Add interning to KxmlPullParser.

Adding just a small interning pool improves performance even further.
Combined with the first round of optimizations, total improvement for
three large files is 51% 56% and 42%. Performance on a small file
improved 3%. When interning is checked in, Kxml will be significantly
faster than Expat's pull parser for everything but very small files.

                                      /sdcard/xml/com.amazon.mp3.meta             /sdcard/xml/com.cooliris.picasa            /sdcard/xml/com.rhapsody.Deauth              /sdcard/xml/com.snoggdoggler.r
benchmark                 run      us linear runtime                     %     us linear runtime                     %    us linear runtime                     %      us linear runtime                    %
      Dom   baseline / master 210,256 ==============================  184% 53,227 ==============================  171% 2,183 ==============================  151% 164,708 =============================  200%
      Dom first optimizations 174,580 ========================        153% 40,964 =======================         132% 1,968 ===========================     136% 130,814 =======================        159%
      Dom       new interning 163,366 =======================         143% 35,736 ====================            115% 2,116 =============================   147% 121,870 ======================         148%
ExpatPull   baseline / master 130,078 ==================              114% 21,700 ============                     70%   759 ==========                       53%  85,578 ===============                104%
ExpatPull first optimizations 129,776 ==================              114% 21,621 ============                     70%   734 ==========                       51%  86,799 ===============                105%
ExpatPull       new interning 130,971 ==================              115% 21,627 ============                     70%   723 =========                        50%  86,555 ===============                105%
 KxmlPull   baseline / master 114,317 ================                100% 31,040 =================               100% 1,443 ===================             100%  82,478 ===============                100%
 KxmlPull first optimizations  88,716 ============                     78% 20,578 ===========                      66% 1,560 =====================           108%  58,567 ==========                      71%
 KxmlPull       new interning  55,773 =======                          49% 13,692 =======                          44% 1,394 ===================              97%  48,068 ========                        58%

http://b/3090550
Change-Id: I4515546abbbcf940de7be22f26925c4334e59146

1 files changed, 7 insertions, 4 deletions

diff --git a/xml/src/main/java/org/kxml2/io/KXmlParser.java b/xml/src/main/java/org/kxml2/io/KXmlParser.java
index 9ca555b..9c20e0d 100644
--- a/xml/src/main/java/org/kxml2/io/KXmlParser.java
+++ b/xml/src/main/java/org/kxml2/io/KXmlParser.java
@@ -28,6 +28,7 @@ import java.io.InputStreamReader;
 import java.io.Reader;
 import java.util.HashMap;
 import java.util.Map;
+import libcore.internal.StringPool;
 import org.xmlpull.v1.XmlPullParser;
 import org.xmlpull.v1.XmlPullParserException;
 
@@ -106,6 +107,8 @@ public class KXmlParser implements XmlPullParser {
     private boolean unresolved;
     private boolean token;
 
+    public final StringPool stringPool = new StringPool();
+
     /**
      * Retains namespace attributes like {@code xmlns="http://foo"} or {@code xmlns:foo="http:foo"}
      * in pulled elements. Most applications will only be interested in the effective namespaces of
@@ -403,7 +406,7 @@ public class KXmlParser implements XmlPullParser {
         if (!returnText) {
             return null;
         } else if (result == null) {
-            return new String(buffer, start, end - start);
+            return stringPool.get(buffer, start, end - start);
         } else {
             result.append(buffer, start, end - start);
             return result.toString();
@@ -495,7 +498,7 @@ public class KXmlParser implements XmlPullParser {
 
         if (assignText) {
             if (result == null) {
-                text = new String(buffer, start, position - start - 1); // omit the '>'
+                text = stringPool.get(buffer, start, position - start - 1); // omit the '>'
             } else {
                 result.append(buffer, start, position - start - 1); // omit the '>'
                 text = result.toString();
@@ -882,7 +885,7 @@ public class KXmlParser implements XmlPullParser {
         }
 
         if (result == null) {
-            return new String(buffer, start, position - start);
+            return stringPool.get(buffer, start, position - start);
         } else {
             result.append(buffer, start, position - start);
             return result.toString();
@@ -1016,7 +1019,7 @@ public class KXmlParser implements XmlPullParser {
 
             // we encountered a non-name character. done!
             if (result == null) {
-                return new String(buffer, start, position - start);
+                return stringPool.get(buffer, start, position - start);
             } else {
                 result.append(buffer, start, position - start);
                 return result.toString();