Address minor style and documentation comments.

clients/unshaded/src/main/java/tachyon/client/InStream.java

@@ -28,7 +28,7 @@ public abstract class InStream extends InputStream {
    * Moves the starting read position of the stream to the specified position which is relative to
    * the start of the stream. Seeking to a position before the current read position is supported.
    *
-   * @param pos The position to seek to, it must be between 0 and the size of the block.
+   * @param pos The position to seek to, it must be between 0 and the size of the block - 1.
    * @throws IOException if the seek fails due to an error accessing the stream at the position
    */
   public abstract void seek(long pos) throws IOException;

clients/unshaded/src/main/java/tachyon/client/ResourcePool.java

@@ -20,15 +20,18 @@
 
 /**
  * Class representing a pool of resources to be temporarily used and returned. Inheriting classes
- * should implement the close method as well as initialize the resources in the constructor.
+ * should implement the close method as well as initialize the resources in the constructor. The
+ * implemented methods are thread-safe and inheriting classes should also written in a
+ * thread-safe manner. See {@link tachyon.client.file.FSMasterClientPool} as an example.
  *
  * @param <T> The type of resource this pool manages.
  */
+// TODO: This may fit better in the common module
 public abstract class ResourcePool<T> {
   protected final Object mCapacityLock;
-  protected int mCurrentCapacity;
   protected final int mMaxCapacity;
-  protected BlockingQueue<T> mResources;
+  protected final BlockingQueue<T> mResources;
+  protected int mCurrentCapacity;
 
   public ResourcePool(int maxCapacity) {
     mCapacityLock = new Object();

clients/unshaded/src/main/java/tachyon/client/TachyonFSTestUtils.java

@@ -38,8 +38,8 @@ public final class TachyonFSTestUtils {
    */
   public static TachyonFile createByteFile(TachyonFileSystem tfs, String fileName,
       ClientOptions options, int len) throws IOException {
-    return createByteFile(tfs, fileName, options.getTachyonStorageType(), options.getUnderStorageType(),
-        len, options.getBlockSize());
+    return createByteFile(tfs, fileName, options.getTachyonStorageType(),
+        options.getUnderStorageType(), len, options.getBlockSize());
   }
 
   /**

clients/unshaded/src/main/java/tachyon/client/block/LocalBlockInStream.java

@@ -30,7 +30,8 @@
 
 /**
  * This class provides a streaming API to read a block in Tachyon. The data will be directly read
- * from the local machine's storage.
+ * from the local machine's storage. The instances of this class should only be used by one
+ * thread and are not thread safe.
  */
 public class LocalBlockInStream extends BlockInStream {
   private final long mBlockId;
@@ -86,7 +87,7 @@ public void close() throws IOException {
 
   @Override
   public int read() throws IOException {
-    failIfClosed();
+    checkIfClosed();
     if (mData.remaining() == 0) {
       close();
       return -1;
@@ -96,13 +97,13 @@ public int read() throws IOException {
 
   @Override
   public int read(byte[] b) throws IOException {
-    failIfClosed();
+    checkIfClosed();
     return read(b, 0, b.length);
   }
 
   @Override
   public int read(byte[] b, int off, int len) throws IOException {
-    failIfClosed();
+    checkIfClosed();
     Preconditions.checkArgument(b != null, "Buffer is null");
     Preconditions.checkArgument(off >= 0 && len >= 0 && len + off <= b.length, String
         .format("Buffer length (%d), offset(%d), len(%d)", b.length, off, len));
@@ -124,8 +125,9 @@ public long remaining() {
     return mData.remaining();
   }
 
+  @Override
   public void seek(long pos) throws IOException {
-    failIfClosed();
+    checkIfClosed();
     Preconditions.checkArgument(pos >= 0, "Seek position is negative: " + pos);
     Preconditions.checkArgument(pos <= mData.limit(), "Seek position is past buffer limit: " + pos
         + ", Buffer Size = " + mData.limit());
@@ -134,7 +136,7 @@ public void seek(long pos) throws IOException {
 
   @Override
   public long skip(long n) throws IOException {
-    failIfClosed();
+    checkIfClosed();
     if (n <= 0) {
       return 0;
     }
@@ -147,9 +149,7 @@ public long skip(long n) throws IOException {
     return ret;
   }
 
-  private void failIfClosed() throws IOException {
-    if (mClosed) {
-      throw new IOException("Cannot do operations on a closed BlockInStream");
-    }
+  private void checkIfClosed() throws IOException {
+    Preconditions.checkState(!mClosed, "Cannot do operations on a closed BlockInStream");
   }
 }

clients/unshaded/src/main/java/tachyon/client/block/LocalBlockOutStream.java

@@ -32,8 +32,9 @@
 import tachyon.worker.WorkerClient;
 
 /**
- * Provides a streaming API to write to a Tachyon block. This output stream will directly write
- * the input to a file in local Tachyon storage.
+ * Provides a streaming API to write to a Tachyon block. This output stream will directly write the
+ * input to a file in local Tachyon storage. The instances of this class should only be used by one
+ * thread and are not thread safe.
  */
 public class LocalBlockOutStream extends BufferedBlockOutStream {
   private final Closer mCloser;

clients/unshaded/src/main/java/tachyon/client/block/RemoteBlockInStream.java

@@ -28,7 +28,8 @@
 
 /**
  * This class provides a streaming API to read a block in Tachyon. The data will be transferred
- * through a Tachyon worker's dataserver to the client.
+ * through a Tachyon worker's dataserver to the client. The instances of this class should only be
+ * used by one thread and are not thread safe.
  */
 public class RemoteBlockInStream extends BlockInStream {
   private final long mBlockId;

clients/unshaded/src/main/java/tachyon/client/block/RemoteBlockOutStream.java

@@ -23,7 +23,8 @@
 
 /**
  * Provides a streaming API to write to a Tachyon block. This output stream will send the write
- * through a Tachyon worker which will then write the block to a file in Tachyon storage.
+ * through a Tachyon worker which will then write the block to a file in Tachyon storage. The
+ * instances of this class should only be used by one thread and are not thread safe.
  */
 public final class RemoteBlockOutStream extends BufferedBlockOutStream {
   private final RemoteBlockWriter mRemoteWriter;

clients/unshaded/src/main/java/tachyon/client/block/TachyonBlockStore.java

@@ -52,7 +52,7 @@ public static synchronized TachyonBlockStore get() {
   /**
    * Creates a Tachyon block store.
    */
-  public TachyonBlockStore() {
+  private TachyonBlockStore() {
     mContext = BSContext.INSTANCE;
   }