1 /*
2 * Copyright (c) 1996, 2008, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package sun.net.www.http;
27
28 import java.io.*;
29 import sun.net.ProgressSource;
30 import sun.net.www.MeteredStream;
31
32 /**
33 * A stream that has the property of being able to be kept alive for
34 * multiple downloads from the same server.
35 *
36 * @author Stephen R. Pietrowicz (NCSA)
37 * @author Dave Brown
38 */
39 public
40 class KeepAliveStream extends MeteredStream implements Hurryable {
41
42 // instance variables
43 HttpClient hc;
44
45 boolean hurried;
46
47 // has this KeepAliveStream been put on the queue for asynchronous cleanup.
48 protected boolean queuedForCleanup = false;
49
50 private static final KeepAliveStreamCleaner queue = new KeepAliveStreamCleaner();
51 private static Thread cleanerThread; // null
52
53 /**
54 * Constructor
55 */
56 public KeepAliveStream(InputStream is, ProgressSource pi, long expected, HttpClient hc) {
57 super(is, pi, expected);
58 this.hc = hc;
59 }
60
61 /**
62 * Attempt to cache this connection
63 */
64 public void close() throws IOException {
65 // If the inputstream is closed already, just return.
66 if (closed) {
67 return;
68 }
69
70 // If this stream has already been queued for cleanup.
71 if (queuedForCleanup) {
72 return;
73 }
74
75 // Skip past the data that's left in the Inputstream because
76 // some sort of error may have occurred.
77 // Do this ONLY if the skip won't block. The stream may have
78 // been closed at the beginning of a big file and we don't want
79 // to hang around for nothing. So if we can't skip without blocking
80 // we just close the socket and, therefore, terminate the keepAlive
81 // NOTE: Don't close super class
82 try {
83 if (expected > count) {
84 long nskip = (long) (expected - count);
85 if (nskip <= available()) {
86 long n = 0;
87 while (n < nskip) {
88 nskip = nskip - n;
89 n = skip(nskip);
90 }
91 } else if (expected <= KeepAliveStreamCleaner.MAX_DATA_REMAINING && !hurried) {
92 //put this KeepAliveStream on the queue so that the data remaining
93 //on the socket can be cleanup asyncronously.
94 queueForCleanup(new KeepAliveCleanerEntry(this, hc));
95 } else {
96 hc.closeServer();
97 }
98 }
99 if (!closed && !hurried && !queuedForCleanup) {
100 hc.finished();
101 }
102 } finally {
103 if (pi != null)
104 pi.finishTracking();
105
106 if (!queuedForCleanup) {
107 // nulling out the underlying inputstream as well as
108 // httpClient to let gc collect the memories faster
109 in = null;
110 hc = null;
111 closed = true;
112 }
113 }
114 }
115
116 /* we explicitly do not support mark/reset */
117
118 public boolean markSupported() {
119 return false;
120 }
121
122 public void mark(int limit) {}
123
124 public void reset() throws IOException {
125 throw new IOException("mark/reset not supported");
126 }
127
128 public synchronized boolean hurry() {
129 try {
130 /* CASE 0: we're actually already done */
131 if (closed || count >= expected) {
132 return false;
133 } else if (in.available() < (expected - count)) {
134 /* CASE I: can't meet the demand */
135 return false;
136 } else {
137 /* CASE II: fill our internal buffer
138 * Remind: possibly check memory here
139 */
140 int size = (int) (expected - count);
141 byte[] buf = new byte[size];
142 DataInputStream dis = new DataInputStream(in);
143 dis.readFully(buf);
144 in = new ByteArrayInputStream(buf);
145 hurried = true;
146 return true;
147 }
148 } catch (IOException e) {
149 // e.printStackTrace();
150 return false;
151 }
152 }
153
154 private static void queueForCleanup(KeepAliveCleanerEntry kace) {
155 synchronized(queue) {
156 if(!kace.getQueuedForCleanup()) {
157 if (!queue.offer(kace)) {
158 kace.getHttpClient().closeServer();
159 return;
160 }
161
162 kace.setQueuedForCleanup();
163 queue.notifyAll();
164 }
165
166 boolean startCleanupThread = (cleanerThread == null);
167 if (!startCleanupThread) {
168 if (!cleanerThread.isAlive()) {
169 startCleanupThread = true;
170 }
171 }
172
173 if (startCleanupThread) {
174 java.security.AccessController.doPrivileged(
175 new java.security.PrivilegedAction<Void>() {
176 public Void run() {
177 // We want to create the Keep-Alive-SocketCleaner in the
178 // system threadgroup
179 ThreadGroup grp = Thread.currentThread().getThreadGroup();
180 ThreadGroup parent = null;
181 while ((parent = grp.getParent()) != null) {
182 grp = parent;
183 }
184
185 cleanerThread = new Thread(grp, queue, "Keep-Alive-SocketCleaner");
186 cleanerThread.setDaemon(true);
187 cleanerThread.setPriority(Thread.MAX_PRIORITY - 2);
188 // Set the context class loader to null in order to avoid
189 // keeping a strong reference to an application classloader.
190 cleanerThread.setContextClassLoader(null);
191 cleanerThread.start();
192 return null;
193 }
194 });
195 }
196 } // queue
197 }
198
199 protected long remainingToRead() {
200 return expected - count;
201 }
202
203 protected void setClosed() {
204 in = null;
205 hc = null;
206 closed = true;
207 }
208 }
209
210
211 class KeepAliveCleanerEntry
212 {
213 KeepAliveStream kas;
214 HttpClient hc;
215
216 public KeepAliveCleanerEntry(KeepAliveStream kas, HttpClient hc) {
217 this.kas = kas;
218 this.hc = hc;
219 }
220
221 protected KeepAliveStream getKeepAliveStream() {
222 return kas;
223 }
224
225 protected HttpClient getHttpClient() {
226 return hc;
227 }
228
229 protected void setQueuedForCleanup() {
230 kas.queuedForCleanup = true;
231 }
232
233 protected boolean getQueuedForCleanup() {
234 return kas.queuedForCleanup;
235 }
236
237 }