/*
    * Copyright 2012 The Netty Project
    *
    * The Netty Project licenses this file to you under the Apache License,
    * version 2.0 (the "License"); you may not use this file except in compliance
    * with the License. You may obtain a copy of the License at:
    *
    *   http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
   * License for the specific language governing permissions and limitations
   * under the License.
   */
  package io.netty.util.internal;
  
  import io.netty.util.internal.logging.InternalLogger;
  import io.netty.util.internal.logging.InternalLoggerFactory;
  import org.jctools.queues.MpscArrayQueue;
  import org.jctools.queues.MpscChunkedArrayQueue;
  import org.jctools.queues.MpscUnboundedArrayQueue;
  import org.jctools.queues.SpscLinkedQueue;
  import org.jctools.queues.atomic.MpscAtomicArrayQueue;
  import org.jctools.queues.atomic.MpscGrowableAtomicArrayQueue;
  import org.jctools.queues.atomic.MpscUnboundedAtomicArrayQueue;
  import org.jctools.queues.atomic.SpscLinkedAtomicQueue;
  import org.jctools.util.Pow2;
  import org.jctools.util.UnsafeAccess;
  
  import java.io.File;
  import java.lang.reflect.Method;
  import java.nio.ByteBuffer;
  import java.nio.ByteOrder;
  import java.security.AccessController;
  import java.security.PrivilegedAction;
  import java.util.Deque;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  import java.util.Queue;
  import java.util.Random;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentLinkedDeque;
  import java.util.concurrent.ConcurrentMap;
  import java.util.concurrent.LinkedBlockingDeque;
  import java.util.concurrent.atomic.AtomicLong;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import static java.lang.Math.max;
  import static java.lang.Math.min;
  
  /**
   * Utility that detects various properties specific to the current runtime
   * environment, such as Java version and the availability of the
   * {@code sun.misc.Unsafe} object.
   * <p>
   * You can disable the use of {@code sun.misc.Unsafe} if you specify
   * the system property <strong>io.netty.noUnsafe</strong>.
   */
  public final class PlatformDependent {
  
      private static final InternalLogger logger = InternalLoggerFactory.getInstance(PlatformDependent.class);
  
      private static final Pattern MAX_DIRECT_MEMORY_SIZE_ARG_PATTERN = Pattern.compile(
              "\\s*-XX:MaxDirectMemorySize\\s*=\\s*([0-9]+)\\s*([kKmMgG]?)\\s*$");
  
      private static final boolean IS_WINDOWS = isWindows0();
      private static final boolean IS_OSX = isOsx0();
  
      private static final boolean MAYBE_SUPER_USER;
  
      private static final boolean CAN_ENABLE_TCP_NODELAY_BY_DEFAULT = !isAndroid();
  
      private static final boolean HAS_UNSAFE = hasUnsafe0();
      private static final boolean DIRECT_BUFFER_PREFERRED =
              HAS_UNSAFE && !SystemPropertyUtil.getBoolean("io.netty.noPreferDirect", false);
      private static final long MAX_DIRECT_MEMORY = maxDirectMemory0();
  
      private static final int MPSC_CHUNK_SIZE =  1024;
      private static final int MIN_MAX_MPSC_CAPACITY =  MPSC_CHUNK_SIZE * 2;
      private static final int MAX_ALLOWED_MPSC_CAPACITY = Pow2.MAX_POW2;
  
      private static final long ARRAY_BASE_OFFSET = arrayBaseOffset0();
  
      private static final File TMPDIR = tmpdir0();
  
      private static final int BIT_MODE = bitMode0();
      private static final String NORMALIZED_ARCH = normalizeArch(SystemPropertyUtil.get("os.arch", ""));
      private static final String NORMALIZED_OS = normalizeOs(SystemPropertyUtil.get("os.name", ""));
  
      private static final int ADDRESS_SIZE = addressSize0();
      private static final boolean USE_DIRECT_BUFFER_NO_CLEANER;
      private static final AtomicLong DIRECT_MEMORY_COUNTER;
      private static final long DIRECT_MEMORY_LIMIT;
      private static final ThreadLocalRandomProvider RANDOM_PROVIDER;
      private static final Cleaner CLEANER;
      private static final int UNINITIALIZED_ARRAY_ALLOCATION_THRESHOLD;
 
     public static final boolean BIG_ENDIAN_NATIVE_ORDER = ByteOrder.nativeOrder() == ByteOrder.BIG_ENDIAN;
 
     private static final Cleaner NOOP = new Cleaner() {
         @Override
         public void freeDirectBuffer(ByteBuffer buffer) {
             // NOOP
         }
     };
 
     static {
         if (javaVersion() >= 7) {
             RANDOM_PROVIDER = new ThreadLocalRandomProvider() {
                 @Override
                 public Random current() {
                     return java.util.concurrent.ThreadLocalRandom.current();
                 }
             };
         } else {
             RANDOM_PROVIDER = new ThreadLocalRandomProvider() {
                 @Override
                 public Random current() {
                     return ThreadLocalRandom.current();
                 }
             };
         }
         if (logger.isDebugEnabled()) {
             logger.debug("-Dio.netty.noPreferDirect: {}", !DIRECT_BUFFER_PREFERRED);
         }
 
         /*
          * We do not want to log this message if unsafe is explicitly disabled. Do not remove the explicit no unsafe
          * guard.
          */
         if (!hasUnsafe() && !isAndroid() && !PlatformDependent0.isExplicitNoUnsafe()) {
             logger.info(
                     "Your platform does not provide complete low-level API for accessing direct buffers reliably. " +
                     "Unless explicitly requested, heap buffer will always be preferred to avoid potential system " +
                     "instability.");
         }
 
         // Here is how the system property is used:
         //
         // * <  0  - Don't use cleaner, and inherit max direct memory from java. In this case the
         //           "practical max direct memory" would be 2 * max memory as defined by the JDK.
         // * == 0  - Use cleaner, Netty will not enforce max memory, and instead will defer to JDK.
         // * >  0  - Don't use cleaner. This will limit Netty's total direct memory
         //           (note: that JDK's direct memory limit is independent of this).
         long maxDirectMemory = SystemPropertyUtil.getLong("io.netty.maxDirectMemory", -1);
 
         if (maxDirectMemory == 0 || !hasUnsafe() || !PlatformDependent0.hasDirectBufferNoCleanerConstructor()) {
             USE_DIRECT_BUFFER_NO_CLEANER = false;
             DIRECT_MEMORY_COUNTER = null;
         } else {
             USE_DIRECT_BUFFER_NO_CLEANER = true;
             if (maxDirectMemory < 0) {
                 maxDirectMemory = maxDirectMemory0();
                 if (maxDirectMemory <= 0) {
                     DIRECT_MEMORY_COUNTER = null;
                 } else {
                     DIRECT_MEMORY_COUNTER = new AtomicLong();
                 }
             } else {
                 DIRECT_MEMORY_COUNTER = new AtomicLong();
             }
         }
         DIRECT_MEMORY_LIMIT = maxDirectMemory;
         logger.debug("-Dio.netty.maxDirectMemory: {} bytes", maxDirectMemory);
 
         int tryAllocateUninitializedArray =
                 SystemPropertyUtil.getInt("io.netty.uninitializedArrayAllocationThreshold", 1024);
         UNINITIALIZED_ARRAY_ALLOCATION_THRESHOLD = javaVersion() >= 9 && PlatformDependent0.hasAllocateArrayMethod() ?
                 tryAllocateUninitializedArray : -1;
         logger.debug("-Dio.netty.uninitializedArrayAllocationThreshold: {}", UNINITIALIZED_ARRAY_ALLOCATION_THRESHOLD);
 
         MAYBE_SUPER_USER = maybeSuperUser0();
 
         if (!isAndroid() && hasUnsafe()) {
             // only direct to method if we are not running on android.
             // See https://github.com/netty/netty/issues/2604
             if (javaVersion() >= 9) {
                 CLEANER = CleanerJava9.isSupported() ? new CleanerJava9() : NOOP;
             } else {
                 CLEANER = CleanerJava6.isSupported() ? new CleanerJava6() : NOOP;
             }
         } else {
             CLEANER = NOOP;
         }
     }
 
     public static boolean hasDirectBufferNoCleanerConstructor() {
         return PlatformDependent0.hasDirectBufferNoCleanerConstructor();
     }
 
     public static byte[] allocateUninitializedArray(int size) {
         return UNINITIALIZED_ARRAY_ALLOCATION_THRESHOLD < 0 || UNINITIALIZED_ARRAY_ALLOCATION_THRESHOLD > size ?
                 new byte[size] : PlatformDependent0.allocateUninitializedArray(size);
     }
 
     /**
      * Returns {@code true} if and only if the current platform is Android
      */
     public static boolean isAndroid() {
         return PlatformDependent0.isAndroid();
     }
 
     /**
      * Return {@code true} if the JVM is running on Windows
      */
     public static boolean isWindows() {
         return IS_WINDOWS;
     }
 
     /**
      * Return {@code true} if the JVM is running on OSX / MacOS
      */
     public static boolean isOsx() {
         return IS_OSX;
     }
 
     /**
      * Return {@code true} if the current user may be a super-user. Be aware that this is just an hint and so it may
      * return false-positives.
      */
     public static boolean maybeSuperUser() {
         return MAYBE_SUPER_USER;
     }
 
     /**
      * Return the version of Java under which this library is used.
      */
     public static int javaVersion() {
         return PlatformDependent0.javaVersion();
     }
 
     /**
      * Returns {@code true} if and only if it is fine to enable TCP_NODELAY socket option by default.
      */
     public static boolean canEnableTcpNoDelayByDefault() {
         return CAN_ENABLE_TCP_NODELAY_BY_DEFAULT;
     }
 
     /**
      * Return {@code true} if {@code sun.misc.Unsafe} was found on the classpath and can be used for accelerated
      * direct memory access.
      */
     public static boolean hasUnsafe() {
         return HAS_UNSAFE;
     }
 
     /**
      * Return the reason (if any) why {@code sun.misc.Unsafe} was not available.
      */
     public static Throwable getUnsafeUnavailabilityCause() {
         return PlatformDependent0.getUnsafeUnavailabilityCause();
     }
 
     /**
      * {@code true} if and only if the platform supports unaligned access.
      *
      * @see <a href="http://en.wikipedia.org/wiki/Segmentation_fault#Bus_error">Wikipedia on segfault</a>
      */
     public static boolean isUnaligned() {
         return PlatformDependent0.isUnaligned();
     }
 
     /**
      * Returns {@code true} if the platform has reliable low-level direct buffer access API and a user has not specified
      * {@code -Dio.netty.noPreferDirect} option.
      */
     public static boolean directBufferPreferred() {
         return DIRECT_BUFFER_PREFERRED;
     }
 
     /**
      * Returns the maximum memory reserved for direct buffer allocation.
      */
     public static long maxDirectMemory() {
         return MAX_DIRECT_MEMORY;
     }
 
     /**
      * Returns the temporary directory.
      */
     public static File tmpdir() {
         return TMPDIR;
     }
 
     /**
      * Returns the bit mode of the current VM (usually 32 or 64.)
      */
     public static int bitMode() {
         return BIT_MODE;
     }
 
     /**
      * Return the address size of the OS.
      * 4 (for 32 bits systems ) and 8 (for 64 bits systems).
      */
     public static int addressSize() {
         return ADDRESS_SIZE;
     }
 
     public static long allocateMemory(long size) {
         return PlatformDependent0.allocateMemory(size);
     }
 
     public static void freeMemory(long address) {
         PlatformDependent0.freeMemory(address);
     }
 
     /**
      * Raises an exception bypassing compiler checks for checked exceptions.
      */
     public static void throwException(Throwable t) {
         if (hasUnsafe()) {
             PlatformDependent0.throwException(t);
         } else {
             PlatformDependent.<RuntimeException>throwException0(t);
         }
     }
 
     @SuppressWarnings("unchecked")
     private static <E extends Throwable> void throwException0(Throwable t) throws E {
         throw (E) t;
     }
 
     /**
      * Creates a new fastest {@link ConcurrentMap} implementation for the current platform.
      */
     public static <K, V> ConcurrentMap<K, V> newConcurrentHashMap() {
         return new ConcurrentHashMap<K, V>();
     }
 
     /**
      * Creates a new fastest {@link LongCounter} implementation for the current platform.
      */
     public static LongCounter newLongCounter() {
         if (javaVersion() >= 8) {
             return new LongAdderCounter();
         } else {
             return new AtomicLongCounter();
         }
     }
 
     /**
      * Creates a new fastest {@link ConcurrentMap} implementation for the current platform.
      */
     public static <K, V> ConcurrentMap<K, V> newConcurrentHashMap(int initialCapacity) {
         return new ConcurrentHashMap<K, V>(initialCapacity);
     }
 
     /**
      * Creates a new fastest {@link ConcurrentMap} implementation for the current platform.
      */
     public static <K, V> ConcurrentMap<K, V> newConcurrentHashMap(int initialCapacity, float loadFactor) {
         return new ConcurrentHashMap<K, V>(initialCapacity, loadFactor);
     }
 
     /**
      * Creates a new fastest {@link ConcurrentMap} implementation for the current platform.
      */
     public static <K, V> ConcurrentMap<K, V> newConcurrentHashMap(
             int initialCapacity, float loadFactor, int concurrencyLevel) {
         return new ConcurrentHashMap<K, V>(initialCapacity, loadFactor, concurrencyLevel);
     }
 
     /**
      * Creates a new fastest {@link ConcurrentMap} implementation for the current platform.
      */
     public static <K, V> ConcurrentMap<K, V> newConcurrentHashMap(Map<? extends K, ? extends V> map) {
         return new ConcurrentHashMap<K, V>(map);
     }
 
     /**
      * Try to deallocate the specified direct {@link ByteBuffer}. Please note this method does nothing if
      * the current platform does not support this operation or the specified buffer is not a direct buffer.
      */
     public static void freeDirectBuffer(ByteBuffer buffer) {
         CLEANER.freeDirectBuffer(buffer);
     }
 
     public static long directBufferAddress(ByteBuffer buffer) {
         return PlatformDependent0.directBufferAddress(buffer);
     }
 
     public static ByteBuffer directBuffer(long memoryAddress, int size) {
         if (PlatformDependent0.hasDirectBufferNoCleanerConstructor()) {
             return PlatformDependent0.newDirectBuffer(memoryAddress, size);
         }
         throw new UnsupportedOperationException(
                 "sun.misc.Unsafe or java.nio.DirectByteBuffer.<init>(long, int) not available");
     }
 
     public static int getInt(Object object, long fieldOffset) {
         return PlatformDependent0.getInt(object, fieldOffset);
     }
 
     public static byte getByte(long address) {
         return PlatformDependent0.getByte(address);
     }
 
     public static short getShort(long address) {
         return PlatformDependent0.getShort(address);
     }
 
     public static int getInt(long address) {
         return PlatformDependent0.getInt(address);
     }
 
     public static long getLong(long address) {
         return PlatformDependent0.getLong(address);
     }
 
     public static byte getByte(byte[] data, int index) {
         return PlatformDependent0.getByte(data, index);
     }
 
     public static short getShort(byte[] data, int index) {
         return PlatformDependent0.getShort(data, index);
     }
 
     public static int getInt(byte[] data, int index) {
         return PlatformDependent0.getInt(data, index);
     }
 
     public static long getLong(byte[] data, int index) {
         return PlatformDependent0.getLong(data, index);
     }
 
     public static void putByte(long address, byte value) {
         PlatformDependent0.putByte(address, value);
     }
 
     public static void putShort(long address, short value) {
         PlatformDependent0.putShort(address, value);
     }
 
     public static void putInt(long address, int value) {
         PlatformDependent0.putInt(address, value);
     }
 
     public static void putLong(long address, long value) {
         PlatformDependent0.putLong(address, value);
     }
 
     public static void putByte(byte[] data, int index, byte value) {
         PlatformDependent0.putByte(data, index, value);
     }
 
     public static void putShort(byte[] data, int index, short value) {
         PlatformDependent0.putShort(data, index, value);
     }
 
     public static void putInt(byte[] data, int index, int value) {
         PlatformDependent0.putInt(data, index, value);
     }
 
     public static void putLong(byte[] data, int index, long value) {
         PlatformDependent0.putLong(data, index, value);
     }
 
     public static void copyMemory(long srcAddr, long dstAddr, long length) {
         PlatformDependent0.copyMemory(srcAddr, dstAddr, length);
     }
 
     public static void copyMemory(byte[] src, int srcIndex, long dstAddr, long length) {
         PlatformDependent0.copyMemory(src, ARRAY_BASE_OFFSET + srcIndex, null, dstAddr, length);
     }
 
     public static void copyMemory(long srcAddr, byte[] dst, int dstIndex, long length) {
         PlatformDependent0.copyMemory(null, srcAddr, dst, ARRAY_BASE_OFFSET + dstIndex, length);
     }
 
     public static void setMemory(byte[] dst, int dstIndex, long bytes, byte value) {
         PlatformDependent0.setMemory(dst, ARRAY_BASE_OFFSET + dstIndex, bytes, value);
     }
 
     public static void setMemory(long address, long bytes, byte value) {
         PlatformDependent0.setMemory(address, bytes, value);
     }
 
     /**
      * Allocate a new {@link ByteBuffer} with the given {@code capacity}. {@link ByteBuffer}s allocated with
      * this method <strong>MUST</strong> be deallocated via {@link #freeDirectNoCleaner(ByteBuffer)}.
      */
     public static ByteBuffer allocateDirectNoCleaner(int capacity) {
         assert USE_DIRECT_BUFFER_NO_CLEANER;
 
         incrementMemoryCounter(capacity);
         try {
             return PlatformDependent0.allocateDirectNoCleaner(capacity);
         } catch (Throwable e) {
             decrementMemoryCounter(capacity);
             throwException(e);
             return null;
         }
     }
 
     /**
      * Reallocate a new {@link ByteBuffer} with the given {@code capacity}. {@link ByteBuffer}s reallocated with
      * this method <strong>MUST</strong> be deallocated via {@link #freeDirectNoCleaner(ByteBuffer)}.
      */
     public static ByteBuffer reallocateDirectNoCleaner(ByteBuffer buffer, int capacity) {
         assert USE_DIRECT_BUFFER_NO_CLEANER;
 
         int len = capacity - buffer.capacity();
         incrementMemoryCounter(len);
         try {
             return PlatformDependent0.reallocateDirectNoCleaner(buffer, capacity);
         } catch (Throwable e) {
             decrementMemoryCounter(len);
             throwException(e);
             return null;
         }
     }
 
     /**
      * This method <strong>MUST</strong> only be called for {@link ByteBuffer}s that were allocated via
      * {@link #allocateDirectNoCleaner(int)}.
      */
     public static void freeDirectNoCleaner(ByteBuffer buffer) {
         assert USE_DIRECT_BUFFER_NO_CLEANER;
 
         int capacity = buffer.capacity();
         PlatformDependent0.freeMemory(PlatformDependent0.directBufferAddress(buffer));
         decrementMemoryCounter(capacity);
     }
 
     private static void incrementMemoryCounter(int capacity) {
         if (DIRECT_MEMORY_COUNTER != null) {
             for (;;) {
                 long usedMemory = DIRECT_MEMORY_COUNTER.get();
                 long newUsedMemory = usedMemory + capacity;
                 if (newUsedMemory > DIRECT_MEMORY_LIMIT) {
                     throw new OutOfDirectMemoryError("failed to allocate " + capacity
                             + " byte(s) of direct memory (used: " + usedMemory + ", max: " + DIRECT_MEMORY_LIMIT + ')');
                 }
                 if (DIRECT_MEMORY_COUNTER.compareAndSet(usedMemory, newUsedMemory)) {
                     break;
                 }
             }
         }
     }
 
     private static void decrementMemoryCounter(int capacity) {
         if (DIRECT_MEMORY_COUNTER != null) {
             long usedMemory = DIRECT_MEMORY_COUNTER.addAndGet(-capacity);
             assert usedMemory >= 0;
         }
     }
 
     public static boolean useDirectBufferNoCleaner() {
         return USE_DIRECT_BUFFER_NO_CLEANER;
     }
 
     /**
      * Determine if a subsection of an array is zero.
      * @param bytes The byte array.
      * @param startPos The starting index (inclusive) in {@code bytes}.
      * @param length The amount of bytes to check for zero.
      * @return {@code false} if {@code bytes[startPos:startsPos+length)} contains a value other than zero.
      */
     public static boolean isZero(byte[] bytes, int startPos, int length) {
         return !hasUnsafe() || !isUnaligned() ?
                 isZeroSafe(bytes, startPos, length) :
                 PlatformDependent0.isZero(bytes, startPos, length);
     }
 
     private static final class Mpsc {
         private static final boolean USE_MPSC_CHUNKED_ARRAY_QUEUE;
 
         private Mpsc() {
         }
 
         static {
             Object unsafe = null;
             if (hasUnsafe()) {
                 // jctools goes through its own process of initializing unsafe; of
                 // course, this requires permissions which might not be granted to calling code, so we
                 // must mark this block as privileged too
                 unsafe = AccessController.doPrivileged(new PrivilegedAction<Object>() {
                     @Override
                     public Object run() {
                         // force JCTools to initialize unsafe
                         return UnsafeAccess.UNSAFE;
                     }
                 });
             }
 
             if (unsafe == null) {
                 logger.debug("org.jctools-core.MpscChunkedArrayQueue: unavailable");
                 USE_MPSC_CHUNKED_ARRAY_QUEUE = false;
             } else {
                 logger.debug("org.jctools-core.MpscChunkedArrayQueue: available");
                 USE_MPSC_CHUNKED_ARRAY_QUEUE = true;
             }
         }
 
         static <T> Queue<T> newMpscQueue(final int maxCapacity) {
             // Calculate the max capacity which can not be bigger then MAX_ALLOWED_MPSC_CAPACITY.
             // This is forced by the MpscChunkedArrayQueue implementation as will try to round it
             // up to the next power of two and so will overflow otherwise.
             final int capacity = max(min(maxCapacity, MAX_ALLOWED_MPSC_CAPACITY), MIN_MAX_MPSC_CAPACITY);
             return USE_MPSC_CHUNKED_ARRAY_QUEUE ? new MpscChunkedArrayQueue<T>(MPSC_CHUNK_SIZE, capacity)
                                                 : new MpscGrowableAtomicArrayQueue<T>(MPSC_CHUNK_SIZE, capacity);
         }
 
         static <T> Queue<T> newMpscQueue() {
             return USE_MPSC_CHUNKED_ARRAY_QUEUE ? new MpscUnboundedArrayQueue<T>(MPSC_CHUNK_SIZE)
                                                 : new MpscUnboundedAtomicArrayQueue<T>(MPSC_CHUNK_SIZE);
         }
     }
 
     /**
      * Create a new {@link Queue} which is safe to use for multiple producers (different threads) and a single
      * consumer (one thread!).
      * @return A MPSC queue which may be unbounded.
      */
     public static <T> Queue<T> newMpscQueue() {
         return Mpsc.newMpscQueue();
     }
 
     /**
      * Create a new {@link Queue} which is safe to use for multiple producers (different threads) and a single
      * consumer (one thread!).
      */
     public static <T> Queue<T> newMpscQueue(final int maxCapacity) {
         return Mpsc.newMpscQueue(maxCapacity);
     }
 
     /**
      * Create a new {@link Queue} which is safe to use for single producer (one thread!) and a single
      * consumer (one thread!).
      */
     public static <T> Queue<T> newSpscQueue() {
         return hasUnsafe() ? new SpscLinkedQueue<T>() : new SpscLinkedAtomicQueue<T>();
     }
 
     /**
      * Create a new {@link Queue} which is safe to use for multiple producers (different threads) and a single
      * consumer (one thread!) with the given fixes {@code capacity}.
      */
     public static <T> Queue<T> newFixedMpscQueue(int capacity) {
         return hasUnsafe() ? new MpscArrayQueue<T>(capacity) : new MpscAtomicArrayQueue<T>(capacity);
     }
 
     /**
      * Return the {@link ClassLoader} for the given {@link Class}.
      */
     public static ClassLoader getClassLoader(final Class<?> clazz) {
         return PlatformDependent0.getClassLoader(clazz);
     }
 
     /**
      * Return the context {@link ClassLoader} for the current {@link Thread}.
      */
     public static ClassLoader getContextClassLoader() {
         return PlatformDependent0.getContextClassLoader();
     }
 
     /**
      * Return the system {@link ClassLoader}.
      */
     public static ClassLoader getSystemClassLoader() {
         return PlatformDependent0.getSystemClassLoader();
     }
 
     /**
      * Returns a new concurrent {@link Deque}.
      */
     public static <C> Deque<C> newConcurrentDeque() {
         if (javaVersion() < 7) {
             return new LinkedBlockingDeque<C>();
         } else {
             return new ConcurrentLinkedDeque<C>();
         }
     }
 
     /**
      * Return a {@link Random} which is not-threadsafe and so can only be used from the same thread.
      */
     public static Random threadLocalRandom() {
         return RANDOM_PROVIDER.current();
     }
 
     private static boolean isWindows0() {
         boolean windows = SystemPropertyUtil.get("os.name", "").toLowerCase(Locale.US).contains("win");
         if (windows) {
             logger.debug("Platform: Windows");
         }
         return windows;
     }
 
     private static boolean isOsx0() {
         String osname = SystemPropertyUtil.get("os.name", "").toLowerCase(Locale.US)
                 .replaceAll("[^a-z0-9]+", "");
         boolean osx = osname.startsWith("macosx") || osname.startsWith("osx");
 
         if (osx) {
             logger.debug("Platform: MacOS");
         }
         return osx;
     }
 
     private static boolean maybeSuperUser0() {
         String username = SystemPropertyUtil.get("user.name");
         if (isWindows()) {
             return "Administrator".equals(username);
         }
         // Check for root and toor as some BSDs have a toor user that is basically the same as root.
         return "root".equals(username) || "toor".equals(username);
     }
 
     private static boolean hasUnsafe0() {
         if (isAndroid()) {
             logger.debug("sun.misc.Unsafe: unavailable (Android)");
             return false;
         }
 
         if (PlatformDependent0.isExplicitNoUnsafe()) {
             return false;
         }
 
         try {
             boolean hasUnsafe = PlatformDependent0.hasUnsafe();
             logger.debug("sun.misc.Unsafe: {}", hasUnsafe ? "available" : "unavailable");
             return hasUnsafe;
         } catch (Throwable t) {
             logger.trace("Could not determine if Unsafe is available", t);
             // Probably failed to initialize PlatformDependent0.
             return false;
         }
     }
 
     private static long arrayBaseOffset0() {
         if (!hasUnsafe()) {
             return -1;
         }
 
         return PlatformDependent0.arrayBaseOffset();
     }
 
     private static long maxDirectMemory0() {
         long maxDirectMemory = 0;
         ClassLoader systemClassLoader = null;
         try {
             // Try to get from sun.misc.VM.maxDirectMemory() which should be most accurate.
             systemClassLoader = getSystemClassLoader();
             Class<?> vmClass = Class.forName("sun.misc.VM", true, systemClassLoader);
             Method m = vmClass.getDeclaredMethod("maxDirectMemory");
             maxDirectMemory = ((Number) m.invoke(null)).longValue();
         } catch (Throwable ignored) {
             // Ignore
         }
 
         if (maxDirectMemory > 0) {
             return maxDirectMemory;
         }
 
         try {
             // Now try to get the JVM option (-XX:MaxDirectMemorySize) and parse it.
             // Note that we are using reflection because Android doesn't have these classes.
             Class<?> mgmtFactoryClass = Class.forName(
                     "java.lang.management.ManagementFactory", true, systemClassLoader);
             Class<?> runtimeClass = Class.forName(
                     "java.lang.management.RuntimeMXBean", true, systemClassLoader);
 
             Object runtime = mgmtFactoryClass.getDeclaredMethod("getRuntimeMXBean").invoke(null);
 
             @SuppressWarnings("unchecked")
             List<String> vmArgs = (List<String>) runtimeClass.getDeclaredMethod("getInputArguments").invoke(runtime);
             for (int i = vmArgs.size() - 1; i >= 0; i --) {
                 Matcher m = MAX_DIRECT_MEMORY_SIZE_ARG_PATTERN.matcher(vmArgs.get(i));
                 if (!m.matches()) {
                     continue;
                 }
 
                 maxDirectMemory = Long.parseLong(m.group(1));
                 switch (m.group(2).charAt(0)) {
                     case 'k': case 'K':
                         maxDirectMemory *= 1024;
                         break;
                     case 'm': case 'M':
                         maxDirectMemory *= 1024 * 1024;
                         break;
                     case 'g': case 'G':
                         maxDirectMemory *= 1024 * 1024 * 1024;
                         break;
                 }
                 break;
             }
         } catch (Throwable ignored) {
             // Ignore
         }
 
         if (maxDirectMemory <= 0) {
             maxDirectMemory = Runtime.getRuntime().maxMemory();
             logger.debug("maxDirectMemory: {} bytes (maybe)", maxDirectMemory);
         } else {
             logger.debug("maxDirectMemory: {} bytes", maxDirectMemory);
         }
 
         return maxDirectMemory;
     }
 
     private static File tmpdir0() {
         File f;
         try {
             f = toDirectory(SystemPropertyUtil.get("io.netty.tmpdir"));
             if (f != null) {
                 logger.debug("-Dio.netty.tmpdir: {}", f);
                 return f;
             }
 
             f = toDirectory(SystemPropertyUtil.get("java.io.tmpdir"));
             if (f != null) {
                 logger.debug("-Dio.netty.tmpdir: {} (java.io.tmpdir)", f);
                 return f;
             }
 
             // This shouldn't happen, but just in case ..
             if (isWindows()) {
                 f = toDirectory(System.getenv("TEMP"));
                 if (f != null) {
                     logger.debug("-Dio.netty.tmpdir: {} (%TEMP%)", f);
                     return f;
                 }
 
                 String userprofile = System.getenv("USERPROFILE");
                 if (userprofile != null) {
                     f = toDirectory(userprofile + "\\AppData\\Local\\Temp");
                     if (f != null) {
                         logger.debug("-Dio.netty.tmpdir: {} (%USERPROFILE%\\AppData\\Local\\Temp)", f);
                         return f;
                     }
 
                     f = toDirectory(userprofile + "\\Local Settings\\Temp");
                     if (f != null) {
                         logger.debug("-Dio.netty.tmpdir: {} (%USERPROFILE%\\Local Settings\\Temp)", f);
                         return f;
                     }
                 }
             } else {
                 f = toDirectory(System.getenv("TMPDIR"));
                 if (f != null) {
                     logger.debug("-Dio.netty.tmpdir: {} ($TMPDIR)", f);
                     return f;
                 }
             }
         } catch (Throwable ignored) {
             // Environment variable inaccessible
         }
 
         // Last resort.
         if (isWindows()) {
             f = new File("C:\\Windows\\Temp");
         } else {
             f = new File("/tmp");
         }
 
         logger.warn("Failed to get the temporary directory; falling back to: {}", f);
         return f;
     }
 
     @SuppressWarnings("ResultOfMethodCallIgnored")
     private static File toDirectory(String path) {
         if (path == null) {
             return null;
         }
 
         File f = new File(path);
         f.mkdirs();
 
         if (!f.isDirectory()) {
             return null;
         }
 
         try {
             return f.getAbsoluteFile();
         } catch (Exception ignored) {
             return f;
         }
     }
 
     private static int bitMode0() {
         // Check user-specified bit mode first.
         int bitMode = SystemPropertyUtil.getInt("io.netty.bitMode", 0);
         if (bitMode > 0) {
             logger.debug("-Dio.netty.bitMode: {}", bitMode);
             return bitMode;
         }
 
         // And then the vendor specific ones which is probably most reliable.
         bitMode = SystemPropertyUtil.getInt("sun.arch.data.model", 0);
         if (bitMode > 0) {
             logger.debug("-Dio.netty.bitMode: {} (sun.arch.data.model)", bitMode);
             return bitMode;
         }
         bitMode = SystemPropertyUtil.getInt("com.ibm.vm.bitmode", 0);
         if (bitMode > 0) {
             logger.debug("-Dio.netty.bitMode: {} (com.ibm.vm.bitmode)", bitMode);
             return bitMode;
         }
 
         // os.arch also gives us a good hint.
         String arch = SystemPropertyUtil.get("os.arch", "").toLowerCase(Locale.US).trim();
         if ("amd64".equals(arch) || "x86_64".equals(arch)) {
             bitMode = 64;
         } else if ("i386".equals(arch) || "i486".equals(arch) || "i586".equals(arch) || "i686".equals(arch)) {
             bitMode = 32;
         }
 
         if (bitMode > 0) {
             logger.debug("-Dio.netty.bitMode: {} (os.arch: {})", bitMode, arch);
         }
 
         // Last resort: guess from VM name and then fall back to most common 64-bit mode.
         String vm = SystemPropertyUtil.get("java.vm.name", "").toLowerCase(Locale.US);
         Pattern BIT_PATTERN = Pattern.compile("([1-9][0-9]+)-?bit");
         Matcher m = BIT_PATTERN.matcher(vm);
         if (m.find()) {
             return Integer.parseInt(m.group(1));
         } else {
             return 64;
         }
     }
 
     private static int addressSize0() {
         if (!hasUnsafe()) {
             return -1;
         }
         return PlatformDependent0.addressSize();
     }
 
     private static boolean isZeroSafe(byte[] bytes, int startPos, int length) {
         final int end = startPos + length;
         for (; startPos < end; ++startPos) {
             if (bytes[startPos] != 0) {
                 return false;
             }
         }
         return true;
     }
 
     public static String normalizedArch() {
         return NORMALIZED_ARCH;
     }
 
     public static String normalizedOs() {
         return NORMALIZED_OS;
     }
 
     private static String normalize(String value) {
         return value.toLowerCase(Locale.US).replaceAll("[^a-z0-9]+", "");
     }
 
     private static String normalizeArch(String value) {
         value = normalize(value);
         if (value.matches("^(x8664|amd64|ia32e|em64t|x64)$")) {
             return "x86_64";
         }
         if (value.matches("^(x8632|x86|i[3-6]86|ia32|x32)$")) {
             return "x86_32";
         }
         if (value.matches("^(ia64|itanium64)$")) {
             return "itanium_64";
         }
         if (value.matches("^(sparc|sparc32)$")) {
             return "sparc_32";
         }
         if (value.matches("^(sparcv9|sparc64)$")) {
             return "sparc_64";
         }
         if (value.matches("^(arm|arm32)$")) {
             return "arm_32";
         }
         if ("aarch64".equals(value)) {
             return "aarch_64";
         }
         if (value.matches("^(ppc|ppc32)$")) {
             return "ppc_32";
         }
         if ("ppc64".equals(value)) {
             return "ppc_64";
         }
         if ("ppc64le".equals(value)) {
             return "ppcle_64";
         }
         if ("s390".equals(value)) {
             return "s390_32";
         }
         if ("s390x".equals(value)) {
             return "s390_64";
         }
 
         return "unknown";
     }
 
     private static String normalizeOs(String value) {
         value = normalize(value);
         if (value.startsWith("aix")) {
             return "aix";
         }
         if (value.startsWith("hpux")) {
             return "hpux";
         }
         if (value.startsWith("os400")) {
             // Avoid the names such as os4000
             if (value.length() <= 5 || !Character.isDigit(value.charAt(5))) {
                 return "os400";
             }
         }
         if (value.startsWith("linux")) {
             return "linux";
         }
         if (value.startsWith("macosx") || value.startsWith("osx")) {
             return "osx";
         }
         if (value.startsWith("freebsd")) {
             return "freebsd";
         }
         if (value.startsWith("openbsd")) {
             return "openbsd";
         }
         if (value.startsWith("netbsd")) {
             return "netbsd";
         }
         if (value.startsWith("solaris") || value.startsWith("sunos")) {
             return "sunos";
         }
         if (value.startsWith("windows")) {
             return "windows";
         }
 
         return "unknown";
     }
 
     private static final class AtomicLongCounter extends AtomicLong implements LongCounter {
         @Override
         public void add(long delta) {
             addAndGet(delta);
         }
 
         @Override
         public void increment() {
             incrementAndGet();
         }
 
         @Override
         public void decrement() {
             decrementAndGet();
         }
 
         @Override
         public long value() {
             return get();
         }
     }
 
     private interface ThreadLocalRandomProvider {
         Random current();
     }
 
     private PlatformDependent() {
         // only static method supported
     }
 }