[GitHub] [ignite] akalash commented on a change in pull request #8577: IGNITE-13856 make linear performance for DirectByteBufferStreamImplV2.writeString

[GitBox <gi...@apache.org>]

akalash commented on a change in pull request #8577:
URL: https://github.com/apache/ignite/pull/8577#discussion_r545905042



##########
File path: modules/core/src/main/java/org/apache/ignite/internal/direct/stream/v2/DirectByteBufferStreamImplV2.java
##########
@@ -301,6 +302,9 @@
     /** */
     protected boolean lastFinished;
 
+    /** map for cashing byte-array representations of strings */
+    private Map<String, byte[]> stringsMap;

Review comment:
       Why are you using a map here? A simple byte array is enough, isn't it?

##########
File path: modules/core/src/main/java/org/apache/ignite/internal/direct/stream/v2/DirectByteBufferStreamImplV2.java
##########
@@ -584,7 +588,29 @@ public DirectByteBufferStreamImplV2(MessageFactory msgFactory) {
 
     /** {@inheritDoc} */
     @Override public void writeString(String val) {
-        writeByteArray(val != null ? val.getBytes() : null);
+        if (val != null) {
+            if (buf.capacity() < val.length()) {
+                if (stringsMap == null)
+                    stringsMap = new HashMap<>();
+
+                byte[] bytes = stringsMap.computeIfAbsent(val, s -> s.getBytes());
+
+                try {
+                    writeByteArray(bytes);
+                }
+                catch (Exception e) {

Review comment:
       I believe if an exception appears here, this whole object will be invalid, for example, arrOff would be incorrect, so perhaps it's not necessary to handle this exception here.




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