fix: wrap BatchRequest InputStream with BufferedInputStream (#1749)

If reading byte-by-byte from a GZipInputStream is slow, then wrapping in a BufferedInputStream should minimize this effect by reading in larger, buffered chunks.

Added a test to ensure that parsing a large BatchResponse does not take an exorbitant amount of time.

Fixes #1573  ☕️

google-api-client/src/main/java/com/google/api/client/googleapis/batch/BatchRequest.java

@@ -27,6 +27,7 @@
 import com.google.api.client.http.MultipartContent;
 import com.google.api.client.util.Preconditions;
 import com.google.api.client.util.Sleeper;
+import java.io.BufferedInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
@@ -259,7 +260,7 @@ public void execute() throws IOException {
         String boundary = "--" + response.getMediaType().getParameter("boundary");
 
         // Parse the content stream.
-        InputStream contentStream = response.getContent();
+        InputStream contentStream = new BufferedInputStream(response.getContent());
         batchResponse =
             new BatchUnparsedResponse(contentStream, boundary, requestInfos, retryAllowed);
 

google-api-client/src/test/java/com/google/api/client/googleapis/batch/BatchRequestStressTest.java

@@ -0,0 +1,121 @@
+/*
+ * Copyright 2021 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
+ * in compliance with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License
+ * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
+ * or implied. See the License for the specific language governing permissions and limitations under
+ * the License.
+ */
+
+package com.google.api.client.googleapis.batch;
+
+import static org.junit.Assert.assertEquals;
+
+import com.google.api.client.http.ByteArrayContent;
+import com.google.api.client.http.GenericUrl;
+import com.google.api.client.http.HttpHeaders;
+import com.google.api.client.http.HttpMediaType;
+import com.google.api.client.http.HttpRequest;
+import com.google.api.client.http.HttpTransport;
+import com.google.api.client.http.LowLevelHttpRequest;
+import com.google.api.client.http.LowLevelHttpResponse;
+import com.google.api.client.testing.http.MockHttpTransport;
+import com.google.api.client.testing.http.MockLowLevelHttpRequest;
+import com.google.api.client.testing.http.MockLowLevelHttpResponse;
+import com.google.api.client.util.Charsets;
+import java.io.IOException;
+import java.io.PipedInputStream;
+import java.io.PipedOutputStream;
+import java.util.Arrays;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.zip.GZIPOutputStream;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+/** Tests {@link BatchRequest}. */
+public class BatchRequestStressTest {
+
+  private static final int BATCH_SIZE = 100;
+  public static BatchRequest batchRequest;
+  private static AtomicInteger parseCount = new AtomicInteger(0);
+  private static AtomicInteger errorCount = new AtomicInteger(0);
+
+  @BeforeClass
+  public static void setup() throws IOException {
+    HttpTransport transport =
+        new MockHttpTransport() {
+          @Override
+          public LowLevelHttpRequest buildRequest(String method, String url) throws IOException {
+            return new MockLowLevelHttpRequest() {
+              @Override
+              public LowLevelHttpResponse execute() throws IOException {
+                MockLowLevelHttpResponse response = new MockLowLevelHttpResponse();
+                response.setStatusCode(200);
+                response.addHeader("Content-Type", "multipart/mixed; boundary=__END_OF_PART__");
+                response.setContentEncoding("gzip");
+                StringBuilder responseContent = new StringBuilder();
+                for (int i = 0; i < BATCH_SIZE; i++) {
+                  responseContent
+                      .append("--" + "__END_OF_PART__" + "\n")
+                      .append("Content-Type: application/http\n")
+                      .append("Content-ID: response-" + i + "\n\n")
+                      .append("HTTP/1.1 200 OK\n")
+                      .append("Content-Type: application/json\n\n")
+                      .append("{}\n\n");
+                }
+                responseContent.append("--" + "__END_OF_PART__--" + "\n\n");
+
+                // gzip this content
+                PipedInputStream is = new PipedInputStream();
+                PipedOutputStream os = new PipedOutputStream(is);
+                GZIPOutputStream gzip = new GZIPOutputStream(os);
+                gzip.write(responseContent.toString().getBytes("UTF-8"));
+                gzip.close();
+                response.setContent(is);
+                return response;
+              }
+            };
+          }
+        };
+
+    BatchCallback<Void, Void> callback =
+        new BatchCallback<Void, Void>() {
+          @Override
+          public void onSuccess(Void t, HttpHeaders responseHeaders) {
+            parseCount.incrementAndGet();
+          }
+
+          @Override
+          public void onFailure(Void e, HttpHeaders responseHeaders) {
+            errorCount.incrementAndGet();
+          }
+        };
+    batchRequest = new BatchRequest(transport, null);
+    byte[] content = new byte[300];
+    Arrays.fill(content, (byte) ' ');
+    HttpRequest request1 =
+        transport
+            .createRequestFactory()
+            .buildRequest(
+                "POST",
+                new GenericUrl("http://www.google.com/"),
+                new ByteArrayContent(
+                    new HttpMediaType("text/plain").setCharsetParameter(Charsets.UTF_8).build(),
+                    content));
+    for (int i = 0; i < BATCH_SIZE; i++) {
+      batchRequest.queue(request1, Void.class, Void.class, callback);
+    }
+  }
+
+  @Test(timeout = 4000)
+  public void testResponse() throws IOException {
+    batchRequest.execute();
+    assertEquals(BATCH_SIZE, parseCount.get());
+    assertEquals(0, errorCount.get());
+  }
+}