Fix serialization in TaskReportFileWriters. (#12938)

* Fix serialization in TaskReportFileWriters.

For some reason, serializing a Map<String, TaskReport> would omit the
"type" field. Explicitly sending each value through the ObjectMapper
fixes this, because the type information does not get lost.

* Fixes for static analysis.

indexing-service/src/main/java/org/apache/druid/indexing/common/IngestionStatsAndErrorsTaskReport.java

@@ -20,11 +20,9 @@
 package org.apache.druid.indexing.common;
 
 import com.fasterxml.jackson.annotation.JsonProperty;
-import com.fasterxml.jackson.annotation.JsonTypeName;
 
 import java.util.Objects;
 
-@JsonTypeName("ingestionStatsAndErrors")
 public class IngestionStatsAndErrorsTaskReport implements TaskReport
 {
   public static final String REPORT_KEY = "ingestionStatsAndErrors";
@@ -90,13 +88,4 @@ public class IngestionStatsAndErrorsTaskReport implements TaskReport
            ", payload=" + payload +
            '}';
   }
-
-  // TaskReports are put into a Map and serialized.
-  // Jackson doesn't normally serialize the TaskReports with a "type" field in that situation,
-  // so explictly serialize the "type" field (otherwise, deserialization fails).
-  @JsonProperty("type")
-  private String getType()
-  {
-    return "ingestionStatsAndErrors";
-  }
 }

indexing-service/src/main/java/org/apache/druid/indexing/common/MultipleFileTaskReportFileWriter.java

@@ -24,6 +24,7 @@ import org.apache.druid.java.util.common.FileUtils;
 import org.apache.druid.java.util.common.logger.Logger;
 
 import java.io.File;
+import java.io.FileOutputStream;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -49,7 +50,10 @@ public class MultipleFileTaskReportFileWriter implements TaskReportFileWriter
       if (reportsFileParent != null) {
         FileUtils.mkdirp(reportsFileParent);
       }
-      objectMapper.writeValue(reportsFile, reports);
+
+      try (final FileOutputStream outputStream = new FileOutputStream(reportsFile)) {
+        SingleFileTaskReportFileWriter.writeReportToStream(objectMapper, outputStream, reports);
+      }
     }
     catch (Exception e) {
       log.error(e, "Encountered exception in write().");

indexing-service/src/main/java/org/apache/druid/indexing/common/SingleFileTaskReportFileWriter.java

@@ -19,11 +19,16 @@
 
 package org.apache.druid.indexing.common;
 
+import com.fasterxml.jackson.core.JsonGenerator;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.SerializerProvider;
 import org.apache.druid.java.util.common.FileUtils;
+import org.apache.druid.java.util.common.jackson.JacksonUtils;
 import org.apache.druid.java.util.common.logger.Logger;
 
 import java.io.File;
+import java.io.FileOutputStream;
+import java.io.OutputStream;
 import java.util.Map;
 
 public class SingleFileTaskReportFileWriter implements TaskReportFileWriter
@@ -46,17 +51,39 @@ public class SingleFileTaskReportFileWriter implements TaskReportFileWriter
       if (reportsFileParent != null) {
         FileUtils.mkdirp(reportsFileParent);
       }
-      objectMapper.writeValue(reportsFile, reports);
+
+      try (final FileOutputStream outputStream = new FileOutputStream(reportsFile)) {
+        writeReportToStream(objectMapper, outputStream, reports);
+      }
     }
     catch (Exception e) {
       log.error(e, "Encountered exception in write().");
     }
   }
 
-
   @Override
   public void setObjectMapper(ObjectMapper objectMapper)
   {
     this.objectMapper = objectMapper;
   }
+
+  public static void writeReportToStream(
+      final ObjectMapper objectMapper,
+      final OutputStream outputStream,
+      final Map<String, TaskReport> reports
+  ) throws Exception
+  {
+    final SerializerProvider serializers = objectMapper.getSerializerProviderInstance();
+
+    try (final JsonGenerator jg = objectMapper.getFactory().createGenerator(outputStream)) {
+      jg.writeStartObject();
+
+      for (final Map.Entry<String, TaskReport> entry : reports.entrySet()) {
+        jg.writeFieldName(entry.getKey());
+        JacksonUtils.writeObjectUsingSerializerProvider(jg, serializers, entry.getValue());
+      }
+
+      jg.writeEndObject();
+    }
+  }
 }

indexing-service/src/test/java/org/apache/druid/indexing/common/task/TaskReportSerdeTest.java

@@ -25,17 +25,24 @@ import com.google.common.collect.ImmutableMap;
 import org.apache.druid.indexer.IngestionState;
 import org.apache.druid.indexing.common.IngestionStatsAndErrorsTaskReport;
 import org.apache.druid.indexing.common.IngestionStatsAndErrorsTaskReportData;
+import org.apache.druid.indexing.common.SingleFileTaskReportFileWriter;
 import org.apache.druid.indexing.common.TaskReport;
 import org.apache.druid.indexing.common.TestUtils;
 import org.junit.Assert;
+import org.junit.Rule;
 import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
 
+import java.io.File;
 import java.util.Map;
 
 public class TaskReportSerdeTest
 {
   private final ObjectMapper jsonMapper;
 
+  @Rule
+  public final TemporaryFolder temporaryFolder = new TemporaryFolder();
+
   public TaskReportSerdeTest()
   {
     TestUtils testUtils = new TestUtils();
@@ -61,20 +68,22 @@ public class TaskReportSerdeTest
         )
     );
     String report1serialized = jsonMapper.writeValueAsString(report1);
-    IngestionStatsAndErrorsTaskReport report2 = jsonMapper.readValue(
+    IngestionStatsAndErrorsTaskReport report2 = (IngestionStatsAndErrorsTaskReport) jsonMapper.readValue(
         report1serialized,
-        IngestionStatsAndErrorsTaskReport.class
+        TaskReport.class
     );
     Assert.assertEquals(report1, report2);
     Assert.assertEquals(report1.hashCode(), report2.hashCode());
 
+    final File reportFile = temporaryFolder.newFile();
+    final SingleFileTaskReportFileWriter writer = new SingleFileTaskReportFileWriter(reportFile);
+    writer.setObjectMapper(jsonMapper);
     Map<String, TaskReport> reportMap1 = TaskReport.buildTaskReports(report1);
-    String reportMapSerialized = jsonMapper.writeValueAsString(reportMap1);
+    writer.write("testID", reportMap1);
+
     Map<String, TaskReport> reportMap2 = jsonMapper.readValue(
-        reportMapSerialized,
+        reportFile,
-        new TypeReference<Map<String, TaskReport>>()
+        new TypeReference<Map<String, TaskReport>>() {}
-        {
-        }
     );
     Assert.assertEquals(reportMap1, reportMap2);
   }