Add a performance example and reduce garbage produced.

Author: peter-lawrey

README.md

@@ -66,6 +66,7 @@ Version 1.8 - Add MutableDecimal and FIX support.
 
 Version 1.7.1 - Bug fix and OGSi support.
            Sonar and IntelliJ code analysis - thank you, Mani.
+           Add appendDate and appendDateTime
 
 Version 1.7 - Add support to the DataModel for arbitrary events to be sent such as timestamps, heartbeats, changes in stages which can picked up by listeners.
            Add support for the DataModel for arbitrary annotations on the data so each map/collection can have additional configuration

chronicle/src/main/java/com/higherfrequencytrading/chronicle/ByteStringAppender.java

@@ -46,6 +46,10 @@ public interface ByteStringAppender extends Appendable {
 
     ByteStringAppender appendTime(long timeInMS);
 
+    ByteStringAppender appendDate(long timeInMS);
+
+    ByteStringAppender appendDateTime(long timeInMS);
+
 // TODO
 //   ByteStringAppender append(float f);
 

chronicle/src/main/java/com/higherfrequencytrading/chronicle/impl/AbstractExcerpt.java

@@ -26,6 +26,8 @@
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.nio.MappedByteBuffer;
+import java.nio.charset.Charset;
+import java.text.SimpleDateFormat;
 import java.util.*;
 import java.util.concurrent.atomic.AtomicBoolean;
 
@@ -34,6 +36,7 @@
  */
 public abstract class AbstractExcerpt implements Excerpt {
     private static final int MIN_SIZE = 8;
+    public static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1");
 
     protected final DirectChronicle chronicle;
     protected long index = -1;
@@ -1116,6 +1119,33 @@ public ByteStringAppender append(long num) {
         return this;
     }
 
+    private SimpleDateFormat dateFormat = null;
+    private long lastDay = Long.MIN_VALUE;
+    private byte[] lastDateStr = null;
+
+    @Override
+    public ByteStringAppender appendDate(long timeInMS) {
+        if (dateFormat == null) {
+            dateFormat = new SimpleDateFormat("yyyy/MM/dd");
+            dateFormat.setTimeZone(TimeZone.getTimeZone("GMT"));
+        }
+        long date = timeInMS / 86400000;
+        if (lastDay != date) {
+            lastDateStr = dateFormat.format(new Date(timeInMS)).getBytes(ISO_8859_1);
+            lastDay = date;
+        }
+        append(lastDateStr);
+        return this;
+    }
+
+    @Override
+    public ByteStringAppender appendDateTime(long timeInMS) {
+        appendDate(timeInMS);
+        writeByte('T');
+        appendTime(timeInMS);
+        return this;
+    }
+
     @Override
     public ByteStringAppender appendTime(long timeInMS) {
         int hours = (int) (timeInMS / (60 * 60 * 1000));

chronicle/src/main/java/com/higherfrequencytrading/chronicle/impl/WrappedExcerpt.java

@@ -410,6 +410,18 @@ public ByteStringAppender append(long num) {
         return this;
     }
 
+    @Override
+    public ByteStringAppender appendDate(long timeInMS) {
+        excerpt.appendDate(timeInMS);
+        return this;
+    }
+
+    @Override
+    public ByteStringAppender appendDateTime(long timeInMS) {
+        excerpt.appendDateTime(timeInMS);
+        return this;
+    }
+
     public ByteStringAppender appendTime(long timeInMS) {
         excerpt.appendTime(timeInMS);
         return this;