feat: Add HTTP/2 enabled transport as default transport

pom.xml

@@ -455,6 +455,11 @@
             <artifactId>netty-transport</artifactId>
             <version>${netty.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.apache.httpcomponents.client5</groupId>
+            <artifactId>httpclient5</artifactId>
+            <version>5.3.1</version>
+        </dependency>
 
         <!-- Test Dependencies -->
         <dependency>
@@ -488,5 +493,10 @@
             <version>3.0</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.mock-server</groupId>
+            <artifactId>mockserver-junit-rule-no-dependencies</artifactId>
+            <version>5.14.0</version>
+        </dependency>
     </dependencies>
 </project>

src/main/java/com/google/firebase/internal/ApacheHttp2AsyncEntityProducer.java

@@ -0,0 +1,150 @@
+/*
+ * Copyright 2024 Google Inc.
+ *
+ * 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.firebase.internal;
+
+import com.google.api.client.util.StreamingContent;
+import com.google.common.annotations.VisibleForTesting;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.atomic.AtomicReference;
+
+import org.apache.hc.core5.http.ContentType;
+import org.apache.hc.core5.http.nio.AsyncEntityProducer;
+import org.apache.hc.core5.http.nio.DataStreamChannel;
+
+public class ApacheHttp2AsyncEntityProducer implements AsyncEntityProducer {
+  private ByteBuffer bytebuf;
+  private ByteArrayOutputStream baos;
+  private final StreamingContent content;
+  private final ContentType contentType;
+  private final long contentLength;
+  private final String contentEncoding;
+  private final CompletableFuture<Void> writeFuture;
+  private final AtomicReference<Exception> exception;
+
+  public ApacheHttp2AsyncEntityProducer(StreamingContent content, ContentType contentType,
+      String contentEncoding, long contentLength, CompletableFuture<Void> writeFuture) {
+    this.content = content;
+    this.contentType = contentType;
+    this.contentEncoding = contentEncoding;
+    this.contentLength = contentLength;
+    this.writeFuture = writeFuture;
+    this.bytebuf = null;
+
+    this.baos = new ByteArrayOutputStream((int) (contentLength < 0 ? 0 : contentLength));
+    this.exception = new AtomicReference<>();
+  }
+
+  public ApacheHttp2AsyncEntityProducer(ApacheHttp2Request request,
+      CompletableFuture<Void> writeFuture) {
+    this(
+        request.getStreamingContent(),
+        ContentType.parse(request.getContentType()),
+        request.getContentEncoding(),
+        request.getContentLength(),
+        writeFuture);
+  }
+
+  @Override
+  public boolean isRepeatable() {
+    return true;
+  }
+
+  @Override
+  public String getContentType() {
+    return contentType != null ? contentType.toString() : null;
+  }
+
+  @Override
+  public long getContentLength() {
+    return contentLength;
+  }
+
+  @Override
+  public int available() {
+    return Integer.MAX_VALUE;
+  }
+
+  @Override
+  public String getContentEncoding() {
+    return contentEncoding;
+  }
+
+  @Override
+  public boolean isChunked() {
+    return contentLength == -1;
+  }
+
+  @Override
+  public Set<String> getTrailerNames() {
+    return null;
+  }
+
+  @Override
+  public void produce(DataStreamChannel channel) throws IOException {
+    if (bytebuf == null) {
+      if (content != null) {
+        try {
+          content.writeTo(baos);
+        } catch (IOException e) {
+          failed(e);
+          throw e;
+        }
+      }
+
+      this.bytebuf = ByteBuffer.wrap(baos.toByteArray());
+    }
+
+    if (bytebuf.hasRemaining()) {
+      channel.write(bytebuf);
+    }
+
+    if (!bytebuf.hasRemaining()) {
+      channel.endStream();
+      writeFuture.complete(null);
+      releaseResources();
+    }
+  }
+
+  @Override
+  public void failed(Exception cause) {
+    if (exception.compareAndSet(null, cause)) {
+      releaseResources();
+      writeFuture.completeExceptionally(cause);
+    }
+  }
+
+  public final Exception getException() {
+    return exception.get();
+  }
+
+  @Override
+  public void releaseResources() {
+    if (bytebuf != null) {
+      bytebuf.clear();
+    }
+  }
+
+  @VisibleForTesting
+  ByteBuffer getBytebuf() {
+    return bytebuf;
+  }
+}

src/main/java/com/google/firebase/internal/ApacheHttp2Request.java

@@ -0,0 +1,147 @@
+/*
+ * Copyright 2024 Google Inc.
+ *
+ * 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.firebase.internal;
+
+import com.google.api.client.http.LowLevelHttpRequest;
+import com.google.api.client.http.LowLevelHttpResponse;
+import com.google.common.annotations.VisibleForTesting;
+
+import java.io.IOException;
+import java.net.SocketTimeoutException;
+import java.util.concurrent.CancellationException;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+import org.apache.hc.client5.http.ConnectTimeoutException;
+import org.apache.hc.client5.http.HttpHostConnectException;
+import org.apache.hc.client5.http.async.methods.SimpleHttpRequest;
+import org.apache.hc.client5.http.async.methods.SimpleHttpResponse;
+import org.apache.hc.client5.http.async.methods.SimpleRequestBuilder;
+import org.apache.hc.client5.http.async.methods.SimpleResponseConsumer;
+import org.apache.hc.client5.http.config.RequestConfig;
+import org.apache.hc.client5.http.impl.async.CloseableHttpAsyncClient;
+import org.apache.hc.core5.concurrent.FutureCallback;
+import org.apache.hc.core5.http.nio.support.BasicRequestProducer;
+import org.apache.hc.core5.http2.H2StreamResetException;
+import org.apache.hc.core5.util.Timeout;
+
+final class ApacheHttp2Request extends LowLevelHttpRequest {
+  private final CloseableHttpAsyncClient httpAsyncClient;
+  private final SimpleRequestBuilder requestBuilder;
+  private SimpleHttpRequest request;
+  private final RequestConfig.Builder requestConfig;
+  private int writeTimeout;
+  private ApacheHttp2AsyncEntityProducer entityProducer;
+
+  ApacheHttp2Request(
+      CloseableHttpAsyncClient httpAsyncClient, SimpleRequestBuilder requestBuilder) {
+    this.httpAsyncClient = httpAsyncClient;
+    this.requestBuilder = requestBuilder;
+    this.writeTimeout = 0;
+
+    this.requestConfig = RequestConfig.custom()
+        .setRedirectsEnabled(false);
+  }
+
+  @Override
+  public void addHeader(String name, String value) {
+    requestBuilder.addHeader(name, value);
+  }
+
+  @Override
+  public void setTimeout(int connectionTimeout, int readTimeout) throws IOException {
+    requestConfig
+        .setConnectTimeout(Timeout.ofMilliseconds(connectionTimeout))
+        .setResponseTimeout(Timeout.ofMilliseconds(readTimeout));
+  }
+
+  @Override
+  public void setWriteTimeout(int writeTimeout) throws IOException {
+    this.writeTimeout = writeTimeout;
+  }
+
+  @Override
+  public LowLevelHttpResponse execute() throws IOException {
+    // Set request configs
+    requestBuilder.setRequestConfig(requestConfig.build());
+
+    // Build request
+    request = requestBuilder.build();
+
+    // Make Producer
+    CompletableFuture<Void> writeFuture = new CompletableFuture<>();
+    entityProducer = new ApacheHttp2AsyncEntityProducer(this, writeFuture);
+
+    // Execute
+    final Future<SimpleHttpResponse> responseFuture = httpAsyncClient.execute(
+        new BasicRequestProducer(request, entityProducer),
+        SimpleResponseConsumer.create(),
+        new FutureCallback<SimpleHttpResponse>() {
+          @Override
+          public void completed(final SimpleHttpResponse response) {
+          }
+
+          @Override
+          public void failed(final Exception exception) {
+          }
+
+          @Override
+          public void cancelled() {
+          }
+        });
+
+    // Wait for write
+    try {
+      if (writeTimeout != 0) {
+        writeFuture.get(writeTimeout, TimeUnit.MILLISECONDS);
+      }
+    } catch (TimeoutException e) {
+      throw new IOException("Write Timeout", e.getCause());
+    } catch (Exception e) {
+      throw new IOException("Exception in write", e.getCause());
+    }
+
+    // Wait for response
+    try {
+      final SimpleHttpResponse response = responseFuture.get();
+      return new ApacheHttp2Response(response);
+    } catch (ExecutionException e) {
+      if (e.getCause() instanceof ConnectTimeoutException 
+          || e.getCause() instanceof SocketTimeoutException) {
+        throw new IOException("Connection Timeout", e.getCause());
+      } else if (e.getCause() instanceof HttpHostConnectException) {
+        throw new IOException("Connection exception in request", e.getCause());
+      } else if (e.getCause() instanceof H2StreamResetException) {
+        throw new IOException("Stream exception in request", e.getCause());
+      } else {
+        throw new IOException("Unknown exception in request", e);
+      }
+    } catch (InterruptedException e) {
+      throw new IOException("Request Interrupted", e);
+    } catch (CancellationException e) {
+      throw new IOException("Request Cancelled", e);
+    }
+  }
+
+  @VisibleForTesting
+  ApacheHttp2AsyncEntityProducer getEntityProducer() {
+    return entityProducer;
+  }
+}