File decompression uses new class StringKeeper to make sure a file is… #22
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… being handled only by one thread at a time
| * @author cmrose | ||
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| public class StringKeeper { |
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This is really a type of Lock (see https://docs.oracle.com/javase/tutorial/essential/concurrency/locksync.html and https://winterbe.com/posts/2015/04/30/java8-concurrency-tutorial-synchronized-locks-examples/) - perhaps StringLock?
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It is now called StringLocker
| private List stringList = Collections.synchronizedList(new ArrayList<String>()); | ||
| private boolean waiting = false; | ||
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| public synchronized void control(String item) { |
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This will block all threads trying to control an item not just ones trying to access the item won't it? (only one thread can be running this particular bit of code at a time) Will have the desired effect still but is overly restrictive. Could have just added synchronized to makeUncompressed above to do this.
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My understanding is that the wait() will cause the thread to wait and to no longer be synchronised on the the object thus allowing another thread to come in and add a file to the list. https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html#wait This is evidenced to be the case by the fact that I observe more than one file appearing in the list at any given time.
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OK, thanks for the explanation. Can see how that works now.
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| stringKeeper.release(filename); |
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Better in a single try finally block so we always know its going to be released?
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I have done so in the second commit. There was already a try..catch in the method that calls makeUncompressed (getRaf) which I added the finally to.
Move calls to stringLocker.control() and stringLocker.release() into try..catch..finally in NetcdfFile.getRaf for more easily read code and guaranteed release of the lock.
#22) File decompression uses new class StringLocker to make sure a file is being handled only by one thread at a time
… being handled only by one thread at a time