Cleanup Redundant BlobStoreFormat Class (#42195)

* No need to have an abstract class here when there's only a single impl.

Author: original-brownbear

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

@@ -23,6 +23,7 @@
 import org.apache.lucene.index.IndexFormatTooNewException;
 import org.apache.lucene.index.IndexFormatTooOldException;
 import org.apache.lucene.store.OutputStreamIndexOutput;
+import org.elasticsearch.cluster.metadata.MetaData;
 import org.elasticsearch.common.CheckedConsumer;
 import org.elasticsearch.common.CheckedFunction;
 import org.elasticsearch.common.blobstore.BlobContainer;
@@ -33,24 +34,43 @@
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.lucene.store.ByteArrayIndexInput;
 import org.elasticsearch.common.lucene.store.IndexOutputOutputStream;
+import org.elasticsearch.common.xcontent.LoggingDeprecationHandler;
 import org.elasticsearch.common.xcontent.NamedXContentRegistry;
 import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
+import org.elasticsearch.common.xcontent.XContentHelper;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.common.xcontent.XContentType;
 import org.elasticsearch.core.internal.io.Streams;
 import org.elasticsearch.gateway.CorruptStateException;
+import org.elasticsearch.snapshots.SnapshotInfo;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.util.HashMap;
+import java.util.Locale;
+import java.util.Map;
 
 /**
  * Snapshot metadata file format used in v2.0 and above
  */
-public class ChecksumBlobStoreFormat<T extends ToXContent> extends BlobStoreFormat<T> {
+public final class ChecksumBlobStoreFormat<T extends ToXContent> {
+
+    // Serialization parameters to specify correct context for metadata serialization
+    private static final ToXContent.Params SNAPSHOT_ONLY_FORMAT_PARAMS;
+
+    static {
+        Map<String, String> snapshotOnlyParams = new HashMap<>();
+        // when metadata is serialized certain elements of the metadata shouldn't be included into snapshot
+        // exclusion of these elements is done by setting MetaData.CONTEXT_MODE_PARAM to MetaData.CONTEXT_MODE_SNAPSHOT
+        snapshotOnlyParams.put(MetaData.CONTEXT_MODE_PARAM, MetaData.CONTEXT_MODE_SNAPSHOT);
+        // serialize SnapshotInfo using the SNAPSHOT mode
+        snapshotOnlyParams.put(SnapshotInfo.CONTEXT_MODE_PARAM, SnapshotInfo.CONTEXT_MODE_SNAPSHOT);
+        SNAPSHOT_ONLY_FORMAT_PARAMS = new ToXContent.MapParams(snapshotOnlyParams);
+    }
 
     private static final XContentType DEFAULT_X_CONTENT_TYPE = XContentType.SMILE;
 
@@ -59,12 +79,18 @@ public class ChecksumBlobStoreFormat<T extends ToXContent> extends BlobStoreForm
 
     private static final int BUFFER_SIZE = 4096;
 
-    protected final XContentType xContentType;
+    private final XContentType xContentType;
 
-    protected final boolean compress;
+    private final boolean compress;
 
     private final String codec;
 
+    private final String blobNameFormat;
+
+    private final CheckedFunction<XContentParser, T, IOException> reader;
+
+    private final NamedXContentRegistry namedXContentRegistry;
+
     /**
      * @param codec          codec name
      * @param blobNameFormat format of the blobname in {@link String#format} format
@@ -74,7 +100,9 @@ public class ChecksumBlobStoreFormat<T extends ToXContent> extends BlobStoreForm
      */
     public ChecksumBlobStoreFormat(String codec, String blobNameFormat, CheckedFunction<XContentParser, T, IOException> reader,
                                    NamedXContentRegistry namedXContentRegistry, boolean compress, XContentType xContentType) {
-        super(blobNameFormat, reader, namedXContentRegistry);
+        this.reader = reader;
+        this.blobNameFormat = blobNameFormat;
+        this.namedXContentRegistry = namedXContentRegistry;
         this.xContentType = xContentType;
         this.compress = compress;
         this.codec = codec;
@@ -91,6 +119,29 @@ public ChecksumBlobStoreFormat(String codec, String blobNameFormat, CheckedFunct
         this(codec, blobNameFormat, reader, namedXContentRegistry, compress, DEFAULT_X_CONTENT_TYPE);
     }
 
+    /**
+     * Reads and parses the blob with given name, applying name translation using the {link #blobName} method
+     *
+     * @param blobContainer blob container
+     * @param name          name to be translated into
+     * @return parsed blob object
+     */
+    public T read(BlobContainer blobContainer, String name) throws IOException {
+        String blobName = blobName(name);
+        return readBlob(blobContainer, blobName);
+    }
+
+    /**
+     * Deletes obj in the blob container
+     */
+    public void delete(BlobContainer blobContainer, String name) throws IOException {
+        blobContainer.deleteBlob(blobName(name));
+    }
+
+    public String blobName(String name) {
+        return String.format(Locale.ROOT, blobNameFormat, name);
+    }
+
     /**
      * Reads blob with specified name without resolving the blobName using using {@link #blobName} method.
      *
@@ -108,8 +159,10 @@ public T readBlob(BlobContainer blobContainer, String blobName) throws IOExcepti
                 CodecUtil.checkHeader(indexInput, codec, VERSION, VERSION);
                 long filePointer = indexInput.getFilePointer();
                 long contentSize = indexInput.length() - CodecUtil.footerLength() - filePointer;
-                BytesReference bytesReference = new BytesArray(bytes, (int) filePointer, (int) contentSize);
-                return read(bytesReference);
+                try (XContentParser parser = XContentHelper.createParser(namedXContentRegistry, LoggingDeprecationHandler.INSTANCE,
+                        new BytesArray(bytes, (int) filePointer, (int) contentSize))) {
+                    return reader.apply(parser);
+                }
             } catch (CorruptIndexException | IndexFormatTooOldException | IndexFormatTooNewException ex) {
                 // we trick this into a dedicated exception with the original stacktrace
                 throw new CorruptStateException(ex);
@@ -156,7 +209,17 @@ public void write(T obj, BlobContainer blobContainer, String name) throws IOExce
     }
 
     private void writeTo(final T obj, final String blobName, final CheckedConsumer<BytesArray, IOException> consumer) throws IOException {
-        final BytesReference bytes = write(obj);
+        final BytesReference bytes;
+        try (BytesStreamOutput bytesStreamOutput = new BytesStreamOutput()) {
+            if (compress) {
+                try (StreamOutput compressedStreamOutput = CompressorFactory.COMPRESSOR.streamOutput(bytesStreamOutput)) {
+                    write(obj, compressedStreamOutput);
+                }
+            } else {
+                write(obj, bytesStreamOutput);
+            }
+            bytes = bytesStreamOutput.bytes();
+        }
         try (ByteArrayOutputStream outputStream = new ByteArrayOutputStream()) {
             final String resourceDesc = "ChecksumBlobStoreFormat.writeBlob(blob=\"" + blobName + "\")";
             try (OutputStreamIndexOutput indexOutput = new OutputStreamIndexOutput(resourceDesc, blobName, outputStream, BUFFER_SIZE)) {
@@ -176,20 +239,7 @@ public void close() {
         }
     }
 
-    protected BytesReference write(T obj) throws IOException {
-        try (BytesStreamOutput bytesStreamOutput = new BytesStreamOutput()) {
-            if (compress) {
-                try (StreamOutput compressedStreamOutput = CompressorFactory.COMPRESSOR.streamOutput(bytesStreamOutput)) {
-                    write(obj, compressedStreamOutput);
-                }
-            } else {
-                write(obj, bytesStreamOutput);
-            }
-            return bytesStreamOutput.bytes();
-        }
-    }
-
-    protected void write(T obj, StreamOutput streamOutput) throws IOException {
+    private void write(T obj, StreamOutput streamOutput) throws IOException {
         try (XContentBuilder builder = XContentFactory.contentBuilder(xContentType, streamOutput)) {
             builder.startObject();
             obj.toXContent(builder, SNAPSHOT_ONLY_FORMAT_PARAMS);