Merge pull request brianfrankcooper#999 from manolama/iterators_reset

[core] Add a reset() method to the ByteIterator abstract and implemen…

core/src/main/java/com/yahoo/ycsb/ByteArrayByteIterator.java

@@ -20,6 +20,7 @@
  *  A ByteIterator that iterates through a byte array.
  */
 public class ByteArrayByteIterator extends ByteIterator {
+  private final int originalOffset;
   private byte[] str;
   private int off;
   private final int len;
@@ -28,12 +29,14 @@ public ByteArrayByteIterator(byte[] s) {
     this.str = s;
     this.off = 0;
     this.len = s.length;
+    originalOffset = 0;
   }
 
   public ByteArrayByteIterator(byte[] s, int off, int len) {
     this.str = s;
     this.off = off;
     this.len = off + len;
+    originalOffset = off;
   }
 
   @Override
@@ -53,4 +56,9 @@ public long bytesLeft() {
     return len - off;
   }
 
+  @Override
+  public void reset() {
+    off = originalOffset;
+  }
+
 }

core/src/main/java/com/yahoo/ycsb/ByteIterator.java

@@ -73,6 +73,15 @@ public void remove() {
     throw new UnsupportedOperationException();
   }
 
+  /** Resets the iterator so that it can be consumed again. Not all
+   * implementations support this call.
+   * @throws UnsupportedOperationException if the implementation hasn't implemented
+   * the method.
+   */
+  public void reset() {
+    throw new UnsupportedOperationException();
+  }
+
   /** Consumes remaining contents of this object, and returns them as a string. */
   public String toString() {
     Charset cset = Charset.forName("UTF-8");

core/src/main/java/com/yahoo/ycsb/InputStreamByteIterator.java

@@ -16,6 +16,7 @@
  */
 package com.yahoo.ycsb;
 
+import java.io.IOException;
 import java.io.InputStream;
 
 /**
@@ -25,11 +26,16 @@ public class InputStreamByteIterator extends ByteIterator {
   private long len;
   private InputStream ins;
   private long off;
+  private final boolean resetable;
 
   public InputStreamByteIterator(InputStream ins, long len) {
     this.len = len;
     this.ins = ins;
     off = 0;
+    resetable = ins.markSupported();
+    if (resetable) {
+      ins.mark((int) len);
+    }
   }
 
   @Override
@@ -57,4 +63,17 @@ public long bytesLeft() {
     return len - off;
   }
 
+  @Override
+  public void reset() {
+    if (resetable) {
+      try {
+        ins.reset();
+        ins.mark((int) len);
+      } catch (IOException e) {
+        throw new IllegalStateException("Failed to reset the input stream", e);
+      }
+    }
+    throw new UnsupportedOperationException();
+  }
+
 }

core/src/main/java/com/yahoo/ycsb/RandomByteIterator.java

@@ -93,4 +93,10 @@ public int nextBuf(byte[] buffer, int bufOffset) {
   public long bytesLeft() {
     return len - off - bufOff;
   }
+
+  @Override
+  public void reset() {
+    off = 0;
+  }
+
 }

core/src/main/java/com/yahoo/ycsb/StringByteIterator.java

@@ -96,6 +96,11 @@ public long bytesLeft() {
     return str.length() - off;
   }
 
+  @Override
+  public void reset() {
+    off = 0;
+  }
+
   /**
    * Specialization of general purpose toString() to avoid unnecessary
    * copies.