From 7ec7b76ee970888b0ab09bbd58d6cf56cf85ee7a Mon Sep 17 00:00:00 2001
From: Ivan Sopov <i.sopov@corp.mail.ru>
Date: Mon, 19 Mar 2018 17:24:10 +0300
Subject: [PATCH] [core] Optimize toArray of all ByteIterators except
 RandomByteIterator

Method nextBuf is a clever hack that outperforms Random.nextBytes
but performs poorly for all other ByteIterator implementations

This commit moves it to RandomByteIterator and adds efficient
toArray implementations for other ByteIterator classes.

Also InputStreamByteIterator.reset method that unconditionally
throws UnsupportedOperationException is fixed
---
 .../com/yahoo/ycsb/ByteArrayByteIterator.java | 13 +++++++++--
 .../java/com/yahoo/ycsb/ByteIterator.java     |  8 +++----
 .../yahoo/ycsb/InputStreamByteIterator.java   | 23 ++++++++++++++++---
 .../com/yahoo/ycsb/RandomByteIterator.java    | 20 +++++++++++++---
 .../com/yahoo/ycsb/StringByteIterator.java    | 12 +++++++++-
 5 files changed, 63 insertions(+), 13 deletions(-)

diff --git a/core/src/main/java/com/yahoo/ycsb/ByteArrayByteIterator.java b/core/src/main/java/com/yahoo/ycsb/ByteArrayByteIterator.java
index 8f8762b4f2..cf1470cbc0 100644
--- a/core/src/main/java/com/yahoo/ycsb/ByteArrayByteIterator.java
+++ b/core/src/main/java/com/yahoo/ycsb/ByteArrayByteIterator.java
@@ -21,7 +21,7 @@
  */
 public class ByteArrayByteIterator extends ByteIterator {
   private final int originalOffset;
-  private byte[] str;
+  private final byte[] str;
   private int off;
   private final int len;
 
@@ -60,5 +60,14 @@ public long bytesLeft() {
   public void reset() {
     off = originalOffset;
   }
-  
+
+  @Override
+  public byte[] toArray() {
+    int size = (int) bytesLeft();
+    byte[] bytes = new byte[size];
+    System.arraycopy(str, off, bytes, 0, size);
+    off = len;
+    return bytes;
+  }
+
 }
diff --git a/core/src/main/java/com/yahoo/ycsb/ByteIterator.java b/core/src/main/java/com/yahoo/ycsb/ByteIterator.java
index 9be84d5a05..281e2b98c9 100644
--- a/core/src/main/java/com/yahoo/ycsb/ByteIterator.java
+++ b/core/src/main/java/com/yahoo/ycsb/ByteIterator.java
@@ -81,7 +81,7 @@ public void remove() {
   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");
@@ -95,10 +95,10 @@ public byte[] toArray() {
     if (left != (int) left) {
       throw new ArrayIndexOutOfBoundsException("Too much data to fit in one array!");
     }
+
     byte[] ret = new byte[(int) left];
-    int off = 0;
-    while (off < ret.length) {
-      off = nextBuf(ret, off);
+    for (int i = 0; i < ret.length; i++) {
+      ret[i] = nextByte();
     }
     return ret;
   }
diff --git a/core/src/main/java/com/yahoo/ycsb/InputStreamByteIterator.java b/core/src/main/java/com/yahoo/ycsb/InputStreamByteIterator.java
index 02ca38006c..31c37065ba 100644
--- a/core/src/main/java/com/yahoo/ycsb/InputStreamByteIterator.java
+++ b/core/src/main/java/com/yahoo/ycsb/InputStreamByteIterator.java
@@ -23,8 +23,8 @@
  *  A ByteIterator that iterates through an inputstream of bytes.
  */
 public class InputStreamByteIterator extends ByteIterator {
-  private long len;
-  private InputStream ins;
+  private final long len;
+  private final InputStream ins;
   private long off;
   private final boolean resetable;
 
@@ -63,17 +63,34 @@ public long bytesLeft() {
     return len - off;
   }
 
+  @Override
+  public byte[] toArray() {
+    int size = (int) bytesLeft();
+    byte[] bytes = new byte[size];
+    try {
+      if (ins.read(bytes) < size) {
+        throw new IllegalStateException("Past EOF!");
+      }
+    } catch (IOException e) {
+      throw new IllegalStateException(e);
+    }
+    off = len;
+    return bytes;
+  }
+  
   @Override
   public void reset() {
     if (resetable) {
       try {
         ins.reset();
         ins.mark((int) len);
+        off = 0;
       } catch (IOException e) {
         throw new IllegalStateException("Failed to reset the input stream", e);
       }
+    } else {
+      throw new UnsupportedOperationException();
     }
-    throw new UnsupportedOperationException();
   }
   
 }
diff --git a/core/src/main/java/com/yahoo/ycsb/RandomByteIterator.java b/core/src/main/java/com/yahoo/ycsb/RandomByteIterator.java
index 681224e8fb..76d765c7a5 100644
--- a/core/src/main/java/com/yahoo/ycsb/RandomByteIterator.java
+++ b/core/src/main/java/com/yahoo/ycsb/RandomByteIterator.java
@@ -20,10 +20,10 @@
  *  A ByteIterator that generates a random sequence of bytes.
  */
 public class RandomByteIterator extends ByteIterator {
-  private long len;
+  private final long len;
   private long off;
   private int bufOff;
-  private byte[] buf;
+  private final byte[] buf;
 
   @Override
   public boolean hasNext() {
@@ -98,5 +98,19 @@ public long bytesLeft() {
   public void reset() {
     off = 0;
   }
-  
+
+  /** Consumes remaining contents of this object, and returns them as a byte array. */
+  public byte[] toArray() {
+    long left = bytesLeft();
+    if (left != (int) left) {
+      throw new ArrayIndexOutOfBoundsException("Too much data to fit in one array!");
+    }
+    byte[] ret = new byte[(int) left];
+    int bufOffset = 0;
+    while (bufOffset < ret.length) {
+      bufOffset = nextBuf(ret, bufOffset);
+    }
+    return ret;
+  }
+
 }
diff --git a/core/src/main/java/com/yahoo/ycsb/StringByteIterator.java b/core/src/main/java/com/yahoo/ycsb/StringByteIterator.java
index 8223549188..63dba89469 100644
--- a/core/src/main/java/com/yahoo/ycsb/StringByteIterator.java
+++ b/core/src/main/java/com/yahoo/ycsb/StringByteIterator.java
@@ -100,7 +100,17 @@ public long bytesLeft() {
   public void reset() {
     off = 0;
   }
-  
+
+  @Override
+  public byte[] toArray() {
+    byte[] bytes = new byte[(int) bytesLeft()];
+    for (int i = 0; i < bytes.length; i++) {
+      bytes[i] = (byte) str.charAt(off + i);
+    }
+    off = str.length();
+    return bytes;
+  }
+
   /**
    * Specialization of general purpose toString() to avoid unnecessary
    * copies.