yegor256#306 persistent connection implementation

src/main/java/org/takes/http/BkReuse.java

@@ -0,0 +1,364 @@
+/**
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2015 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.takes.http;
+
+import java.io.BufferedInputStream;
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.FilterInputStream;
+import java.io.FilterOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.PrintWriter;
+import java.net.HttpURLConnection;
+import java.net.Socket;
+import java.net.SocketTimeoutException;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+import org.takes.HttpException;
+import org.takes.Request;
+import org.takes.Response;
+import org.takes.rq.RqGreedy;
+import org.takes.rq.RqHeaders;
+import org.takes.rq.RqLive;
+import org.takes.rq.RqMethod;
+import org.takes.rs.RsPrint;
+import org.takes.rs.RsText;
+import org.takes.rs.RsWithStatus;
+
+/**
+ * Back that can reuse connections.
+ * @author Shan Huang ([email protected])
+ * @version $Id$
+ * @checkstyle ClassDataAbstractionCouplingCheck (500 lines)
+ */
+public final class BkReuse implements Back {
+    /**
+     * Max header size for buffer.
+     */
+    private static final int MAX_HEADER_SIZE = 4096;
+
+    /**
+     * Timeout for timeout input stream.
+     */
+    private static final long TIMEOUT = 5000;
+
+    /**
+     * Origin back-end.
+     */
+    private final transient Back origin;
+
+    /**
+     * Constructor of BkReuse.
+     * @param back Origin back-end.
+     */
+    public BkReuse(final Back back) {
+        this.origin = back;
+    }
+
+    @Override
+    public void accept(final Socket socket) throws IOException {
+        final InputStream input =
+                new TimeoutInputStream(
+                        new BufferedInputStream(socket.getInputStream()),
+                        BkReuse.TIMEOUT
+                );
+        final OutputStream output = socket.getOutputStream();
+        final CloselessSocket closeless =
+                new CloselessSocket(socket, input, output);
+        boolean keepAlive = true;
+        while (keepAlive) {
+            try {
+                if (this.isEndOfStream(input)) {
+                    break;
+                }
+                final Request req = this.extractHeaders(input);
+                keepAlive = this.isKeepAlive(req);
+                if (keepAlive && this.isRequireLen(output, req)) {
+                    continue;
+                }
+            } catch (final SocketTimeoutException ex) {
+                break;
+            }
+            this.origin.accept(closeless);
+        }
+        input.close();
+        output.close();
+    }
+
+    /**
+     * Extract http headers from input stream.
+     * @param input Input stream.
+     * @return Request with headers.
+     * @throws IOException IOException.
+     */
+    private Request extractHeaders(final InputStream input)
+            throws IOException {
+        input.mark(MAX_HEADER_SIZE);
+        final Request req = new RqLive(input);
+        input.reset();
+        return req;
+    }
+
+    /**
+     * Examine whether Content-Length is required.
+     * @param output Output stream.
+     * @param req Target Request.
+     * @return True if content-length is required.
+     * @throws IOException IOException.
+     */
+    private boolean isRequireLen(final OutputStream output,
+            final Request req) throws IOException {
+        boolean toBeContinue = false;
+        if (!"GET".equalsIgnoreCase(new RqMethod.Base(req).method())) {
+            try {
+                new RqHeaders.Smart(
+                        new RqHeaders.Base(req)
+                        ).single("Content-Length");
+            } catch (final HttpException ex) {
+                new RqGreedy(req);
+                new RsPrint(
+                        BkReuse.failure(
+                                ex,
+                                HttpURLConnection.HTTP_LENGTH_REQUIRED
+                                )
+                        ).print(output);
+                toBeContinue = true;
+            }
+        }
+        return toBeContinue;
+    }
+
+    /**
+     * Examine whether input is at end of stream.
+     * @param input Input Stream.
+     * @return True if hits end of stream.
+     * @throws IOException IOException.
+     */
+    private boolean isEndOfStream(final InputStream input)
+            throws IOException {
+        input.mark(1);
+        final int data = input.read();
+        input.reset();
+        return data == -1;
+    }
+
+    /**
+     * Examine whether the connection should be keep-alive.
+     * @param req Request to be examined.
+     * @return True if connection should be keep-alive.
+     * @throws IOException Socket IOException.
+     */
+    private boolean isKeepAlive(final Request req) throws IOException {
+        return !"close".equalsIgnoreCase(
+                new RqHeaders.Smart(
+                        new RqHeaders.Base(req)
+                ).single("connection", "keep-alive")
+        );
+    }
+
+    /**
+     * Make a failure response.
+     * @param err Error
+     * @param code HTTP error code
+     * @return Response
+     */
+    private static Response failure(final Throwable err, final int code) {
+        final ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        final PrintWriter writer = new PrintWriter(baos);
+        err.printStackTrace(writer);
+        writer.close();
+        return new RsWithStatus(
+            new RsText(new ByteArrayInputStream(baos.toByteArray())),
+            code
+        );
+    }
+
+    /**
+     * CloselessSocket.
+     * @author Shan Huang ([email protected])
+     * @version $Id$
+     */
+    final class CloselessSocket extends Socket {
+        /**
+         * Origin socket.
+         */
+        private final transient Socket origin;
+        /**
+         * InputStream of the origin socket.
+         */
+        private final transient InputStream input;
+        /**
+         * OutputStream of the origin socket.
+         */
+        private final transient OutputStream output;
+
+        /**
+         * Constructor for CloselessSocket.
+         * @param socket Socket to be wrapped.
+         * @param inpt InputStream of target socket.
+         * @param outpt OutputStream of target socket.
+         */
+        public CloselessSocket(final Socket socket, final InputStream inpt,
+                final OutputStream outpt) {
+            super();
+            this.origin = socket;
+            this.input = inpt;
+            this.output = outpt;
+        }
+
+        @Override
+        public InputStream getInputStream() throws IOException {
+            return new CloselessInputStream(this.input);
+        }
+
+        @Override
+        public OutputStream getOutputStream() throws IOException {
+            return new CloselessOutputStream(this.output);
+        }
+    }
+
+    /**
+     * CloselessInputStream.
+     * @author Shan Huang ([email protected])
+     * @version $Id$
+     */
+    final class CloselessInputStream extends FilterInputStream {
+
+        /**
+         * Closeless input stream constructor.
+         * @param input Origin input stream.
+         */
+        public CloselessInputStream(final InputStream input) {
+            super(input);
+        }
+
+        @Override
+        public void close() throws IOException {
+            // Do nothing.
+        }
+
+    }
+
+    /**
+     * CloselessOutputStream.
+     * @author Shan Huang ([email protected])
+     * @version $Id$
+     */
+    final class CloselessOutputStream extends FilterOutputStream {
+
+        /**
+         * Closeless output stream constructor.
+         * @param output Origin output stream.
+         */
+        public CloselessOutputStream(final OutputStream output) {
+            super(output);
+        }
+
+        @Override
+        public void close() throws IOException {
+            super.flush();
+        }
+
+    }
+
+    /**
+     * Input stream with a timeout.
+     * @author Shan Huang ([email protected])
+     * @version $Id$
+     */
+    final class TimeoutInputStream extends FilterInputStream {
+
+        /**
+         * Asynchronous task executor.
+         */
+        private final transient ExecutorService executor;
+        /**
+         * Timeout.
+         */
+        private final transient long timeout;
+
+        /**
+         * Constructor for timeout input stream.
+         * @param input Origin input stream.
+         * @param tmout Timeout.
+         */
+        public TimeoutInputStream(final InputStream input, final long tmout) {
+            super(input);
+            this.timeout = tmout;
+            this.executor = Executors.newSingleThreadExecutor();
+        }
+
+        @Override
+        public int read() throws IOException {
+            Integer data = -1;
+            final Future<Integer> future =
+                    this.executor.submit(new Task(super.in));
+            try {
+                data = future.get(this.timeout, TimeUnit.MILLISECONDS);
+            } catch (final InterruptedException ex) {
+                throw new IOException(ex);
+            } catch (final ExecutionException ex) {
+                throw new IOException(ex);
+            } catch (final TimeoutException ex) {
+                final SocketTimeoutException stex =
+                        new SocketTimeoutException();
+                stex.initCause(ex);
+                throw stex;
+            }
+            return data;
+        }
+
+        /**
+         * Input stream read task.
+         * @author Huang
+         * @version $Id$
+         */
+        class Task implements Callable<Integer> {
+            /**
+             * Origin input stream.
+             */
+            private final transient InputStream origin;
+
+            /**
+             * Constructor for read task.
+             * @param input Origin input stream.
+             */
+            public Task(final InputStream input) {
+                this.origin = input;
+            }
+
+            @Override
+            public Integer call() throws IOException {
+                return this.origin.read();
+            }
+        }
+    }
+}