Don't use reflection for epoll/unix domain sockets

The classes are available, even on Windows. Trying to use them though
won't work. You'll get an error like:
java.lang.UnsatisfiedLinkError: no netty-transport-native-epoll in java.library.path

benchmarks/build.gradle

@@ -39,12 +39,9 @@ dependencies {
             project(':grpc-interop-testing'),
             libraries.junit,
             libraries.mockito,
-            libraries.hdrhistogram
-    if (osdetector.os == "linux") {
-        // These are only available on linux.
-        compile libraries.netty_tcnative,
+            libraries.hdrhistogram,
+            libraries.netty_tcnative,
             libraries.netty_transport_native_epoll
-    }
 
     alpnboot alpnboot_package_name
 }

benchmarks/src/main/java/io/grpc/benchmarks/qps/Utils.java

@@ -44,8 +44,12 @@ import io.grpc.transport.netty.NegotiationType;
 import io.grpc.transport.netty.NettyChannelBuilder;
 import io.grpc.transport.okhttp.OkHttpChannelBuilder;
 import io.netty.channel.EventLoopGroup;
+import io.netty.channel.epoll.EpollDomainSocketChannel;
+import io.netty.channel.epoll.EpollEventLoopGroup;
+import io.netty.channel.epoll.EpollSocketChannel;
 import io.netty.channel.nio.NioEventLoopGroup;
 import io.netty.channel.socket.nio.NioSocketChannel;
+import io.netty.channel.unix.DomainSocketAddress;
 import io.netty.handler.ssl.SslContext;
 import io.netty.handler.ssl.SslProvider;
 
@@ -79,24 +83,22 @@ final class Utils {
   static SocketAddress parseSocketAddress(String value) {
     if (value.startsWith(UNIX_DOMAIN_SOCKET_PREFIX)) {
       // Unix Domain Socket address.
-      try {
       // Create the underlying file for the Unix Domain Socket.
       String filePath = value.substring(UNIX_DOMAIN_SOCKET_PREFIX.length());
       File file = new File(filePath);
       if (!file.isAbsolute()) {
         throw new IllegalArgumentException("File path must be absolute: " + filePath);
       }
+      try {
         if (file.createNewFile()) {
           // If this application created the file, delete it when the application exits.
           file.deleteOnExit();
         }
-        // Create the SocketAddress referencing the file.
-        Class<?> addressClass = Class.forName("io.netty.channel.unix.DomainSocketAddress");
-        return (SocketAddress) addressClass.getDeclaredConstructor(File.class)
-            .newInstance(file);
-      } catch (Exception e) {
-        throw new RuntimeException(e);
+      } catch (IOException ex) {
+        throw new RuntimeException(ex);
       }
+      // Create the SocketAddress referencing the file.
+      return new DomainSocketAddress(file);
     } else {
       // Standard TCP/IP address.
       String[] parts = value.split(":", 2);
@@ -146,46 +148,27 @@ final class Utils {
     final EventLoopGroup group;
     final Class<? extends io.netty.channel.Channel> channelType;
     switch (config.transport) {
-      case NETTY_NIO: {
+      case NETTY_NIO:
         group = new NioEventLoopGroup();
         channelType = NioSocketChannel.class;
         break;
-      }
-      case NETTY_EPOLL: {
-        try {
-          // These classes are only available on linux.
-          Class<?> groupClass = Class.forName("io.netty.channel.epoll.EpollEventLoopGroup");
-          @SuppressWarnings("unchecked")
-          Class<? extends io.netty.channel.Channel> channelClass =
-              (Class<? extends io.netty.channel.Channel>) Class.forName(
-                  "io.netty.channel.epoll.EpollSocketChannel");
-          group = (EventLoopGroup) groupClass.newInstance();
-          channelType = channelClass;
+
+      case NETTY_EPOLL:
+        // These classes only work on Linux.
+        group = new EpollEventLoopGroup();
+        channelType = EpollSocketChannel.class;
         break;
-        } catch (Exception e) {
-          throw new RuntimeException(e);
-        }
-      }
-      case NETTY_UNIX_DOMAIN_SOCKET: {
-        try {
-          // These classes are only available on linux.
-          Class<?> groupClass = Class.forName("io.netty.channel.epoll.EpollEventLoopGroup");
-          @SuppressWarnings("unchecked")
-          Class<? extends io.netty.channel.Channel> channelClass =
-              (Class<? extends io.netty.channel.Channel>) Class.forName(
-                  "io.netty.channel.epoll.EpollDomainSocketChannel");
-          group = (EventLoopGroup) groupClass.newInstance();
-          channelType = channelClass;
+
+      case NETTY_UNIX_DOMAIN_SOCKET:
+        // These classes only work on Linux.
+        group = new EpollEventLoopGroup();
+        channelType = EpollDomainSocketChannel.class;
         break;
-        } catch (Exception e) {
-          throw new RuntimeException(e);
-        }
-      }
-      default: {
+
+      default:
         // Should never get here.
         throw new IllegalArgumentException("Unsupported transport: " + config.transport);
     }
-    }
     return NettyChannelBuilder
         .forAddress(config.address)
         .eventLoopGroup(group)

build.gradle

@@ -93,6 +93,16 @@ subprojects {
           }
         }
 
+        def tcnative_suffix = "";
+        if (osdetector.classifier in ["linux-x86_64", "osx-x86_64", "windows-x86_64"]) {
+            // The native code is only pre-compiled on certain platforms.
+            tcnative_suffix = ":" + osdetector.classifier
+        }
+        def epoll_suffix = "";
+        if (osdetector.classifier in ["linux-x86_64"]) {
+            // The native code is only pre-compiled on certain platforms.
+            epoll_suffix = ":" + osdetector.classifier
+        }
         libraries = [
                 guava: 'com.google.guava:guava:18.0',
                 // used to collect benchmark results
@@ -108,8 +118,8 @@ subprojects {
                 protobuf_plugin: 'com.google.protobuf:protobuf-gradle-plugin:0.4.1',
 
                 netty: 'io.netty:netty-codec-http2:4.1.0.Beta5',
-                netty_tcnative: "io.netty:netty-tcnative:1.1.33.Fork2:${osdetector.classifier}",
-                netty_transport_native_epoll: "io.netty:netty-transport-native-epoll:4.1.0.Beta5:${osdetector.classifier}",
+                netty_tcnative: 'io.netty:netty-tcnative:1.1.33.Fork2' + tcnative_suffix,
+                netty_transport_native_epoll: 'io.netty:netty-transport-native-epoll:4.1.0.Beta5' + epoll_suffix,
 
                 // Test dependencies.
                 junit: 'junit:junit:4.11',