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Problem in Andrew's Denny DVD - CleanExit.java?

 
Zonglin Li
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Posts: 12
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Hi everyone:
I think there is a mistake in Andrew's DVD example. Inside the book, it uses 'CleanExit.java' to handle the server shut down. When the user shut down the server, 'CleanExit' will called by the JVM and do some clean up.

Code:
/**
* This method will be executed by the JVM when the application is shutdown.
* It ensures that the database is in a clean state for shutdown (that is,
* there are no outstanding writes occuring).
*/
public void run() {
log.info("Ensuring a clean shutdown");
try {
DvdDatabase database = new DvdDatabase(dbLocation);
database.setDatabaseLocked(true);
} catch (IOException e) {
log.log(Level.SEVERE, "Failed to lock database before exiting", e);
}
}

I assume this is wrong. Because it creates a new database and locks the new database. The real database which has been used by the clients has not been locked for clean up.

Could anyone address please!

Thank you very much!
 
Zhongbo Li
Greenhorn
Posts: 23
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Only one database can get lock.
 
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