SOLR-17682: QueryResponseWriter hierarchy refactor

solr/core/src/java/org/apache/solr/client/solrj/embedded/EmbeddedSolrServer.java

@@ -58,7 +58,6 @@
 import org.apache.solr.request.SolrRequestHandler;
 import org.apache.solr.request.SolrRequestInfo;
 import org.apache.solr.response.BinaryResponseWriter;
-import org.apache.solr.response.QueryResponseWriterUtil;
 import org.apache.solr.response.ResultContext;
 import org.apache.solr.response.SolrQueryResponse;
 import org.apache.solr.servlet.SolrRequestParsers;
@@ -276,8 +275,7 @@ ByteArrayInputStream toInputStream() {
         };
 
     if (callback == null) {
-      QueryResponseWriterUtil.writeQueryResponse(
-          byteBuffer, req.getResponseWriter(), req, rsp, null);
+      req.getResponseWriter().write(byteBuffer, req, rsp);
     } else {
       // mostly stream results to the callback; rest goes into the byteBuffer
       if (!(responseParser instanceof BinaryResponseParser))

solr/core/src/java/org/apache/solr/core/SolrCore.java

@@ -3053,7 +3053,8 @@ public PluginBag<QueryResponseWriter> getResponseWriters() {
   private static BinaryResponseWriter getFileStreamWriter() {
     return new BinaryResponseWriter() {
       @Override
-      public void write(OutputStream out, SolrQueryRequest req, SolrQueryResponse response)
+      public void write(
+          OutputStream out, SolrQueryRequest req, SolrQueryResponse response, String contentType)
           throws IOException {
         RawWriter rawWriter = (RawWriter) response.getValues().get(ReplicationAPIBase.FILE_STREAM);
         if (rawWriter != null) {

solr/core/src/java/org/apache/solr/jersey/MessageBodyWriters.java

@@ -39,7 +39,6 @@
 import org.apache.solr.response.BinaryResponseWriter;
 import org.apache.solr.response.CSVResponseWriter;
 import org.apache.solr.response.QueryResponseWriter;
-import org.apache.solr.response.QueryResponseWriterUtil;
 import org.apache.solr.response.RawResponseWriter;
 import org.apache.solr.response.SolrQueryResponse;
 import org.apache.solr.response.XMLResponseWriter;
@@ -141,8 +140,7 @@ public void writeTo(
           (SolrQueryResponse) requestContext.getProperty(SOLR_QUERY_RESPONSE);
 
       V2ApiUtils.squashIntoSolrResponseWithHeader(solrQueryResponse, toWrite);
-      QueryResponseWriterUtil.writeQueryResponse(
-          entityStream, responseWriter, solrQueryRequest, solrQueryResponse, mediaType.toString());
+      responseWriter.write(entityStream, solrQueryRequest, solrQueryResponse, mediaType.toString());
     }
   }
 }

solr/core/src/java/org/apache/solr/response/BinaryResponseWriter.java

@@ -23,7 +23,6 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
-import java.io.Writer;
 import java.lang.invoke.MethodHandles;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -45,12 +44,14 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-public class BinaryResponseWriter implements BinaryQueryResponseWriter {
+/** Solr's "javabin" format. TODO rename accordingly. */
+public class BinaryResponseWriter implements QueryResponseWriter {
   //  public static boolean useUtf8CharSeq = true;
   private static final Logger log = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
 
   @Override
-  public void write(OutputStream out, SolrQueryRequest req, SolrQueryResponse response)
+  public void write(
+      OutputStream out, SolrQueryRequest req, SolrQueryResponse response, String contentType)
       throws IOException {
     Resolver resolver = new Resolver(req, response.getReturnFields());
     if (req.getParams().getBool(CommonParams.OMIT_HEADER, false)) response.removeResponseHeader();
@@ -59,12 +60,6 @@ public void write(OutputStream out, SolrQueryRequest req, SolrQueryResponse resp
     }
   }
 
-  @Override
-  public void write(Writer writer, SolrQueryRequest request, SolrQueryResponse response)
-      throws IOException {
-    throw new RuntimeException("This is a binary writer , Cannot write to a characterstream");
-  }
-
   @Override
   public String getContentType(SolrQueryRequest request, SolrQueryResponse response) {
     return BinaryResponseParser.BINARY_CONTENT_TYPE;

solr/core/src/java/org/apache/solr/response/CSVResponseWriter.java

@@ -37,8 +37,8 @@
 import org.apache.solr.schema.StrField;
 import org.apache.solr.search.ReturnFields;
 
-/** Response writer for csv data */
-public class CSVResponseWriter implements QueryResponseWriter {
+/** Response writer for CSV data */
+public class CSVResponseWriter implements TextQueryResponseWriter {
 
   @Override
   public void write(Writer writer, SolrQueryRequest req, SolrQueryResponse rsp) throws IOException {

solr/core/src/java/org/apache/solr/response/CborResponseWriter.java

@@ -30,7 +30,7 @@
  * A response writer impl that can write results in CBOR (cbor.io) format when wt=cbor. It uses the
  * jackson library to write the stream out
  */
-public class CborResponseWriter extends BinaryResponseWriter {
+public class CborResponseWriter implements QueryResponseWriter {
   final CBORFactory cborFactory;
   final CBORFactory cborFactoryCompact;
 
@@ -40,7 +40,8 @@ public CborResponseWriter() {
   }
 
   @Override
-  public void write(OutputStream out, SolrQueryRequest req, SolrQueryResponse response)
+  public void write(
+      OutputStream out, SolrQueryRequest req, SolrQueryResponse response, String contentType)
       throws IOException {
     boolean useStringRef = req.getParams().getBool("string_ref", true);
     WriterImpl writer =

solr/core/src/java/org/apache/solr/response/GraphMLResponseWriter.java

@@ -28,7 +28,12 @@
 import org.apache.solr.handler.GraphHandler;
 import org.apache.solr.request.SolrQueryRequest;
 
-public class GraphMLResponseWriter implements QueryResponseWriter {
+/**
+ * Used with streaming expressions to export graphs to be visualized.
+ *
+ * @see <a href="http://graphml.graphdrawing.org/">GraphML</a>
+ */
+public class GraphMLResponseWriter implements TextQueryResponseWriter {
 
   @Override
   public String getContentType(SolrQueryRequest req, SolrQueryResponse res) {

solr/core/src/java/org/apache/solr/response/JSONResponseWriter.java

@@ -29,8 +29,8 @@
 import org.apache.solr.request.SolrQueryRequest;
 import org.apache.solr.search.ReturnFields;
 
-/** */
-public class JSONResponseWriter implements QueryResponseWriter {
+/** JSON {@link QueryResponseWriter}. */
+public class JSONResponseWriter implements TextQueryResponseWriter {
   public static String CONTENT_TYPE_JSON_UTF8 = "application/json; charset=UTF-8";
 
   private String contentType = CONTENT_TYPE_JSON_UTF8;

solr/core/src/java/org/apache/solr/response/JacksonJsonWriter.java

@@ -23,13 +23,17 @@
 import com.fasterxml.jackson.core.util.DefaultPrettyPrinter;
 import java.io.IOException;
 import java.io.OutputStream;
+import java.io.UnsupportedEncodingException;
+import java.io.Writer;
 import java.math.BigDecimal;
 import java.math.BigInteger;
+import java.util.Arrays;
 import org.apache.solr.common.PushWriter;
+import org.apache.solr.common.util.ContentStreamBase;
 import org.apache.solr.request.SolrQueryRequest;
 
 /** A JSON ResponseWriter that uses jackson. */
-public class JacksonJsonWriter extends BinaryResponseWriter {
+public class JacksonJsonWriter implements TextQueryResponseWriter {
 
   protected final JsonFactory jsonfactory;
   protected static final DefaultPrettyPrinter pretty =
@@ -43,17 +47,42 @@ public JacksonJsonWriter() {
     jsonfactory = new JsonFactory();
   }
 
+  // let's also implement the binary version since Jackson supports that (probably faster)
   @Override
-  public void write(OutputStream out, SolrQueryRequest request, SolrQueryResponse response)
+  public void write(
+      OutputStream out, SolrQueryRequest request, SolrQueryResponse response, String contentType)
       throws IOException {
-    WriterImpl sw = new WriterImpl(jsonfactory, out, request, response);
+    out = new NonFlushingStream(out);
+    // resolve the encoding
+    final String charSet = ContentStreamBase.getCharsetFromContentType(contentType);
+    JsonEncoding jsonEncoding;
+    if (charSet != null) {
+      assert JsonEncoding.values().length < 10; // fast to iterate
+      jsonEncoding =
+          Arrays.stream(JsonEncoding.values())
+              .filter(e -> e.getJavaName().equalsIgnoreCase(charSet))
+              .findAny()
+              .orElseThrow(() -> new UnsupportedEncodingException(charSet));
+    } else {
+      jsonEncoding = JsonEncoding.UTF8;
+    }
+
+    var sw = new WriterImpl(request, response, jsonfactory.createGenerator(out, jsonEncoding));
+    sw.writeResponse();
+    sw.close();
+  }
+
+  @Override
+  public void write(Writer writer, SolrQueryRequest request, SolrQueryResponse response)
+      throws IOException {
+    var sw = new WriterImpl(request, response, jsonfactory.createGenerator(writer));
     sw.writeResponse();
     sw.close();
   }
 
   public PushWriter getWriter(
-      OutputStream out, SolrQueryRequest request, SolrQueryResponse response) {
-    return new WriterImpl(jsonfactory, out, request, response);
+      OutputStream out, SolrQueryRequest request, SolrQueryResponse response) throws IOException {
+    return new WriterImpl(request, response, jsonfactory.createGenerator(out, JsonEncoding.UTF8));
   }
 
   @Override
@@ -67,16 +96,11 @@ public static class WriterImpl extends JSONWriter {
 
     protected JsonGenerator gen;
 
-    public WriterImpl(
-        JsonFactory j, OutputStream out, SolrQueryRequest req, SolrQueryResponse rsp) {
+    public WriterImpl(SolrQueryRequest req, SolrQueryResponse rsp, JsonGenerator generator) {
       super(null, req, rsp);
-      try {
-        gen = j.createGenerator(out, JsonEncoding.UTF8);
-        if (doIndent) {
-          gen.setPrettyPrinter(pretty.createInstance());
-        }
-      } catch (IOException e) {
-        throw new RuntimeException(e);
+      gen = generator;
+      if (doIndent) {
+        gen.setPrettyPrinter(pretty.createInstance());
       }
     }
 

solr/core/src/java/org/apache/solr/response/PrometheusResponseWriter.java

@@ -47,12 +47,15 @@
  * org.apache.solr.handler.admin.MetricsHandler}
  */
 @SuppressWarnings(value = "unchecked")
-public class PrometheusResponseWriter extends RawResponseWriter {
+public class PrometheusResponseWriter implements QueryResponseWriter {
+  // not TextQueryResponseWriter because Prometheus libs work with an OutputStream
+
   private static final String CONTENT_TYPE_PROMETHEUS = "text/plain; version=0.0.4";
   private static final Logger log = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
 
   @Override
-  public void write(OutputStream out, SolrQueryRequest request, SolrQueryResponse response)
+  public void write(
+      OutputStream out, SolrQueryRequest request, SolrQueryResponse response, String contentType)
       throws IOException {
     NamedList<Object> prometheusRegistries =
         (NamedList<Object>) response.getValues().get("metrics");

solr/core/src/java/org/apache/solr/response/QueryResponseWriter.java

@@ -16,14 +16,16 @@
  */
 package org.apache.solr.response;
 
+import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.io.Writer;
+import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
+import net.jcip.annotations.ThreadSafe;
 import org.apache.solr.request.SolrQueryRequest;
 import org.apache.solr.util.plugin.NamedListInitializedPlugin;
 
 /**
- * Implementations of <code>QueryResponseWriter</code> are used to format responses to query
- * requests.
+ * Used to format responses to the client (not necessarily a "query").
  *
  * <p>Different <code>QueryResponseWriter</code>s are registered with the <code>SolrCore</code>. One
  * way to register a QueryResponseWriter with the core is through the <code>solrconfig.xml</code>
@@ -39,23 +41,26 @@
  * <p>A single instance of any registered QueryResponseWriter is created via the default constructor
  * and is reused for all relevant queries.
  */
+@ThreadSafe
 public interface QueryResponseWriter extends NamedListInitializedPlugin {
   public static String CONTENT_TYPE_XML_UTF8 = "application/xml; charset=UTF-8";
   public static String CONTENT_TYPE_TEXT_UTF8 = "text/plain; charset=UTF-8";
   public static String CONTENT_TYPE_TEXT_ASCII = "text/plain; charset=US-ASCII";
 
   /**
-   * Write a SolrQueryResponse, this method must be thread save.
-   *
-   * <p>Information about the request (in particular: formatting options) may be obtained from
-   * <code>req</code> but the dominant source of information should be <code>rsp</code>.
-   *
-   * <p>There are no mandatory actions that write must perform. An empty write implementation would
-   * fulfill all interface obligations.
+   * Writes the response to the {@link OutputStream}. {@code contentType} is from {@link
+   * #getContentType(SolrQueryRequest, SolrQueryResponse)}, and it's often ignored.
    */
-  public void write(Writer writer, SolrQueryRequest request, SolrQueryResponse response)
+  void write(
+      OutputStream out, SolrQueryRequest request, SolrQueryResponse response, String contentType)
       throws IOException;
 
+  // should be "final" if interfaces allowed that
+  default void write(OutputStream out, SolrQueryRequest request, SolrQueryResponse response)
+      throws IOException {
+    write(out, request, response, getContentType(request, response));
+  }
+
   /**
    * Return the applicable Content Type for a request, this method must be thread safe.
    *
@@ -64,5 +69,13 @@ public void write(Writer writer, SolrQueryRequest request, SolrQueryResponse res
    *
    * @return a Content-Type string, which may not be null.
    */
-  public String getContentType(SolrQueryRequest request, SolrQueryResponse response);
+  String getContentType(SolrQueryRequest request, SolrQueryResponse response);
+
+  /** Writes a String for debugging / testing purposes. */
+  default String writeToString(SolrQueryRequest request, SolrQueryResponse response)
+      throws IOException {
+    var buffer = new ByteArrayOutputStream(32000);
+    write(buffer, request, response);
+    return buffer.toString(StandardCharsets.UTF_8);
+  }
 }