| 1 | /* |
| 2 | |
| 3 | Derby - Class org.apache.derby.impl.store.raw.xact.TransactionTable |
| 4 | |
| 5 | Copyright 1997, 2004 The Apache Software Foundation or its licensors, as applicable. |
| 6 | |
| 7 | Licensed under the Apache License, Version 2.0 (the "License"); |
| 8 | you may not use this file except in compliance with the License. |
| 9 | You may obtain a copy of the License at |
| 10 | |
| 11 | http://www.apache.org/licenses/LICENSE-2.0 |
| 12 | |
| 13 | Unless required by applicable law or agreed to in writing, software |
| 14 | distributed under the License is distributed on an "AS IS" BASIS, |
| 15 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 16 | See the License for the specific language governing permissions and |
| 17 | limitations under the License. |
| 18 | |
| 19 | */ |
| 20 | |
| 21 | package org.apache.derby.impl.store.raw.xact; |
| 22 | |
| 23 | import org.apache.derby.iapi.services.context.ContextManager; |
| 24 | |
| 25 | import org.apache.derby.iapi.services.sanity.SanityManager; |
| 26 | import org.apache.derby.iapi.services.io.Formatable; |
| 27 | import org.apache.derby.iapi.services.io.FormatIdUtil; |
| 28 | import org.apache.derby.iapi.services.io.StoredFormatIds; |
| 29 | |
| 30 | import org.apache.derby.iapi.store.access.TransactionInfo; |
| 31 | |
| 32 | import org.apache.derby.iapi.store.raw.GlobalTransactionId; |
| 33 | |
| 34 | import org.apache.derby.iapi.store.raw.log.LogInstant; |
| 35 | |
| 36 | import org.apache.derby.iapi.store.raw.xact.RawTransaction; |
| 37 | import org.apache.derby.iapi.store.raw.xact.TransactionId; |
| 38 | |
| 39 | import org.apache.derby.iapi.error.StandardException; |
| 40 | |
| 41 | import org.apache.derby.iapi.services.io.CompressedNumber; |
| 42 | |
| 43 | import java.util.Hashtable; |
| 44 | import java.util.Enumeration; |
| 45 | import java.io.ObjectOutput; |
| 46 | import java.io.ObjectInput; |
| 47 | import java.io.IOException; |
| 48 | |
| 49 | /** |
| 50 | The transaction table is used by the transaction factory to keep track of |
| 51 | all transactions that are in the system. |
| 52 | |
| 53 | <BR> The transction table serves the following purposes: <OL> |
| 54 | |
| 55 | <LI> checkpoint - when a checkpoint log record is written out, it writes |
| 56 | out also all transactions that have updated the database. RESOLVE: this is |
| 57 | actually not used right now - rather, the transaction table is |
| 58 | reconstructed during the redo phase by traversing from the undo LWM. It is |
| 59 | a goal to use this transaction table (and traversing from the redoLWM) |
| 60 | instead of rebuilding it to speed up recovery. |
| 61 | |
| 62 | <LI> Quiesce State - when a system enters the quiesce state, it needs to account |
| 63 | for all transactions in the system, even those which are just started and |
| 64 | are in their IDLE state. |
| 65 | |
| 66 | <LI> TransactionTable VTI - we need to get a snapshot of all transactions |
| 67 | in the system for diagnostic purposes. |
| 68 | </OL> |
| 69 | |
| 70 | In order to speed up the time it takes to look up a transaction from the |
| 71 | transaction table, each transaction must have a unique transaction Id. |
| 72 | This means newly coined transaction must also have a transaction Id. |
| 73 | |
| 74 | <P>During recovery, there is only one real xact object doing all the |
| 75 | recovery work, but there could be many outstanding transactions that are |
| 76 | gleamed from the log. Each of these "recovery transactions" have its on |
| 77 | entry into the transaction table but they all share the same Xact object. |
| 78 | |
| 79 | <P>Multithreading considerations:<BR> |
| 80 | TransactionTable must be MT-safe it is called upon by many threads |
| 81 | simultaneously (except during recovery) |
| 82 | |
| 83 | <P><B> This class depends on Hashtable synchronization!! </B> |
| 84 | |
| 85 | */ |
| 86 | |
| 87 | public class TransactionTable implements Formatable |
| 88 | { |
| 89 | /* |
| 90 | * Fields |
| 91 | */ |
| 92 | |
| 93 | private Hashtable trans; |
| 94 | |
| 95 | private TransactionId largestUpdateXactId; |
| 96 | |
| 97 | /** |
| 98 | MT - not needed for constructor |
| 99 | */ |
| 100 | public TransactionTable() |
| 101 | { |
| 102 | trans = new Hashtable(17); |
| 103 | } |
| 104 | |
| 105 | /************************************************************* |
| 106 | * generic methods called by all clients of transaction table |
| 107 | * Must be MT -safe |
| 108 | ************************************************************/ |
| 109 | private TransactionTableEntry findTransactionEntry(TransactionId id) |
| 110 | { |
| 111 | |
| 112 | if (SanityManager.DEBUG) |
| 113 | SanityManager.ASSERT( |
| 114 | id != null, "findTransacionEntry with null id"); |
| 115 | |
| 116 | // Hashtable is synchronized |
| 117 | return (TransactionTableEntry)trans.get(id); |
| 118 | } |
| 119 | |
| 120 | |
| 121 | |
| 122 | |
| 123 | void add(Xact xact, boolean exclude) |
| 124 | { |
| 125 | TransactionId id = xact.getId(); |
| 126 | |
| 127 | synchronized(this) |
| 128 | { |
| 129 | TransactionTableEntry ent = findTransactionEntry(id); |
| 130 | |
| 131 | if (ent == null) |
| 132 | { |
| 133 | ent = new TransactionTableEntry |
| 134 | (xact, id, 0, |
| 135 | exclude ? TransactionTableEntry.EXCLUDE : 0); |
| 136 | |
| 137 | trans.put(id, ent); |
| 138 | |
| 139 | if (SanityManager.DEBUG) |
| 140 | { |
| 141 | if (SanityManager.DEBUG_ON("TranTrace")) |
| 142 | { |
| 143 | SanityManager.DEBUG( |
| 144 | "TranTrace", "adding transaction " + id); |
| 145 | SanityManager.showTrace(new Throwable("TranTrace")); |
| 146 | } |
| 147 | } |
| 148 | } |
| 149 | |
| 150 | if (SanityManager.DEBUG) |
| 151 | { |
| 152 | if (exclude != ent.needExclusion()) |
| 153 | SanityManager.THROWASSERT( |
| 154 | "adding the same transaction with different exclusion: " + |
| 155 | exclude + " " + ent.needExclusion()); |
| 156 | } |
| 157 | } |
| 158 | |
| 159 | if (SanityManager.DEBUG) { |
| 160 | |
| 161 | if (SanityManager.DEBUG_ON("memoryLeakTrace")) { |
| 162 | |
| 163 | if (trans.size() > 50) |
| 164 | System.out.println("memoryLeakTrace:TransactionTable " + trans.size()); |
| 165 | } |
| 166 | } |
| 167 | } |
| 168 | |
| 169 | /* |
| 170 | remove the transaction Id an return false iff the transaction is found |
| 171 | in the table and it doesn't need exclusion during quiesce state |
| 172 | */ |
| 173 | boolean remove(TransactionId id) |
| 174 | { |
| 175 | if (SanityManager.DEBUG) |
| 176 | SanityManager.ASSERT( |
| 177 | id != null, |
| 178 | "cannot remove transaction from table with null id"); |
| 179 | |
| 180 | if (SanityManager.DEBUG) |
| 181 | { |
| 182 | if (SanityManager.DEBUG_ON("TranTrace")) |
| 183 | { |
| 184 | SanityManager.DEBUG( |
| 185 | "TranTrace", "removing transaction " + id); |
| 186 | SanityManager.showTrace(new Throwable("TranTrace")); |
| 187 | } |
| 188 | } |
| 189 | |
| 190 | // Hashtable is synchronized |
| 191 | TransactionTableEntry ent = (TransactionTableEntry)trans.remove(id); |
| 192 | return (ent == null || ent.needExclusion()); |
| 193 | } |
| 194 | |
| 195 | |
| 196 | /** |
| 197 | Change a transaction to update or add an update transaction to this table. |
| 198 | |
| 199 | @param tid the transaction id |
| 200 | @param tran the transaction to be added |
| 201 | @param transactionStatus the transaction status that is stored in the |
| 202 | BeginXact log record |
| 203 | */ |
| 204 | public void addUpdateTransaction(TransactionId tid, RawTransaction tran, |
| 205 | int transactionStatus) |
| 206 | { |
| 207 | |
| 208 | // we need to synchronize on the transaction table because we have to |
| 209 | // prevent this state change from happening when the transaction table |
| 210 | // itself is written out to the checkpoint. This is the only |
| 211 | // protection the TransactionTableEntry has to prevent fields in myxact |
| 212 | // from changing underneath it while it is being written out. |
| 213 | synchronized(this) |
| 214 | { |
| 215 | TransactionTableEntry ent = findTransactionEntry(tid); |
| 216 | |
| 217 | if (ent != null) |
| 218 | { |
| 219 | // this happens during run time, when a transaction that is |
| 220 | // already started changed status to an update transaction |
| 221 | |
| 222 | ent.updateTransactionStatus((Xact)tran, transactionStatus, |
| 223 | TransactionTableEntry.UPDATE) ; |
| 224 | } |
| 225 | else |
| 226 | { |
| 227 | // this happens during recovery, that's why we haven't seen |
| 228 | // this transaction before - it is added in the doMe of the |
| 229 | // BeginXact log record. |
| 230 | // |
| 231 | // No matter what this transaction is, it won't need to be run |
| 232 | // in quiesce state because we are in recovery. |
| 233 | ent = new TransactionTableEntry((Xact)tran, tid, transactionStatus, |
| 234 | TransactionTableEntry.UPDATE | |
| 235 | TransactionTableEntry.EXCLUDE | |
| 236 | TransactionTableEntry.RECOVERY); |
| 237 | trans.put(tid, ent); |
| 238 | |
| 239 | } |
| 240 | |
| 241 | if (XactId.compare(ent.getXid(), largestUpdateXactId) > 0) |
| 242 | largestUpdateXactId = ent.getXid(); |
| 243 | } |
| 244 | } |
| 245 | |
| 246 | /** |
| 247 | Change update transaction to non-update |
| 248 | |
| 249 | <P>MT - MT safe, since vector is MT-safe. |
| 250 | |
| 251 | @param id the transaction Id |
| 252 | */ |
| 253 | void removeUpdateTransaction(TransactionId id) |
| 254 | { |
| 255 | // we need to synchronize on the transaction table because we have to |
| 256 | // prevent this state change from happening when the transaction table |
| 257 | // itself is written out to the checkpoint. This is the only |
| 258 | // protection the TransactionTableEntry has to prevent fields in myxact |
| 259 | // from changing underneath it while it is being written out. |
| 260 | |
| 261 | synchronized (this) |
| 262 | { |
| 263 | TransactionTableEntry ent = findTransactionEntry(id); |
| 264 | |
| 265 | if (SanityManager.DEBUG) |
| 266 | { |
| 267 | SanityManager.ASSERT(ent != null, |
| 268 | "removing update transaction that is not there"); |
| 269 | } |
| 270 | |
| 271 | ent.removeUpdateTransaction(); |
| 272 | |
| 273 | // If we are committing a recovery transaction, remove it from the |
| 274 | // transaction table. The xact object which is doing the work is |
| 275 | // not going to be closed even though the transaction is done. |
| 276 | if (ent.isRecovery()) |
| 277 | remove(id); |
| 278 | } |
| 279 | |
| 280 | return; |
| 281 | } |
| 282 | |
| 283 | /************************************************************************** |
| 284 | * Transaction table methods used by XA. |
| 285 | ************************************************************************** |
| 286 | */ |
| 287 | |
| 288 | /** |
| 289 | * Return the hash table to the XA layer. |
| 290 | * <p> |
| 291 | * The XA code will do linear read-only operations on the hash table, |
| 292 | * write operations are only done in this module. It is a little ugly |
| 293 | * to export the hash table, but I wanted to move the XA specific code |
| 294 | * into the XA module, so that we could configure out the XA code if |
| 295 | * necessary. |
| 296 | * <p> |
| 297 | * |
| 298 | * Must be MT -safe, depends on sync hash table, and must get |
| 299 | * synchronized(hash_table) for linear searches. |
| 300 | * |
| 301 | * @return The ContextManager of the transaction being searched for. |
| 302 | * |
| 303 | **/ |
| 304 | public Hashtable getTableForXA() |
| 305 | { |
| 306 | return(trans); |
| 307 | } |
| 308 | |
| 309 | /** |
| 310 | Change transaction to prepared. |
| 311 | |
| 312 | <P>MT - unsafe, caller is recovery, which is single threaded. |
| 313 | |
| 314 | @param id the transaction Id |
| 315 | */ |
| 316 | void prepareTransaction(TransactionId id) |
| 317 | { |
| 318 | // we need to synchronize on the transaction table because we have to |
| 319 | // prevent this state change from happening when the transaction table |
| 320 | // itself is written out to the checkpoint. This is the only |
| 321 | // protection the TransactionTableEntry has to prevent fields in myxact |
| 322 | // from changing underneath it while it is being written out. |
| 323 | |
| 324 | TransactionTableEntry ent = findTransactionEntry(id); |
| 325 | |
| 326 | if (SanityManager.DEBUG) |
| 327 | { |
| 328 | SanityManager.ASSERT( |
| 329 | ent != null, "preparing transaction that is not there"); |
| 330 | } |
| 331 | |
| 332 | ent.prepareTransaction(); |
| 333 | |
| 334 | return; |
| 335 | } |
| 336 | |
| 337 | /** |
| 338 | * Find a transaction in the table by Global transaction id. |
| 339 | * <p> |
| 340 | * This routine use to be only called during offline recovery so performance |
| 341 | * was not critical. Since that time more calls have been made, including |
| 342 | * one in startGlobalTransaction() so a linear search may no longer |
| 343 | * be appropriate. See DERBY-828. |
| 344 | * |
| 345 | * @return The ContextManager of the transaction being searched for. |
| 346 | * |
| 347 | * @param global_id The global transaction we are searching for. |
| 348 | **/ |
| 349 | public ContextManager findTransactionContextByGlobalId( |
| 350 | GlobalXactId global_id) |
| 351 | { |
| 352 | ContextManager cm = null; |
| 353 | |
| 354 | // Need to hold sync while linear searching the hash table. |
| 355 | synchronized (trans) |
| 356 | { |
| 357 | for (Enumeration e = trans.elements(); e.hasMoreElements();) |
| 358 | { |
| 359 | TransactionTableEntry entry = |
| 360 | (TransactionTableEntry) e.nextElement(); |
| 361 | |
| 362 | if (entry != null) |
| 363 | { |
| 364 | GlobalTransactionId entry_gid = entry.getGid(); |
| 365 | |
| 366 | if (entry_gid != null && entry_gid.equals(global_id)) |
| 367 | { |
| 368 | cm = entry.getXact().getContextManager(); |
| 369 | break; |
| 370 | } |
| 371 | } |
| 372 | } |
| 373 | } |
| 374 | |
| 375 | return(cm); |
| 376 | } |
| 377 | |
| 378 | |
| 379 | /*********************************************************** |
| 380 | * called when system is being quiesced, must be MT - safe |
| 381 | ***********************************************************/ |
| 382 | /** |
| 383 | Return true if there is no transaction actively updating the database. |
| 384 | New transaction may be started or old transaction committed |
| 385 | right afterward, the caller of this routine must have other ways to |
| 386 | stop transactions from starting or ending. |
| 387 | |
| 388 | <P>MT - safe |
| 389 | */ |
| 390 | boolean hasActiveUpdateTransaction() |
| 391 | { |
| 392 | synchronized (this) |
| 393 | { |
| 394 | for (Enumeration e = trans.elements(); e.hasMoreElements(); ) |
| 395 | { |
| 396 | TransactionTableEntry ent = (TransactionTableEntry)e.nextElement(); |
| 397 | if (ent != null && ent.isUpdate()) |
| 398 | return true; |
| 399 | } |
| 400 | } |
| 401 | return false; |
| 402 | } |
| 403 | |
| 404 | |
| 405 | |
| 406 | /************************************************************ |
| 407 | * methods called only by checkpoint |
| 408 | ***********************************************************/ |
| 409 | /* |
| 410 | * Formatable methods |
| 411 | */ |
| 412 | |
| 413 | /** |
| 414 | Return my format identifier. |
| 415 | */ |
| 416 | public int getTypeFormatId() { |
| 417 | return StoredFormatIds.RAW_STORE_TRANSACTION_TABLE; |
| 418 | } |
| 419 | |
| 420 | /** |
| 421 | @exception IOException problem reading the transaction table |
| 422 | */ |
| 423 | public void writeExternal(ObjectOutput out) throws IOException |
| 424 | { |
| 425 | //don't let the transactions status change while writing out(beetle:5533) |
| 426 | //Note: syncing both on trans and this variable could be avoided if |
| 427 | //all the routines in this class are sycned on "this" and does not |
| 428 | //depend on hash table synchronization. But that will be overkill |
| 429 | //because this routine gets called only on checkpoints and others |
| 430 | //are used more often. |
| 431 | |
| 432 | synchronized(this) |
| 433 | { |
| 434 | // don't touch the transaction table when I am being written out |
| 435 | synchronized(trans) |
| 436 | { |
| 437 | int count = 0; |
| 438 | int maxcount = trans.size(); |
| 439 | |
| 440 | // first count up the number of active update transactions |
| 441 | for (Enumeration e = trans.elements(); |
| 442 | e.hasMoreElements(); ) |
| 443 | { |
| 444 | TransactionTableEntry ent = (TransactionTableEntry)e.nextElement(); |
| 445 | if (ent != null && ent.isUpdate()) |
| 446 | count++; |
| 447 | } |
| 448 | |
| 449 | CompressedNumber.writeInt(out, count); |
| 450 | |
| 451 | // now write them out |
| 452 | if (count > 0) |
| 453 | { |
| 454 | for (Enumeration e = trans.elements(); |
| 455 | e.hasMoreElements() ; ) |
| 456 | { |
| 457 | TransactionTableEntry ent = (TransactionTableEntry)e.nextElement(); |
| 458 | if (ent != null && ent.isUpdate()) |
| 459 | { |
| 460 | // only writes out update transaction |
| 461 | out.writeObject(ent); |
| 462 | } |
| 463 | } |
| 464 | } |
| 465 | } |
| 466 | } |
| 467 | } |
| 468 | |
| 469 | /************************************************************ |
| 470 | * methods called only by recovery |
| 471 | ************************************************************/ |
| 472 | |
| 473 | |
| 474 | /** |
| 475 | @exception IOException problem reading the transaction table |
| 476 | @exception ClassNotFoundException problem reading the transaction table |
| 477 | */ |
| 478 | public void readExternal(ObjectInput in) |
| 479 | throws IOException, ClassNotFoundException |
| 480 | { |
| 481 | // RESOLVE: this is only read in checkpoint record, but we have not |
| 482 | // finish the work on using this transaction table to cut down on redo |
| 483 | // so this transaction table is effectively and futilely thrown away! |
| 484 | |
| 485 | int count = CompressedNumber.readInt(in); |
| 486 | if (count == 0) |
| 487 | return; |
| 488 | |
| 489 | for (int i = 0; i < count; i++) |
| 490 | { |
| 491 | TransactionTableEntry ent = |
| 492 | (TransactionTableEntry)in.readObject(); |
| 493 | |
| 494 | if (SanityManager.DEBUG) |
| 495 | SanityManager.ASSERT( |
| 496 | ent.getXid() != null, |
| 497 | "read in transaction table entry with null id"); |
| 498 | |
| 499 | trans.put(ent.getXid(), ent); |
| 500 | |
| 501 | if (ent.isUpdate() && |
| 502 | XactId.compare(ent.getXid(), largestUpdateXactId) > 0) |
| 503 | { |
| 504 | largestUpdateXactId = ent.getXid(); |
| 505 | } |
| 506 | } |
| 507 | |
| 508 | |
| 509 | } |
| 510 | |
| 511 | /** |
| 512 | Return the largest update transactionId I have seen so far. |
| 513 | |
| 514 | <P>MT - unsafe, caller is recovery, which is single threaded. |
| 515 | */ |
| 516 | public TransactionId largestUpdateXactId() |
| 517 | { |
| 518 | return largestUpdateXactId; |
| 519 | } |
| 520 | |
| 521 | |
| 522 | /** |
| 523 | Is there an active internal transaction in the transaction table. |
| 524 | |
| 525 | <P>MT - unsafe, caller is recovery, which is single threaded. |
| 526 | */ |
| 527 | public boolean hasRollbackFirstTransaction() |
| 528 | { |
| 529 | for (Enumeration e = trans.elements(); |
| 530 | e.hasMoreElements() ; ) |
| 531 | { |
| 532 | TransactionTableEntry ent = (TransactionTableEntry)e.nextElement(); |
| 533 | |
| 534 | if (ent != null && ent.isRecovery() && |
| 535 | (ent.getTransactionStatus() & |
| 536 | Xact.RECOVERY_ROLLBACK_FIRST) != 0) |
| 537 | { |
| 538 | return true; |
| 539 | } |
| 540 | } |
| 541 | return false; |
| 542 | } |
| 543 | |
| 544 | /** |
| 545 | Is there a prepared transaction in the transaction table. |
| 546 | |
| 547 | <P>MT - unsafe, caller is recovery, which is single threaded. |
| 548 | */ |
| 549 | public boolean hasPreparedRecoveredXact() |
| 550 | { |
| 551 | for (Enumeration e = trans.elements(); e.hasMoreElements(); ) |
| 552 | { |
| 553 | TransactionTableEntry ent = (TransactionTableEntry) e.nextElement(); |
| 554 | |
| 555 | if (ent != null && ent.isRecovery() && |
| 556 | (ent.getTransactionStatus() & Xact.END_PREPARED) != 0) |
| 557 | { |
| 558 | return true; |
| 559 | } |
| 560 | } |
| 561 | return false; |
| 562 | } |
| 563 | |
| 564 | |
| 565 | /** |
| 566 | Get the most recently added transaction that says it needs to be |
| 567 | rolled back first (an InternalXact) from the transaction table and make |
| 568 | the passed in transaction assume its identity. |
| 569 | <B> Should only be used in recovery undo !! </B> |
| 570 | RESOLVE: (sku)I don't think even these internal transactions need to be |
| 571 | rolled back in the reverse order, because they are physical in nature. |
| 572 | But it won't hurt. |
| 573 | |
| 574 | <P>MT - unsafe, caller is recovery, which is single threaded. |
| 575 | */ |
| 576 | public boolean getMostRecentRollbackFirstTransaction(RawTransaction tran) |
| 577 | { |
| 578 | |
| 579 | if (trans.isEmpty()) |
| 580 | { |
| 581 | // set tranaction to idle |
| 582 | return findAndAssumeTransaction((TransactionId)null, tran); |
| 583 | } |
| 584 | |
| 585 | TransactionId id = null; |
| 586 | for (Enumeration e = trans.elements(); |
| 587 | e.hasMoreElements() ; ) |
| 588 | { |
| 589 | TransactionTableEntry ent = (TransactionTableEntry)e.nextElement(); |
| 590 | |
| 591 | if (ent != null && ent.isUpdate() && ent.isRecovery() && |
| 592 | (ent.getTransactionStatus() & Xact.RECOVERY_ROLLBACK_FIRST) != 0) |
| 593 | { |
| 594 | // try to locate the most recent one |
| 595 | if (id == null || XactId.compare(id, ent.getXid()) < 0) |
| 596 | id = ent.getXid(); |
| 597 | } |
| 598 | } |
| 599 | |
| 600 | if (id == null) // set transaction to idle |
| 601 | { |
| 602 | return findAndAssumeTransaction(id, tran); |
| 603 | } |
| 604 | else |
| 605 | { |
| 606 | // there is a rollback first transaction |
| 607 | boolean found = |
| 608 | findAndAssumeTransaction(id, tran); |
| 609 | |
| 610 | if (SanityManager.DEBUG) |
| 611 | { |
| 612 | if (!found) |
| 613 | { |
| 614 | SanityManager.THROWASSERT( |
| 615 | "cannot find transaction " + id + " in table"); |
| 616 | } |
| 617 | } |
| 618 | |
| 619 | return true; |
| 620 | } |
| 621 | } |
| 622 | |
| 623 | /** |
| 624 | Get the most recently non-prepared added transaction from the |
| 625 | transaction table and make the passed in transaction assume its |
| 626 | identity. Prepared transactions will not be undone. |
| 627 | |
| 628 | RESOLVE: (sku) I don't think normal user transactions needs to be |
| 629 | rolled back in order, but it won't hurt. |
| 630 | |
| 631 | <B> Should only be used in recovery undo !! </B> |
| 632 | |
| 633 | <P>MT - unsafe, caller is recovery, which is single threaded. |
| 634 | */ |
| 635 | public boolean getMostRecentTransactionForRollback(RawTransaction tran) |
| 636 | { |
| 637 | TransactionId id = null; |
| 638 | |
| 639 | if (!trans.isEmpty()) |
| 640 | { |
| 641 | for (Enumeration e = trans.elements(); |
| 642 | e.hasMoreElements() ; ) |
| 643 | { |
| 644 | TransactionTableEntry ent = |
| 645 | (TransactionTableEntry)e.nextElement(); |
| 646 | |
| 647 | if (ent != null && |
| 648 | ent.isUpdate() && |
| 649 | ent.isRecovery() && |
| 650 | !ent.isPrepared()) |
| 651 | { |
| 652 | // try to locate the most recent one |
| 653 | if (id == null || XactId.compare(id, ent.getXid()) < 0) |
| 654 | id = ent.getXid(); |
| 655 | } |
| 656 | |
| 657 | if (SanityManager.DEBUG) |
| 658 | { |
| 659 | if (ent != null && |
| 660 | ent.isUpdate() && |
| 661 | ent.isRecovery() && |
| 662 | (ent.getTransactionStatus() & |
| 663 | Xact.RECOVERY_ROLLBACK_FIRST) != 0) |
| 664 | { |
| 665 | SanityManager.THROWASSERT( |
| 666 | "still rollback first xacts in the tran table!"); |
| 667 | } |
| 668 | } |
| 669 | } |
| 670 | |
| 671 | if (SanityManager.DEBUG) |
| 672 | { |
| 673 | // if all transactions are prepared then it is possible that |
| 674 | // no transaction will be found, in that case id will be null. |
| 675 | if (id != null) |
| 676 | { |
| 677 | SanityManager.ASSERT(findTransactionEntry(id) != null); |
| 678 | } |
| 679 | else |
| 680 | { |
| 681 | // all transactions in the table must be prepared. |
| 682 | for (Enumeration e = trans.elements(); e.hasMoreElements();) |
| 683 | { |
| 684 | TransactionTableEntry ent = |
| 685 | (TransactionTableEntry)e.nextElement(); |
| 686 | SanityManager.ASSERT(ent.isPrepared()); |
| 687 | } |
| 688 | } |
| 689 | } |
| 690 | } |
| 691 | |
| 692 | return(findAndAssumeTransaction(id, tran)); |
| 693 | } |
| 694 | |
| 695 | /** |
| 696 | Get the most recently added transaction that says it is prepared during |
| 697 | recovery the transaction table and make the passed in transaction |
| 698 | assume its identity. This routine turns off the isRecovery() state |
| 699 | <B> Should only be used in recovery handle prepare after undo !! </B> |
| 700 | |
| 701 | <P>MT - unsafe, caller is recovery, which is single threaded. |
| 702 | */ |
| 703 | |
| 704 | /** |
| 705 | * Get the most recent recovered prepared transaction. |
| 706 | * <p> |
| 707 | * Get the most recently added transaction that says it is prepared during |
| 708 | * recovery the transaction table and make the passed in transaction |
| 709 | * assume its identity. |
| 710 | * <p> |
| 711 | * This routine, unlike the redo and rollback getMostRecent*() routines |
| 712 | * expects a brand new transaction to be passed in. If a candidate |
| 713 | * transaction is found, then upon return the transaction table will |
| 714 | * be altered such that the old entry no longer exists, and a new entry |
| 715 | * will exist pointing to the transaction passed in. The new entry will |
| 716 | * look the same as if the prepared transaction had been created during |
| 717 | * runtime rather than recovery. |
| 718 | * |
| 719 | * <B> Should only be used in recovery handle prepare after undo !! </B> |
| 720 | * |
| 721 | * <P>MT - unsafe, caller is recovery, which is single threaded. |
| 722 | * |
| 723 | * @return true if a candidate transaction has been found. false if no |
| 724 | * prepared/recovery transactions found in the table. |
| 725 | * |
| 726 | * @param tran Newly allocated transaction to add to link to a entry. |
| 727 | * |
| 728 | **/ |
| 729 | public boolean getMostRecentPreparedRecoveredXact( |
| 730 | RawTransaction tran) |
| 731 | { |
| 732 | TransactionTableEntry found_ent = null; |
| 733 | |
| 734 | if (!trans.isEmpty()) |
| 735 | { |
| 736 | TransactionId id = null; |
| 737 | GlobalTransactionId gid = null; |
| 738 | TransactionTableEntry ent; |
| 739 | |
| 740 | for (Enumeration e = trans.elements(); e.hasMoreElements(); ) |
| 741 | { |
| 742 | ent = (TransactionTableEntry)e.nextElement(); |
| 743 | |
| 744 | if (ent != null && |
| 745 | ent.isRecovery() && |
| 746 | ent.isPrepared()) |
| 747 | { |
| 748 | // try to locate the most recent one |
| 749 | if (id == null || XactId.compare(id, ent.getXid()) < 0) |
| 750 | { |
| 751 | found_ent = ent; |
| 752 | id = ent.getXid(); |
| 753 | gid = ent.getGid(); |
| 754 | } |
| 755 | } |
| 756 | } |
| 757 | |
| 758 | if (SanityManager.DEBUG) |
| 759 | { |
| 760 | if (found_ent == null) |
| 761 | { |
| 762 | // if no entry's were found then the transaction table |
| 763 | // should have the passed in idle tran, and the rest should |
| 764 | // be non-recover, prepared global transactions. |
| 765 | for (Enumeration e = trans.elements(); e.hasMoreElements();) |
| 766 | { |
| 767 | ent = (TransactionTableEntry)e.nextElement(); |
| 768 | |
| 769 | if (XactId.compare(ent.getXid(), tran.getId()) != 0) |
| 770 | { |
| 771 | SanityManager.ASSERT( |
| 772 | !ent.isRecovery() && ent.isPrepared()); |
| 773 | SanityManager.ASSERT(ent.getGid() != null); |
| 774 | } |
| 775 | } |
| 776 | } |
| 777 | } |
| 778 | |
| 779 | if (found_ent != null) |
| 780 | { |
| 781 | // At this point there are 2 tt entries of interest: |
| 782 | // new_ent - the read only transaction entry that was |
| 783 | // created when we allocated a new transaction. |
| 784 | // We will just throw this one away after |
| 785 | // assuming the identity of the global xact. |
| 786 | // found_ent |
| 787 | // - the entry of the transaction that we are going |
| 788 | // to take over. |
| 789 | TransactionTableEntry new_ent = |
| 790 | (TransactionTableEntry) trans.remove(tran.getId()); |
| 791 | |
| 792 | // At this point only the found_ent should be in the table. |
| 793 | if (SanityManager.DEBUG) |
| 794 | { |
| 795 | SanityManager.ASSERT(findTransactionEntry(id) == found_ent); |
| 796 | } |
| 797 | |
| 798 | ((Xact) tran).assumeGlobalXactIdentity(found_ent); |
| 799 | |
| 800 | // transform this recovery entry, into a runtime entry. |
| 801 | found_ent.unsetRecoveryStatus(); |
| 802 | } |
| 803 | } |
| 804 | |
| 805 | return(found_ent != null); |
| 806 | } |
| 807 | |
| 808 | /** |
| 809 | Get the least recently added (oldest) transaction |
| 810 | @return the RawTransaction's first log instant |
| 811 | |
| 812 | <P>MT - safe, caller can be recovery or checkpoint |
| 813 | */ |
| 814 | public LogInstant getFirstLogInstant() |
| 815 | { |
| 816 | // assume for now that it is acceptable to return null if a transaction |
| 817 | // starts right in the middle of this call. |
| 818 | |
| 819 | if (trans.isEmpty()) |
| 820 | { |
| 821 | return null; |
| 822 | } |
| 823 | else |
| 824 | { |
| 825 | LogInstant logInstant = null; |
| 826 | |
| 827 | // bug 5632: need to sychronize so that another thread does not |
| 828 | // come in and disrupt the for loop, we got an exception on next, |
| 829 | // likely because hash table changed by another thread after |
| 830 | // hasMoreElements() called, but before nextElement(). |
| 831 | |
| 832 | synchronized (trans) |
| 833 | { |
| 834 | for (Enumeration e = trans.elements(); e.hasMoreElements(); ) |
| 835 | { |
| 836 | TransactionTableEntry ent = |
| 837 | (TransactionTableEntry)e.nextElement(); |
| 838 | |
| 839 | if (ent != null && ent.isUpdate()) |
| 840 | { |
| 841 | if (logInstant == null || |
| 842 | ent.getFirstLog().lessThan(logInstant)) |
| 843 | { |
| 844 | logInstant = ent.getFirstLog(); |
| 845 | } |
| 846 | } |
| 847 | } |
| 848 | } |
| 849 | |
| 850 | return logInstant; |
| 851 | } |
| 852 | } |
| 853 | |
| 854 | /** |
| 855 | Find a transaction using the transaction id, and make the passed in |
| 856 | transaction assume the identity and properties of that transaction. |
| 857 | |
| 858 | <P>MT - unsafe, caller is recovery, which is single threaded. |
| 859 | |
| 860 | @param id transaction Id |
| 861 | @param tran the transaction that was made to assume the transactionID |
| 862 | and all other relavent information stored in the transaction table |
| 863 | @return true if transaction can be found, false otherwise |
| 864 | */ |
| 865 | boolean findAndAssumeTransaction( |
| 866 | TransactionId id, |
| 867 | RawTransaction tran) |
| 868 | { |
| 869 | // the only caller for this method right now is recovery. |
| 870 | // No need to put in any concurrency control |
| 871 | TransactionTableEntry ent = null; |
| 872 | |
| 873 | if (id != null && !trans.isEmpty()) |
| 874 | { |
| 875 | ent = findTransactionEntry(id); |
| 876 | |
| 877 | if (SanityManager.DEBUG) |
| 878 | { |
| 879 | if (ent != null) |
| 880 | SanityManager.ASSERT(ent.isRecovery(), |
| 881 | "assuming the id of a non-recovery transaction"); |
| 882 | } |
| 883 | } |
| 884 | |
| 885 | // if no transaction entry found, set transaction to idle |
| 886 | ((Xact)tran).assumeIdentity(ent); |
| 887 | |
| 888 | return(ent != null); |
| 889 | |
| 890 | } |
| 891 | |
| 892 | /********************************************************** |
| 893 | * Transaction table vti and diagnostics |
| 894 | * MT - unsafe, caller is getting a snap shot which may be inconsistent |
| 895 | *********************************************************/ |
| 896 | |
| 897 | /** |
| 898 | Get a printable version of the transaction table |
| 899 | */ |
| 900 | public TransactionInfo[] getTransactionInfo() |
| 901 | { |
| 902 | if (trans.isEmpty()) |
| 903 | return null; |
| 904 | |
| 905 | // while taking a snap shot, no adding or removing of transaction |
| 906 | TransactionInfo[] tinfo; |
| 907 | |
| 908 | if (SanityManager.DEBUG) |
| 909 | SanityManager.DEBUG("TranTrace", toString()); |
| 910 | |
| 911 | synchronized(this) |
| 912 | { |
| 913 | int ntran = trans.size(); |
| 914 | tinfo = new TransactionTableEntry[ntran]; |
| 915 | |
| 916 | LogInstant logInstant = null; |
| 917 | int i = 0; |
| 918 | |
| 919 | for (Enumeration e = trans.elements(); |
| 920 | e.hasMoreElements(); ) |
| 921 | { |
| 922 | TransactionTableEntry ent = |
| 923 | (TransactionTableEntry)e.nextElement(); |
| 924 | |
| 925 | if (ent != null) |
| 926 | tinfo[i++] = (TransactionTableEntry)ent.clone(); |
| 927 | |
| 928 | if (SanityManager.DEBUG) |
| 929 | SanityManager.ASSERT(ent != null, "transaction table has null entry"); |
| 930 | } |
| 931 | } |
| 932 | |
| 933 | return tinfo; |
| 934 | } |
| 935 | |
| 936 | public String toString() |
| 937 | { |
| 938 | if (SanityManager.DEBUG) |
| 939 | { |
| 940 | StringBuffer str = new StringBuffer(1000). |
| 941 | append("\n**************************\n"). |
| 942 | append(super.toString()). |
| 943 | append("\nTransaction Table: size = ").append(trans.size()). |
| 944 | append(" largestUpdateXactId = ").append(largestUpdateXactId). |
| 945 | append("\n"); |
| 946 | |
| 947 | boolean hasReadOnlyTransaction = false; |
| 948 | |
| 949 | for (Enumeration e = trans.elements(); |
| 950 | e.hasMoreElements(); ) |
| 951 | { |
| 952 | TransactionTableEntry ent = |
| 953 | (TransactionTableEntry)e.nextElement(); |
| 954 | |
| 955 | if (ent != null && ent.isUpdate()) |
| 956 | str.append(ent.toString()); |
| 957 | |
| 958 | if (ent != null && !ent.isUpdate()) |
| 959 | hasReadOnlyTransaction = true; |
| 960 | } |
| 961 | |
| 962 | if (hasReadOnlyTransaction) |
| 963 | { |
| 964 | str.append("\n READ ONLY TRANSACTIONS \n"); |
| 965 | |
| 966 | for (Enumeration e = trans.elements(); |
| 967 | e.hasMoreElements(); ) |
| 968 | { |
| 969 | TransactionTableEntry ent = |
| 970 | (TransactionTableEntry)e.nextElement(); |
| 971 | |
| 972 | if (ent != null && !ent.isUpdate()) |
| 973 | str.append(ent.toString()); |
| 974 | } |
| 975 | } |
| 976 | str.append("---------------------------"); |
| 977 | return str.toString(); |
| 978 | } |
| 979 | else |
| 980 | return null; |
| 981 | } |
| 982 | |
| 983 | |
| 984 | } |
| 985 | |