| 1 | /* |
| 2 | |
| 3 | Derby - Class org.apache.derby.impl.store.raw.xact.RowLocking3 |
| 4 | |
| 5 | Copyright 1998, 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.locks.LockFactory; |
| 24 | import org.apache.derby.iapi.services.locks.C_LockFactory; |
| 25 | import org.apache.derby.iapi.services.locks.Latch; |
| 26 | |
| 27 | import org.apache.derby.iapi.services.sanity.SanityManager; |
| 28 | |
| 29 | import org.apache.derby.iapi.store.raw.ContainerHandle; |
| 30 | import org.apache.derby.iapi.store.raw.ContainerLock; |
| 31 | import org.apache.derby.iapi.store.raw.RecordHandle; |
| 32 | import org.apache.derby.iapi.store.raw.RowLock; |
| 33 | import org.apache.derby.iapi.store.raw.Transaction; |
| 34 | import org.apache.derby.iapi.store.raw.LockingPolicy; |
| 35 | |
| 36 | import org.apache.derby.iapi.error.StandardException; |
| 37 | |
| 38 | |
| 39 | /** |
| 40 | A locking policy that implements row level locking with isolation degree 3. |
| 41 | |
| 42 | @see org.apache.derby.iapi.store.raw.LockingPolicy |
| 43 | */ |
| 44 | public class RowLocking3 extends NoLocking |
| 45 | { |
| 46 | // no locking has no state, so it's safe to hold |
| 47 | // it as a static |
| 48 | private static final LockingPolicy NO_LOCK = new NoLocking(); |
| 49 | |
| 50 | protected final LockFactory lf; |
| 51 | |
| 52 | protected RowLocking3(LockFactory lf) |
| 53 | { |
| 54 | this.lf = lf; |
| 55 | } |
| 56 | |
| 57 | /** |
| 58 | * Get type of lock to get while reading data. |
| 59 | * <p> |
| 60 | * This routine is provided so that class's like RowLockingRR can |
| 61 | * override just this routine to get RS2 locks vs RS3 locks, and still |
| 62 | * reuse all the other code in this class. |
| 63 | * <p> |
| 64 | * |
| 65 | * @return The lock type of a shared lock for this locking policy. |
| 66 | **/ |
| 67 | protected RowLock getReadLockType() |
| 68 | { |
| 69 | return(RowLock.RS3); |
| 70 | } |
| 71 | |
| 72 | /** |
| 73 | * Get type of lock to get while requesting "update" lock. |
| 74 | * <p> |
| 75 | * This routine is provided so that class's like RowLockingRR can |
| 76 | * override just this routine to get RU2 locks vs RU3 locks, and still |
| 77 | * reuse all the other code in this class. |
| 78 | * <p> |
| 79 | * |
| 80 | * @return The lock type of a shared lock for this locking policy. |
| 81 | **/ |
| 82 | protected RowLock getUpdateLockType() |
| 83 | { |
| 84 | return(RowLock.RU3); |
| 85 | } |
| 86 | |
| 87 | /** |
| 88 | * Get type of lock to get while writing data. |
| 89 | * <p> |
| 90 | * This routine is provided so that class's like RowLockingRR can |
| 91 | * override just this routine to get RX2 locks vs RX3 locks, and still |
| 92 | * reuse all the other code in this class. |
| 93 | * <p> |
| 94 | * |
| 95 | * @return The lock type of a shared lock for this locking policy. |
| 96 | **/ |
| 97 | protected RowLock getWriteLockType() |
| 98 | { |
| 99 | return(RowLock.RX3); |
| 100 | } |
| 101 | |
| 102 | |
| 103 | /** |
| 104 | * Obtain container level intent lock. |
| 105 | * <p> |
| 106 | * This implementation of row locking is 2 level, ie. table and row locking. |
| 107 | * It will interact correctly with tables opened with ContainerLocking3 |
| 108 | * locking mode. |
| 109 | * <p> |
| 110 | * Updater's will get table level IX locks, and X row locks. |
| 111 | * <p> |
| 112 | * Reader's will get table level IS locks, and S row locks. |
| 113 | * |
| 114 | * @param t Transaction to associate lock with. |
| 115 | * @param container Container to lock. |
| 116 | * @param waitForLock Should lock request wait until granted? |
| 117 | * @param forUpdate Should container be locked for update, or read? |
| 118 | * |
| 119 | * @return true if the lock was obtained, false if it wasn't. |
| 120 | * False should only be returned if the waitForLock policy was set to |
| 121 | * "false," and the lock was unavailable. |
| 122 | * |
| 123 | * @exception StandardException Standard exception policy. |
| 124 | **/ |
| 125 | public boolean lockContainer( |
| 126 | Transaction t, |
| 127 | ContainerHandle container, |
| 128 | boolean waitForLock, |
| 129 | boolean forUpdate) |
| 130 | throws StandardException |
| 131 | { |
| 132 | Object qualifier = forUpdate ? ContainerLock.CIX : ContainerLock.CIS; |
| 133 | |
| 134 | boolean gotLock = |
| 135 | lf.lockObject( |
| 136 | t.getCompatibilitySpace(), t, container.getId(), qualifier, |
| 137 | waitForLock ? C_LockFactory.TIMED_WAIT : C_LockFactory.NO_WAIT); |
| 138 | |
| 139 | if (gotLock) { |
| 140 | // look for covering table locks |
| 141 | // CIS is covered by CX or CS |
| 142 | // CIX is covered by CX |
| 143 | |
| 144 | if (lf.isLockHeld(t.getCompatibilitySpace(), t, container.getId(), ContainerLock.CX) || |
| 145 | ((!forUpdate) && lf.isLockHeld(t.getCompatibilitySpace(), t, container.getId(), ContainerLock.CS))) { |
| 146 | |
| 147 | |
| 148 | container.setLockingPolicy(NO_LOCK); |
| 149 | } |
| 150 | } |
| 151 | |
| 152 | return gotLock; |
| 153 | |
| 154 | } |
| 155 | |
| 156 | |
| 157 | /** |
| 158 | * Obtain lock on record being read. |
| 159 | * <p> |
| 160 | * Assumes that a table level IS has been acquired. Will acquire a Shared |
| 161 | * or Update lock on the row, depending on the "forUpdate" parameter. |
| 162 | * <p> |
| 163 | * |
| 164 | * @param t The transaction to associate the lock with. |
| 165 | * @param record The record to be locked. |
| 166 | * @param waitForLock Should lock request wait until granted? |
| 167 | * @param forUpdate Whether to open for read or write access. |
| 168 | * |
| 169 | * @return true if the lock was granted, false if waitForLock was false |
| 170 | * and the lock could not be granted. |
| 171 | * |
| 172 | * @exception StandardException Standard exception policy. |
| 173 | **/ |
| 174 | public boolean lockRecordForRead( |
| 175 | Transaction t, |
| 176 | ContainerHandle container_handle, |
| 177 | RecordHandle record, |
| 178 | boolean waitForLock, |
| 179 | boolean forUpdate) |
| 180 | throws StandardException |
| 181 | { |
| 182 | // RESOLVE - Did I do the right thing with the "forUpdate" variable. |
| 183 | |
| 184 | // For now just lock the row in Shared mode. |
| 185 | Object qualifier = forUpdate ? getUpdateLockType() : getReadLockType(); |
| 186 | |
| 187 | return( |
| 188 | lf.lockObject( |
| 189 | t.getCompatibilitySpace(), t, record, qualifier, |
| 190 | waitForLock ? |
| 191 | C_LockFactory.TIMED_WAIT : C_LockFactory.NO_WAIT)); |
| 192 | } |
| 193 | |
| 194 | /** |
| 195 | * Obtain lock on record being read while holding a latch. |
| 196 | * <p> |
| 197 | * Assumes that a table level IS has been acquired. Will acquire a Shared |
| 198 | * or Update lock on the row, depending on the "forUpdate" parameter. |
| 199 | * <p> |
| 200 | * |
| 201 | * @param latch The latch being held. |
| 202 | * @param record The record to be locked. |
| 203 | * @param forUpdate Whether to open for read or write access. |
| 204 | * |
| 205 | * @exception StandardException Standard exception policy. |
| 206 | **/ |
| 207 | public void lockRecordForRead( |
| 208 | Latch latch, |
| 209 | RecordHandle record, |
| 210 | boolean forUpdate) |
| 211 | throws StandardException |
| 212 | { |
| 213 | // RESOLVE - Did I do the right thing with the "forUpdate" variable. |
| 214 | |
| 215 | // For now just lock the row in Shared mode. |
| 216 | Object qualifier = forUpdate ? getUpdateLockType() : getReadLockType(); |
| 217 | |
| 218 | lf.lockObject( |
| 219 | latch.getCompatabilitySpace(), record, qualifier, |
| 220 | C_LockFactory.TIMED_WAIT, latch); |
| 221 | } |
| 222 | |
| 223 | /** |
| 224 | * Obtain lock on record being written. |
| 225 | * <p> |
| 226 | * Assumes that a table level IX has been acquired. Will acquire an |
| 227 | * Exclusive (X) lock on the row. |
| 228 | * <p> |
| 229 | * |
| 230 | * @param t transaction to associate the lock with. |
| 231 | * @param record The record to be locked. |
| 232 | * @param lockForInsertPreviousKey Lock is for a previous key of a insert. |
| 233 | * @param waitForLock Should lock request wait until granted? |
| 234 | * |
| 235 | * @return true if the lock was granted, false if waitForLock was false |
| 236 | * and the lock could not be granted. |
| 237 | * |
| 238 | * @exception StandardException Standard exception policy. |
| 239 | **/ |
| 240 | public boolean zeroDurationLockRecordForWrite( |
| 241 | Transaction t, |
| 242 | RecordHandle record, |
| 243 | boolean lockForInsertPreviousKey, |
| 244 | boolean waitForLock) |
| 245 | throws StandardException |
| 246 | { |
| 247 | return(lf.zeroDurationlockObject( |
| 248 | t.getCompatibilitySpace(), record, |
| 249 | (lockForInsertPreviousKey ? RowLock.RIP : getWriteLockType()), |
| 250 | waitForLock ? C_LockFactory.TIMED_WAIT : C_LockFactory.NO_WAIT)); |
| 251 | } |
| 252 | |
| 253 | /** |
| 254 | * Obtain lock on record being written. |
| 255 | * <p> |
| 256 | * Assumes that a table level IX has been acquired. Will acquire an |
| 257 | * Exclusive (X) lock on the row. |
| 258 | * <p> |
| 259 | * |
| 260 | * @param t The transaction to associate the lock with. |
| 261 | * @param record The record to be locked. |
| 262 | * @param lockForInsert Lock is for an insert. |
| 263 | * @param waitForLock Should lock request wait until granted? |
| 264 | * |
| 265 | * @return true if the lock was granted, false if waitForLock was false |
| 266 | * and the lock could not be granted. |
| 267 | * |
| 268 | * @exception StandardException Standard exception policy. |
| 269 | **/ |
| 270 | public boolean lockRecordForWrite( |
| 271 | Transaction t, |
| 272 | RecordHandle record, |
| 273 | boolean lockForInsert, |
| 274 | boolean waitForLock) |
| 275 | throws StandardException |
| 276 | { |
| 277 | return(lf.lockObject( |
| 278 | t.getCompatibilitySpace(), t, record, |
| 279 | lockForInsert ? RowLock.RI : getWriteLockType(), |
| 280 | waitForLock ? C_LockFactory.TIMED_WAIT : C_LockFactory.NO_WAIT)); |
| 281 | } |
| 282 | |
| 283 | /** |
| 284 | * Obtain lock on record being written while holding a latch. |
| 285 | * <p> |
| 286 | * Assumes that a table level IX has been acquired. Will acquire an |
| 287 | * Exclusive (X) lock on the row. |
| 288 | * <p> |
| 289 | * |
| 290 | * @param latch The latch being held |
| 291 | * @param record The record to be locked. |
| 292 | * |
| 293 | * @exception StandardException Standard exception policy. |
| 294 | **/ |
| 295 | public void lockRecordForWrite( |
| 296 | Latch latch, |
| 297 | RecordHandle record) |
| 298 | throws StandardException |
| 299 | { |
| 300 | lf.lockObject( |
| 301 | latch.getCompatabilitySpace(), |
| 302 | record, |
| 303 | getWriteLockType(), |
| 304 | C_LockFactory.TIMED_WAIT, |
| 305 | latch); |
| 306 | } |
| 307 | |
| 308 | public int getMode() { |
| 309 | return MODE_RECORD; |
| 310 | } |
| 311 | |
| 312 | |
| 313 | /* |
| 314 | ** We can inherit all the others methods of NoLocking since we hold the |
| 315 | ** container lock and row locks until the end of transaction. |
| 316 | */ |
| 317 | } |