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comparison src/org/dancres/blitz/entry/FindEntryOpInfo.java @ 0:3dc0c5604566

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Initial checkin of blitz 2.0 fcs - no installer yet.
author Dan Creswell <dan.creswell@gmail.com>
date Sat, 21 Mar 2009 11:00:06 +0000
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-1:000000000000 0:3dc0c5604566
1 package org.dancres.blitz.entry;
2
3 import java.io.IOException;
4
5 import org.dancres.blitz.mangler.MangledEntry;
6
7 import org.dancres.blitz.txn.TxnState;
8
9 import org.dancres.blitz.oid.OID;
10
11 import org.dancres.blitz.arc.CacheBlockDescriptor;
12
13 class FindEntryOpInfo implements OpInfo {
14 static final long serialVersionUID = -7864125234426980910L;
15
16 private boolean isTake;
17 private OID theOID;
18 private String theType;
19
20 FindEntryOpInfo(String aType, OID aOID, boolean doTake) {
21 isTake = doTake;
22 theType = aType;
23 theOID = aOID;
24 }
25
26 public boolean isDebugOp() {
27 // Find's are always non-null so never false though they can be aborted
28 //
29 return false;
30 }
31
32 public void restore() throws IOException {
33 // Nothing to do - a previous write op info will restore the entry
34 // or it's already deleted in which case we'll find out at commit
35 }
36
37 public MangledEntry commit(TxnState aState) throws IOException {
38 MangledEntry myEntry = null;
39
40 EntryReposRecovery myRepos =
41 EntryRepositoryFactory.get().getAdmin(theType);
42
43 // System.err.println("Looking for: " + theOID);
44
45 CacheBlockDescriptor myCBD = myRepos.load(theOID);
46
47 if (myCBD != null) {
48 // System.err.println("Got CBD: " + theOID);
49
50 EntrySleeveImpl mySleeve = (EntrySleeveImpl) myCBD.getContent();
51
52 boolean isDeleted = mySleeve.getState().test(SleeveState.DELETED);
53
54 if (isTake) {
55 // System.err.println("Deleted: " + theOID);
56 mySleeve.getState().set(SleeveState.DELETED);
57 mySleeve.markDirty();
58
59 /*
60 We could leave this dead entry sitting in cache and wait
61 for it to be aged out but it's better to force the state
62 to disk early so as to clean out the database. Of course,
63 we only do this for stuff that's come from disk - there's
64 no point in doing it for something that's never been on
65 disk.
66
67 The net effect of this is to improve the ratio of live to
68 dead data on the disk in favour of liveness which has
69 benefits for out of cache searching by reducing the number
70 of disk blocks we scan and skip.
71 */
72 if (! mySleeve.getState().test(SleeveState.NOT_ON_DISK)) {
73 // System.err.println("On disk - early flush: " + theOID);
74 myRepos.flush(myCBD);
75 }
76 } else {
77 if (!isDeleted)
78 myEntry = mySleeve.getEntry();
79 }
80
81 myCBD.release();
82
83 // Update counters outside lock
84 if (isTake)
85 myRepos.getCounters().didTake();
86 else
87 myRepos.getCounters().didRead();
88 }
89
90 return myEntry;
91 }
92
93 public MangledEntry abort(TxnState aState) throws IOException {
94 MangledEntry myEntry = null;
95
96 EntryReposRecovery myRepos =
97 EntryRepositoryFactory.get().getAdmin(theType);
98
99 CacheBlockDescriptor myCBD = myRepos.load(theOID);
100
101 if (myCBD != null) {
102
103 EntrySleeveImpl mySleeve = (EntrySleeveImpl) myCBD.getContent();
104
105 if (!mySleeve.getState().test(SleeveState.DELETED))
106 myEntry = mySleeve.getEntry();
107
108 myCBD.release();
109 }
110
111 return myEntry;
112 }
113
114 public OID getOID() {
115 return theOID;
116 }
117
118 public String getType() {
119 return theType;
120 }
121
122 public String toString() {
123 if (isTake)
124 return "T : " + theType + " : " + theOID;
125 else
126 return "R : " + theType + " : " + theOID;
127 }
128 }