Added DataBuffer indexOf and lastIndexOf

This commit introduces DataBuffer.indexOf(IntPredicate) and
lastIndexOf(IntPredicate), for finding the index of a byte in a
DataBuffer.
It also introduces DataBufferUtils.tokenize, which tokenizes a
DataBuffer into separate tokens, given a delimiter function.

spring-web-reactive/src/main/java/org/springframework/core/io/buffer/DataBuffer.java

@@ -19,6 +19,7 @@ package org.springframework.core.io.buffer;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.nio.ByteBuffer;
+import java.util.function.IntPredicate;
 
 /**
  * Basic abstraction over byte buffers.
@@ -34,12 +35,22 @@ public interface DataBuffer {
 	DataBufferAllocator allocator();
 
 	/**
-	 * Gets the byte at the specified index.
-	 * @param index the index
-	 * @return the byte at the specified index
-	 * @throws IndexOutOfBoundsException if the given index is out of bounds
+	 * Returns the index of the first byte in this buffer that matches the given
+	 * predicate.
+	 * @param predicate the predicate to match
+	 * @return the index of the first byte that matches {@code predicate}; or {@code -1}
+	 * if none match
 	 */
-	byte get(int index);
+	int indexOf(IntPredicate predicate);
+
+	/**
+	 * Returns the index of the last byte in this buffer that matches the given
+	 * predicate.
+	 * @param predicate the predicate to match
+	 * @return the index of the last byte that matches {@code predicate}; or {@code -1}
+	 * if none match
+	 */
+	int lastIndexOf(IntPredicate predicate);
 
 	/**
 	 * Returns the number of bytes that can be read from this data buffer.
@@ -113,11 +124,22 @@ public interface DataBuffer {
 	 */
 	DataBuffer write(ByteBuffer... buffers);
 
+	/**
+	 * Creates a new {@code DataBuffer} whose contents is a shared subsequence of this
+	 * data buffer's content.  Data between this data buffer and the returned buffer is
+	 * shared; though changes in the returned buffer's position will not be reflected
+	 * in the reading nor writing position of this data buffer.
+	 * @param index the index at which to start the slice
+	 * @param length the length of the slice
+	 * @return the specified slice of this data buffer
+	 */
+	DataBuffer slice(int index, int length);
+
 	/**
 	 * Exposes this buffer's bytes as a {@link ByteBuffer}. Data between this {@code
 	 * DataBuffer} and the returned {@code ByteBuffer} is shared; though changes in the
 	 * returned buffer's {@linkplain ByteBuffer#position() position} will not be reflected
-	 * in the position(s) of this data buffer.
+	 * in the reading nor writing position of this data buffer.
 	 * @return this data buffer as a byte buffer
 	 */
 	ByteBuffer asByteBuffer();

spring-web-reactive/src/main/java/org/springframework/core/io/buffer/DefaultDataBuffer.java

@@ -22,6 +22,7 @@ import java.io.OutputStream;
 import java.nio.ByteBuffer;
 import java.util.Arrays;
 import java.util.function.Function;
+import java.util.function.IntPredicate;
 
 import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
@@ -82,8 +83,25 @@ public class DefaultDataBuffer implements DataBuffer {
 	}
 
 	@Override
-	public byte get(int index) {
-		return this.byteBuffer.get(index);
+	public int indexOf(IntPredicate predicate) {
+		for (int i = 0; i < readableByteCount(); i++) {
+			byte b = this.byteBuffer.get(i);
+			if (predicate.test(b)) {
+				return i;
+			}
+		}
+		return -1;
+	}
+
+	@Override
+	public int lastIndexOf(IntPredicate predicate) {
+		for (int i = readableByteCount() - 1; i >= 0; i--) {
+			byte b = this.byteBuffer.get(i);
+			if (predicate.test(b)) {
+				return i;
+			}
+		}
+		return -1;
 	}
 
 	@Override
@@ -120,14 +138,16 @@ public class DefaultDataBuffer implements DataBuffer {
 	 */
 	private <T> T readInternal(Function<ByteBuffer, T> function) {
 		this.byteBuffer.position(this.readPosition);
-		T result = function.apply(this.byteBuffer);
+		try {
+			return function.apply(this.byteBuffer);
+		}
+		finally {
 			this.readPosition = this.byteBuffer.position();
-		return result;
+		}
 	}
 
 	@Override
 	public DefaultDataBuffer write(byte b) {
-
 		ensureExtraCapacity(1);
 		writeInternal(buffer -> buffer.put(b));
 
@@ -184,9 +204,27 @@ public class DefaultDataBuffer implements DataBuffer {
 	 */
 	private <T> T writeInternal(Function<ByteBuffer, T> function) {
 		this.byteBuffer.position(this.writePosition);
-		T result = function.apply(this.byteBuffer);
+		try {
+			return function.apply(this.byteBuffer);
+		}
+		finally {
 			this.writePosition = this.byteBuffer.position();
-		return result;
+		}
+	}
+
+	@Override
+	public DataBuffer slice(int index, int length) {
+		int oldPosition = this.byteBuffer.position();
+		try {
+			this.byteBuffer.position(index);
+			ByteBuffer slice = this.byteBuffer.slice();
+			slice.limit(length);
+			return new SlicedDefaultDataBuffer(slice, 0, length, this.allocator);
+		}
+		finally {
+			this.byteBuffer.position(oldPosition);
+		}
+
 	}
 
 	@Override
@@ -214,7 +252,7 @@ public class DefaultDataBuffer implements DataBuffer {
 		}
 	}
 
-	private void grow(int minCapacity) {
+	void grow(int minCapacity) {
 		ByteBuffer oldBuffer = this.byteBuffer;
 		ByteBuffer newBuffer =
 				(oldBuffer.isDirect() ? ByteBuffer.allocateDirect(minCapacity) :
@@ -227,6 +265,7 @@ public class DefaultDataBuffer implements DataBuffer {
 		oldBuffer.clear();
 	}
 
+
 	@Override
 	public int hashCode() {
 		return this.byteBuffer.hashCode();
@@ -294,4 +333,18 @@ public class DefaultDataBuffer implements DataBuffer {
 			writeInternal(buffer -> buffer.put(bytes, off, len));
 		}
 	}
+
+	private static class SlicedDefaultDataBuffer extends DefaultDataBuffer {
+
+		SlicedDefaultDataBuffer(ByteBuffer byteBuffer, int readPosition,
+				int writePosition, DefaultDataBufferAllocator allocator) {
+			super(byteBuffer, readPosition, writePosition, allocator);
+		}
+
+		@Override
+		void grow(int minCapacity) {
+			throw new UnsupportedOperationException(
+					"Growing the capacity of a sliced buffer is not supported");
+		}
+	}
 }

spring-web-reactive/src/main/java/org/springframework/core/io/buffer/NettyDataBuffer.java

@@ -20,6 +20,7 @@ import java.io.InputStream;
 import java.io.OutputStream;
 import java.nio.ByteBuffer;
 import java.util.Arrays;
+import java.util.function.IntPredicate;
 
 import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufInputStream;
@@ -68,8 +69,15 @@ public class NettyDataBuffer implements PooledDataBuffer {
 	}
 
 	@Override
-	public byte get(int index) {
-		return this.byteBuf.getByte(index);
+	public int indexOf(IntPredicate predicate) {
+		IntPredicate negated = predicate.negate();
+		return this.byteBuf.forEachByte(negated::test);
+	}
+
+	@Override
+	public int lastIndexOf(IntPredicate predicate) {
+		IntPredicate negated = predicate.negate();
+		return this.byteBuf.forEachByteDesc(negated::test);
 	}
 
 	@Override
@@ -166,6 +174,12 @@ public class NettyDataBuffer implements PooledDataBuffer {
 		return this;
 	}
 
+	@Override
+	public DataBuffer slice(int index, int length) {
+		ByteBuf slice = this.byteBuf.slice(index, length);
+		return new NettyDataBuffer(slice, this.allocator);
+	}
+
 	@Override
 	public ByteBuffer asByteBuffer() {
 		return this.byteBuf.nioBuffer();
@@ -183,8 +197,7 @@ public class NettyDataBuffer implements PooledDataBuffer {
 
 	@Override
 	public PooledDataBuffer retain() {
-		this.byteBuf.retain();
-		return this;
+		return new NettyDataBuffer(this.byteBuf.retain(), allocator);
 	}
 
 	@Override

spring-web-reactive/src/main/java/org/springframework/core/io/buffer/support/DataBufferUtils.java

@@ -21,15 +21,16 @@ import java.io.InputStream;
 import java.nio.ByteBuffer;
 import java.nio.channels.Channels;
 import java.nio.channels.ReadableByteChannel;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
 import java.util.concurrent.atomic.AtomicLong;
 import java.util.function.BiFunction;
 import java.util.function.Consumer;
+import java.util.function.IntPredicate;
 
 import org.reactivestreams.Publisher;
-import org.reactivestreams.Subscriber;
-import org.reactivestreams.Subscription;
 import reactor.core.publisher.Flux;
-import reactor.core.publisher.FluxSource;
 import reactor.core.subscriber.SignalEmitter;
 
 import org.springframework.core.io.buffer.DataBuffer;
@@ -102,76 +103,91 @@ public abstract class DataBufferUtils {
 		Assert.notNull(publisher, "'publisher' must not be null");
 		Assert.isTrue(maxByteCount >= 0, "'maxByteCount' must be a positive number");
 
-		return new TakeByteUntilCount(publisher, maxByteCount);
+		AtomicLong byteCountDown = new AtomicLong(maxByteCount);
+
+		return Flux.from(publisher).
+				takeWhile(dataBuffer -> {
+					int delta = -dataBuffer.readableByteCount();
+					long currentCount = byteCountDown.getAndAdd(delta);
+					return currentCount >= 0;
+				}).
+				map(dataBuffer -> {
+					long currentCount = byteCountDown.get();
+					if (currentCount >= 0) {
+						return dataBuffer;
+					}
+					else {
+						// last buffer
+						int size = (int) (currentCount + dataBuffer.readableByteCount());
+						return dataBuffer.slice(0, size);
+					}
+				});
 	}
 
 	/**
-	 * Releases the given data buffer, if it is a {@link PooledDataBuffer}.
-	 * @param dataBuffer the data buffer to release
-	 * @return {@code true} if the buffer was released; {@code false} otherwise.
+	 * Tokenize the {@link DataBuffer} using the given delimiter
+	 * function. Does not include the delimiter in the result.
+	 * @param dataBuffer the data buffer to tokenize
+	 * @param delimiter the delimiter function
+	 * @return the tokens
 	 */
-	public static boolean release(DataBuffer dataBuffer) {
-		if (dataBuffer instanceof PooledDataBuffer) {
-			return ((PooledDataBuffer) dataBuffer).release();
+	public static List<DataBuffer> tokenize(DataBuffer dataBuffer,
+			IntPredicate delimiter) {
+		Assert.notNull(dataBuffer, "'dataBuffer' must not be null");
+		Assert.notNull(delimiter, "'delimiter' must not be null");
+
+		List<DataBuffer> results = new ArrayList<DataBuffer>();
+		int idx;
+		do {
+			idx = dataBuffer.indexOf(delimiter);
+			if (idx < 0) {
+				results.add(dataBuffer);
 			}
-		return false;
+			else {
+				if (idx > 0) {
+					DataBuffer slice = dataBuffer.slice(0, idx);
+					slice = retain(slice);
+					results.add(slice);
 				}
-
-	private static final class TakeByteUntilCount extends FluxSource<DataBuffer, DataBuffer> {
-
-		final long maxByteCount;
-
-		TakeByteUntilCount(Publisher<? extends DataBuffer> source, long maxByteCount) {
-			super(source);
-			this.maxByteCount = maxByteCount;
+				int remainingLen = dataBuffer.readableByteCount() - (idx + 1);
+				if (remainingLen > 0) {
+					dataBuffer = dataBuffer.slice(idx + 1, remainingLen);
 				}
-
-		@Override
-		public void subscribe(Subscriber<? super DataBuffer> subscriber) {
-			source.subscribe(new Subscriber<DataBuffer>() {
-
-				private Subscription subscription;
-
-				private final AtomicLong byteCount = new AtomicLong();
-
-				@Override
-				public void onSubscribe(Subscription s) {
-					this.subscription = s;
-					subscriber.onSubscribe(s);
+				else {
+					release(dataBuffer);
+					idx = -1;
 				}
-
-				@Override
-				public void onNext(DataBuffer dataBuffer) {
-					int delta = dataBuffer.readableByteCount();
-					long currentCount = this.byteCount.addAndGet(delta);
-					if (currentCount > maxByteCount) {
-						int size = (int) (maxByteCount - currentCount + delta);
-						ByteBuffer byteBuffer =
-								(ByteBuffer) dataBuffer.asByteBuffer().limit(size);
-						DataBuffer partialBuffer =
-								dataBuffer.allocator().allocateBuffer(size);
-						partialBuffer.write(byteBuffer);
-
-						subscriber.onNext(partialBuffer);
-						subscriber.onComplete();
-						this.subscription.cancel();
 			}
-					else {
-						subscriber.onNext(dataBuffer);
 		}
+		while (idx != -1);
+		return Collections.unmodifiableList(results);
 	}
 
-				@Override
-				public void onError(Throwable t) {
-					subscriber.onError(t);
+	/**
+	 * Retains the given data buffer, it it is a {@link PooledDataBuffer}.
+	 * @param dataBuffer the data buffer to retain
+	 * @return the retained buffer
+	 */
+	@SuppressWarnings("unchecked")
+	public static <T extends DataBuffer> T retain(T dataBuffer) {
+		if (dataBuffer instanceof PooledDataBuffer) {
+			return (T) ((PooledDataBuffer) dataBuffer).retain();
 		}
-
-				@Override
-				public void onComplete() {
-					subscriber.onComplete();
+		else {
+			return dataBuffer;
 		}
-			});
 	}
+
+	/**
+	 * Releases the given data buffer, if it is a {@link PooledDataBuffer}.
+	 * @param dataBuffer the data buffer to release
+	 * @return {@code true} if the buffer was released; {@code false} otherwise.
+	 */
+	public static boolean release(DataBuffer dataBuffer) {
+		if (dataBuffer instanceof PooledDataBuffer) {
+			return ((PooledDataBuffer) dataBuffer).release();
+		}
+		return false;
 	}
 
 	private static class ReadableByteChannelGenerator

spring-web-reactive/src/test/java/org/springframework/core/io/buffer/DataBufferTests.java

@@ -24,8 +24,7 @@ import java.util.Arrays;
 
 import org.junit.Test;
 
-import static org.junit.Assert.assertArrayEquals;
-import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.*;
 
 /**
  * @author Arjen Poutsma
@@ -184,7 +183,65 @@ public class DataBufferTests extends AbstractDataBufferAllocatingTestCase {
 		assertArrayEquals(new byte[]{'b', 'c'}, resultBytes);
 
 		release(buffer);
+	}
+
+	@Test
+	public void indexOf() {
+		DataBuffer buffer = createDataBuffer(3);
+		buffer.write(new byte[]{'a', 'b', 'c'});
 
+		int result = buffer.indexOf(b -> b == 'c');
+		assertEquals(2, result);
+
+		result = buffer.indexOf(b -> b == 'z');
+		assertEquals(-1, result);
+
+		release(buffer);
+	}
+
+	@Test
+	public void lastIndexOf() {
+		DataBuffer buffer = createDataBuffer(3);
+		buffer.write(new byte[]{'a', 'b', 'c'});
+
+		int result = buffer.lastIndexOf(b -> b == 'b');
+		assertEquals(1, result);
+
+		result = buffer.lastIndexOf(b -> b == 'z');
+		assertEquals(-1, result);
+
+		release(buffer);
+	}
+
+	@Test
+	public void slice() {
+		DataBuffer buffer = createDataBuffer(3);
+		buffer.write(new byte[]{'a', 'b'});
+
+		DataBuffer slice = buffer.slice(1, 2);
+		assertEquals(2, slice.readableByteCount());
+		try {
+			slice.write((byte) 0);
+			fail("IndexOutOfBoundsException expected");
+		}
+		catch (Exception ignored) {
+		}
+		buffer.write((byte) 'c');
+
+		assertEquals(3, buffer.readableByteCount());
+		byte[] result = new byte[3];
+		buffer.read(result);
+
+		assertArrayEquals(new byte[]{'a', 'b', 'c'}, result);
+
+		assertEquals(2, slice.readableByteCount());
+		result = new byte[2];
+		slice.read(result);
+
+		assertArrayEquals(new byte[]{'b', 'c'}, result);
+
+
+		release(buffer);
 	}
 
 

spring-web-reactive/src/test/java/org/springframework/core/io/buffer/support/DataBufferUtilsTests.java

@@ -19,8 +19,10 @@ package org.springframework.core.io.buffer.support;
 import java.io.InputStream;
 import java.net.URI;
 import java.nio.channels.FileChannel;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Paths;
 import java.nio.file.StandardOpenOption;
+import java.util.List;
 
 import org.junit.Test;
 import reactor.core.publisher.Flux;
@@ -29,6 +31,7 @@ import reactor.core.test.TestSubscriber;
 import org.springframework.core.io.buffer.AbstractDataBufferAllocatingTestCase;
 import org.springframework.core.io.buffer.DataBuffer;
 
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 
 /**
@@ -103,7 +106,25 @@ public class DataBufferUtilsTests extends AbstractDataBufferAllocatingTestCase {
 				assertComplete().
 				assertValuesWith(stringConsumer("foo"), stringConsumer("ba"));
 
-		release(bar, baz);
+		release(baz);
+	}
+
+	@Test
+	public void tokenize() {
+		DataBuffer dataBuffer = stringBuffer("-foo--bar-");
+
+		List<DataBuffer> results = DataBufferUtils.tokenize(dataBuffer, b -> b == '-');
+		assertEquals(2, results.size());
+
+		DataBuffer result = results.get(0);
+		String value = DataBufferTestUtils.dumpString(result, StandardCharsets.UTF_8);
+		assertEquals("foo", value);
+
+		result = results.get(1);
+		value = DataBufferTestUtils.dumpString(result, StandardCharsets.UTF_8);
+		assertEquals("bar", value);
+
+		results.stream().forEach(b -> release(b));
 	}