HTTP/2 Headers Type Updates

Motivation:
The HTTP/2 RFC (https://tools.ietf.org/html/rfc7540#section-8.1.2) indicates that header names consist of ASCII characters. We currently use ByteString to represent HTTP/2 header names. The HTTP/2 RFC (https://tools.ietf.org/html/rfc7540#section-10.3) also eludes to header values inheriting the same validity characteristics as HTTP/1.x. Using AsciiString for the value type of HTTP/2 headers would allow for re-use of predefined HTTP/1.x values, and make comparisons more intuitive. The Headers<T> interface could also be expanded to allow for easier use of header types which do not have the same Key and Value type.

Motivation:
- Change Headers<T> to Headers<K, V>
- Change Http2Headers<ByteString> to Http2Headers<CharSequence, CharSequence>
- Remove ByteString. Having AsciiString extend ByteString complicates equality comparisons when the hash code algorithm is no longer shared.

Result:
Http2Header types are more representative of the HTTP/2 RFC, and relationship between HTTP/2 header name/values more directly relates to HTTP/1.x header names/values.

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

@@ -33,6 +33,7 @@
 import java.nio.channels.ScatteringByteChannel;
 import java.nio.charset.Charset;
 
+import static io.netty.util.internal.MathUtil.isOutOfBounds;
 
 /**
  * A skeletal implementation of a buffer.
@@ -1110,32 +1111,28 @@ protected final void checkIndex(int index, int fieldLength) {
     }
 
     final void checkIndex0(int index, int fieldLength) {
-        if (isInvalid(index, fieldLength, capacity())) {
+        if (isOutOfBounds(index, fieldLength, capacity())) {
             throw new IndexOutOfBoundsException(String.format(
                     "index: %d, length: %d (expected: range(0, %d))", index, fieldLength, capacity()));
         }
     }
 
     protected final void checkSrcIndex(int index, int length, int srcIndex, int srcCapacity) {
         checkIndex(index, length);
-        if (isInvalid(srcIndex, length, srcCapacity)) {
+        if (isOutOfBounds(srcIndex, length, srcCapacity)) {
             throw new IndexOutOfBoundsException(String.format(
                     "srcIndex: %d, length: %d (expected: range(0, %d))", srcIndex, length, srcCapacity));
         }
     }
 
     protected final void checkDstIndex(int index, int length, int dstIndex, int dstCapacity) {
         checkIndex(index, length);
-        if (isInvalid(dstIndex, length, dstCapacity)) {
+        if (isOutOfBounds(dstIndex, length, dstCapacity)) {
             throw new IndexOutOfBoundsException(String.format(
                     "dstIndex: %d, length: %d (expected: range(0, %d))", dstIndex, length, dstCapacity));
         }
     }
 
-    static boolean isInvalid(int index, int length, int capacity) {
-        return (index | length | (index + length) | (capacity - (index + length))) < 0;
-    }
-
     /**
      * Throws an {@link IndexOutOfBoundsException} if the current
      * {@linkplain #readableBytes() readable bytes} of this buffer is less

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

@@ -19,6 +19,8 @@
 
 import java.nio.ByteOrder;
 
+import static io.netty.util.internal.PlatformDependent.BIG_ENDIAN_NATIVE_ORDER;
+
 /**
  * Special {@link SwappedByteBuf} for {@link ByteBuf}s that is using unsafe.
  */
@@ -30,7 +32,7 @@ abstract class AbstractUnsafeSwappedByteBuf extends SwappedByteBuf {
         super(buf);
         assert PlatformDependent.isUnaligned();
         wrapped = buf;
-        nativeByteOrder = UnsafeByteBufUtil.BIG_ENDIAN_NATIVE_ORDER == (order() == ByteOrder.BIG_ENDIAN);
+        nativeByteOrder = BIG_ENDIAN_NATIVE_ORDER == (order() == ByteOrder.BIG_ENDIAN);
     }
 
     @Override

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

@@ -15,11 +15,8 @@
  */
 package io.netty.buffer;
 
-import static io.netty.util.internal.ObjectUtil.checkNotNull;
-
 import io.netty.util.AsciiString;
 import io.netty.util.ByteProcessor;
-import io.netty.util.ByteString;
 import io.netty.util.CharsetUtil;
 import io.netty.util.Recycler;
 import io.netty.util.Recycler.Handle;
@@ -41,6 +38,9 @@
 import java.util.Arrays;
 import java.util.Locale;
 
+import static io.netty.util.internal.ObjectUtil.checkNotNull;
+import static io.netty.util.internal.MathUtil.isOutOfBounds;
+
 /**
  * A collection of utility methods that is related with handling {@link ByteBuf},
  * such as the generation of hex dump and swapping an integer's byte order.
@@ -661,7 +661,7 @@ public static ByteBuf threadLocalDirectBuffer() {
      * The copy will start at {@link ByteBuf#readerIndex()} and copy {@link ByteBuf#readableBytes()} bytes.
      */
     public static byte[] getBytes(ByteBuf buf) {
-        return getBytes(buf, checkNotNull(buf, "buf").readerIndex(), buf.readableBytes());
+        return getBytes(buf,  buf.readerIndex(), buf.readableBytes());
     }
 
     /**
@@ -679,7 +679,7 @@ public static byte[] getBytes(ByteBuf buf, int start, int length) {
      * If {@code copy} is false the underlying storage will be shared, if possible.
      */
     public static byte[] getBytes(ByteBuf buf, int start, int length, boolean copy) {
-        if (start < 0 || length > checkNotNull(buf, "buf").capacity() - start) {
+        if (isOutOfBounds(start, length, buf.capacity())) {
             throw new IndexOutOfBoundsException("expected: " + "0 <= start(" + start + ") <= start + length(" + length
                     + ") <= " + "buf.capacity(" + buf.capacity() + ')');
         }
@@ -706,12 +706,10 @@ public static byte[] getBytes(ByteBuf buf, int start, int length, boolean copy)
      * @param dstIdx the starting offset in the destination byte array.
      * @param length the number of characters to copy.
      */
-    public static void copy(ByteString src, int srcIdx, ByteBuf dst, int dstIdx, int length) {
-        final int thisLen = src.length();
-
-        if (srcIdx < 0 || length > thisLen - srcIdx) {
+    public static void copy(AsciiString src, int srcIdx, ByteBuf dst, int dstIdx, int length) {
+        if (isOutOfBounds(srcIdx, length, src.length())) {
             throw new IndexOutOfBoundsException("expected: " + "0 <= srcIdx(" + srcIdx + ") <= srcIdx + length("
-                            + length + ") <= srcLen(" + thisLen + ')');
+                            + length + ") <= srcLen(" + src.length() + ')');
         }
 
         checkNotNull(dst, "dst").setBytes(dstIdx, src.array(), srcIdx + src.arrayOffset(), length);
@@ -724,12 +722,10 @@ public static void copy(ByteString src, int srcIdx, ByteBuf dst, int dstIdx, int
      * @param dst the destination byte array.
      * @param length the number of characters to copy.
      */
-    public static void copy(ByteString src, int srcIdx, ByteBuf dst, int length) {
-        final int thisLen = src.length();
-
-        if (srcIdx < 0 || length > thisLen - srcIdx) {
+    public static void copy(AsciiString src, int srcIdx, ByteBuf dst, int length) {
+        if (isOutOfBounds(srcIdx, length, src.length())) {
             throw new IndexOutOfBoundsException("expected: " + "0 <= srcIdx(" + srcIdx + ") <= srcIdx + length("
-                            + length + ") <= srcLen(" + thisLen + ')');
+                            + length + ") <= srcLen(" + src.length() + ')');
         }
 
         checkNotNull(dst, "dst").writeBytes(src.array(), srcIdx + src.arrayOffset(), length);
@@ -771,7 +767,7 @@ public static void appendPrettyHexDump(StringBuilder dump, ByteBuf buf) {
      * the given {@code length}.
      */
     public static void appendPrettyHexDump(StringBuilder dump, ByteBuf buf, int offset, int length) {
-        if (offset < 0 || length  > checkNotNull(buf, "buf").capacity() - offset) {
+        if (isOutOfBounds(offset, length, buf.capacity())) {
             throw new IndexOutOfBoundsException(
                     "expected: " + "0 <= offset(" + offset + ") <= offset + length(" + length
                                                 + ") <= " + "buf.capacity(" + buf.capacity() + ')');

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

@@ -23,14 +23,14 @@
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 
+import static io.netty.util.internal.MathUtil.isOutOfBounds;
 import static io.netty.util.internal.ObjectUtil.checkNotNull;
+import static io.netty.util.internal.PlatformDependent.BIG_ENDIAN_NATIVE_ORDER;
 
 /**
  * All operations get and set as {@link ByteOrder#BIG_ENDIAN}.
  */
 final class UnsafeByteBufUtil {
-
-    static final boolean BIG_ENDIAN_NATIVE_ORDER = ByteOrder.nativeOrder() == ByteOrder.BIG_ENDIAN;
     private static final boolean UNALIGNED = PlatformDependent.isUnaligned();
 
     static byte getByte(long address) {
@@ -282,7 +282,7 @@ static int setBytes(AbstractByteBuf buf, long addr, int index, InputStream in, i
     static void getBytes(AbstractByteBuf buf, long addr, int index, ByteBuf dst, int dstIndex, int length) {
         buf.checkIndex(index, length);
         checkNotNull(dst, "dst");
-        if (AbstractByteBuf.isInvalid(dstIndex, length, dst.capacity())) {
+        if (isOutOfBounds(dstIndex, length, dst.capacity())) {
             throw new IndexOutOfBoundsException("dstIndex: " + dstIndex);
         }
 
@@ -298,7 +298,7 @@ static void getBytes(AbstractByteBuf buf, long addr, int index, ByteBuf dst, int
     static void getBytes(AbstractByteBuf buf, long addr, int index, byte[] dst, int dstIndex, int length) {
         buf.checkIndex(index, length);
         checkNotNull(dst, "dst");
-        if (AbstractByteBuf.isInvalid(dstIndex, length, dst.length)) {
+        if (isOutOfBounds(dstIndex, length, dst.length)) {
             throw new IndexOutOfBoundsException("dstIndex: " + dstIndex);
         }
         if (length != 0) {
@@ -328,7 +328,7 @@ static void getBytes(AbstractByteBuf buf, long addr, int index, ByteBuffer dst)
     static void setBytes(AbstractByteBuf buf, long addr, int index, ByteBuf src, int srcIndex, int length) {
         buf.checkIndex(index, length);
         checkNotNull(src, "src");
-        if (AbstractByteBuf.isInvalid(srcIndex, length, src.capacity())) {
+        if (isOutOfBounds(srcIndex, length, src.capacity())) {
             throw new IndexOutOfBoundsException("srcIndex: " + srcIndex);
         }