Decouple XContentType from StreamInput/Output (#28927)

This removes the readFrom and writeTo methods from XContentType, instead using
the more generic `readEnum` and `writeEnum` methods. Luckily they are both
encoded exactly the same way, so there is no compatibility layer needed for
backwards compatibility.

Relates to #28504

modules/percolator/src/main/java/org/elasticsearch/percolator/PercolateQueryBuilder.java

@@ -274,7 +274,7 @@ public class PercolateQueryBuilder extends AbstractQueryBuilder<PercolateQueryBu
         }
         if (documents.isEmpty() == false) {
             if (in.getVersion().onOrAfter(Version.V_5_3_0)) {
-                documentXContentType = XContentType.readFrom(in);
+                documentXContentType = in.readEnum(XContentType.class);
             } else {
                 documentXContentType = XContentFactory.xContentType(documents.iterator().next());
             }
@@ -331,7 +331,7 @@ public class PercolateQueryBuilder extends AbstractQueryBuilder<PercolateQueryBu
             out.writeOptionalBytesReference(doc);
         }
         if (documents.isEmpty() == false && out.getVersion().onOrAfter(Version.V_5_3_0)) {
-            documentXContentType.writeTo(out);
+            out.writeEnum(documentXContentType);
         }
     }
 

server/src/main/java/org/elasticsearch/action/admin/cluster/storedscripts/PutStoredScriptRequest.java

@@ -123,7 +123,7 @@ public class PutStoredScriptRequest extends AcknowledgedRequest<PutStoredScriptR
         id = in.readOptionalString();
         content = in.readBytesReference();
         if (in.getVersion().onOrAfter(Version.V_5_3_0)) {
-            xContentType = XContentType.readFrom(in);
+            xContentType = in.readEnum(XContentType.class);
         } else {
             xContentType = XContentFactory.xContentType(content);
         }
@@ -145,7 +145,7 @@ public class PutStoredScriptRequest extends AcknowledgedRequest<PutStoredScriptR
         out.writeOptionalString(id);
         out.writeBytesReference(content);
         if (out.getVersion().onOrAfter(Version.V_5_3_0)) {
-            xContentType.writeTo(out);
+            out.writeEnum(xContentType);
         }
         if (out.getVersion().onOrAfter(Version.V_6_0_0_alpha2)) {
             out.writeOptionalString(context);

server/src/main/java/org/elasticsearch/action/index/IndexRequest.java

@@ -542,7 +542,11 @@ public class IndexRequest extends ReplicatedWriteRequest<IndexRequest> implement
         pipeline = in.readOptionalString();
         isRetry = in.readBoolean();
         autoGeneratedTimestamp = in.readLong();
-        contentType = in.readOptionalWriteable(XContentType::readFrom);
+        if (in.readBoolean()) {
+            contentType = in.readEnum(XContentType.class);
+        } else {
+            contentType = null;
+        }
     }
 
     @Override
@@ -566,7 +570,12 @@ public class IndexRequest extends ReplicatedWriteRequest<IndexRequest> implement
         out.writeOptionalString(pipeline);
         out.writeBoolean(isRetry);
         out.writeLong(autoGeneratedTimestamp);
-        out.writeOptionalWriteable(contentType);
+        if (contentType != null) {
+            out.writeBoolean(true);
+            out.writeEnum(contentType);
+        } else {
+            out.writeBoolean(false);
+        }
     }
 
     @Override

server/src/main/java/org/elasticsearch/action/ingest/PutPipelineRequest.java

@@ -81,7 +81,7 @@ public class PutPipelineRequest extends AcknowledgedRequest<PutPipelineRequest>
         id = in.readString();
         source = in.readBytesReference();
         if (in.getVersion().onOrAfter(Version.V_5_3_0)) {
-            xContentType = XContentType.readFrom(in);
+            xContentType = in.readEnum(XContentType.class);
         } else {
             xContentType = XContentFactory.xContentType(source);
         }
@@ -93,7 +93,7 @@ public class PutPipelineRequest extends AcknowledgedRequest<PutPipelineRequest>
         out.writeString(id);
         out.writeBytesReference(source);
         if (out.getVersion().onOrAfter(Version.V_5_3_0)) {
-            xContentType.writeTo(out);
+            out.writeEnum(xContentType);
         }
     }
 }

server/src/main/java/org/elasticsearch/action/ingest/SimulatePipelineRequest.java

@@ -76,7 +76,7 @@ public class SimulatePipelineRequest extends ActionRequest {
         verbose = in.readBoolean();
         source = in.readBytesReference();
         if (in.getVersion().onOrAfter(Version.V_5_3_0)) {
-            xContentType = XContentType.readFrom(in);
+            xContentType = in.readEnum(XContentType.class);
         } else {
             xContentType = XContentFactory.xContentType(source);
         }
@@ -123,7 +123,7 @@ public class SimulatePipelineRequest extends ActionRequest {
         out.writeBoolean(verbose);
         out.writeBytesReference(source);
         if (out.getVersion().onOrAfter(Version.V_5_3_0)) {
-            xContentType.writeTo(out);
+            out.writeEnum(xContentType);
         }
     }
 

server/src/main/java/org/elasticsearch/action/termvectors/TermVectorsRequest.java

@@ -516,7 +516,7 @@ public class TermVectorsRequest extends SingleShardRequest<TermVectorsRequest> i
         if (in.readBoolean()) {
             doc = in.readBytesReference();
             if (in.getVersion().onOrAfter(Version.V_5_3_0)) {
-                xContentType = XContentType.readFrom(in);
+                xContentType = in.readEnum(XContentType.class);
             } else {
                 xContentType = XContentFactory.xContentType(doc);
             }
@@ -561,7 +561,7 @@ public class TermVectorsRequest extends SingleShardRequest<TermVectorsRequest> i
         if (doc != null) {
             out.writeBytesReference(doc);
             if (out.getVersion().onOrAfter(Version.V_5_3_0)) {
-                xContentType.writeTo(out);
+                out.writeEnum(xContentType);
             }
         }
         out.writeOptionalString(routing);

server/src/main/java/org/elasticsearch/common/xcontent/XContentParser.java

@@ -19,8 +19,7 @@
 
 package org.elasticsearch.common.xcontent;
 
-import org.elasticsearch.common.lease.Releasable;
+import java.io.Closeable;
-
 import java.io.IOException;
 import java.nio.CharBuffer;
 import java.util.List;
@@ -37,7 +36,7 @@ import java.util.Map;
  *          NamedXContentRegistry.EMPTY, ParserField."{\"key\" : \"value\"}");
  * </pre>
  */
-public interface XContentParser extends Releasable {
+public interface XContentParser extends Closeable {
 
     enum Token {
         START_OBJECT {

server/src/main/java/org/elasticsearch/common/xcontent/XContentType.java

@@ -19,22 +19,18 @@
 
 package org.elasticsearch.common.xcontent;
 
-import org.elasticsearch.common.io.stream.StreamInput;
-import org.elasticsearch.common.io.stream.StreamOutput;
-import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.xcontent.cbor.CborXContent;
 import org.elasticsearch.common.xcontent.json.JsonXContent;
 import org.elasticsearch.common.xcontent.smile.SmileXContent;
 import org.elasticsearch.common.xcontent.yaml.YamlXContent;
 
-import java.io.IOException;
 import java.util.Locale;
 import java.util.Objects;
 
 /**
  * The content type of {@link org.elasticsearch.common.xcontent.XContent}.
  */
-public enum XContentType implements Writeable {
+public enum XContentType {
 
     /**
      * A JSON based content type.
@@ -183,18 +179,4 @@ public enum XContentType implements Writeable {
 
     public abstract String mediaTypeWithoutParameters();
 
-    public static XContentType readFrom(StreamInput in) throws IOException {
-        int index = in.readVInt();
-        for (XContentType contentType : values()) {
-            if (index == contentType.index) {
-                return contentType;
-            }
-        }
-        throw new IllegalStateException("Unknown XContentType with index [" + index + "]");
-    }
-
-    @Override
-    public void writeTo(StreamOutput out) throws IOException {
-        out.writeVInt(index);
-    }
 }

server/src/main/java/org/elasticsearch/index/query/MoreLikeThisQueryBuilder.java

@@ -221,7 +221,7 @@ public class MoreLikeThisQueryBuilder extends AbstractQueryBuilder<MoreLikeThisQ
             if (in.readBoolean()) {
                 doc = (BytesReference) in.readGenericValue();
                 if (in.getVersion().onOrAfter(Version.V_5_3_0)) {
-                    xContentType = XContentType.readFrom(in);
+                    xContentType = in.readEnum(XContentType.class);
                 } else {
                     xContentType = XContentFactory.xContentType(doc);
                 }
@@ -243,7 +243,7 @@ public class MoreLikeThisQueryBuilder extends AbstractQueryBuilder<MoreLikeThisQ
             if (doc != null) {
                 out.writeGenericValue(doc);
                 if (out.getVersion().onOrAfter(Version.V_5_3_0)) {
-                    xContentType.writeTo(out);
+                    out.writeEnum(xContentType);
                 }
             } else {
                 out.writeString(id);

server/src/main/java/org/elasticsearch/ingest/PipelineConfiguration.java

@@ -120,7 +120,7 @@ public final class PipelineConfiguration extends AbstractDiffable<PipelineConfig
 
     public static PipelineConfiguration readFrom(StreamInput in) throws IOException {
         if (in.getVersion().onOrAfter(Version.V_5_3_0)) {
-            return new PipelineConfiguration(in.readString(), in.readBytesReference(), XContentType.readFrom(in));
+            return new PipelineConfiguration(in.readString(), in.readBytesReference(), in.readEnum(XContentType.class));
         } else {
             final String id = in.readString();
             final BytesReference config = in.readBytesReference();
@@ -137,7 +137,7 @@ public final class PipelineConfiguration extends AbstractDiffable<PipelineConfig
         out.writeString(id);
         out.writeBytesReference(config);
         if (out.getVersion().onOrAfter(Version.V_5_3_0)) {
-            xContentType.writeTo(out);
+            out.writeEnum(xContentType);
         }
     }
 

server/src/main/java/org/elasticsearch/script/Script.java

@@ -507,7 +507,7 @@ public final class Script implements ToXContentObject, Writeable {
 
             if (in.readBoolean()) {
                 this.options = new HashMap<>();
-                XContentType contentType = XContentType.readFrom(in);
+                XContentType contentType = in.readEnum(XContentType.class);
                 this.options.put(CONTENT_TYPE_OPTION, contentType.mediaType());
             } else if (type == ScriptType.INLINE) {
                 options = new HashMap<>();
@@ -571,7 +571,7 @@ public final class Script implements ToXContentObject, Writeable {
             if (options != null && options.containsKey(CONTENT_TYPE_OPTION)) {
                 XContentType contentType = XContentType.fromMediaTypeOrFormat(options.get(CONTENT_TYPE_OPTION));
                 out.writeBoolean(true);
-                contentType.writeTo(out);
+                out.writeEnum(contentType);
             } else {
                 out.writeBoolean(false);
             }