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1
4 package com.tc.util;
5
6 import com.tc.io.TCFile;
7 import com.tc.io.TCFileChannel;
8 import com.tc.io.TCFileLock;
9 import com.tc.io.TCRandomFileAccess;
10 import com.tc.logging.TCLogger;
11 import com.tc.logging.TCLogging;
12 import com.tc.util.startuplock.FileNotCreatedException;
13 import com.tc.util.startuplock.LocationNotCreatedException;
14
15 import java.io.FileNotFoundException  ;
16 import java.io.IOException ;
17 import java.nio.channels.OverlappingFileLockException ;
18
19
22 public class StartupLock {
23 private static final TCLogger logger = TCLogging.getLogger(StartupLock.class);
24 private final TCFile location;
25 private TCFileLock lock;
26 private TCFileChannel channel;
27
28 public StartupLock(TCFile location) {
29 this.location = location;
30 }
31
32 public synchronized void release() {
33 try {
34 if (lock != null) {
35 try {
36 this.lock.release();
37 } catch (IOException e) {
38 logger.error(e);
39 }
40 }
41
42 if (channel != null) {
43 try {
44 channel.close();
45 } catch (IOException e) {
46 logger.error(e);
47 }
48 }
49 } finally {
50 lock = null;
51 channel = null;
52 }
53 }
54
55 public synchronized boolean canProceed(TCRandomFileAccess randomFileAccess, boolean block)
56 throws LocationNotCreatedException, FileNotCreatedException {
57
59 TCFile tcFile = location.createNewTCFile(location, "startup.lck");
60
61 ensureLocationExists();
62 ensureFileExists(tcFile);
63
64 try {
65 channel = randomFileAccess.getChannel(tcFile, "rw");
66 } catch (FileNotFoundException fnfe) {
67 throw new TCAssertionError(fnfe);
68 }
69
70 try {
71 if (block) {
72 lock = channel.lock();
73 } else {
74 lock = channel.tryLock();
75 }
76 } catch (OverlappingFileLockException e) {
77 } catch (IOException ioe) {
79 throw new TCAssertionError(ioe);
80 }
81
82 Assert.eval(tcFile.exists());
83 return lock != null;
84 }
85
86 private void ensureFileExists(TCFile file) throws FileNotCreatedException {
87 if (!file.exists()) {
88 try {
89 file.createNewFile();
90 } catch (IOException e) {
91 throw new FileNotCreatedException("Could not create file for startup lock: " + file
92 + ". Please ensure that this file can be created.");
93 }
94 Assert.eval(file.exists());
95 }
96 }
97
98 private void ensureLocationExists() throws LocationNotCreatedException {
99 if (!location.exists()) {
100 try {
101 location.forceMkdir();
102 } catch (IOException e) {
103 throw new LocationNotCreatedException("Could not create location for startup lock: " + location
104 + ". Please ensure that this directory can be created.");
105 }
106 }
107 }
108 }
109 |
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