opendev/gerrit
Code Issues Proposed changes

Support SSH ZLib Compression

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In the general case, we want to disable transparent
compression, since the majority of our data transfer
is highly compressed Git pack files and we cannot
make them any smaller than they already are.

However, if there are CPU in abundance and the server
is reachable through slow networks; gits with huge
amount of refs can benefit from SSH-compression since
git does not compress the ref announcement during the
handshake.

Compression can be especially useful when Gerrit slaves
are being used for the larger clones and fetches and
the master server mostly takes small receive-packs.

To enable compression use sshd.enableCompression in
gerrit.config.

Change-Id: I7ff9efd26e746db5f1400017816984d652585008
This commit is contained in:
Gustaf Lundh 2015-08-03 16:18:33 +02:00
parent c7eb9fc190
commit d60e90f714
2 changed files with 45 additions and 7 deletions
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17
Documentation/config-gerrit.txt
View File

@ -3289,6 +3289,23 @@ namespace. To alias `replication start` to `gerrit replicate`:
[[sshd]]
=== Section sshd
[[sshd.enableCompression]]sshd.enableCompression::
+
In the general case, we want to disable transparent compression, since
the majority of our data transfer is highly compressed Git pack files
and we cannot make them any smaller than they already are.
+
However, if there are CPU in abundance and the server is reachable
through slow networks, gits with huge amount of refs can benefit from
SSH-compression since git does not compress the ref announcement during
handshake.
+
Compression can be especially useful when Gerrit slaves are being used
for the larger clones and fetches and the master server mostly takes
small receive-packs.
+
By default, `false`.
[[sshd.backend]]sshd.backend::
+
Starting from version 0.9.0 Apache SSHD project added support for NIO2

35
gerrit-sshd/src/main/java/com/google/gerrit/sshd/SshDaemon.java
View File

@ -61,6 +61,7 @@ import org.apache.sshd.common.cipher.BlowfishCBC;
import org.apache.sshd.common.cipher.CipherNone;
import org.apache.sshd.common.cipher.TripleDESCBC;
import org.apache.sshd.common.compression.CompressionNone;
import org.apache.sshd.common.compression.CompressionZlib;
import org.apache.sshd.common.file.FileSystemFactory;
import org.apache.sshd.common.file.FileSystemView;
import org.apache.sshd.common.file.SshFile;
@ -216,6 +217,9 @@ public class SshDaemon extends SshServer implements SshInfo, LifecycleListener {
final String kerberosPrincipal = cfg.getString(
"sshd", null, "kerberosPrincipal");
final boolean enableCompression = cfg.getBoolean(
"sshd", "enableCompression", false);
SshSessionBackend backend = cfg.getEnum(
"sshd", null, "backend", SshSessionBackend.MINA);
@ -236,7 +240,7 @@ public class SshDaemon extends SshServer implements SshInfo, LifecycleListener {
initForwarding();
initFileSystemFactory();
initSubsystems();
initCompression();
initCompression(enableCompression);
initUserAuth(userAuth, kerberosAuth, kerberosKeytab, kerberosPrincipal);
setKeyPairProvider(hostKeyProvider);
setCommandFactory(commandFactory);
@ -594,13 +598,30 @@ public class SshDaemon extends SshServer implements SshInfo, LifecycleListener {
new SignatureECDSA.NISTP521Factory()));
}
private void initCompression() {
// 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.
private void initCompression(boolean enableCompression) {
List<NamedFactory<Compression>> compressionFactories =
Lists.newArrayList();
// Always support no compression over SSHD.
compressionFactories.add(new CompressionNone.Factory());
// In the general case, we want to disable transparent compression, since
// the majority of our data transfer is highly compressed Git pack files
// and we cannot make them any smaller than they already are.
//
setCompressionFactories(Arrays
.<NamedFactory<Compression>> asList(new CompressionNone.Factory()));
// However, if there are CPU in abundance and the server is reachable through
// slow networks, gits with huge amount of refs can benefit from SSH-compression
// since git does not compress the ref announcement during the handshake.
//
// Compression can be especially useful when Gerrit slaves are being used
// for the larger clones and fetches and the master server mostly takes small
// receive-packs.
if (enableCompression) {
compressionFactories.add(new CompressionZlib.Factory());
}
setCompressionFactories(compressionFactories);
}
private void initChannels() {