Use WritableByteChannel for HttpDownloader

Using WritableByteChannel#write instead of OutputStream#write apparently
speeds up the download. I don't see any way to make sure it does but
on my machine I get normal download speed with that change (compared
to the previous version).

--
Change-Id: I77db80ecd199efe2a5a9673ca0ad0bbcaaf74e56
Reviewed-on: https://bazel-review.googlesource.com/#/c/1630/
MOS_MIGRATED_REVID=98296070

1 files changed, 3 insertions, 1 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/bazel/repository/HttpDownloader.java b/src/main/java/com/google/devtools/build/lib/bazel/repository/HttpDownloader.java
index 020c0bd134..d01b91870b 100644
--- a/src/main/java/com/google/devtools/build/lib/bazel/repository/HttpDownloader.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/repository/HttpDownloader.java
@@ -29,6 +29,7 @@ import java.net.URL;
 import java.nio.ByteBuffer;
 import java.nio.channels.Channels;
 import java.nio.channels.ReadableByteChannel;
+import java.nio.channels.WritableByteChannel;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.ScheduledFuture;
@@ -72,12 +73,13 @@ public class HttpDownloader {
 
     try (OutputStream outputStream = destination.getOutputStream()) {
       ReadableByteChannel rbc = getChannel(url);
+      WritableByteChannel obc = Channels.newChannel(outputStream);
       ByteBuffer byteBuffer = ByteBuffer.allocate(BUFFER_SIZE);
       while ((currentBytes = rbc.read(byteBuffer)) > 0) {
         totalBytes.addAndGet(currentBytes);
         byteBuffer.flip();
         while (byteBuffer.hasRemaining()) {
-          outputStream.write(byteBuffer.get());
+          obc.write(byteBuffer);
         }
         byteBuffer.flip();
       }