Java 8 Migration: remove uneccessary if statement (#8755)

Motivation:

As netty 4.x supported Java 6 we had various if statements to check for java versions < 8. We can remove these now.

Modification:

Remove unnecessary if statements that check for java versions < 8.

Result:

Cleanup code.

buffer/src/main/java/io/netty/buffer/PooledUnsafeHeapByteBuf.java

@@ -130,26 +130,18 @@ final class PooledUnsafeHeapByteBuf extends PooledHeapByteBuf {
 
     @Override
     public ByteBuf setZero(int index, int length) {
-        if (PlatformDependent.javaVersion() >= 7) {
+        checkIndex(index, length);
-            checkIndex(index, length);
+        UnsafeByteBufUtil.setZero(memory, idx(index), length);
-            // Only do on java7+ as the needed Unsafe call was only added there.
+        return this;
-            UnsafeByteBufUtil.setZero(memory, idx(index), length);
-            return this;
-        }
-        return super.setZero(index, length);
     }
 
     @Override
     public ByteBuf writeZero(int length) {
-        if (PlatformDependent.javaVersion() >= 7) {
+        ensureWritable(length);
-            // Only do on java7+ as the needed Unsafe call was only added there.
+        int wIndex = writerIndex;
-            ensureWritable(length);
+        UnsafeByteBufUtil.setZero(memory, idx(wIndex), length);
-            int wIndex = writerIndex;
+        writerIndex = wIndex + length;
-            UnsafeByteBufUtil.setZero(memory, idx(wIndex), length);
+        return this;
-            writerIndex = wIndex + length;
-            return this;
-        }
-        return super.writeZero(length);
     }
 
     @Override

buffer/src/main/java/io/netty/buffer/UnpooledUnsafeHeapByteBuf.java

@@ -243,26 +243,18 @@ class UnpooledUnsafeHeapByteBuf extends UnpooledHeapByteBuf {
 
     @Override
     public ByteBuf setZero(int index, int length) {
-        if (PlatformDependent.javaVersion() >= 7) {
+        checkIndex(index, length);
-            // Only do on java7+ as the needed Unsafe call was only added there.
+        UnsafeByteBufUtil.setZero(array, index, length);
-            checkIndex(index, length);
+        return this;
-            UnsafeByteBufUtil.setZero(array, index, length);
-            return this;
-        }
-        return super.setZero(index, length);
     }
 
     @Override
     public ByteBuf writeZero(int length) {
-        if (PlatformDependent.javaVersion() >= 7) {
+        ensureWritable(length);
-            // Only do on java7+ as the needed Unsafe call was only added there.
+        int wIndex = writerIndex;
-            ensureWritable(length);
+        UnsafeByteBufUtil.setZero(array, wIndex, length);
-            int wIndex = writerIndex;
+        writerIndex = wIndex + length;
-            UnsafeByteBufUtil.setZero(array, wIndex, length);
+        return this;
-            writerIndex = wIndex + length;
-            return this;
-        }
-        return super.writeZero(length);
     }
 
     @Override

codec-http/src/main/java/io/netty/handler/codec/spdy/SpdyHeaderBlockEncoder.java

@@ -23,14 +23,7 @@ abstract class SpdyHeaderBlockEncoder {
 
     static SpdyHeaderBlockEncoder newInstance(
             SpdyVersion version, int compressionLevel, int windowBits, int memLevel) {
-
+        return new SpdyHeaderBlockZlibEncoder(version, compressionLevel);
-        if (PlatformDependent.javaVersion() >= 7) {
-            return new SpdyHeaderBlockZlibEncoder(
-                    version, compressionLevel);
-        } else {
-            return new SpdyHeaderBlockJZlibEncoder(
-                    version, compressionLevel, windowBits, memLevel);
-        }
     }
 
     abstract ByteBuf encode(ByteBufAllocator alloc, SpdyHeadersFrame frame) throws Exception;

codec/src/main/java/io/netty/handler/codec/compression/ByteBufChecksum.java

@@ -52,16 +52,13 @@ abstract class ByteBufChecksum implements Checksum {
     };
 
     private static Method updateByteBuffer(Checksum checksum) {
-        if (PlatformDependent.javaVersion() >= 8) {
+        try {
-            try {
+            Method method = checksum.getClass().getDeclaredMethod("update", ByteBuffer.class);
-                Method method = checksum.getClass().getDeclaredMethod("update", ByteBuffer.class);
+            method.invoke(method, ByteBuffer.allocate(1));
-                method.invoke(method, ByteBuffer.allocate(1));
+            return method;
-                return method;
+        } catch (Throwable ignore) {
-            } catch (Throwable ignore) {
+            return null;
-                return null;
-            }
         }
-        return null;
     }
 
     static ByteBufChecksum wrapChecksum(Checksum checksum) {

codec/src/main/java/io/netty/handler/codec/compression/ZlibCodecFactory.java

@@ -34,14 +34,13 @@ public final class ZlibCodecFactory {
     private static final boolean supportsWindowSizeAndMemLevel;
 
     static {
-        noJdkZlibDecoder = SystemPropertyUtil.getBoolean("io.netty.noJdkZlibDecoder",
+        noJdkZlibDecoder = SystemPropertyUtil.getBoolean("io.netty.noJdkZlibDecoder", false);
-                PlatformDependent.javaVersion() < 7);
         logger.debug("-Dio.netty.noJdkZlibDecoder: {}", noJdkZlibDecoder);
 
         noJdkZlibEncoder = SystemPropertyUtil.getBoolean("io.netty.noJdkZlibEncoder", false);
         logger.debug("-Dio.netty.noJdkZlibEncoder: {}", noJdkZlibEncoder);
 
-        supportsWindowSizeAndMemLevel = noJdkZlibDecoder || PlatformDependent.javaVersion() >= 7;
+        supportsWindowSizeAndMemLevel = true;
     }
 
     /**
@@ -52,7 +51,7 @@ public final class ZlibCodecFactory {
     }
 
     public static ZlibEncoder newZlibEncoder(int compressionLevel) {
-        if (PlatformDependent.javaVersion() < 7 || noJdkZlibEncoder) {
+        if (noJdkZlibEncoder) {
             return new JZlibEncoder(compressionLevel);
         } else {
             return new JdkZlibEncoder(compressionLevel);
@@ -60,7 +59,7 @@ public final class ZlibCodecFactory {
     }
 
     public static ZlibEncoder newZlibEncoder(ZlibWrapper wrapper) {
-        if (PlatformDependent.javaVersion() < 7 || noJdkZlibEncoder) {
+        if (noJdkZlibEncoder) {
             return new JZlibEncoder(wrapper);
         } else {
             return new JdkZlibEncoder(wrapper);
@@ -68,7 +67,7 @@ public final class ZlibCodecFactory {
     }
 
     public static ZlibEncoder newZlibEncoder(ZlibWrapper wrapper, int compressionLevel) {
-        if (PlatformDependent.javaVersion() < 7 || noJdkZlibEncoder) {
+        if (noJdkZlibEncoder) {
             return new JZlibEncoder(wrapper, compressionLevel);
         } else {
             return new JdkZlibEncoder(wrapper, compressionLevel);
@@ -76,7 +75,7 @@ public final class ZlibCodecFactory {
     }
 
     public static ZlibEncoder newZlibEncoder(ZlibWrapper wrapper, int compressionLevel, int windowBits, int memLevel) {
-        if (PlatformDependent.javaVersion() < 7 || noJdkZlibEncoder ||
+        if (noJdkZlibEncoder ||
                 windowBits != DEFAULT_JDK_WINDOW_SIZE || memLevel != DEFAULT_JDK_MEM_LEVEL) {
             return new JZlibEncoder(wrapper, compressionLevel, windowBits, memLevel);
         } else {
@@ -85,7 +84,7 @@ public final class ZlibCodecFactory {
     }
 
     public static ZlibEncoder newZlibEncoder(byte[] dictionary) {
-        if (PlatformDependent.javaVersion() < 7 || noJdkZlibEncoder) {
+        if (noJdkZlibEncoder) {
             return new JZlibEncoder(dictionary);
         } else {
             return new JdkZlibEncoder(dictionary);
@@ -93,7 +92,7 @@ public final class ZlibCodecFactory {
     }
 
     public static ZlibEncoder newZlibEncoder(int compressionLevel, byte[] dictionary) {
-        if (PlatformDependent.javaVersion() < 7 || noJdkZlibEncoder) {
+        if (noJdkZlibEncoder) {
             return new JZlibEncoder(compressionLevel, dictionary);
         } else {
             return new JdkZlibEncoder(compressionLevel, dictionary);
@@ -101,7 +100,7 @@ public final class ZlibCodecFactory {
     }
 
     public static ZlibEncoder newZlibEncoder(int compressionLevel, int windowBits, int memLevel, byte[] dictionary) {
-        if (PlatformDependent.javaVersion() < 7 || noJdkZlibEncoder ||
+        if (noJdkZlibEncoder ||
                 windowBits != DEFAULT_JDK_WINDOW_SIZE || memLevel != DEFAULT_JDK_MEM_LEVEL) {
             return new JZlibEncoder(compressionLevel, windowBits, memLevel, dictionary);
         } else {
@@ -110,7 +109,7 @@ public final class ZlibCodecFactory {
     }
 
     public static ZlibDecoder newZlibDecoder() {
-        if (PlatformDependent.javaVersion() < 7 || noJdkZlibDecoder) {
+        if (noJdkZlibDecoder) {
             return new JZlibDecoder();
         } else {
             return new JdkZlibDecoder(true);
@@ -118,7 +117,7 @@ public final class ZlibCodecFactory {
     }
 
     public static ZlibDecoder newZlibDecoder(ZlibWrapper wrapper) {
-        if (PlatformDependent.javaVersion() < 7 || noJdkZlibDecoder) {
+        if (noJdkZlibDecoder) {
             return new JZlibDecoder(wrapper);
         } else {
             return new JdkZlibDecoder(wrapper, true);
@@ -126,7 +125,7 @@ public final class ZlibCodecFactory {
     }
 
     public static ZlibDecoder newZlibDecoder(byte[] dictionary) {
-        if (PlatformDependent.javaVersion() < 7 || noJdkZlibDecoder) {
+        if (noJdkZlibDecoder) {
             return new JZlibDecoder(dictionary);
         } else {
             return new JdkZlibDecoder(dictionary);

common/src/main/java/io/netty/util/NetUtil.java

@@ -1114,7 +1114,7 @@ public final class NetUtil {
      * @return the host string
      */
     public static String getHostname(InetSocketAddress addr) {
-        return PlatformDependent.javaVersion() >= 7 ? addr.getHostString() : addr.getHostName();
+        return addr.getHostString();
     }
 
     /**

common/src/main/java/io/netty/util/internal/NativeLibraryLoader.java

@@ -441,12 +441,6 @@ public final class NativeLibraryLoader {
     private static final class NoexecVolumeDetector {
 
         private static boolean canExecuteExecutable(File file) throws IOException {
-            if (PlatformDependent.javaVersion() < 7) {
-                // Pre-JDK7, the Java API did not directly support POSIX permissions; instead of implementing a custom
-                // work-around, assume true, which disables the check.
-                return true;
-            }
-
             // If we can already execute, there is nothing to do.
             if (file.canExecute()) {
                 return true;

common/src/main/java/io/netty/util/internal/PlatformDependent.java

@@ -40,7 +40,6 @@ import java.util.List;
 import java.util.Locale;
 import java.util.Queue;
 import java.util.concurrent.ConcurrentLinkedDeque;
-import java.util.concurrent.LinkedBlockingDeque;
 import java.util.concurrent.atomic.AtomicLong;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -867,11 +866,7 @@ public final class PlatformDependent {
      * Returns a new concurrent {@link Deque}.
      */
     public static <C> Deque<C> newConcurrentDeque() {
-        if (javaVersion() < 7) {
+        return new ConcurrentLinkedDeque<>();
-            return new LinkedBlockingDeque<>();
-        } else {
-            return new ConcurrentLinkedDeque<>();
-        }
     }
 
     private static boolean isWindows0() {

common/src/main/java/io/netty/util/internal/SocketUtils.java

@@ -186,14 +186,7 @@ public final class SocketUtils {
         return AccessController.doPrivileged(new PrivilegedAction<InetAddress>() {
             @Override
             public InetAddress run() {
-                if (PlatformDependent.javaVersion() >= 7) {
+                return InetAddress.getLoopbackAddress();
-                    return InetAddress.getLoopbackAddress();
-                }
-                try {
-                    return InetAddress.getByName(null);
-                } catch (UnknownHostException e) {
-                    throw new IllegalStateException(e);
-                }
             }
         });
     }

common/src/main/java/io/netty/util/internal/ThrowableUtil.java

@@ -54,15 +54,8 @@ public final class ThrowableUtil {
         }
     }
 
-    public static boolean haveSuppressed() {
-        return PlatformDependent.javaVersion() >= 7;
-    }
-
     @SuppressJava6Requirement(reason = "Throwable addSuppressed is only available for >= 7. Has check for < 7.")
     public static void addSuppressed(Throwable target, Throwable suppressed) {
-        if (!haveSuppressed()) {
-            return;
-        }
         target.addSuppressed(suppressed);
     }
 

common/src/test/java/io/netty/util/internal/NativeLibraryLoaderTest.java

@@ -32,9 +32,7 @@ public class NativeLibraryLoaderTest {
             fail();
         } catch (UnsatisfiedLinkError error) {
             assertTrue(error.getCause() instanceof FileNotFoundException);
-            if (PlatformDependent.javaVersion() >= 7) {
+            verifySuppressedException(error, UnsatisfiedLinkError.class);
-                verifySuppressedException(error, UnsatisfiedLinkError.class);
-            }
         }
     }
 
@@ -45,9 +43,7 @@ public class NativeLibraryLoaderTest {
             fail();
         } catch (UnsatisfiedLinkError error) {
             assertTrue(error.getCause() instanceof FileNotFoundException);
-            if (PlatformDependent.javaVersion() >= 7) {
+            verifySuppressedException(error, ClassNotFoundException.class);
-                verifySuppressedException(error, ClassNotFoundException.class);
-            }
         }
     }
 

handler/src/main/java/io/netty/handler/ssl/Conscrypt.java

@@ -44,7 +44,7 @@ final class Conscrypt {
      * Indicates whether or not conscrypt is available on the current system.
      */
     static boolean isAvailable() {
-        return IS_CONSCRYPT_SSLENGINE != null && PlatformDependent.javaVersion() >= 8;
+        return IS_CONSCRYPT_SSLENGINE != null;
     }
 
     static boolean isEngineSupported(SSLEngine engine) {

handler/src/main/java/io/netty/handler/ssl/OpenSslTlsv13X509ExtendedTrustManager.java

@@ -94,7 +94,7 @@ final class OpenSslTlsv13X509ExtendedTrustManager extends X509ExtendedTrustManag
 
                 @Override
                 public SSLSession getHandshakeSession() {
-                    if (PlatformDependent.javaVersion() >= 7 && session instanceof ExtendedOpenSslSession) {
+                    if (session instanceof ExtendedOpenSslSession) {
                         final ExtendedOpenSslSession extendedOpenSslSession = (ExtendedOpenSslSession) session;
                         return new ExtendedOpenSslSession(extendedOpenSslSession) {
                             @Override

handler/src/main/java/io/netty/handler/ssl/ReferenceCountedOpenSslContext.java

@@ -599,7 +599,7 @@ public abstract class ReferenceCountedOpenSslContext extends SslContext implemen
     }
 
     static boolean useExtendedTrustManager(X509TrustManager trustManager) {
-        return PlatformDependent.javaVersion() >= 7 && trustManager instanceof X509ExtendedTrustManager;
+        return trustManager instanceof X509ExtendedTrustManager;
     }
 
     @Override
@@ -673,31 +673,29 @@ public abstract class ReferenceCountedOpenSslContext extends SslContext implemen
                 if (cause instanceof CertificateNotYetValidException) {
                     return CertificateVerifier.X509_V_ERR_CERT_NOT_YET_VALID;
                 }
-                if (PlatformDependent.javaVersion() >= 7) {
+                if (cause instanceof CertificateRevokedException) {
-                    if (cause instanceof CertificateRevokedException) {
+                    return CertificateVerifier.X509_V_ERR_CERT_REVOKED;
-                        return CertificateVerifier.X509_V_ERR_CERT_REVOKED;
+                }
-                    }
 
-                    // The X509TrustManagerImpl uses a Validator which wraps a CertPathValidatorException into
+                // The X509TrustManagerImpl uses a Validator which wraps a CertPathValidatorException into
-                    // an CertificateException. So we need to handle the wrapped CertPathValidatorException to be
+                // an CertificateException. So we need to handle the wrapped CertPathValidatorException to be
-                    // able to send the correct alert.
+                // able to send the correct alert.
-                    Throwable wrapped = cause.getCause();
+                Throwable wrapped = cause.getCause();
-                    while (wrapped != null) {
+                while (wrapped != null) {
-                        if (wrapped instanceof CertPathValidatorException) {
+                    if (wrapped instanceof CertPathValidatorException) {
-                            CertPathValidatorException ex = (CertPathValidatorException) wrapped;
+                        CertPathValidatorException ex = (CertPathValidatorException) wrapped;
-                            CertPathValidatorException.Reason reason = ex.getReason();
+                        CertPathValidatorException.Reason reason = ex.getReason();
-                            if (reason == CertPathValidatorException.BasicReason.EXPIRED) {
+                        if (reason == CertPathValidatorException.BasicReason.EXPIRED) {
-                                return CertificateVerifier.X509_V_ERR_CERT_HAS_EXPIRED;
+                            return CertificateVerifier.X509_V_ERR_CERT_HAS_EXPIRED;
-                            }
+                        }
-                            if (reason == CertPathValidatorException.BasicReason.NOT_YET_VALID) {
+                        if (reason == CertPathValidatorException.BasicReason.NOT_YET_VALID) {
-                                return CertificateVerifier.X509_V_ERR_CERT_NOT_YET_VALID;
+                            return CertificateVerifier.X509_V_ERR_CERT_NOT_YET_VALID;
-                            }
+                        }
-                            if (reason == CertPathValidatorException.BasicReason.REVOKED) {
+                        if (reason == CertPathValidatorException.BasicReason.REVOKED) {
-                                return CertificateVerifier.X509_V_ERR_CERT_REVOKED;
+                            return CertificateVerifier.X509_V_ERR_CERT_REVOKED;
-                            }
                         }
-                        wrapped = wrapped.getCause();
                     }
+                    wrapped = wrapped.getCause();
                 }
 
                 // Could not detect a specific error code to use, so fallback to a default code.

handler/src/main/java/io/netty/handler/ssl/ReferenceCountedOpenSslEngine.java

@@ -246,82 +246,78 @@ public class ReferenceCountedOpenSslEngine extends SSLEngine implements Referenc
         this.alloc = checkNotNull(alloc, "alloc");
         apn = (OpenSslApplicationProtocolNegotiator) context.applicationProtocolNegotiator();
         clientMode = context.isClient();
-        if (PlatformDependent.javaVersion() >= 7) {
+        session = new ExtendedOpenSslSession(new DefaultOpenSslSession(context.sessionContext())) {
-            session = new ExtendedOpenSslSession(new DefaultOpenSslSession(context.sessionContext())) {
+            private String[] peerSupportedSignatureAlgorithms;
-                private String[] peerSupportedSignatureAlgorithms;
+            private List requestedServerNames;
-                private List requestedServerNames;
 
-                @Override
+            @Override
-                public List getRequestedServerNames() {
+            public List getRequestedServerNames() {
-                    if (clientMode) {
+                if (clientMode) {
-                        return Java8SslUtils.getSniHostNames(sniHostNames);
+                    return Java8SslUtils.getSniHostNames(sniHostNames);
-                    } else {
+                } else {
-                        synchronized (ReferenceCountedOpenSslEngine.this) {
+                    synchronized (ReferenceCountedOpenSslEngine.this) {
-                            if (requestedServerNames == null) {
+                        if (requestedServerNames == null) {
-                                if (isDestroyed()) {
+                            if (isDestroyed()) {
+                                requestedServerNames = Collections.emptyList();
+                            } else {
+                                String name = SSL.getSniHostname(ssl);
+                                if (name == null) {
                                     requestedServerNames = Collections.emptyList();
                                 } else {
-                                    String name = SSL.getSniHostname(ssl);
+                                    // Convert to bytes as we do not want to do any strict validation of the
-                                    if (name == null) {
+                                    // SNIHostName while creating it.
-                                        requestedServerNames = Collections.emptyList();
+                                    requestedServerNames =
-                                    } else {
+                                            Java8SslUtils.getSniHostName(
-                                        // Convert to bytes as we do not want to do any strict validation of the
+                                                    SSL.getSniHostname(ssl).getBytes(CharsetUtil.UTF_8));
-                                        // SNIHostName while creating it.
-                                        requestedServerNames =
-                                                Java8SslUtils.getSniHostName(
-                                                        SSL.getSniHostname(ssl).getBytes(CharsetUtil.UTF_8));
-                                    }
                                 }
                             }
-                            return requestedServerNames;
                         }
+                        return requestedServerNames;
                     }
                 }
+            }
 
-                @Override
+            @Override
-                public String[] getPeerSupportedSignatureAlgorithms() {
+            public String[] getPeerSupportedSignatureAlgorithms() {
-                    synchronized (ReferenceCountedOpenSslEngine.this) {
+                synchronized (ReferenceCountedOpenSslEngine.this) {
-                        if (peerSupportedSignatureAlgorithms == null) {
+                    if (peerSupportedSignatureAlgorithms == null) {
-                            if (isDestroyed()) {
+                        if (isDestroyed()) {
+                            peerSupportedSignatureAlgorithms = EmptyArrays.EMPTY_STRINGS;
+                        } else {
+                            String[] algs = SSL.getSigAlgs(ssl);
+                            if (algs == null) {
                                 peerSupportedSignatureAlgorithms = EmptyArrays.EMPTY_STRINGS;
                             } else {
-                                String[] algs = SSL.getSigAlgs(ssl);
+                                Set<String> algorithmList = new LinkedHashSet<>(algs.length);
-                                if (algs == null) {
+                                for (String alg: algs) {
-                                    peerSupportedSignatureAlgorithms = EmptyArrays.EMPTY_STRINGS;
+                                    String converted = SignatureAlgorithmConverter.toJavaName(alg);
-                                } else {
-                                    Set<String> algorithmList = new LinkedHashSet<>(algs.length);
-                                    for (String alg: algs) {
-                                        String converted = SignatureAlgorithmConverter.toJavaName(alg);
 
-                                        if (converted != null) {
+                                    if (converted != null) {
-                                            algorithmList.add(converted);
+                                        algorithmList.add(converted);
-                                        }
                                     }
-                                    peerSupportedSignatureAlgorithms = algorithmList.toArray(new String[0]);
                                 }
+                                peerSupportedSignatureAlgorithms = algorithmList.toArray(new String[0]);
                             }
                         }
-                        return peerSupportedSignatureAlgorithms.clone();
                     }
+                    return peerSupportedSignatureAlgorithms.clone();
                 }
+            }
 
-                @Override
+            @Override
-                public List<byte[]> getStatusResponses() {
+            public List<byte[]> getStatusResponses() {
-                    byte[] ocspResponse = null;
+                byte[] ocspResponse = null;
-                    if (enableOcsp && clientMode) {
+                if (enableOcsp && clientMode) {
-                        synchronized (ReferenceCountedOpenSslEngine.this) {
+                    synchronized (ReferenceCountedOpenSslEngine.this) {
-                            if (!isDestroyed()) {
+                        if (!isDestroyed()) {
-                                ocspResponse = SSL.getOcspResponse(ssl);
+                            ocspResponse = SSL.getOcspResponse(ssl);
-                            }
                         }
                     }
-                    return ocspResponse == null ?
-                            Collections.<byte[]>emptyList() : Collections.singletonList(ocspResponse);
                 }
-            };
+                return ocspResponse == null ?
-        } else {
+                        Collections.<byte[]>emptyList() : Collections.singletonList(ocspResponse);
-            session = new DefaultOpenSslSession(context.sessionContext());
+            }
-        }
+        };
         engineMap = context.engineMap;
         enableOcsp = context.enableOcsp;
         // context.keyCertChain will only be non-null if we do not use the KeyManagerFactory. In this case

handler/src/main/java/io/netty/handler/ssl/ReferenceCountedOpenSslServerContext.java

@@ -168,13 +168,10 @@ public final class ReferenceCountedOpenSslServerContext extends ReferenceCounted
                     }
                 }
 
-                if (PlatformDependent.javaVersion() >= 8) {
+                // IMPORTANT: The callbacks set for hostname matching must be static to prevent memory leak as
-                    // Only do on Java8+ as SNIMatcher is not supported in earlier releases.
+                //            otherwise the context can never be collected. This is because the JNI code holds
-                    // IMPORTANT: The callbacks set for hostname matching must be static to prevent memory leak as
+                //            a global reference to the matcher.
-                    //            otherwise the context can never be collected. This is because the JNI code holds
+                SSLContext.setSniHostnameMatcher(ctx, new OpenSslSniHostnameMatcher(engineMap));
-                    //            a global reference to the matcher.
-                    SSLContext.setSniHostnameMatcher(ctx, new OpenSslSniHostnameMatcher(engineMap));
-                }
             } catch (SSLException e) {
                 throw e;
             } catch (Exception e) {

handler/src/main/java/io/netty/handler/ssl/SslHandler.java

@@ -1133,8 +1133,7 @@ public class SslHandler extends ByteToMessageDecoder implements ChannelOutboundH
                     }
 
                     // also match against SctpChannel via String matching as it may not present.
-                    if (PlatformDependent.javaVersion() >= 7
+                    if ("com.sun.nio.sctp.SctpChannel".equals(clazz.getSuperclass().getName())) {
-                            && "com.sun.nio.sctp.SctpChannel".equals(clazz.getSuperclass().getName())) {
                         return true;
                     }
                 } catch (Throwable cause) {

handler/src/main/java/io/netty/handler/ssl/util/SimpleTrustManagerFactory.java

@@ -135,12 +135,10 @@ public abstract class SimpleTrustManagerFactory extends TrustManagerFactory {
             TrustManager[] trustManagers = this.trustManagers;
             if (trustManagers == null) {
                 trustManagers = parent.engineGetTrustManagers();
-                if (PlatformDependent.javaVersion() >= 7) {
+                for (int i = 0; i < trustManagers.length; i++) {
-                    for (int i = 0; i < trustManagers.length; i++) {
+                    final TrustManager tm = trustManagers[i];
-                        final TrustManager tm = trustManagers[i];
+                    if (tm instanceof X509TrustManager && !(tm instanceof X509ExtendedTrustManager)) {
-                        if (tm instanceof X509TrustManager && !(tm instanceof X509ExtendedTrustManager)) {
+                        trustManagers[i] = new X509TrustManagerWrapper((X509TrustManager) tm);
-                            trustManagers[i] = new X509TrustManagerWrapper((X509TrustManager) tm);
-                        }
                     }
                 }
                 this.trustManagers = trustManagers;

handler/src/test/java/io/netty/handler/ssl/OpenSslEngineTest.java

@@ -1038,7 +1038,6 @@ public class OpenSslEngineTest extends SSLEngineTest {
 
     @Test
     public void testSNIMatchersDoesNotThrow() throws Exception {
-        assumeTrue(PlatformDependent.javaVersion() >= 8);
         SelfSignedCertificate ssc = new SelfSignedCertificate();
         serverSslCtx = SslContextBuilder.forServer(ssc.certificate(), ssc.privateKey())
                                         .sslProvider(sslServerProvider())
@@ -1059,7 +1058,6 @@ public class OpenSslEngineTest extends SSLEngineTest {
 
     @Test
     public void testSNIMatchersWithSNINameWithUnderscore() throws Exception {
-        assumeTrue(PlatformDependent.javaVersion() >= 8);
         byte[] name = "rb8hx3pww30y3tvw0mwy.v1_1".getBytes(CharsetUtil.UTF_8);
         SelfSignedCertificate ssc = new SelfSignedCertificate();
         serverSslCtx = SslContextBuilder.forServer(ssc.certificate(), ssc.privateKey())
@@ -1138,10 +1136,7 @@ public class OpenSslEngineTest extends SSLEngineTest {
 
     @Override
     protected SSLEngine wrapEngine(SSLEngine engine) {
-        if (PlatformDependent.javaVersion() >= 8) {
+        return Java8SslTestUtils.wrapSSLEngineForTesting(engine);
-            return Java8SslTestUtils.wrapSSLEngineForTesting(engine);
-        }
-        return engine;
     }
 
     ReferenceCountedOpenSslEngine unwrapEngine(SSLEngine engine) {

handler/src/test/java/io/netty/handler/ssl/SniClientTest.java

@@ -83,13 +83,11 @@ public class SniClientTest {
 
     @Test(timeout = 30000)
     public void testSniSNIMatcherMatchesClient() throws Exception {
-        Assume.assumeTrue(PlatformDependent.javaVersion() >= 8);
         SniClientJava8TestUtil.testSniClient(serverProvider, clientProvider, true);
     }
 
     @Test(timeout = 30000, expected = SSLException.class)
     public void testSniSNIMatcherDoesNotMatchClient() throws Exception {
-        Assume.assumeTrue(PlatformDependent.javaVersion() >= 8);
         SniClientJava8TestUtil.testSniClient(serverProvider, clientProvider, false);
     }
 
@@ -111,10 +109,7 @@ public class SniClientTest {
                                                     .build();
             } else {
                 // The used OpenSSL version does support a KeyManagerFactory, so use it.
-                KeyManagerFactory kmf = PlatformDependent.javaVersion() >= 8 ?
+                KeyManagerFactory kmf = SniClientJava8TestUtil.newSniX509KeyManagerFactory(cert, sniHostName);
-                        SniClientJava8TestUtil.newSniX509KeyManagerFactory(cert, sniHostName) :
-                        SslContext.buildKeyManagerFactory(
-                                new X509Certificate[] { cert.cert() }, cert.key(), null, null);
 
                sslServerContext = SslContextBuilder.forServer(kmf)
                                                    .sslProvider(sslServerProvider)
@@ -137,9 +132,7 @@ public class SniClientTest {
                 }
             }).bind(address).syncUninterruptibly().channel();
 
-            TrustManagerFactory tmf = PlatformDependent.javaVersion() >= 8 ?
+            TrustManagerFactory tmf = SniClientJava8TestUtil.newSniX509TrustmanagerFactory(sniHostName);
-                    SniClientJava8TestUtil.newSniX509TrustmanagerFactory(sniHostName) :
-                    InsecureTrustManagerFactory.INSTANCE;
             sslClientContext = SslContextBuilder.forClient().trustManager(tmf)
                                                      .sslProvider(sslClientProvider).build();
             Bootstrap cb = new Bootstrap();
@@ -154,10 +147,8 @@ public class SniClientTest {
             handler.handshakeFuture().syncUninterruptibly();
             Assert.assertNull(handler.engine().getHandshakeSession());
 
-            if (PlatformDependent.javaVersion() >= 8) {
+            SniClientJava8TestUtil.assertSSLSession(
-                SniClientJava8TestUtil.assertSSLSession(
+                    handler.engine().getUseClientMode(), handler.engine().getSession(), sniHostName);
-                        handler.engine().getUseClientMode(), handler.engine().getSession(), sniHostName);
-            }
         } finally {
             if (cc != null) {
                 cc.close().syncUninterruptibly();

resolver-dns/src/main/java/io/netty/resolver/dns/DefaultAuthoritativeDnsServerCache.java

@@ -45,10 +45,7 @@ public class DefaultAuthoritativeDnsServerCache implements AuthoritativeDnsServe
 
         @Override
         protected boolean equals(InetSocketAddress entry, InetSocketAddress otherEntry) {
-            if (PlatformDependent.javaVersion() >= 7) {
+            return entry.getHostString().equalsIgnoreCase(otherEntry.getHostString());
-                return entry.getHostString().equalsIgnoreCase(otherEntry.getHostString());
-            }
-            return entry.getHostName().equalsIgnoreCase(otherEntry.getHostName());
         }
 
         @Override
@@ -101,7 +98,7 @@ public class DefaultAuthoritativeDnsServerCache implements AuthoritativeDnsServe
         checkNotNull(address, "address");
         checkNotNull(loop, "loop");
 
-        if (PlatformDependent.javaVersion() >= 7 && address.getHostString() == null) {
+        if (address.getHostString() == null) {
             // We only cache addresses that have also a host string as we will need it later when trying to replace
             // unresolved entries in the cache.
             return;

resolver-dns/src/main/java/io/netty/resolver/dns/DnsResolveContext.java

@@ -400,8 +400,7 @@ abstract class DnsResolveContext<T> {
                                            final DnsQueryLifecycleObserver queryLifecycleObserver,
                                            final Promise<List<T>> promise,
                                            final Throwable cause) {
-        final String nameServerName = PlatformDependent.javaVersion() >= 7 ?
+        final String nameServerName = nameServerAddr.getHostString();
-                nameServerAddr.getHostString() : nameServerAddr.getHostName();
         assert nameServerName != null;
 
         // Placeholder so we will not try to finish the original query yet.

resolver-dns/src/test/java/io/netty/resolver/dns/DnsNameResolverTest.java

@@ -1281,8 +1281,7 @@ public class DnsNameResolverTest {
 
         // Java7 will strip of the "." so we need to adjust the expected dnsname. Both are valid in terms of the RFC
         // so its ok.
-        String expectedDnsName = PlatformDependent.javaVersion() == 7 ?
+        String expectedDnsName = "dns4.some.record.netty.io.";
-                "dns4.some.record.netty.io" : "dns4.some.record.netty.io.";
 
         try {
             resolver.resolveAll(hostname).syncUninterruptibly();

transport-native-unix-common/src/main/java/io/netty/channel/unix/UnixChannelUtil.java

@@ -43,17 +43,15 @@ public final class UnixChannelUtil {
 
     public static InetSocketAddress computeRemoteAddr(InetSocketAddress remoteAddr, InetSocketAddress osRemoteAddr) {
         if (osRemoteAddr != null) {
-            if (PlatformDependent.javaVersion() >= 7) {
+            try {
-                try {
+                // Only try to construct a new InetSocketAddress if we using java >= 7 as getHostString() does not
-                    // Only try to construct a new InetSocketAddress if we using java >= 7 as getHostString() does not
+                // exists in earlier releases and so the retrieval of the hostname could block the EventLoop if a
-                    // exists in earlier releases and so the retrieval of the hostname could block the EventLoop if a
+                // reverse lookup would be needed.
-                    // reverse lookup would be needed.
+                return new InetSocketAddress(InetAddress.getByAddress(remoteAddr.getHostString(),
-                    return new InetSocketAddress(InetAddress.getByAddress(remoteAddr.getHostString(),
+                        osRemoteAddr.getAddress().getAddress()),
-                            osRemoteAddr.getAddress().getAddress()),
+                        osRemoteAddr.getPort());
-                            osRemoteAddr.getPort());
+            } catch (UnknownHostException ignore) {
-                } catch (UnknownHostException ignore) {
+                // Should never happen but fallback to osRemoteAddr anyway.
-                    // Should never happen but fallback to osRemoteAddr anyway.
-                }
             }
             return osRemoteAddr;
         }

transport/src/main/java/io/netty/channel/socket/nio/NioDatagramChannel.java

@@ -104,9 +104,6 @@ public final class NioDatagramChannel
     }
 
     private static void checkJavaVersion() {
-        if (PlatformDependent.javaVersion() < 7) {
-            throw new UnsupportedOperationException("Only supported on java 7+.");
-        }
     }
 
     /**
@@ -194,11 +191,7 @@ public final class NioDatagramChannel
     }
 
     private void doBind0(SocketAddress localAddress) throws Exception {
-        if (PlatformDependent.javaVersion() >= 7) {
+        SocketUtils.bind(javaChannel(), localAddress);
-            SocketUtils.bind(javaChannel(), localAddress);
-        } else {
-            javaChannel().socket().bind(localAddress);
-        }
     }
 
     @Override

transport/src/main/java/io/netty/channel/socket/nio/NioDatagramChannelConfig.java

@@ -210,7 +210,7 @@ class NioDatagramChannelConfig extends DefaultDatagramChannelConfig {
 
     @Override
     public <T> boolean setOption(ChannelOption<T> option, T value) {
-        if (PlatformDependent.javaVersion() >= 7 && option instanceof NioChannelOption) {
+        if (option instanceof NioChannelOption) {
             return NioChannelOption.setOption(javaChannel, (NioChannelOption<T>) option, value);
         }
         return super.setOption(option, value);
@@ -218,7 +218,7 @@ class NioDatagramChannelConfig extends DefaultDatagramChannelConfig {
 
     @Override
     public <T> T getOption(ChannelOption<T> option) {
-        if (PlatformDependent.javaVersion() >= 7 && option instanceof NioChannelOption) {
+        if (option instanceof NioChannelOption) {
             return NioChannelOption.getOption(javaChannel, (NioChannelOption<T>) option);
         }
         return super.getOption(option);
@@ -227,9 +227,6 @@ class NioDatagramChannelConfig extends DefaultDatagramChannelConfig {
     @SuppressWarnings("unchecked")
     @Override
     public Map<ChannelOption<?>, Object> getOptions() {
-        if (PlatformDependent.javaVersion() >= 7) {
+        return getOptions(super.getOptions(), NioChannelOption.getOptions(javaChannel));
-            return getOptions(super.getOptions(), NioChannelOption.getOptions(javaChannel));
-        }
-        return super.getOptions();
     }
 }

transport/src/main/java/io/netty/channel/socket/nio/NioServerSocketChannel.java

@@ -137,11 +137,7 @@ public class NioServerSocketChannel extends AbstractNioMessageChannel
 
     @Override
     protected void doBind(SocketAddress localAddress) throws Exception {
-        if (PlatformDependent.javaVersion() >= 7) {
+        javaChannel().bind(localAddress, config.getBacklog());
-            javaChannel().bind(localAddress, config.getBacklog());
-        } else {
-            javaChannel().socket().bind(localAddress, config.getBacklog());
-        }
     }
 
     @Override
@@ -215,7 +211,7 @@ public class NioServerSocketChannel extends AbstractNioMessageChannel
 
         @Override
         public <T> boolean setOption(ChannelOption<T> option, T value) {
-            if (PlatformDependent.javaVersion() >= 7 && option instanceof NioChannelOption) {
+            if (option instanceof NioChannelOption) {
                 return NioChannelOption.setOption(jdkChannel(), (NioChannelOption<T>) option, value);
             }
             return super.setOption(option, value);
@@ -223,7 +219,7 @@ public class NioServerSocketChannel extends AbstractNioMessageChannel
 
         @Override
         public <T> T getOption(ChannelOption<T> option) {
-            if (PlatformDependent.javaVersion() >= 7 && option instanceof NioChannelOption) {
+            if (option instanceof NioChannelOption) {
                 return NioChannelOption.getOption(jdkChannel(), (NioChannelOption<T>) option);
             }
             return super.getOption(option);
@@ -232,10 +228,7 @@ public class NioServerSocketChannel extends AbstractNioMessageChannel
         @SuppressWarnings("unchecked")
         @Override
         public Map<ChannelOption<?>, Object> getOptions() {
-            if (PlatformDependent.javaVersion() >= 7) {
+            return getOptions(super.getOptions(), NioChannelOption.getOptions(jdkChannel()));
-                return getOptions(super.getOptions(), NioChannelOption.getOptions(jdkChannel()));
-            }
-            return super.getOptions();
         }
 
         private ServerSocketChannel jdkChannel() {

transport/src/main/java/io/netty/channel/socket/nio/NioSocketChannel.java

@@ -156,11 +156,7 @@ public class NioSocketChannel extends AbstractNioByteChannel implements io.netty
     @UnstableApi
     @Override
     protected final void doShutdownOutput() throws Exception {
-        if (PlatformDependent.javaVersion() >= 7) {
+        javaChannel().shutdownOutput();
-            javaChannel().shutdownOutput();
-        } else {
-            javaChannel().socket().shutdownOutput();
-        }
     }
 
     @Override
@@ -272,11 +268,7 @@ public class NioSocketChannel extends AbstractNioByteChannel implements io.netty
     }
 
     private void shutdownInput0() throws Exception {
-        if (PlatformDependent.javaVersion() >= 7) {
+        javaChannel().shutdownInput();
-            javaChannel().shutdownInput();
-        } else {
-            javaChannel().socket().shutdownInput();
-        }
     }
 
     @Override
@@ -295,11 +287,7 @@ public class NioSocketChannel extends AbstractNioByteChannel implements io.netty
     }
 
     private void doBind0(SocketAddress localAddress) throws Exception {
-        if (PlatformDependent.javaVersion() >= 7) {
+        SocketUtils.bind(javaChannel(), localAddress);
-            SocketUtils.bind(javaChannel(), localAddress);
-        } else {
-            SocketUtils.bind(javaChannel().socket(), localAddress);
-        }
     }
 
     @Override
@@ -483,7 +471,7 @@ public class NioSocketChannel extends AbstractNioByteChannel implements io.netty
 
         @Override
         public <T> boolean setOption(ChannelOption<T> option, T value) {
-            if (PlatformDependent.javaVersion() >= 7 && option instanceof NioChannelOption) {
+            if (option instanceof NioChannelOption) {
                 return NioChannelOption.setOption(jdkChannel(), (NioChannelOption<T>) option, value);
             }
             return super.setOption(option, value);
@@ -491,7 +479,7 @@ public class NioSocketChannel extends AbstractNioByteChannel implements io.netty
 
         @Override
         public <T> T getOption(ChannelOption<T> option) {
-            if (PlatformDependent.javaVersion() >= 7 && option instanceof NioChannelOption) {
+            if (option instanceof NioChannelOption) {
                 return NioChannelOption.getOption(jdkChannel(), (NioChannelOption<T>) option);
             }
             return super.getOption(option);
@@ -500,10 +488,7 @@ public class NioSocketChannel extends AbstractNioByteChannel implements io.netty
         @SuppressWarnings("unchecked")
         @Override
         public Map<ChannelOption<?>, Object> getOptions() {
-            if (PlatformDependent.javaVersion() >= 7) {
+            return getOptions(super.getOptions(), NioChannelOption.getOptions(jdkChannel()));
-                return getOptions(super.getOptions(), NioChannelOption.getOptions(jdkChannel()));
-            }
-            return super.getOptions();
         }
 
         void setMaxBytesPerGatheringWrite(int maxBytesPerGatheringWrite) {