SOLR-9502: ResponseWriters should natively support MapSerializable

solr/CHANGES.txt

@@ -169,6 +169,8 @@ Other Changes
 * SOLR-9365: Reduce noise in solr logs during graceful shutdown. (Cao Manh Dat via shalin)
 
 * SOLR-9451: Make clusterstatus command logging less verbose. (Varun Thacker)
+
+* SOLR-9502: ResponseWriters should natively support MapSerializable  (noble)
 ==================  6.2.1 ==================
 
 Bug Fixes

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

@@ -22,6 +22,7 @@ import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
 
+import org.apache.solr.common.MapSerializable;
 import org.apache.solr.common.SolrException;
 import org.apache.solr.common.params.CoreAdminParams;
 import org.apache.solr.common.util.StrUtils;
@@ -228,7 +229,7 @@ public class ConfigOverlay implements MapSerializable {
   }
 
   @Override
-  public Map<String, Object> toMap() {
+  public Map<String, Object> toMap(Map<String, Object> map) {
     Map result = new LinkedHashMap();
     result.put(ZNODEVER, znodeVersion);
     result.putAll(data);

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

@@ -16,6 +16,7 @@
  */
 package org.apache.solr.core;
 
+import org.apache.solr.common.MapSerializable;
 import org.apache.solr.common.util.NamedList;
 import org.apache.solr.util.DOMUtil;
 import org.w3c.dom.Node;
@@ -33,7 +34,7 @@ import static org.apache.solr.schema.FieldType.CLASS_NAME;
  * An Object which represents a Plugin of any type 
  *
  */
-public class PluginInfo implements MapSerializable{
+public class PluginInfo implements MapSerializable {
   public final String name, className, type;
   public final NamedList initArgs;
   public final Map<String, String> attributes;
@@ -128,21 +129,23 @@ public class PluginInfo implements MapSerializable{
     List<PluginInfo> l = getChildren(type);
     return  l.isEmpty() ? null:l.get(0);
   }
- public Map<String,Object> toMap(){
+
-    LinkedHashMap m = new LinkedHashMap(attributes);
+  public Map<String, Object> toMap(Map<String, Object> map) {
+    map.putAll(attributes);
+    Map m = map;
     if(initArgs!=null ) m.putAll(initArgs.asMap(3));
     if(children != null){
       for (PluginInfo child : children) {
         Object old = m.get(child.name);
         if(old == null){
-          m.put(child.name, child.toMap());
+          m.put(child.name, child.toMap(new LinkedHashMap<>()));
         } else if (old instanceof List) {
           List list = (List) old;
-          list.add(child.toMap());
+          list.add(child.toMap(new LinkedHashMap<>()));
         }  else {
           ArrayList l = new ArrayList();
           l.add(old);
-          l.add(child.toMap());
+          l.add(child.toMap(new LinkedHashMap<>()));
           m.put(child.name,l);
         }
       }

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

@@ -28,6 +28,7 @@ import java.util.Map;
 
 import com.google.common.collect.ImmutableMap;
 import org.apache.solr.cloud.ZkSolrResourceLoader;
+import org.apache.solr.common.MapSerializable;
 import org.apache.solr.common.SolrException;
 import org.apache.solr.common.cloud.SolrZkClient;
 import org.apache.solr.common.params.MapSolrParams;
@@ -124,7 +125,7 @@ public class RequestParams implements MapSerializable {
   }
 
   @Override
-  public Map<String, Object> toMap() {
+  public Map<String, Object> toMap(Map<String, Object> map) {
     return getMapWithVersion(data, znodeVersion);
   }
 
@@ -140,7 +141,7 @@ public class RequestParams implements MapSerializable {
     Map p = (Map) deepCopy.get(NAME);
     if (p == null) deepCopy.put(NAME, p = new LinkedHashMap());
     if (paramSet == null) p.remove(name);
-    else p.put(name, paramSet.toMap());
+    else p.put(name, paramSet.toMap(new LinkedHashMap<>()));
     return new RequestParams(deepCopy, znodeVersion);
   }
 
@@ -225,8 +226,7 @@ public class RequestParams implements MapSerializable {
     }
 
     @Override
-    public Map<String, Object> toMap() {
+    public Map<String, Object> toMap(Map<String, Object> result) {
-      LinkedHashMap result = new LinkedHashMap();
       result.putAll(defaults);
       if (appends != null) result.put(APPENDS, appends);
       if (invariants != null) result.put(INVARIANTS, invariants);

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

@@ -47,6 +47,7 @@ import org.apache.lucene.index.IndexDeletionPolicy;
 import org.apache.lucene.search.BooleanQuery;
 import org.apache.lucene.util.Version;
 import org.apache.solr.cloud.ZkSolrResourceLoader;
+import org.apache.solr.common.MapSerializable;
 import org.apache.solr.common.SolrException;
 import org.apache.solr.common.SolrException.ErrorCode;
 import org.apache.solr.common.util.IOUtils;
@@ -537,8 +538,7 @@ public class SolrConfig extends Config implements MapSerializable {
     }
 
     @Override
-    public Map<String, Object> toMap() {
+    public Map<String, Object> toMap(Map<String, Object> map) {
-      LinkedHashMap map = new LinkedHashMap();
       map.put("agentId", agentId);
       map.put("serviceUrl", serviceUrl);
       map.put("rootName", rootName);
@@ -561,7 +561,7 @@ public class SolrConfig extends Config implements MapSerializable {
         = Pattern.compile("\\bmax-age=(\\d+)");
 
     @Override
-    public Map<String, Object> toMap() {
+    public Map<String, Object> toMap(Map<String, Object> map) {
       return makeMap("never304", never304,
           "etagSeed", etagSeed,
           "lastModFrom", lastModFrom.name().toLowerCase(Locale.ROOT),
@@ -675,7 +675,7 @@ public class SolrConfig extends Config implements MapSerializable {
 
 
     @Override
-    public Map<String, Object> toMap() {
+    public Map<String, Object> toMap(Map<String, Object> map) {
       LinkedHashMap result = new LinkedHashMap();
       result.put("indexWriter", makeMap("closeWaitsForMerges", indexWriterCloseWaitsForMerges));
       result.put("commitWithin", makeMap("softCommit", commitWithinSoftCommit));
@@ -841,11 +841,10 @@ public class SolrConfig extends Config implements MapSerializable {
   }
 
   @Override
-  public Map<String, Object> toMap() {
+  public Map<String, Object> toMap(Map<String, Object> result) {
-    LinkedHashMap result = new LinkedHashMap();
     if (getZnodeVersion() > -1) result.put(ZNODEVER, getZnodeVersion());
     result.put("luceneMatchVersion", luceneMatchVersion);
-    result.put("updateHandler", getUpdateHandlerInfo().toMap());
+    result.put("updateHandler", getUpdateHandlerInfo());
     Map m = new LinkedHashMap();
     result.put("query", m);
     m.put("useFilterForSortedQuery", useFilterForSortedQuery);
@@ -853,7 +852,7 @@ public class SolrConfig extends Config implements MapSerializable {
     m.put("queryResultMaxDocsCached", queryResultMaxDocsCached);
     m.put("enableLazyFieldLoading", enableLazyFieldLoading);
     m.put("maxBooleanClauses", booleanQueryMaxClauseCount);
-    if (jmxConfig != null) result.put("jmx", jmxConfig.toMap());
+    if (jmxConfig != null) result.put("jmx", jmxConfig);
     for (SolrPluginInfo plugin : plugins) {
       List<PluginInfo> infos = getPluginInfos(plugin.clazz.getName());
       if (infos == null || infos.isEmpty()) continue;
@@ -861,16 +860,16 @@ public class SolrConfig extends Config implements MapSerializable {
       tag = tag.replace("/", "");
       if (plugin.options.contains(PluginOpts.REQUIRE_NAME)) {
         LinkedHashMap items = new LinkedHashMap();
-        for (PluginInfo info : infos) items.put(info.name, info.toMap());
+        for (PluginInfo info : infos) items.put(info.name, info);
         for (Map.Entry e : overlay.getNamedPlugins(plugin.tag).entrySet()) items.put(e.getKey(), e.getValue());
         result.put(tag, items);
       } else {
         if (plugin.options.contains(MULTI_OK)) {
-          ArrayList<Map> l = new ArrayList<>();
+          ArrayList<MapSerializable> l = new ArrayList<>();
-          for (PluginInfo info : infos) l.add(info.toMap());
+          for (PluginInfo info : infos) l.add(info);
           result.put(tag, l);
         } else {
-          result.put(tag, infos.get(0).toMap());
+          result.put(tag, infos.get(0));
         }
 
       }
@@ -879,15 +878,15 @@ public class SolrConfig extends Config implements MapSerializable {
 
 
     addCacheConfig(m, filterCacheConfig, queryResultCacheConfig, documentCacheConfig, fieldValueCacheConfig);
-    if (jmxConfig != null) result.put("jmx", jmxConfig.toMap());
+    if (jmxConfig != null) result.put("jmx", jmxConfig);
     m = new LinkedHashMap();
     result.put("requestDispatcher", m);
     m.put("handleSelect", handleSelect);
-    if (httpCachingConfig != null) m.put("httpCaching", httpCachingConfig.toMap());
+    if (httpCachingConfig != null) m.put("httpCaching", httpCachingConfig);
     m.put("requestParsers", makeMap("multipartUploadLimitKB", multipartUploadLimitKB,
         "formUploadLimitKB", formUploadLimitKB,
         "addHttpRequestToContext", addHttpRequestToContext));
-    if (indexConfig != null) result.put("indexConfig", indexConfig.toMap());
+    if (indexConfig != null) result.put("indexConfig", indexConfig);
 
     m = new LinkedHashMap();
     result.put("peerSync", m);
@@ -900,7 +899,7 @@ public class SolrConfig extends Config implements MapSerializable {
 
   private void addCacheConfig(Map queryMap, CacheConfig... cache) {
     if (cache == null) return;
-    for (CacheConfig config : cache) if (config != null) queryMap.put(config.getNodeName(), config.toMap());
+    for (CacheConfig config : cache) if (config != null) queryMap.put(config.getNodeName(), config);
 
   }
 

solr/core/src/java/org/apache/solr/handler/SolrConfigHandler.java

@@ -168,7 +168,7 @@ public class SolrConfigHandler extends RequestHandlerBase implements SolrCoreAwa
         resp.add("config", getConfigDetails());
       } else {
         if (ConfigOverlay.NAME.equals(parts.get(1))) {
-          resp.add(ConfigOverlay.NAME, req.getCore().getSolrConfig().getOverlay().toMap());
+          resp.add(ConfigOverlay.NAME, req.getCore().getSolrConfig().getOverlay());
         } else if (RequestParams.NAME.equals(parts.get(1))) {
           if (parts.size() == 3) {
             RequestParams params = req.getCore().getSolrConfig().getRequestParams();
@@ -176,11 +176,11 @@ public class SolrConfigHandler extends RequestHandlerBase implements SolrCoreAwa
             Map m = new LinkedHashMap<>();
             m.put(ZNODEVER, params.getZnodeVersion());
             if (p != null) {
-              m.put(RequestParams.NAME, makeMap(parts.get(2), p.toMap()));
+              m.put(RequestParams.NAME, makeMap(parts.get(2), p.toMap(new LinkedHashMap<>())));
             }
             resp.add(SolrQueryResponse.NAME, m);
           } else {
-            resp.add(SolrQueryResponse.NAME, req.getCore().getSolrConfig().getRequestParams().toMap());
+            resp.add(SolrQueryResponse.NAME, req.getCore().getSolrConfig().getRequestParams());
           }
 
         } else {
@@ -233,14 +233,14 @@ public class SolrConfigHandler extends RequestHandlerBase implements SolrCoreAwa
     }
 
     private Map<String, Object> getConfigDetails() {
-      Map<String, Object> map = req.getCore().getSolrConfig().toMap();
+      Map<String, Object> map = req.getCore().getSolrConfig().toMap(new LinkedHashMap<>());
       Map reqHandlers = (Map) map.get(SolrRequestHandler.TYPE);
       if (reqHandlers == null) map.put(SolrRequestHandler.TYPE, reqHandlers = new LinkedHashMap<>());
       List<PluginInfo> plugins = req.getCore().getImplicitHandlers();
       for (PluginInfo plugin : plugins) {
         if (SolrRequestHandler.TYPE.equals(plugin.type)) {
           if (!reqHandlers.containsKey(plugin.name)) {
-            reqHandlers.put(plugin.name, plugin.toMap());
+            reqHandlers.put(plugin.name, plugin.toMap(new LinkedHashMap<>()));
           }
         }
       }
@@ -354,7 +354,7 @@ public class SolrConfigHandler extends RequestHandlerBase implements SolrCoreAwa
         if (ops.isEmpty()) {
           ZkController.touchConfDir(zkLoader);
         } else {
-          log.debug("persisting params data : {}", Utils.toJSONString(params.toMap()));
+          log.debug("persisting params data : {}", Utils.toJSONString(params.toMap(new LinkedHashMap<>())));
           int latestVersion = ZkController.persistConfigResourceToZooKeeper(zkLoader,
               params.getZnodeVersion(), RequestParams.RESOURCE, params.toByteArray(), true);
 

solr/core/src/java/org/apache/solr/handler/component/RealTimeGetComponent.java

@@ -631,7 +631,7 @@ public class RealTimeGetComponent extends SearchComponent
     // and would avoid mismatch if documents are being actively index especially during PeerSync
     if (doFingerprint) {
       IndexFingerprint fingerprint = IndexFingerprint.getFingerprint(req.getCore(), Long.MAX_VALUE);
-      rb.rsp.add("fingerprint", fingerprint.toObject());
+      rb.rsp.add("fingerprint", fingerprint);
     }
 
     try (UpdateLog.RecentUpdates recentUpdates = ulog.getRecentUpdates()) {
@@ -695,7 +695,7 @@ public class RealTimeGetComponent extends SearchComponent
     if (doFingerprint) {
       long maxVersionForUpdate = Collections.min(versions, PeerSync.absComparator);
       IndexFingerprint fingerprint = IndexFingerprint.getFingerprint(req.getCore(), Math.abs(maxVersionForUpdate));
-      rb.rsp.add("fingerprint", fingerprint.toObject());
+      rb.rsp.add("fingerprint", fingerprint);
     }
 
     List<Object> updates = new ArrayList<>(versions.size());

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

@@ -32,6 +32,7 @@ import org.apache.solr.client.solrj.io.Tuple;
 import org.apache.solr.client.solrj.io.stream.TupleStream;
 import org.apache.solr.client.solrj.io.stream.expr.Explanation;
 import org.apache.solr.common.EnumFieldValue;
+import org.apache.solr.common.MapSerializable;
 import org.apache.solr.common.SolrDocument;
 import org.apache.solr.common.SolrDocumentList;
 import org.apache.solr.common.util.Base64;
@@ -121,7 +122,7 @@ public abstract class TextResponseWriter {
     // to get a handler might be faster (but types must be exact to do that...)
 
     // go in order of most common to least common
-    if (val==null) {
+    if (val == null) {
       writeNull(name);
     } else if (val instanceof String) {
       writeStr(name, val.toString(), true);
@@ -186,6 +187,9 @@ public abstract class TextResponseWriter {
       writeStr(name, val.toString(), true);
     } else if (val instanceof WriteableValue) {
       ((WriteableValue)val).write(name, this);
+    } else if (val instanceof MapSerializable) {
+      //todo find a better way to reuse the map more efficiently
+      writeMap(name, ((MapSerializable) val).toMap(new NamedList().asShallowMap()), false, true);
     } else {
       // default... for debugging only
       writeStr(name, val.getClass().getName() + ':' + val.toString(), true);
@@ -206,7 +210,7 @@ public abstract class TextResponseWriter {
       // it may need special formatting. same for double.
       writeFloat(name, ((Float)val).floatValue());
     } else if (val instanceof Double) {
-      writeDouble(name, ((Double)val).doubleValue());
+      writeDouble(name, ((Double) val).doubleValue());
     } else if (val instanceof Short) {
       writeInt(name, val.toString());
     } else if (val instanceof Byte) {

solr/core/src/java/org/apache/solr/schema/IndexSchema.java

@@ -63,7 +63,7 @@ import org.apache.solr.common.util.NamedList;
 import org.apache.solr.common.util.Pair;
 import org.apache.solr.common.util.SimpleOrderedMap;
 import org.apache.solr.core.Config;
-import org.apache.solr.core.MapSerializable;
+import org.apache.solr.common.MapSerializable;
 import org.apache.solr.core.SolrConfig;
 import org.apache.solr.core.SolrResourceLoader;
 import org.apache.solr.request.LocalSolrQueryRequest;
@@ -1489,7 +1489,7 @@ public class IndexSchema {
 
 
     @Override
-    public Map<String, Object> toMap() {
+    public Map<String, Object> toMap(Map<String, Object> map) {
       return Stream.of(Handler.values())
           .filter(it -> name == null || it.nameLower.equals(name))
           .map(it -> new Pair<>(it.realName, it.fun.apply(this)))
@@ -1507,7 +1507,7 @@ public class IndexSchema {
 
 
   public Map<String, Object> getNamedPropertyValues(String name, SolrParams params) {
-    return new SchemaProps(name, params, this).toMap();
+    return new SchemaProps(name, params, this).toMap(new LinkedHashMap<>());
 
   }
 

solr/core/src/java/org/apache/solr/search/CacheConfig.java

@@ -26,7 +26,7 @@ import java.util.Map;
 
 import org.apache.solr.common.SolrException;
 import org.apache.solr.common.util.StrUtils;
-import org.apache.solr.core.MapSerializable;
+import org.apache.solr.common.MapSerializable;
 import org.apache.solr.core.SolrConfig;
 import org.apache.solr.core.SolrResourceLoader;
 import org.apache.solr.util.DOMUtil;
@@ -148,7 +148,7 @@ public class CacheConfig implements MapSerializable{
   }
 
   @Override
-  public Map<String, Object> toMap() {
+  public Map<String, Object> toMap(Map<String, Object> map) {
     Map result = Collections.unmodifiableMap(args);
     return result;
   }

solr/core/src/java/org/apache/solr/update/IndexFingerprint.java

@@ -26,6 +26,7 @@ import org.apache.lucene.index.LeafReaderContext;
 import org.apache.lucene.queries.function.FunctionValues;
 import org.apache.lucene.queries.function.ValueSource;
 import org.apache.lucene.util.Bits;
+import org.apache.solr.common.MapSerializable;
 import org.apache.solr.common.SolrException;
 import org.apache.solr.common.util.Hash;
 import org.apache.solr.common.util.NamedList;
@@ -38,7 +39,7 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 /** @lucene.internal */
-public class IndexFingerprint {
+public class IndexFingerprint implements MapSerializable {
   private static final Logger log = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass());
 
   private long maxVersionSpecified;
@@ -154,11 +155,8 @@ public class IndexFingerprint {
     return cmp;
   }
 
-  /**
+  @Override
-   * Create a generic object suitable for serializing with ResponseWriters
+  public Map<String, Object> toMap(Map<String, Object> map) {
-   */
-  public Object toObject() {
-    Map<String,Object> map = new LinkedHashMap<>();
     map.put("maxVersionSpecified", maxVersionSpecified);
     map.put("maxVersionEncountered", maxVersionEncountered);
     map.put("maxInHash", maxInHash);
@@ -200,6 +198,6 @@ public class IndexFingerprint {
 
   @Override
   public String toString() {
-    return toObject().toString();
+    return toMap(new LinkedHashMap<>()).toString();
   }
 }

solr/core/src/java/org/apache/solr/update/SolrIndexConfig.java

@@ -36,7 +36,7 @@ import org.apache.lucene.util.Version;
 import org.apache.solr.common.util.NamedList;
 import org.apache.solr.common.util.Utils;
 import org.apache.solr.core.DirectoryFactory;
-import org.apache.solr.core.MapSerializable;
+import org.apache.solr.common.MapSerializable;
 import org.apache.solr.core.PluginInfo;
 import org.apache.solr.core.SolrConfig;
 import org.apache.solr.core.SolrCore;
@@ -187,7 +187,7 @@ public class SolrIndexConfig implements MapSerializable {
   }
 
   @Override
-  public Map<String, Object> toMap() {
+  public Map<String, Object> toMap(Map<String, Object> map) {
     Map<String, Object> m = Utils.makeMap("useCompoundFile", effectiveUseCompoundFileSetting,
         "maxBufferedDocs", maxBufferedDocs,
         "maxMergeDocs", maxMergeDocs,
@@ -196,13 +196,13 @@ public class SolrIndexConfig implements MapSerializable {
         "writeLockTimeout", writeLockTimeout,
         "lockType", lockType,
         "infoStreamEnabled", infoStream != InfoStream.NO_OUTPUT);
-    if(mergeSchedulerInfo != null) m.put("mergeScheduler",mergeSchedulerInfo.toMap());
+    if(mergeSchedulerInfo != null) m.put("mergeScheduler",mergeSchedulerInfo);
     if (mergePolicyInfo != null) {
-      m.put("mergePolicy", mergePolicyInfo.toMap());
+      m.put("mergePolicy", mergePolicyInfo);
     } else if (mergePolicyFactoryInfo != null) {
-      m.put("mergePolicyFactory", mergePolicyFactoryInfo.toMap());
+      m.put("mergePolicyFactory", mergePolicyFactoryInfo);
     }
-    if(mergedSegmentWarmerInfo != null) m.put("mergedSegmentWarmer",mergedSegmentWarmerInfo.toMap());
+    if(mergedSegmentWarmerInfo != null) m.put("mergedSegmentWarmer",mergedSegmentWarmerInfo);
     return m;
   }
 

solr/core/src/test/org/apache/solr/core/TestConfig.java

@@ -19,6 +19,7 @@ package org.apache.solr.core;
 import javax.xml.xpath.XPathConstants;
 import java.io.IOException;
 import java.io.InputStream;
+import java.util.LinkedHashMap;
 
 import org.apache.lucene.index.ConcurrentMergeScheduler;
 import org.apache.lucene.index.IndexWriterConfig;
@@ -147,8 +148,8 @@ public class TestConfig extends SolrTestCaseJ4 {
 
     assertNull("non-null mergedSegmentWarmer", iwc.getMergedSegmentWarmer());
 
-    final int numDefaultsMapped = sic.toMap().size();
+    final int numDefaultsMapped = sic.toMap(new LinkedHashMap<>()).size();
-    assertEquals("numDefaultsTested vs. numDefaultsMapped+numNullDefaults ="+sic.toMap().keySet(), numDefaultsTested, numDefaultsMapped+numNullDefaults);
+    assertEquals("numDefaultsTested vs. numDefaultsMapped+numNullDefaults ="+sic.toMap(new LinkedHashMap<>()).keySet(), numDefaultsTested, numDefaultsMapped+numNullDefaults);
   }
 
 

solr/core/src/test/org/apache/solr/update/SolrIndexConfigTest.java

@@ -17,6 +17,7 @@
 package org.apache.solr.update;
 
 import java.nio.file.Path;
+import java.util.LinkedHashMap;
 import java.util.Map;
 
 import org.apache.lucene.index.ConcurrentMergeScheduler;
@@ -27,6 +28,7 @@ import org.apache.lucene.index.TieredMergePolicy;
 import org.apache.lucene.search.Sort;
 import org.apache.lucene.search.SortField;
 import org.apache.solr.SolrTestCaseJ4;
+import org.apache.solr.common.MapSerializable;
 import org.apache.solr.core.DirectoryFactory;
 import org.apache.solr.core.SolrConfig;
 import org.apache.solr.core.TestMergePolicyConfig;
@@ -152,7 +154,7 @@ public class SolrIndexConfigTest extends SolrTestCaseJ4 {
     }
     assertNotNull(solrIndexConfig.mergeSchedulerInfo);
 
-    Map<String, Object> m = solrIndexConfig.toMap();
+    Map<String, Object> m = solrIndexConfig.toMap(new LinkedHashMap<>());
     int mSizeExpected = 0;
 
     ++mSizeExpected; assertTrue(m.get("useCompoundFile") instanceof Boolean);
@@ -180,18 +182,18 @@ public class SolrIndexConfigTest extends SolrTestCaseJ4 {
       assertFalse(Boolean.valueOf(m.get("infoStreamEnabled").toString()).booleanValue());
     }
     
-    ++mSizeExpected; assertTrue(m.get("mergeScheduler") instanceof Map);
+    ++mSizeExpected; assertTrue(m.get("mergeScheduler") instanceof MapSerializable);
     if (solrConfigFileName.equals(solrConfigFileNameTieredMergePolicyFactory) ||
         solrConfigFileName.equals(solrConfigFileNameWarmerRandomMergePolicyFactory)) {
       assertNull(m.get("mergePolicy"));
-      ++mSizeExpected; assertTrue(m.get("mergePolicyFactory") instanceof Map);
+      ++mSizeExpected; assertTrue(m.get("mergePolicyFactory") instanceof MapSerializable);
     } else {
-      ++mSizeExpected; assertTrue(m.get("mergePolicy") instanceof Map);
+      ++mSizeExpected; assertTrue(m.get("mergePolicy") instanceof MapSerializable);
       assertNull(m.get("mergePolicyFactory"));
     }
     if (solrConfigFileName.equals(solrConfigFileNameWarmerRandomMergePolicy) ||
         solrConfigFileName.equals(solrConfigFileNameWarmerRandomMergePolicyFactory)) {
-      ++mSizeExpected; assertTrue(m.get("mergedSegmentWarmer") instanceof Map);
+      ++mSizeExpected; assertTrue(m.get("mergedSegmentWarmer") instanceof MapSerializable);
     } else {
       assertNull(m.get("mergedSegmentWarmer"));
     }

solr/solrj/src/java/org/apache/solr/common/MapSerializable.java

@@ -14,10 +14,17 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package org.apache.solr.core;
+package org.apache.solr.common;
 
 import java.util.Map;
 
+/**This is to facilitate just in time creation of objects before writing
+ * it to the response.
+ */
 public interface MapSerializable {
-  public Map<String, Object> toMap();
+  /**Use the passed map to minimize object creation.
+   * Do not keep a reference to the passed map and reuse it.
+   * it may be reused by the framework
+   */
+  Map toMap(Map<String, Object> map);
 }

solr/solrj/src/java/org/apache/solr/common/util/JavaBinCodec.java

@@ -33,6 +33,7 @@ import java.util.Map;
 import java.util.Map.Entry;
 
 import org.apache.solr.common.EnumFieldValue;
+import org.apache.solr.common.MapSerializable;
 import org.apache.solr.common.SolrDocument;
 import org.apache.solr.common.SolrDocumentList;
 import org.apache.solr.common.SolrInputDocument;
@@ -336,6 +337,12 @@ public class JavaBinCodec {
       writeMapEntry((Map.Entry)val);
       return true;
     }
+    if (val instanceof MapSerializable) {
+      //todo find a better way to reuse the map more efficiently
+      writeMap(((MapSerializable) val).toMap(new NamedList().asShallowMap()));
+      return true;
+    }
+
     return false;
   }
 

solr/solrj/src/java/org/apache/solr/common/util/NamedList.java

@@ -441,11 +441,16 @@ public class NamedList<T> implements Cloneable, Serializable, Iterable<Map.Entry
 
       @Override
       public void putAll(Map m) {
+        boolean isEmpty = isEmpty();
         for (Object o : m.entrySet()) {
           Map.Entry e = (Entry) o;
+          if (isEmpty) {// we know that there are no duplicates
+            add((String) e.getKey(), (T) e.getValue());
+          } else {
             put(e.getKey() == null ? null : e.getKey().toString(), (T) e.getValue());
           }
         }
+      }
 
       @Override
       public void clear() {