/**
   * Validate streams generate the same output.
   *
   * @param expIn Expected input stream.
   * @param actIn Actual input stream.
   * @param expSize Expected size of the streams.
   * @param seek Seek to use async position-based reading or {@code null} to use simple continuous
   *     reading.
   * @throws IOException In case of any IO exception.
   */
  private void assertEqualStreams(
      InputStream expIn, GridGgfsInputStream actIn, @Nullable Long expSize, @Nullable Long seek)
      throws IOException {
    if (seek != null) expIn.skip(seek);

    int bufSize = 2345;
    byte buf1[] = new byte[bufSize];
    byte buf2[] = new byte[bufSize];
    long pos = 0;

    long start = System.currentTimeMillis();

    while (true) {
      int read = (int) Math.min(bufSize, expSize - pos);

      int i1;

      if (seek == null) i1 = actIn.read(buf1, 0, read);
      else if (seek % 2 == 0) i1 = actIn.read(pos + seek, buf1, 0, read);
      else {
        i1 = read;

        actIn.readFully(pos + seek, buf1, 0, read);
      }

      // Read at least 0 byte, but don't read more then 'i1' or 'read'.
      int i2 = expIn.read(buf2, 0, Math.max(0, Math.min(i1, read)));

      if (i1 != i2) {
        fail(
            "Expects the same data [read="
                + read
                + ", pos="
                + pos
                + ", seek="
                + seek
                + ", i1="
                + i1
                + ", i2="
                + i2
                + ']');
      }

      if (i1 == -1) break; // EOF

      // i1 == bufSize => compare buffers.
      // i1 <  bufSize => Compare part of buffers, rest of buffers are equal from previous
      // iteration.
      assertTrue(
          "Expects the same data [read="
              + read
              + ", pos="
              + pos
              + ", seek="
              + seek
              + ", i1="
              + i1
              + ", i2="
              + i2
              + ']',
          Arrays.equals(buf1, buf2));

      if (read == 0) break; // Nothing more to read.

      pos += i1;
    }

    if (expSize != null) assertEquals(expSize.longValue(), pos);

    long time = System.currentTimeMillis() - start;

    if (time != 0 && log.isInfoEnabled()) {
      log.info(
          String.format(
              "Streams were compared in continuous reading " + "[size=%7d, rate=%3.1f MB/sec]",
              expSize, expSize * 1000. / time / 1024 / 1024));
    }
  }
  /**
   * Checks availability of a classpath resource.
   *
   * @param name Resource name.
   * @return {@code true} if resource is available and ready for read, {@code false} otherwise.
   */
  private boolean resourceAvailable(String name) {
    InputStream cfgStream =
        Thread.currentThread().getContextClassLoader().getResourceAsStream(name);

    if (cfgStream == null) {
      log.error("Classpath resource not found: " + name);

      return false;
    }

    try {
      // Read a single byte to force actual content access by JVM.
      cfgStream.read();

      return true;
    } catch (IOException e) {
      log.error("Failed to read classpath resource: " + name, e);

      return false;
    } finally {
      U.close(cfgStream, log);
    }
  }
  /**
   * Test file creation.
   *
   * @param path Path to file to store.
   * @param size Size of file to store.
   * @param salt Salt for file content generation.
   * @throws Exception In case of any exception.
   */
  private void testCreateFile(final GridGgfsPath path, final long size, final int salt)
      throws Exception {
    info("Create file [path=" + path + ", size=" + size + ", salt=" + salt + ']');

    final AtomicInteger cnt = new AtomicInteger(0);
    final Collection<GridGgfsPath> cleanUp = new ConcurrentLinkedQueue<>();

    long time =
        runMultiThreaded(
            new Callable<Object>() {
              @Override
              public Object call() throws Exception {
                int id = cnt.incrementAndGet();

                GridGgfsPath f = new GridGgfsPath(path.parent(), "asdf" + (id > 1 ? "-" + id : ""));

                try (GridGgfsOutputStream out = fs.create(f, 0, true, null, 0, 1024, null)) {
                  assertNotNull(out);

                  cleanUp.add(f); // Add all created into cleanup list.

                  U.copy(new GridGgfsTestInputStream(size, salt), out);
                }

                return null;
              }
            },
            WRITING_THREADS_CNT,
            "perform-multi-thread-writing");

    if (time > 0) {
      double rate = size * 1000. / time / 1024 / 1024;

      info(
          String.format(
              "Write file [path=%s, size=%d kB, rate=%2.1f MB/s]",
              path, WRITING_THREADS_CNT * size / 1024, WRITING_THREADS_CNT * rate));
    }

    info("Read and validate saved file: " + path);

    final InputStream expIn = new GridGgfsTestInputStream(size, salt);
    final GridGgfsInputStream actIn = fs.open(path, CFG_BLOCK_SIZE * READING_THREADS_CNT * 11 / 10);

    // Validate continuous reading of whole file.
    assertEqualStreams(expIn, actIn, size, null);

    // Validate random seek and reading.
    final Random rnd = new Random();

    runMultiThreaded(
        new Callable<Object>() {
          @Override
          public Object call() throws Exception {
            long skip = Math.abs(rnd.nextLong() % (size + 1));
            long range = Math.min(size - skip, rnd.nextInt(CFG_BLOCK_SIZE * 400));

            assertEqualStreams(new GridGgfsTestInputStream(size, salt), actIn, range, skip);

            return null;
          }
        },
        READING_THREADS_CNT,
        "validate-multi-thread-reading");

    expIn.close();
    actIn.close();

    info("Get stored file info: " + path);

    GridGgfsFile desc = fs.info(path);

    info("Validate stored file info: " + desc);

    assertNotNull(desc);

    if (log.isDebugEnabled()) log.debug("File descriptor: " + desc);

    Collection<GridGgfsBlockLocation> aff = fs.affinity(path, 0, desc.length());

    assertFalse("Affinity: " + aff, desc.length() != 0 && aff.isEmpty());

    int blockSize = desc.blockSize();

    assertEquals("File size", size, desc.length());
    assertEquals("Binary block size", CFG_BLOCK_SIZE, blockSize);
    // assertEquals("Permission", "rwxr-xr-x", desc.getPermission().toString());
    // assertEquals("Permission sticky bit marks this is file", false,
    // desc.getPermission().getStickyBit());
    assertEquals("Type", true, desc.isFile());
    assertEquals("Type", false, desc.isDirectory());

    info("Cleanup files: " + cleanUp);

    for (GridGgfsPath f : cleanUp) {
      fs.delete(f, true);
      assertNull(fs.info(f));
    }
  }