Remove extra check for object existence in repository-gcs read object (#31661)

Author: tlrx

plugins/repository-gcs/src/main/java/org/elasticsearch/repositories/gcs/GoogleCloudStorageBlobStore.java

@@ -54,6 +54,7 @@
 import java.util.Map;
 import java.util.stream.Collectors;
 
+import static java.net.HttpURLConnection.HTTP_NOT_FOUND;
 import static java.net.HttpURLConnection.HTTP_PRECON_FAILED;
 
 class GoogleCloudStorageBlobStore extends AbstractComponent implements BlobStore {
@@ -163,16 +164,19 @@ boolean blobExists(String blobName) throws IOException {
      */
     InputStream readBlob(String blobName) throws IOException {
         final BlobId blobId = BlobId.of(bucketName, blobName);
-        final Blob blob = SocketAccess.doPrivilegedIOException(() -> client().get(blobId));
-        if (blob == null) {
-            throw new NoSuchFileException("Blob [" + blobName + "] does not exit");
-        }
-        final ReadChannel readChannel = SocketAccess.doPrivilegedIOException(blob::reader);
+        final ReadChannel readChannel = SocketAccess.doPrivilegedIOException(() -> client().reader(blobId));
         return Channels.newInputStream(new ReadableByteChannel() {
             @SuppressForbidden(reason = "Channel is based of a socket not a file")
             @Override
             public int read(ByteBuffer dst) throws IOException {
-                return SocketAccess.doPrivilegedIOException(() -> readChannel.read(dst));
+                try {
+                    return SocketAccess.doPrivilegedIOException(() -> readChannel.read(dst));
+                } catch (StorageException e) {
+                    if (e.getCode() == HTTP_NOT_FOUND) {
+                        throw new NoSuchFileException("Blob [" + blobName + "] does not exist");
+                    }
+                    throw e;
+                }
             }
 
             @Override

plugins/repository-gcs/src/test/java/org/elasticsearch/repositories/gcs/MockStorage.java

@@ -167,7 +167,27 @@ public Iterable<Blob> getValues() {
     public ReadChannel reader(BlobId blob, BlobSourceOption... options) {
         if (bucketName.equals(blob.getBucket())) {
             final byte[] bytes = blobs.get(blob.getName());
-            final ReadableByteChannel readableByteChannel = Channels.newChannel(new ByteArrayInputStream(bytes));
+
+            final ReadableByteChannel readableByteChannel;
+            if (bytes != null) {
+                readableByteChannel = Channels.newChannel(new ByteArrayInputStream(bytes));
+            } else {
+                readableByteChannel = new ReadableByteChannel() {
+                    @Override
+                    public int read(ByteBuffer dst) throws IOException {
+                        throw new StorageException(404, "Object not found");
+                    }
+
+                    @Override
+                    public boolean isOpen() {
+                        return false;
+                    }
+
+                    @Override
+                    public void close() throws IOException {
+                    }
+                };
+            }
             return new ReadChannel() {
                 @Override
                 public void close() {

test/framework/src/main/java/org/elasticsearch/repositories/ESBlobStoreContainerTestCase.java

@@ -49,7 +49,11 @@ public abstract class ESBlobStoreContainerTestCase extends ESTestCase {
     public void testReadNonExistingPath() throws IOException {
         try(BlobStore store = newBlobStore()) {
             final BlobContainer container = store.blobContainer(new BlobPath());
-            expectThrows(NoSuchFileException.class, () -> container.readBlob("non-existing"));
+            expectThrows(NoSuchFileException.class, () -> {
+                try (InputStream is = container.readBlob("non-existing")) {
+                    is.read();
+                }
+            });
         }
     }