Ensure our SSHD always disables compression

Currently the SSH daemon always disables compression, but that
default might change in the future.  We know that compression
will never be useful on our data streams, as they are always
moving highly compressed Git pack files.  So we disable them
ourselves just in case the default should ever change in the
upstream SSH daemon code.

Signed-off-by: Shawn O. Pearce <sop@google.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/main/java/com/google/gerrit/server/ssh/SshServlet.java b/src/main/java/com/google/gerrit/server/ssh/SshServlet.java
index 1c9e6b7597..03ce4eb02b 100644
--- a/src/main/java/com/google/gerrit/server/ssh/SshServlet.java
+++ b/src/main/java/com/google/gerrit/server/ssh/SshServlet.java
@@ -20,7 +20,9 @@ import com.google.gwtjsonrpc.server.XsrfException;
 import com.google.gwtorm.client.OrmException;
 
 import org.apache.sshd.SshServer;
+import org.apache.sshd.common.Compression;
 import org.apache.sshd.common.NamedFactory;
+import org.apache.sshd.common.compression.CompressionNone;
 import org.apache.sshd.common.keyprovider.FileKeyPairProvider;
 import org.apache.sshd.common.util.SecurityUtils;
 import org.apache.sshd.server.UserAuth;
@@ -90,6 +92,13 @@ public class SshServlet extends HttpServlet {
       sshd.setKeyPairProvider(keyp);
     }
 
+    // Always disable transparent compression. The majority of our data
+    // transfer is highly compressed Git pack files. We cannot make them
+    // any smaller than they already are.
+    //
+    sshd.setCompressionFactories(Arrays
+        .<NamedFactory<Compression>> asList(new CompressionNone.Factory()));
+
     sshd.setUserAuthFactories(Arrays
         .<NamedFactory<UserAuth>> asList(new UserAuthPublicKey.Factory()));
     sshd.setPublickeyAuthenticator(new DatabasePubKeyAuth());