| 1 | /* |
| 2 | |
| 3 | Derby - Class org.apache.derby.impl.store.raw.xact.ContainerLocking2 |
| 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 | |
| 26 | import org.apache.derby.iapi.store.raw.ContainerHandle; |
| 27 | import org.apache.derby.iapi.store.raw.ContainerLock; |
| 28 | import org.apache.derby.iapi.store.raw.Transaction; |
| 29 | |
| 30 | import org.apache.derby.iapi.error.StandardException; |
| 31 | |
| 32 | |
| 33 | /** |
| 34 | A locking policy that implements container level locking with |
| 35 | isolation degree 2. |
| 36 | |
| 37 | @see org.apache.derby.iapi.store.raw.LockingPolicy |
| 38 | */ |
| 39 | public class ContainerLocking2 extends NoLocking { |
| 40 | |
| 41 | private final LockFactory lf; |
| 42 | |
| 43 | protected ContainerLocking2() |
| 44 | { |
| 45 | this.lf = null; |
| 46 | } |
| 47 | |
| 48 | protected ContainerLocking2(LockFactory lf) |
| 49 | { |
| 50 | this.lf = lf; |
| 51 | } |
| 52 | |
| 53 | /** |
| 54 | Obtain a Container shared or exclusive lock until |
| 55 | the end of the nested transaction. |
| 56 | |
| 57 | @exception StandardException Standard Cloudscape error policy |
| 58 | */ |
| 59 | public boolean lockContainer( |
| 60 | Transaction t, |
| 61 | ContainerHandle container, |
| 62 | boolean waitForLock, |
| 63 | boolean forUpdate) |
| 64 | throws StandardException |
| 65 | { |
| 66 | Object qualifier = forUpdate ? ContainerLock.CX : ContainerLock.CS; |
| 67 | |
| 68 | // for cursor stability put read locks on a separate lock chain, which |
| 69 | // will be released when the container is unlocked. |
| 70 | Object group = |
| 71 | forUpdate ? t : container.getUniqueId(); |
| 72 | |
| 73 | return( |
| 74 | lf.lockObject( |
| 75 | t.getCompatibilitySpace(), group, container.getId(), qualifier, |
| 76 | waitForLock ? |
| 77 | C_LockFactory.TIMED_WAIT : C_LockFactory.NO_WAIT)); |
| 78 | } |
| 79 | |
| 80 | /** |
| 81 | * Unlock read locks. |
| 82 | * <p> |
| 83 | * In Cursor stability release all read locks obtained. unlockContainer() |
| 84 | * will be called when the container is closed. |
| 85 | * <p> |
| 86 | * |
| 87 | * @param t The transaction to associate the lock with. |
| 88 | * @param container Container to unlock. |
| 89 | * |
| 90 | **/ |
| 91 | public void unlockContainer( |
| 92 | Transaction t, |
| 93 | ContainerHandle container) |
| 94 | { |
| 95 | // Only release read locks before end of transaction in level 2. |
| 96 | if (container.isReadOnly()) |
| 97 | { |
| 98 | lf.unlockGroup(t.getCompatibilitySpace(), container.getUniqueId()); |
| 99 | } |
| 100 | } |
| 101 | |
| 102 | public int getMode() { |
| 103 | return MODE_CONTAINER; |
| 104 | } |
| 105 | |
| 106 | |
| 107 | /* |
| 108 | ** We can inherit all the others methods of NoLocking since we hold the |
| 109 | ** container lock until the end of transaction, and we don't obtain row |
| 110 | ** locks. |
| 111 | */ |
| 112 | } |