J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2002 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package com.sun.jndi.ldap.pool; |
| 27 | |
| 28 | import java.util.ArrayList; // JDK 1.2 |
| 29 | import java.util.List; |
| 30 | import java.util.Iterator; |
| 31 | |
| 32 | import java.lang.ref.Reference; |
| 33 | import java.lang.ref.SoftReference; |
| 34 | |
| 35 | import javax.naming.NamingException; |
| 36 | import javax.naming.InterruptedNamingException; |
| 37 | import javax.naming.CommunicationException; |
| 38 | |
| 39 | /** |
| 40 | * Represents a list of PooledConnections (actually, ConnectionDescs) with the |
| 41 | * same pool id. |
| 42 | * The list starts out with an initial number of connections. |
| 43 | * Additional PooledConnections are created lazily upon demand. |
| 44 | * The list has a maximum size. When the number of connections |
| 45 | * reaches the maximum size, a request for a PooledConnection blocks until |
| 46 | * a connection is returned to the list. A maximum size of zero means that |
| 47 | * there is no maximum: connection creation will be attempted when |
| 48 | * no idle connection is available. |
| 49 | * |
| 50 | * The list may also have a preferred size. If the current list size |
| 51 | * is less than the preferred size, a request for a connection will result in |
| 52 | * a PooledConnection being created (even if an idle connection is available). |
| 53 | * If the current list size is greater than the preferred size, |
| 54 | * a connection being returned to the list will be closed and removed from |
| 55 | * the list. A preferred size of zero means that there is no preferred size: |
| 56 | * connections are created only when no idle connection is available and |
| 57 | * a connection being returned to the list is not closed. Regardless of the |
| 58 | * preferred size, connection creation always observes the maximum size: |
| 59 | * a connection won't be created if the list size is at or exceeds the |
| 60 | * maximum size. |
| 61 | * |
| 62 | * @author Rosanna Lee |
| 63 | */ |
| 64 | |
| 65 | // Package private: accessed only by Pool |
| 66 | final class Connections implements PoolCallback { |
| 67 | private static final boolean debug = Pool.debug; |
| 68 | private static final boolean trace = |
| 69 | com.sun.jndi.ldap.LdapPoolManager.trace; |
| 70 | private static final int DEFAULT_SIZE = 10; |
| 71 | |
| 72 | final private int maxSize; |
| 73 | final private int prefSize; |
| 74 | final private List conns; |
| 75 | |
| 76 | private boolean closed = false; // Closed for business |
| 77 | private Reference ref; // maintains reference to id to prevent premature GC |
| 78 | |
| 79 | /** |
| 80 | * @param id the identity (connection request) of the connections in the list |
| 81 | * @param initSize the number of connections to create initially |
| 82 | * @param prefSize the preferred size of the pool. The pool will try |
| 83 | * to maintain a pool of this size by creating and closing connections |
| 84 | * as needed. |
| 85 | * @param maxSize the maximum size of the pool. The pool will not exceed |
| 86 | * this size. If the pool is at this size, a request for a connection |
| 87 | * will block until an idle connection is released to the pool or |
| 88 | * when one is removed. |
| 89 | * @param factory The factory responsible for creating a connection |
| 90 | */ |
| 91 | Connections(Object id, int initSize, int prefSize, int maxSize, |
| 92 | PooledConnectionFactory factory) throws NamingException { |
| 93 | |
| 94 | this.maxSize = maxSize; |
| 95 | if (maxSize > 0) { |
| 96 | // prefSize and initSize cannot exceed specified maxSize |
| 97 | this.prefSize = Math.min(prefSize, maxSize); |
| 98 | initSize = Math.min(initSize, maxSize); |
| 99 | } else { |
| 100 | this.prefSize = prefSize; |
| 101 | } |
| 102 | conns = new ArrayList(maxSize > 0 ? maxSize : DEFAULT_SIZE); |
| 103 | |
| 104 | // Maintain soft ref to id so that this Connections' entry in |
| 105 | // Pool doesn't get GC'ed prematurely |
| 106 | ref = new SoftReference(id); |
| 107 | |
| 108 | d("init size=", initSize); |
| 109 | d("max size=", maxSize); |
| 110 | d("preferred size=", prefSize); |
| 111 | |
| 112 | // Create initial connections |
| 113 | PooledConnection conn; |
| 114 | for (int i = 0; i < initSize; i++) { |
| 115 | conn = factory.createPooledConnection(this); |
| 116 | td("Create ", conn ,factory); |
| 117 | conns.add(new ConnectionDesc(conn)); // Add new idle conn to pool |
| 118 | } |
| 119 | } |
| 120 | |
| 121 | /** |
| 122 | * Retrieves a PooledConnection from this list of connections. |
| 123 | * Use an existing one if one is idle, or create one if the list's |
| 124 | * max size hasn't been reached. If max size has been reached, wait |
| 125 | * for a PooledConnection to be returned, or one to be removed (thus |
| 126 | * not reaching the max size any longer). |
| 127 | * |
| 128 | * @param timeout if > 0, msec to wait until connection is available |
| 129 | * @param factory creates the PooledConnection if one needs to be created |
| 130 | * |
| 131 | * @return A non-null PooledConnection |
| 132 | * @throws NamingException PooledConnection cannot be created, because this |
| 133 | * thread was interrupted while it waited for an available connection, |
| 134 | * or if it timed out while waiting, or the creation of a connection |
| 135 | * resulted in an error. |
| 136 | */ |
| 137 | synchronized PooledConnection get(long timeout, |
| 138 | PooledConnectionFactory factory) throws NamingException { |
| 139 | PooledConnection conn; |
| 140 | long start = (timeout > 0 ? System.currentTimeMillis() : 0); |
| 141 | long waittime = timeout; |
| 142 | |
| 143 | d("get(): before"); |
| 144 | while ((conn = getOrCreateConnection(factory)) == null) { |
| 145 | if (timeout > 0 && waittime <= 0) { |
| 146 | throw new CommunicationException( |
| 147 | "Timeout exceeded while waiting for a connection: " + |
| 148 | timeout + "ms"); |
| 149 | } |
| 150 | try { |
| 151 | d("get(): waiting"); |
| 152 | if (waittime > 0) { |
| 153 | wait(waittime); // Wait until one is released or removed |
| 154 | } else { |
| 155 | wait(); |
| 156 | } |
| 157 | } catch (InterruptedException e) { |
| 158 | throw new InterruptedNamingException( |
| 159 | "Interrupted while waiting for a connection"); |
| 160 | } |
| 161 | // Check whether we timed out |
| 162 | if (timeout > 0) { |
| 163 | long now = System.currentTimeMillis(); |
| 164 | waittime = timeout - (now - start); |
| 165 | } |
| 166 | } |
| 167 | |
| 168 | d("get(): after"); |
| 169 | return conn; |
| 170 | } |
| 171 | |
| 172 | /** |
| 173 | * Retrieves an idle connection from this list if one is available. |
| 174 | * If none is available, create a new one if maxSize hasn't been reached. |
| 175 | * If maxSize has been reached, return null. |
| 176 | * Always called from a synchronized method. |
| 177 | */ |
| 178 | private PooledConnection getOrCreateConnection( |
| 179 | PooledConnectionFactory factory) throws NamingException { |
| 180 | |
| 181 | int size = conns.size(); // Current number of idle/nonidle conns |
| 182 | PooledConnection conn = null; |
| 183 | |
| 184 | if (prefSize <= 0 || size >= prefSize) { |
| 185 | // If no prefSize specified, or list size already meets or |
| 186 | // exceeds prefSize, then first look for an idle connection |
| 187 | ConnectionDesc entry; |
| 188 | for (int i = 0; i < size; i++) { |
| 189 | entry = (ConnectionDesc) conns.get(i); |
| 190 | if ((conn = entry.tryUse()) != null) { |
| 191 | d("get(): use ", conn); |
| 192 | td("Use ", conn); |
| 193 | return conn; |
| 194 | } |
| 195 | } |
| 196 | } |
| 197 | |
| 198 | // Check if list size already at maxSize specified |
| 199 | if (maxSize > 0 && size >= maxSize) { |
| 200 | return null; // List size is at limit; cannot create any more |
| 201 | } |
| 202 | |
| 203 | conn = factory.createPooledConnection(this); |
| 204 | td("Create and use ", conn, factory); |
| 205 | conns.add(new ConnectionDesc(conn, true)); // Add new conn to pool |
| 206 | |
| 207 | return conn; |
| 208 | } |
| 209 | |
| 210 | /** |
| 211 | * Releases connection back into list. |
| 212 | * If the list size is below prefSize, the connection may be reused. |
| 213 | * If the list size exceeds prefSize, then the connection is closed |
| 214 | * and removed from the list. |
| 215 | * |
| 216 | * public because implemented as part of PoolCallback. |
| 217 | */ |
| 218 | public synchronized boolean releasePooledConnection(PooledConnection conn) { |
| 219 | ConnectionDesc entry; |
| 220 | int loc = conns.indexOf(entry=new ConnectionDesc(conn)); |
| 221 | |
| 222 | d("release(): ", conn); |
| 223 | |
| 224 | if (loc >= 0) { |
| 225 | // Found entry |
| 226 | |
| 227 | if (closed || (prefSize > 0 && conns.size() > prefSize)) { |
| 228 | // If list size exceeds prefSize, close connection |
| 229 | |
| 230 | d("release(): closing ", conn); |
| 231 | td("Close ", conn); |
| 232 | |
| 233 | // size must be >= 2 so don't worry about empty list |
| 234 | conns.remove(entry); |
| 235 | conn.closeConnection(); |
| 236 | |
| 237 | } else { |
| 238 | d("release(): release ", conn); |
| 239 | td("Release ", conn); |
| 240 | |
| 241 | // Get ConnectionDesc from list to get correct state info |
| 242 | entry = (ConnectionDesc) conns.get(loc); |
| 243 | // Return connection to list, ready for reuse |
| 244 | entry.release(); |
| 245 | } |
| 246 | notifyAll(); |
| 247 | d("release(): notify"); |
| 248 | return true; |
| 249 | } else { |
| 250 | return false; |
| 251 | } |
| 252 | } |
| 253 | |
| 254 | /** |
| 255 | * Removes PooledConnection from list of connections. |
| 256 | * The closing of the connection is separate from this method. |
| 257 | * This method is called usually when the caller encouters an error |
| 258 | * when using the connection and wants it removed from the pool. |
| 259 | * |
| 260 | * @return true if conn removed; false if it was not in pool |
| 261 | * |
| 262 | * public because implemented as part of PoolCallback. |
| 263 | */ |
| 264 | public synchronized boolean removePooledConnection(PooledConnection conn) { |
| 265 | if (conns.remove(new ConnectionDesc(conn))) { |
| 266 | d("remove(): ", conn); |
| 267 | |
| 268 | notifyAll(); |
| 269 | |
| 270 | d("remove(): notify"); |
| 271 | td("Remove ", conn); |
| 272 | |
| 273 | if (conns.isEmpty()) { |
| 274 | // Remove softref to make pool entry eligible for GC. |
| 275 | // Once ref has been removed, it cannot be reinstated. |
| 276 | ref = null; |
| 277 | } |
| 278 | |
| 279 | return true; |
| 280 | } else { |
| 281 | d("remove(): not found ", conn); |
| 282 | return false; |
| 283 | } |
| 284 | } |
| 285 | |
| 286 | /** |
| 287 | * Goes through all entries in list, removes and closes ones that have been |
| 288 | * idle before threshold. |
| 289 | * |
| 290 | * @param threshold an entry idle since this time has expired. |
| 291 | * @return true if no more connections in list |
| 292 | */ |
| 293 | synchronized boolean expire(long threshold) { |
| 294 | Iterator iter = conns.iterator(); |
| 295 | ConnectionDesc entry; |
| 296 | while (iter.hasNext()) { |
| 297 | entry = (ConnectionDesc) iter.next(); |
| 298 | if (entry.expire(threshold)) { |
| 299 | d("expire(): removing ", entry); |
| 300 | td("Expired ", entry); |
| 301 | |
| 302 | iter.remove(); // remove from pool |
| 303 | |
| 304 | // Don't need to call notify() because we're |
| 305 | // removing only idle connections. If there were |
| 306 | // idle connections, then there should be no waiters. |
| 307 | } |
| 308 | } |
| 309 | return conns.isEmpty(); // whether whole list has 'expired' |
| 310 | } |
| 311 | |
| 312 | /** |
| 313 | * Called when this instance of Connections has been removed from Pool. |
| 314 | * This means that no one can get any pooled connections from this |
| 315 | * Connections any longer. Expire all idle connections as of 'now' |
| 316 | * and leave indicator so that any in-use connections will be closed upon |
| 317 | * their return. |
| 318 | */ |
| 319 | synchronized void close() { |
| 320 | expire(System.currentTimeMillis()); // Expire idle connections |
| 321 | closed = true; // Close in-use connections when they are returned |
| 322 | } |
| 323 | |
| 324 | String getStats() { |
| 325 | int idle = 0; |
| 326 | int busy = 0; |
| 327 | int expired = 0; |
| 328 | long use = 0; |
| 329 | int len; |
| 330 | |
| 331 | synchronized (this) { |
| 332 | len = conns.size(); |
| 333 | |
| 334 | ConnectionDesc entry; |
| 335 | for (int i = 0; i < len; i++) { |
| 336 | entry = (ConnectionDesc) conns.get(i); |
| 337 | use += entry.getUseCount(); |
| 338 | switch (entry.getState()) { |
| 339 | case ConnectionDesc.BUSY: |
| 340 | ++busy; |
| 341 | break; |
| 342 | case ConnectionDesc.IDLE: |
| 343 | ++idle; |
| 344 | break; |
| 345 | case ConnectionDesc.EXPIRED: |
| 346 | ++expired; |
| 347 | } |
| 348 | } |
| 349 | } |
| 350 | return "size=" + len + "; use=" + use + "; busy=" + busy |
| 351 | + "; idle=" + idle + "; expired=" + expired; |
| 352 | } |
| 353 | |
| 354 | private void d(String msg, Object o1) { |
| 355 | if (debug) { |
| 356 | d(msg + o1); |
| 357 | } |
| 358 | } |
| 359 | |
| 360 | private void d(String msg, int i) { |
| 361 | if (debug) { |
| 362 | d(msg + i); |
| 363 | } |
| 364 | } |
| 365 | |
| 366 | private void d(String msg) { |
| 367 | if (debug) { |
| 368 | System.err.println(this + "." + msg + "; size: " + conns.size()); |
| 369 | } |
| 370 | } |
| 371 | |
| 372 | private void td(String msg, Object o1, Object o2) { |
| 373 | if (trace) { // redo test to avoid object creation |
| 374 | td(msg + o1 + "[" + o2 + "]"); |
| 375 | } |
| 376 | } |
| 377 | private void td(String msg, Object o1) { |
| 378 | if (trace) { // redo test to avoid object creation |
| 379 | td(msg + o1); |
| 380 | } |
| 381 | } |
| 382 | private void td(String msg) { |
| 383 | if (trace) { |
| 384 | System.err.println(msg); |
| 385 | } |
| 386 | } |
| 387 | } |