Remove content thread safe from REST layer

there is no need for this anymore, for some time, since in netty now we rely on copying over the buffer and reusing it
closes #10429

src/main/java/org/elasticsearch/http/netty/NettyHttpChannel.java

@@ -137,11 +137,7 @@ public class NettyHttpChannel extends HttpChannel {
         ChannelBuffer buffer;
         boolean addedReleaseListener = false;
         try {
-            if (response.contentThreadSafe()) {
-                buffer = content.toChannelBuffer();
-            } else {
-                buffer = content.copyBytesArray().toChannelBuffer();
-            }
+            buffer = content.toChannelBuffer();
             resp.setContent(buffer);
 
             // If our response doesn't specify a content-type header, set one
@@ -180,7 +176,7 @@ public class NettyHttpChannel extends HttpChannel {
                 future = channel.write(resp);
             }
 
-            if (response.contentThreadSafe() && content instanceof Releasable) {
+            if (content instanceof Releasable) {
                 future.addListener(new ReleaseChannelFutureListener((Releasable) content));
                 addedReleaseListener = true;
             }

src/main/java/org/elasticsearch/rest/BytesRestResponse.java

@@ -34,48 +34,46 @@ public class BytesRestResponse extends RestResponse {
 
     private final RestStatus status;
     private final BytesReference content;
-    private final boolean contentThreadSafe;
     private final String contentType;
 
     public BytesRestResponse(RestStatus status) {
-        this(status, TEXT_CONTENT_TYPE, BytesArray.EMPTY, true);
+        this(status, TEXT_CONTENT_TYPE, BytesArray.EMPTY);
     }
 
     /**
      * Creates a new response based on {@link XContentBuilder}.
      */
     public BytesRestResponse(RestStatus status, XContentBuilder builder) {
-        this(status, builder.contentType().restContentType(), builder.bytes(), true);
+        this(status, builder.contentType().restContentType(), builder.bytes());
     }
 
     /**
      * Creates a new plain text response.
      */
     public BytesRestResponse(RestStatus status, String content) {
-        this(status, TEXT_CONTENT_TYPE, new BytesArray(content), true);
+        this(status, TEXT_CONTENT_TYPE, new BytesArray(content));
     }
 
     /**
      * Creates a new plain text response.
      */
     public BytesRestResponse(RestStatus status, String contentType, String content) {
-        this(status, contentType, new BytesArray(content), true);
+        this(status, contentType, new BytesArray(content));
     }
 
     /**
      * Creates a binary response.
      */
     public BytesRestResponse(RestStatus status, String contentType, byte[] content) {
-        this(status, contentType, new BytesArray(content), true);
+        this(status, contentType, new BytesArray(content));
     }
 
     /**
      * Creates a binary response.
      */
-    public BytesRestResponse(RestStatus status, String contentType, BytesReference content, boolean contentThreadSafe) {
+    public BytesRestResponse(RestStatus status, String contentType, BytesReference content) {
         this.status = status;
         this.content = content;
-        this.contentThreadSafe = contentThreadSafe;
         this.contentType = contentType;
     }
 
@@ -96,7 +94,6 @@ public class BytesRestResponse extends RestResponse {
         if (t instanceof HasRestHeaders) {
             addHeaders(((HasRestHeaders) t).getHeaders());
         }
-        this.contentThreadSafe = true;
     }
 
     @Override
@@ -104,11 +101,6 @@ public class BytesRestResponse extends RestResponse {
         return this.contentType;
     }
 
-    @Override
-    public boolean contentThreadSafe() {
-        return this.contentThreadSafe;
-    }
-
     @Override
     public BytesReference content() {
         return this.content;

src/main/java/org/elasticsearch/rest/RestResponse.java

@@ -42,11 +42,6 @@ public abstract class RestResponse implements HasRestHeaders {
      */
     public abstract String contentType();
 
-    /**
-     * Can the content byte[] be used only with this thread (<tt>false</tt>), or by any thread (<tt>true</tt>).
-     */
-    public abstract boolean contentThreadSafe();
-
     /**
      * The response content. Note, if the content is {@link org.elasticsearch.common.lease.Releasable} it
      * should automatically be released when done by the channel sending it.

src/main/java/org/elasticsearch/rest/action/cat/AbstractCatAction.java

@@ -61,7 +61,7 @@ public abstract class AbstractCatAction extends BaseRestHandler {
                 out.append("\n");
             }
             out.close();
-            channel.sendResponse(new BytesRestResponse(RestStatus.OK, BytesRestResponse.TEXT_CONTENT_TYPE, bytesOutput.bytes(), true));
+            channel.sendResponse(new BytesRestResponse(RestStatus.OK, BytesRestResponse.TEXT_CONTENT_TYPE, bytesOutput.bytes()));
         } else {
             doRequest(request, channel, client);
         }

src/main/java/org/elasticsearch/rest/action/support/RestTable.java

@@ -93,7 +93,7 @@ public class RestTable {
             out.append("\n");
         }
         out.close();
-        return new BytesRestResponse(RestStatus.OK, BytesRestResponse.TEXT_CONTENT_TYPE, bytesOut.bytes(), true);
+        return new BytesRestResponse(RestStatus.OK, BytesRestResponse.TEXT_CONTENT_TYPE, bytesOut.bytes());
     }
 
     private static List<DisplayHeader> buildDisplayHeaders(Table table, RestRequest request) {

src/test/java/org/elasticsearch/rest/RestFilterChainTests.java

@@ -253,11 +253,6 @@ public class RestFilterChainTests extends ElasticsearchTestCase {
             return null;
         }
 
-        @Override
-        public boolean contentThreadSafe() {
-            return false;
-        }
-
         @Override
         public BytesReference content() {
             return null;