Improve HtBody performance yegor256#3

src/main/java/org/cactoos/http/HtBody.java

@@ -26,22 +26,20 @@
 
 import java.io.IOException;
 import java.io.InputStream;
+import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.Queue;
+import org.cactoos.Bytes;
 import org.cactoos.Input;
-import org.cactoos.io.InputOf;
-import org.cactoos.text.TextOf;
+import org.cactoos.io.BytesOf;
 
 /**
  * Head of HTTP response.
  *
  * @author Yegor Bugayenko (yegor256@gmail.com)
+ * @author Victor Noel (victor.noel@crazydwarves.org)
  * @version $Id$
  * @since 0.1
- * @todo #1:30min The implementation of method stream() is less than
- *  effective, because it reads the entire content of the response, turning
- *  it into text and then splitting. What if the content is binary and
- *  can't be converted to string? What if the content is super big
- *  and must be presented as an stream, not a piece of text. Let's fix
- *  it.
  */
 public final class HtBody implements Input {
 
@@ -52,6 +50,7 @@ public final class HtBody implements Input {
 
     /**
      * Ctor.
+     *
      * @param rsp Response
      */
     public HtBody(final Input rsp) {
@@ -60,8 +59,117 @@ public HtBody(final Input rsp) {
 
     @Override
     public InputStream stream() throws IOException {
-        return new InputOf(
-            new TextOf(this.response).asString().split("\r\n\r\n")[1]
-        ).stream();
+        return new SkipInput(this.response, new BytesOf("\r\n\r\n")).stream();
+    }
+
+    /**
+     * {@link Input} that skips until it find some defined bytes.
+     *
+     * @author Victor Noel (victor.noel@crazydwarves.org)
+     * @version $Id$
+     * @since 0.1
+     */
+    static final class SkipInput implements Input {
+
+        /**
+         * The input.
+         */
+        private final Input origin;
+
+        /**
+         * The delimiter.
+         */
+        private final Bytes delimiter;
+
+        /**
+         * Ctor.
+         *
+         * @param origin The input.
+         * @param delimiter The bytes delimiter to skip until.
+         */
+        SkipInput(final Input origin, final Bytes delimiter) {
+            this.origin = origin;
+            this.delimiter = delimiter;
+        }
+
+        @Override
+        public InputStream stream() throws IOException {
+            final byte[] bytes = this.delimiter.asBytes();
+            final BoundedByteBuffer buffer = new BoundedByteBuffer(
+                bytes.length
+            );
+            final InputStream stream = this.origin.stream();
+            boolean eof = false;
+            while (!eof && !buffer.isEqualsTo(bytes)) {
+                final int read = stream.read();
+                if (read < 0) {
+                    eof = true;
+                } else {
+                    buffer.offer((byte) read);
+                }
+            }
+            return stream;
+        }
+    }
+
+    /**
+     * A very simple circular buffer of bytes.
+     *
+     * @author Victor Noel (victor.noel@crazydwarves.org)
+     * @version $Id$
+     * @since 0.1
+     */
+    static final class BoundedByteBuffer {
+
+        /**
+         * The buffer.
+         */
+        private final Queue<Byte> internal;
+
+        /**
+         * The size limit.
+         */
+        private final int limit;
+
+        /**
+         * Ctor.
+         *
+         * @param limit The size limit.
+         */
+        BoundedByteBuffer(final int limit) {
+            this.limit = limit;
+            this.internal = new LinkedList<>();
+        }
+
+        /**
+         * Add a byte to the buffer, potentially by removing the oldest one to
+         * satisfy the size limit.
+         *
+         * @param add The byte to add
+         */
+        public void offer(final byte add) {
+            if (this.internal.size() == this.limit) {
+                this.internal.remove();
+            }
+            this.internal.add(add);
+        }
+
+        /**
+         * Test if the buffer contains exactly the <code>bytes</code>.
+         *
+         * @param bytes The bytes to compare to.
+         * @return The value <code>true</code> if the buffer contains exactly
+         *  the <code>bytes</code>.
+         */
+        public boolean isEqualsTo(final byte[] bytes) {
+            boolean equal = bytes.length == this.internal.size();
+            final Iterator<Byte> iter = this.internal.iterator();
+            int idx = 0;
+            while (iter.hasNext() && equal) {
+                equal = iter.next() == bytes[idx];
+                idx = idx + 1;
+            }
+            return equal;
+        }
     }
 }

src/test/java/org/cactoos/http/HtBodyBoundedByteBufferTest.java

@@ -0,0 +1,55 @@
+/**
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Yegor Bugayenko
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.cactoos.http;
+
+import java.util.Arrays;
+import org.cactoos.http.HtBody.BoundedByteBuffer;
+import org.hamcrest.MatcherAssert;
+import org.hamcrest.Matchers;
+import org.junit.Test;
+
+/**
+ * Test case for {@link HtBody.BoundedByteBuffer}.
+ *
+ * @author Victor Noel (victor.noel@crazydwarves.org)
+ * @version $Id$
+ * @since 0.1
+ * @checkstyle JavadocMethodCheck (500 lines)
+ */
+public final class HtBodyBoundedByteBufferTest {
+
+    @Test
+    public void onlyKeepsTheLastNBytes() {
+        final int limit = 4;
+        final BoundedByteBuffer buffer = new HtBody.BoundedByteBuffer(limit);
+        final int[] bytes = new int[] {1, 2, 3, 4, 5, 6, 7, 8 };
+        Arrays.stream(bytes).forEach(b -> buffer.offer((byte) b));
+        MatcherAssert.assertThat(
+            // @checkstyle MagicNumberCheck (1 line)
+            buffer.isEqualsTo(new byte[] {5, 6, 7, 8 }),
+            Matchers.is(true)
+        );
+    }
+}

src/test/java/org/cactoos/http/HtBodySkipInputTest.java

@@ -0,0 +1,99 @@
+/**
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2018 Yegor Bugayenko
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package org.cactoos.http;
+
+import org.cactoos.io.BytesOf;
+import org.cactoos.io.InputOf;
+import org.cactoos.text.JoinedText;
+import org.cactoos.text.TextOf;
+import org.hamcrest.MatcherAssert;
+import org.hamcrest.Matchers;
+import org.junit.Test;
+
+/**
+ * Test case for {@link HtBody.SkipInput}.
+ *
+ * @author Victor Noel (victor.noel@crazydwarves.org)
+ * @version $Id$
+ * @since 0.1
+ * @checkstyle JavadocMethodCheck (500 lines)
+ */
+public final class HtBodySkipInputTest {
+
+    @Test
+    public void skipsSomeBytes() throws Exception {
+        final String prefix = "Hello dude!";
+        final String suffix = "How are you?";
+        final String delimiter = "\r";
+        MatcherAssert.assertThat(
+            new TextOf(
+                new HtBody.SkipInput(
+                    new InputOf(
+                        new JoinedText(
+                            delimiter,
+                            prefix,
+                            suffix
+                        )
+                    ),
+                    new BytesOf(delimiter)
+                )
+            ).asString(),
+            Matchers.equalTo(suffix)
+        );
+    }
+
+    @Test
+    public void skipsEverythingWhenNoDelimiter() throws Exception {
+        MatcherAssert.assertThat(
+            new TextOf(
+                new HtBody.SkipInput(
+                    new InputOf("Hello, dude! How are you?"),
+                    new BytesOf("\n")
+                )
+            ).asString(),
+            Matchers.equalTo("")
+        );
+    }
+
+    @Test
+    public void skipsEverythingWhenEndingWithDelimiter() throws Exception {
+        final String delimiter = "\r\n";
+        MatcherAssert.assertThat(
+            new TextOf(
+                new HtBody.SkipInput(
+                    new InputOf(
+                        new JoinedText(
+                            "",
+                            "Hello dude! How are you?",
+                            delimiter
+                        )
+                    ),
+                    new BytesOf(delimiter)
+                )
+            ).asString(),
+            Matchers.equalTo("")
+        );
+    }
+}