http.server: Use TemporaryBuffer and compress some responses
The HTTP server side code now uses the same approach that the smart
HTTP client code uses when preparing a request body. The payload
is streamed into a TemporaryBuffer of limited size. If the entire
data fits, its compressed with gzip if the user agent supports that,
and a Content-Length header is used to transmit the fixed length
body to the peer. If however the data overflows the limited memory
segment, its streamed uncompressed to the peer.
One might initially think that larger contents which overflow
the buffer should also be compressed, rather than sent raw, since
they were deemed "large". But usually these larger contents are
actually a pack file which has been already heavily compressed by
Git specific routines. Trying to deflate that with gzip is probably
going to take up more space, not less, so the compression overhead
isn't worthwhile.
This buffer and compress optimization helps repositories with a
large number of references, as their text based advertisements
compress well. For example jgit's own native repository currently
requires 32,628 bytes for its full advertisement of 489 references.
Most repositories have fewer references, and thus could compress
their entire response in one buffer.
Change-Id: I790609c9f763339e0a1db9172aa570e29af96f42
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
14 years ago |
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- /*
- * Copyright (C) 2009-2010, Google Inc.
- * and other copyright owners as documented in the project's IP log.
- *
- * This program and the accompanying materials are made available
- * under the terms of the Eclipse Distribution License v1.0 which
- * accompanies this distribution, is reproduced below, and is
- * available at http://www.eclipse.org/org/documents/edl-v10.php
- *
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or
- * without modification, are permitted provided that the following
- * conditions are met:
- *
- * - Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- *
- * - Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the following
- * disclaimer in the documentation and/or other materials provided
- * with the distribution.
- *
- * - Neither the name of the Eclipse Foundation, Inc. nor the
- * names of its contributors may be used to endorse or promote
- * products derived from this software without specific prior
- * written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
- * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
- * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
- * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
- * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
- package org.eclipse.jgit.http.server;
-
- import static org.eclipse.jgit.util.HttpSupport.ENCODING_GZIP;
- import static org.eclipse.jgit.util.HttpSupport.HDR_ACCEPT_ENCODING;
- import static org.eclipse.jgit.util.HttpSupport.HDR_CONTENT_ENCODING;
- import static org.eclipse.jgit.util.HttpSupport.HDR_ETAG;
- import static org.eclipse.jgit.util.HttpSupport.TEXT_PLAIN;
-
- import java.io.ByteArrayOutputStream;
- import java.io.IOException;
- import java.io.InputStream;
- import java.io.OutputStream;
- import java.security.MessageDigest;
- import java.text.MessageFormat;
- import java.util.zip.GZIPInputStream;
- import java.util.zip.GZIPOutputStream;
-
- import javax.servlet.ServletRequest;
- import javax.servlet.http.HttpServletRequest;
- import javax.servlet.http.HttpServletResponse;
-
- import org.eclipse.jgit.lib.Constants;
- import org.eclipse.jgit.lib.ObjectId;
- import org.eclipse.jgit.lib.Repository;
-
- /** Common utility functions for servlets. */
- public final class ServletUtils {
- /** Request attribute which stores the {@link Repository} instance. */
- public static final String ATTRIBUTE_REPOSITORY = "org.eclipse.jgit.Repository";
-
- /**
- * Get the selected repository from the request.
- *
- * @param req
- * the current request.
- * @return the repository; never null.
- * @throws IllegalStateException
- * the repository was not set by the filter, the servlet is
- * being invoked incorrectly and the programmer should ensure
- * the filter runs before the servlet.
- * @see #ATTRIBUTE_REPOSITORY
- */
- public static Repository getRepository(final ServletRequest req) {
- Repository db = (Repository) req.getAttribute(ATTRIBUTE_REPOSITORY);
- if (db == null)
- throw new IllegalStateException(HttpServerText.get().expectedRepositoryAttribute);
- return db;
- }
-
- /**
- * Open the request input stream, automatically inflating if necessary.
- * <p>
- * This method automatically inflates the input stream if the request
- * {@code Content-Encoding} header was set to {@code gzip} or the legacy
- * {@code x-gzip}.
- *
- * @param req
- * the incoming request whose input stream needs to be opened.
- * @return an input stream to read the raw, uncompressed request body.
- * @throws IOException
- * if an input or output exception occurred.
- */
- public static InputStream getInputStream(final HttpServletRequest req)
- throws IOException {
- InputStream in = req.getInputStream();
- final String enc = req.getHeader(HDR_CONTENT_ENCODING);
- if (ENCODING_GZIP.equals(enc) || "x-gzip".equals(enc)) //$NON-NLS-1$
- in = new GZIPInputStream(in);
- else if (enc != null)
- throw new IOException(MessageFormat.format(HttpServerText.get().encodingNotSupportedByThisLibrary
- , HDR_CONTENT_ENCODING, enc));
- return in;
- }
-
- /**
- * Send a plain text response to a {@code GET} or {@code HEAD} HTTP request.
- * <p>
- * The text response is encoded in the Git character encoding, UTF-8.
- * <p>
- * If the user agent supports a compressed transfer encoding and the content
- * is large enough, the content may be compressed before sending.
- * <p>
- * The {@code ETag} and {@code Content-Length} headers are automatically set
- * by this method. {@code Content-Encoding} is conditionally set if the user
- * agent supports a compressed transfer. Callers are responsible for setting
- * any cache control headers.
- *
- * @param content
- * to return to the user agent as this entity's body.
- * @param req
- * the incoming request.
- * @param rsp
- * the outgoing response.
- * @throws IOException
- * the servlet API rejected sending the body.
- */
- public static void sendPlainText(final String content,
- final HttpServletRequest req, final HttpServletResponse rsp)
- throws IOException {
- final byte[] raw = content.getBytes(Constants.CHARACTER_ENCODING);
- rsp.setContentType(TEXT_PLAIN);
- rsp.setCharacterEncoding(Constants.CHARACTER_ENCODING);
- send(raw, req, rsp);
- }
-
- /**
- * Send a response to a {@code GET} or {@code HEAD} HTTP request.
- * <p>
- * If the user agent supports a compressed transfer encoding and the content
- * is large enough, the content may be compressed before sending.
- * <p>
- * The {@code ETag} and {@code Content-Length} headers are automatically set
- * by this method. {@code Content-Encoding} is conditionally set if the user
- * agent supports a compressed transfer. Callers are responsible for setting
- * {@code Content-Type} and any cache control headers.
- *
- * @param content
- * to return to the user agent as this entity's body.
- * @param req
- * the incoming request.
- * @param rsp
- * the outgoing response.
- * @throws IOException
- * the servlet API rejected sending the body.
- */
- public static void send(byte[] content, final HttpServletRequest req,
- final HttpServletResponse rsp) throws IOException {
- content = sendInit(content, req, rsp);
- final OutputStream out = rsp.getOutputStream();
- try {
- out.write(content);
- out.flush();
- } finally {
- out.close();
- }
- }
-
- private static byte[] sendInit(byte[] content,
- final HttpServletRequest req, final HttpServletResponse rsp)
- throws IOException {
- rsp.setHeader(HDR_ETAG, etag(content));
- if (256 < content.length && acceptsGzipEncoding(req)) {
- content = compress(content);
- rsp.setHeader(HDR_CONTENT_ENCODING, ENCODING_GZIP);
- }
- rsp.setContentLength(content.length);
- return content;
- }
-
- static boolean acceptsGzipEncoding(final HttpServletRequest req) {
- final String accepts = req.getHeader(HDR_ACCEPT_ENCODING);
- return accepts != null && 0 <= accepts.indexOf(ENCODING_GZIP);
- }
-
- private static byte[] compress(final byte[] raw) throws IOException {
- final int maxLen = raw.length + 32;
- final ByteArrayOutputStream out = new ByteArrayOutputStream(maxLen);
- final GZIPOutputStream gz = new GZIPOutputStream(out);
- gz.write(raw);
- gz.finish();
- gz.flush();
- return out.toByteArray();
- }
-
- private static String etag(final byte[] content) {
- final MessageDigest md = Constants.newMessageDigest();
- md.update(content);
- return ObjectId.fromRaw(md.digest()).getName();
- }
-
- private ServletUtils() {
- // static utility class only
- }
- }
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