| 1 | /* |
| 2 | |
| 3 | Derby - Class org.apache.derby.impl.store.raw.xact.RowLocking2nohold |
| 4 | |
| 5 | Copyright 1999, 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.LockingPolicy; |
| 32 | import org.apache.derby.iapi.store.raw.RecordHandle; |
| 33 | import org.apache.derby.iapi.store.raw.RowLock; |
| 34 | import org.apache.derby.iapi.store.raw.Transaction; |
| 35 | |
| 36 | import org.apache.derby.iapi.error.StandardException; |
| 37 | |
| 38 | |
| 39 | /** |
| 40 | A locking policy that implements row level locking with isolation degree 2, |
| 41 | never holding read locks after they are granted. |
| 42 | |
| 43 | Exactly the same as RowLocking2, except that read locks are acquired using |
| 44 | zeroDuration locks, which are immediately released by the lock manager |
| 45 | after they are granted. |
| 46 | |
| 47 | @see org.apache.derby.iapi.store.raw.LockingPolicy |
| 48 | */ |
| 49 | public class RowLocking2nohold extends RowLocking2 |
| 50 | { |
| 51 | protected RowLocking2nohold(LockFactory lf) |
| 52 | { |
| 53 | super(lf); |
| 54 | } |
| 55 | |
| 56 | /** |
| 57 | * Obtain lock on record being read. |
| 58 | * <p> |
| 59 | * Assumes that a table level IS has been acquired. Will acquire a Shared |
| 60 | * or Update lock on the row, depending on the "forUpdate" parameter. |
| 61 | * <p> |
| 62 | * Read lock will be acquired using zeroDuration lock. |
| 63 | * |
| 64 | * @param t The transaction to associate the lock with. |
| 65 | * @param record The record to be locked. |
| 66 | * @param waitForLock Should lock request wait until granted? |
| 67 | * @param forUpdate Whether to open for read or write access. |
| 68 | * |
| 69 | * @return true if the lock was granted, false if waitForLock was false |
| 70 | * and the lock could not be granted. |
| 71 | * |
| 72 | * @exception StandardException Standard exception policy. |
| 73 | **/ |
| 74 | public boolean lockRecordForRead( |
| 75 | Transaction t, |
| 76 | ContainerHandle container_handle, |
| 77 | RecordHandle record, |
| 78 | boolean waitForLock, |
| 79 | boolean forUpdate) |
| 80 | throws StandardException |
| 81 | { |
| 82 | // RESOLVE - figure out what is right for update locks, for now throw |
| 83 | // if they are used. |
| 84 | if (SanityManager.DEBUG) |
| 85 | { |
| 86 | SanityManager.ASSERT(!forUpdate); |
| 87 | } |
| 88 | |
| 89 | return(lf.zeroDurationlockObject( |
| 90 | t.getCompatibilitySpace(), |
| 91 | record, |
| 92 | (forUpdate ? RowLock.RU2 : RowLock.RS2), |
| 93 | waitForLock ? |
| 94 | C_LockFactory.TIMED_WAIT : C_LockFactory.NO_WAIT)); |
| 95 | } |
| 96 | |
| 97 | public void unlockRecordAfterRead( |
| 98 | Transaction t, |
| 99 | ContainerHandle container_handle, |
| 100 | RecordHandle record, |
| 101 | boolean forUpdate, |
| 102 | boolean row_qualified) |
| 103 | { |
| 104 | return; |
| 105 | } |
| 106 | } |