Always send payload in response

As an optimization we sent empty payload if config was unchanged.
This optimization is no longer needed, as configs are small and we can
remove checks several places in config system and ease changes to
config protocol.

1 files changed, 8 insertions, 20 deletions

diff --git a/config/src/main/java/com/yahoo/vespa/config/protocol/JRTServerConfigRequestV3.java b/config/src/main/java/com/yahoo/vespa/config/protocol/JRTServerConfigRequestV3.java
index 446ddf0560b..e6c9bc2175b 100644
--- a/config/src/main/java/com/yahoo/vespa/config/protocol/JRTServerConfigRequestV3.java
+++ b/config/src/main/java/com/yahoo/vespa/config/protocol/JRTServerConfigRequestV3.java
@@ -3,7 +3,6 @@ package com.yahoo.vespa.config.protocol;
 
 import com.fasterxml.jackson.core.JsonFactory;
 import com.fasterxml.jackson.core.JsonGenerator;
-import com.yahoo.vespa.config.PayloadChecksums;
 import com.yahoo.jrt.DataValue;
 import com.yahoo.jrt.Request;
 import com.yahoo.jrt.StringValue;
@@ -11,7 +10,7 @@ import com.yahoo.jrt.Value;
 import com.yahoo.text.Utf8Array;
 import com.yahoo.vespa.config.ConfigKey;
 import com.yahoo.vespa.config.ErrorCode;
-import com.yahoo.vespa.config.util.ConfigUtils;
+import com.yahoo.vespa.config.PayloadChecksums;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
@@ -26,8 +25,7 @@ import static com.yahoo.vespa.config.PayloadChecksum.Type.XXHASH64;
  * The V3 config protocol implemented on the server side. The V3 protocol uses 2 fields:
  *
  * * A metadata field containing json data describing config generation, md5 and compression info
- * * A data field containing compressed or uncompressed json config payload. This field can be empty if the payload
- *   has not changed since last request, triggering an optimization at the client where the previous payload is used instead.
+ * * A data field containing compressed or uncompressed json config payload
  *
  * The implementation of addOkResponse is optimized for doing as little copying of payload data as possible, ensuring
  * that we get a lower memory footprint.
@@ -74,8 +72,6 @@ public class JRTServerConfigRequestV3 implements JRTServerConfigRequest {
     @Override
     public void addOkResponse(Payload payload, long generation, boolean applyOnRestart, PayloadChecksums payloadChecksums) {
         this.applyOnRestart = applyOnRestart;
-        boolean changedConfig = !payloadChecksums.equals(getRequestConfigChecksums());
-        boolean changedConfigAndNewGeneration = changedConfig && ConfigUtils.isGenerationNewer(generation, getRequestGeneration());
         Payload responsePayload = payload.withCompression(getCompressionType());
         ByteArrayOutputStream byteArrayOutputStream = new NoCopyByteArrayOutputStream(4096);
         try {
@@ -93,10 +89,6 @@ public class JRTServerConfigRequestV3 implements JRTServerConfigRequest {
                 throw new RuntimeException("Payload is null for ' " + this + ", not able to create response");
             }
             CompressionInfo compressionInfo = responsePayload.getCompressionInfo();
-            // If payload is not being sent, we must adjust compression info to avoid client confusion.
-            if (!changedConfigAndNewGeneration) {
-                compressionInfo = CompressionInfo.create(compressionInfo.getCompressionType(), 0);
-            }
             compressionInfo.serialize(jsonGenerator);
             jsonGenerator.writeEndObject();
 
@@ -106,17 +98,13 @@ public class JRTServerConfigRequestV3 implements JRTServerConfigRequest {
             throw new IllegalArgumentException("Could not add OK response for " + this);
         }
         request.returnValues().add(createResponseValue(byteArrayOutputStream));
-        if (changedConfigAndNewGeneration) {
-            ByteBuffer buf = responsePayload.getData().wrap();
-            if (buf.hasArray() && buf.remaining() == buf.array().length) {
-                request.returnValues().add(new DataValue(buf.array()));
-            } else {
-                byte [] dst = new byte[buf.remaining()];
-                buf.get(dst);
-                request.returnValues().add(new DataValue(dst));
-            }
+        ByteBuffer buf = responsePayload.getData().wrap();
+        if (buf.hasArray() && buf.remaining() == buf.array().length) {
+            request.returnValues().add(new DataValue(buf.array()));
         } else {
-            request.returnValues().add(new DataValue(new byte[0]));
+            byte[] dst = new byte[buf.remaining()];
+            buf.get(dst);
+            request.returnValues().add(new DataValue(dst));
         }
     }