Added HttpContentDecompressor to HttpBlobStore download pipeline and …

…`Accept-Encoding: gzip` header. bazelbuild#4575

src/main/java/com/google/devtools/build/lib/remote/http/HttpBlobStore.java

@@ -43,6 +43,7 @@
 import io.netty.channel.socket.nio.NioSocketChannel;
 import io.netty.channel.unix.DomainSocketAddress;
 import io.netty.handler.codec.http.HttpClientCodec;
+import io.netty.handler.codec.http.HttpContentDecompressor;
 import io.netty.handler.codec.http.HttpHeaderNames;
 import io.netty.handler.codec.http.HttpObjectAggregator;
 import io.netty.handler.codec.http.HttpRequestEncoder;
@@ -367,6 +368,7 @@ private Future<Channel> acquireDownloadChannel() {
                     "timeout-handler",
                     new IdleTimeoutHandler(timeoutSeconds, ReadTimeoutException.INSTANCE));
                 p.addLast(new HttpClientCodec());
+                p.addLast("inflater", new HttpContentDecompressor());
                 synchronized (credentialsLock) {
                   p.addLast(new HttpDownloadHandler(creds, extraHttpHeaders));
                 }
@@ -397,6 +399,7 @@ private void releaseDownloadChannel(Channel ch) {
       try {
         ch.pipeline().remove(IdleTimeoutHandler.class);
         ch.pipeline().remove(HttpClientCodec.class);
+        ch.pipeline().remove(HttpContentDecompressor.class);
         ch.pipeline().remove(HttpDownloadHandler.class);
       } catch (NoSuchElementException e) {
         // If the channel is in the process of closing but not yet closed, some handlers could have

src/main/java/com/google/devtools/build/lib/remote/http/HttpDownloadHandler.java

@@ -165,6 +165,7 @@ private HttpRequest buildRequest(String path, String host) {
     httpRequest.headers().set(HttpHeaderNames.HOST, host);
     httpRequest.headers().set(HttpHeaderNames.CONNECTION, HttpHeaderValues.KEEP_ALIVE);
     httpRequest.headers().set(HttpHeaderNames.ACCEPT, "*/*");
+    httpRequest.headers().set(HttpHeaderNames.ACCEPT_ENCODING, HttpHeaderValues.GZIP);
     return httpRequest;
   }