete check OK, exit code {0}", exitCode);
                        } else {
                            LogMF.info(l4j, "delete check failed, exit code {0}.  Not deleting file.",
                                    exitCode);
                            tryDelete = false;
                        }
                        break;
                    } catch (IllegalThreadStateException e) {
                        // Ignore.
                    }
                }
            } catch (IOException e) {
                LogMF.info(l4j, "error executing delete check script: {0}.  Not deleting file.", e.toString());
                tryDelete = false;
            }
        }
        RandomAccessFile raf = null;
        if (tryDelete) {
            try {
                raf = new RandomAccessFile(file, "rw");
                FileChannel fc = raf.getChannel();
                FileLock flock = fc.lock();
                // If we got here, we should be good.
                flock.release();
                if (!file.delete()) {
                    throw new RuntimeException(MessageFormat.format("Failed to delete {0}", file));
                }
            } catch (IOException e) {
                throw new RuntimeException(MessageFormat
                        .format("File {0} not deleted, it appears to be open: {1}", file, e.getMessage()));
            } finally {
                if (raf != null) {
                    try {
                        raf.close();
                    } catch (IOException e) {
                        // Ignore.
                    }
                }
            }
        }
    }
}

From source file:de.ailis.oneinstance.OneInstance.java

/**
 * Locks the specified lock file./*from w  w  w.j  a  va  2s .c  o m*/
 * 
 * @param lockFile
 *            The lock file.
 * @return The lock or null if no locking could be performed.
 */
private FileLock lock(final File lockFile) {
    try {
        FileChannel channel = new RandomAccessFile(lockFile, "rw").getChannel();
        return channel.lock();
    } catch (IOException e) {
        LOG.warn("Unable to lock the lock file: " + e + ". Trying to run without a lock.", e);
        return null;
    }
}

From source file:no.sesat.search.http.filters.SiteJspLoaderFilter.java

private void downloadJsp(final HttpServletRequest request, final String jsp) throws MalformedURLException {

    final StopWatch stopWatch = new StopWatch();
    stopWatch.start();/*w  ww.j a v  a2  s.  c om*/

    byte[] golden = new byte[0];

    // search skins for the jsp and write it out to "golden"
    for (Site site = (Site) request.getAttribute(Site.NAME_KEY); 0 == golden.length; site = site.getParent()) {

        if (null == site) {
            if (null == config.getServletContext().getResource(jsp)) {
                throw new ResourceLoadException("Unable to find " + jsp + " in any skin");
            }
            break;
        }

        final Site finalSite = site;
        final BytecodeLoader bcLoader = UrlResourceLoader.newBytecodeLoader(finalSite.getSiteContext(), jsp,
                null);
        bcLoader.abut();
        golden = bcLoader.getBytecode();
    }

    // if golden now contains data save it to a local (ie local web application) file
    if (0 < golden.length) {
        try {
            final File file = new File(root + jsp);

            // create the directory structure
            file.getParentFile().mkdirs();

            // check existing file
            boolean needsUpdating = true;
            final boolean fileExisted = file.exists();
            if (!fileExisted) {
                file.createNewFile();
            }

            // channel.lock() only synchronises file access between programs, but not between threads inside
            //  the current JVM. The latter results in the OverlappingFileLockException.
            //  At least this is my current understanding of java.nio.channels
            //   It may be that no synchronisation or locking is required at all. A beer to whom answers :-)
            // So we must provide synchronisation between our own threads,
            //  synchronisation against the file's path (using the JVM's String.intern() functionality)
            //  should work. (I can't imagine this string be used for any other synchronisation purposes).
            synchronized (file.toString().intern()) {

                RandomAccessFile fileAccess = null;
                FileChannel channel = null;

                try {

                    fileAccess = new RandomAccessFile(file, "rws");
                    channel = fileAccess.getChannel();

                    channel.lock();

                    if (fileExisted) {

                        final byte[] bytes = new byte[(int) channel.size()];
                        final ByteBuffer byteBuffer = ByteBuffer.wrap(bytes);
                        int reads;
                        do {
                            reads = channel.read(byteBuffer);
                        } while (0 < reads);

                        needsUpdating = !Arrays.equals(golden, bytes);
                    }

                    if (needsUpdating) {
                        // download file from skin
                        channel.write(ByteBuffer.wrap(golden), 0);
                        file.deleteOnExit();
                    }
                } finally {
                    if (null != channel) {
                        channel.close();
                    }
                    if (null != fileAccess) {
                        fileAccess.close();
                    }

                    LOG.debug("resource created as " + config.getServletContext().getResource(jsp));
                }
            }

        } catch (IOException ex) {
            LOG.error(ex.getMessage(), ex);
        }
    }

    stopWatch.stop();
    LOG.trace("SiteJspLoaderFilter.downloadJsp(..) took " + stopWatch);
}

From source file:org.apache.htrace.impl.HTracedSpanReceiver.java

void appendToDroppedSpansLog(String text) throws IOException {
    // Is the dropped spans log is disabled?
    if (conf.droppedSpansLogPath.isEmpty() || (conf.droppedSpansLogMaxSize == 0)) {
        return;/*from  w w  w  .  j  a  v  a  2 s  .  com*/
    }
    FileLock lock = null;
    String msg = ISO_DATE_FORMAT.format(new Date()) + ": " + text;
    ByteBuffer bb = ByteBuffer.wrap(msg.getBytes(StandardCharsets.UTF_8));
    // FileChannel locking corresponds to advisory locking on UNIX.  It will
    // protect multiple processes from attempting to write to the same dropped
    // spans log at once.  However, within a single process, we need this
    // synchronized block to ensure that multiple HTracedSpanReceiver objects
    // don't try to write to the same log at once.  (It is unusal to configure
    // multiple HTracedSpanReceiver objects, but possible.)
    synchronized (HTracedSpanReceiver.class) {
        FileChannel channel = FileChannel.open(Paths.get(conf.droppedSpansLogPath), APPEND, CREATE, WRITE);
        try {
            lock = channel.lock();
            long size = channel.size();
            if (size > conf.droppedSpansLogMaxSize) {
                throw new IOException("Dropped spans log " + conf.droppedSpansLogPath + " is already " + size
                        + " bytes; will not add to it.");
            } else if ((size == 0) && (DROPPED_SPANS_FILE_PERMS != null)) {
                // Set the permissions of the dropped spans file so that other
                // processes can write to it.
                Files.setPosixFilePermissions(Paths.get(conf.droppedSpansLogPath), DROPPED_SPANS_FILE_PERMS);
            }
            channel.write(bb);
        } finally {
            try {
                if (lock != null) {
                    lock.release();
                }
            } finally {
                channel.close();
            }
        }
    }
}