Remove non-SMILE Serialization from ChecksumBlobStoreFormat (#44278) (#44326)

* At least all the way back to 6.x we never use anything but `SMILE` in
production code with this class so I removed the more general
constructor and removed the format leniency from the deserialization

server/src/main/java/org/elasticsearch/repositories/blobstore/ChecksumBlobStoreFormat.java

@@ -72,15 +72,11 @@ public final class ChecksumBlobStoreFormat<T extends ToXContent> {
         SNAPSHOT_ONLY_FORMAT_PARAMS = new ToXContent.MapParams(snapshotOnlyParams);
     }
 
-    private static final XContentType DEFAULT_X_CONTENT_TYPE = XContentType.SMILE;
-
     // The format version
     public static final int VERSION = 1;
 
     private static final int BUFFER_SIZE = 4096;
 
-    private final XContentType xContentType;
-
     private final boolean compress;
 
     private final String codec;
@@ -91,23 +87,6 @@ public final class ChecksumBlobStoreFormat<T extends ToXContent> {
 
     private final NamedXContentRegistry namedXContentRegistry;
 
-    /**
-     * @param codec          codec name
-     * @param blobNameFormat format of the blobname in {@link String#format} format
-     * @param reader         prototype object that can deserialize T from XContent
-     * @param compress       true if the content should be compressed
-     * @param xContentType   content type that should be used for write operations
-     */
-    public ChecksumBlobStoreFormat(String codec, String blobNameFormat, CheckedFunction<XContentParser, T, IOException> reader,
-                                   NamedXContentRegistry namedXContentRegistry, boolean compress, XContentType xContentType) {
-        this.reader = reader;
-        this.blobNameFormat = blobNameFormat;
-        this.namedXContentRegistry = namedXContentRegistry;
-        this.xContentType = xContentType;
-        this.compress = compress;
-        this.codec = codec;
-    }
-
     /**
      * @param codec          codec name
      * @param blobNameFormat format of the blobname in {@link String#format} format
@@ -116,7 +95,11 @@ public final class ChecksumBlobStoreFormat<T extends ToXContent> {
      */
     public ChecksumBlobStoreFormat(String codec, String blobNameFormat, CheckedFunction<XContentParser, T, IOException> reader,
                                    NamedXContentRegistry namedXContentRegistry, boolean compress) {
-        this(codec, blobNameFormat, reader, namedXContentRegistry, compress, DEFAULT_X_CONTENT_TYPE);
+        this.reader = reader;
+        this.blobNameFormat = blobNameFormat;
+        this.namedXContentRegistry = namedXContentRegistry;
+        this.compress = compress;
+        this.codec = codec;
     }
 
     /**
@@ -158,7 +141,7 @@ public final class ChecksumBlobStoreFormat<T extends ToXContent> {
             long filePointer = indexInput.getFilePointer();
             long contentSize = indexInput.length() - CodecUtil.footerLength() - filePointer;
             try (XContentParser parser = XContentHelper.createParser(namedXContentRegistry, LoggingDeprecationHandler.INSTANCE,
-                bytes.slice((int) filePointer, (int) contentSize))) {
+                bytes.slice((int) filePointer, (int) contentSize), XContentType.SMILE)) {
                 return reader.apply(parser);
             }
         } catch (CorruptIndexException | IndexFormatTooOldException | IndexFormatTooNewException ex) {
@@ -237,7 +220,7 @@ public final class ChecksumBlobStoreFormat<T extends ToXContent> {
     }
 
     private void write(T obj, StreamOutput streamOutput) throws IOException {
-        try (XContentBuilder builder = XContentFactory.contentBuilder(xContentType, streamOutput)) {
+        try (XContentBuilder builder = XContentFactory.contentBuilder(XContentType.SMILE, streamOutput)) {
             builder.startObject();
             obj.toXContent(builder, SNAPSHOT_ONLY_FORMAT_PARAMS);
             builder.endObject();

server/src/test/java/org/elasticsearch/snapshots/BlobStoreFormatIT.java

@@ -35,7 +35,6 @@ import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.common.xcontent.ToXContentFragment;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
-import org.elasticsearch.common.xcontent.XContentType;
 import org.elasticsearch.index.translog.BufferedChecksumStreamOutput;
 import org.elasticsearch.repositories.blobstore.ChecksumBlobStoreFormat;
 import org.elasticsearch.snapshots.mockstore.BlobContainerWrapper;
@@ -110,24 +109,17 @@ public class BlobStoreFormatIT extends AbstractSnapshotIntegTestCase {
     public void testBlobStoreOperations() throws IOException {
         BlobStore blobStore = createTestBlobStore();
         BlobContainer blobContainer = blobStore.blobContainer(BlobPath.cleanPath());
-        ChecksumBlobStoreFormat<BlobObj> checksumJSON = new ChecksumBlobStoreFormat<>(BLOB_CODEC, "%s", BlobObj::fromXContent,
-            xContentRegistry(), false, XContentType.JSON);
         ChecksumBlobStoreFormat<BlobObj> checksumSMILE = new ChecksumBlobStoreFormat<>(BLOB_CODEC, "%s", BlobObj::fromXContent,
-            xContentRegistry(), false, XContentType.SMILE);
+            xContentRegistry(), false);
         ChecksumBlobStoreFormat<BlobObj> checksumSMILECompressed = new ChecksumBlobStoreFormat<>(BLOB_CODEC, "%s", BlobObj::fromXContent,
-            xContentRegistry(), true, XContentType.SMILE);
+            xContentRegistry(), true);
 
         // Write blobs in different formats
-        checksumJSON.write(new BlobObj("checksum json"), blobContainer, "check-json");
         checksumSMILE.write(new BlobObj("checksum smile"), blobContainer, "check-smile");
         checksumSMILECompressed.write(new BlobObj("checksum smile compressed"), blobContainer, "check-smile-comp");
 
         // Assert that all checksum blobs can be read by all formats
-        assertEquals(checksumJSON.read(blobContainer, "check-json").getText(), "checksum json");
-        assertEquals(checksumSMILE.read(blobContainer, "check-json").getText(), "checksum json");
-        assertEquals(checksumJSON.read(blobContainer, "check-smile").getText(), "checksum smile");
         assertEquals(checksumSMILE.read(blobContainer, "check-smile").getText(), "checksum smile");
-        assertEquals(checksumJSON.read(blobContainer, "check-smile-comp").getText(), "checksum smile compressed");
         assertEquals(checksumSMILE.read(blobContainer, "check-smile-comp").getText(), "checksum smile compressed");
     }
 
@@ -139,9 +131,9 @@ public class BlobStoreFormatIT extends AbstractSnapshotIntegTestCase {
             veryRedundantText.append("Blah ");
         }
         ChecksumBlobStoreFormat<BlobObj> checksumFormat = new ChecksumBlobStoreFormat<>(BLOB_CODEC, "%s", BlobObj::fromXContent,
-            xContentRegistry(), false, randomBoolean() ? XContentType.SMILE : XContentType.JSON);
+            xContentRegistry(), false);
         ChecksumBlobStoreFormat<BlobObj> checksumFormatComp = new ChecksumBlobStoreFormat<>(BLOB_CODEC, "%s", BlobObj::fromXContent,
-            xContentRegistry(), true, randomBoolean() ? XContentType.SMILE : XContentType.JSON);
+            xContentRegistry(), true);
         BlobObj blobObj = new BlobObj(veryRedundantText.toString());
         checksumFormatComp.write(blobObj, blobContainer, "blob-comp");
         checksumFormat.write(blobObj, blobContainer, "blob-not-comp");
@@ -156,7 +148,7 @@ public class BlobStoreFormatIT extends AbstractSnapshotIntegTestCase {
         String testString = randomAlphaOfLength(randomInt(10000));
         BlobObj blobObj = new BlobObj(testString);
         ChecksumBlobStoreFormat<BlobObj> checksumFormat = new ChecksumBlobStoreFormat<>(BLOB_CODEC, "%s", BlobObj::fromXContent,
-            xContentRegistry(), randomBoolean(), randomBoolean() ? XContentType.SMILE : XContentType.JSON);
+            xContentRegistry(), randomBoolean());
         checksumFormat.write(blobObj, blobContainer, "test-path");
         assertEquals(checksumFormat.read(blobContainer, "test-path").getText(), testString);
         randomCorruption(blobContainer, "test-path");
@@ -191,7 +183,7 @@ public class BlobStoreFormatIT extends AbstractSnapshotIntegTestCase {
             }
         };
         final ChecksumBlobStoreFormat<BlobObj> checksumFormat = new ChecksumBlobStoreFormat<>(BLOB_CODEC, "%s", BlobObj::fromXContent,
-            xContentRegistry(), randomBoolean(), randomBoolean() ? XContentType.SMILE : XContentType.JSON);
+            xContentRegistry(), randomBoolean());
         ExecutorService threadPool = Executors.newFixedThreadPool(1);
         try {
             Future<Void> future = threadPool.submit(new Callable<Void>() {
@@ -215,7 +207,7 @@ public class BlobStoreFormatIT extends AbstractSnapshotIntegTestCase {
         final String name = randomAlphaOfLength(10);
         final BlobObj blobObj = new BlobObj("test");
         final ChecksumBlobStoreFormat<BlobObj> checksumFormat = new ChecksumBlobStoreFormat<>(BLOB_CODEC, "%s", BlobObj::fromXContent,
-            xContentRegistry(), randomBoolean(), randomBoolean() ? XContentType.SMILE : XContentType.JSON);
+            xContentRegistry(), randomBoolean());
 
         final BlobStore blobStore = createTestBlobStore();
         final BlobContainer blobContainer = blobStore.blobContainer(BlobPath.cleanPath());